General Anatomy IN DETAIL 4Med Stdss.pdf

General Anatomy
By: Yared Asmare (Asst Prof.)
UoG, CMHS, Dept of Human Anatomy
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Objective
Describe the nature and organization of the major
systems of the human body
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HISTORY OF ANATOMY
“The past is not dead history, it is living material out of
which man builds for the future”.
Rene Dubos (1901-1982)
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References
Printed Materials (Textbooks, Handouts, Anatomy atlases )
Text Books
∴Drake RL.,Vogl W., and Mitchell AW.Gray’s anatomy for
students. 2007
∴Keith L. Moore, T.V.N. Persaud and Mark G Turchia. The
developing human. Clinically oriented embryology.9th
edition. 2013
∴Elaine N. Marieb: Human Anatomy , 6
th
ed.
∴Gerard J, Tortora. Introduction to the human body, 6
th
ed.
∴Snell, Richard S. Clinical neuroanatomy , 7
th
ed.
∴Van De Graaff: Human Anatomy, Sixth Edition
∴Kent ….
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Terminology
⃙OSCE stands for “Objective Structured Clinical Examination.”
⃙OSCEs are very helpful in medical education because they allow a
student to practice and demonstrate clinical skills in a standardized
medical scenario.
⃙The OSCE isa versatile multipurpose evaluative tool that can be
utilized to evaluate health care professionals in a clinical setting.
⃙It assesses competency, based on objective testing through direct
observation.
⃙Theobjective structured practical examination(OSPE) was used as
an objective instrument for assessment of laboratory exercises in
preclinical sciences, particularly physiology.
⃙It was adapted from the objective structured clinical examination
(OSCE).
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…
Introduction to Anatomy (4hrs)
⃙Definition of Anatomy and historical background
⃙Subdivisions of Anatomy
⃙Approaches to studying Anatomy
⃙Levels of Structural Complexity of the body
⃙Body Planes and Sections
⃙Axes of the body
⃙Movement of the body
⃙Body Cavities
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The Human Anatomy was taught in Greece by:
Hippocrates (460-377) before Crysto(
B.C
)who is regarded as
the father of the medicine and a founder of the science of
anatomy.
Aristotle (384-322
B.C
)was the first person to use the term
“Anatome”.
Galena philosopher to born in 130
B.C
who used dissection of
human and animal bodies.
During the renaissance artists and anatomists like Leonardo da
Vinci, Michel Angelo, and Vesalius (1514-1564)began to
accurately display, and describe the parts of the human body
and thus to revise, amend and correct many concepts.
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DEFINITION OF ANATOMY
The word “Anatomy” is derived from the Greek term “Anatome”
consisting of two words Anaup/apart and Tomecutting.
Therefore Anatomy means to cut apart, divide or dissect
Anatomy is the study of the structure of the human body its
parts.
oIt is also called morphology, the science of form.
oAn old and proud science that has been a field of serious
intellectual investigation for at least 2300 years.
oIt was the most prestigious biological discipline of the 1800s
and is still dynamic.
Therefore:
∴Anatomy is a branch of science that deals with structure of
the body and their relation.
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…
oIf you are preparing for a career in the health sciences, your
knowledge of human anatomy is the foundationof your clinical
practice.
oAnatomy is closely related to physiology.
oAnatomy and physiology are studied in separate courses, but
they are truly inseparable, because structure supports function.
For example, the lens of the eye is transparent and curved; it could not
perform its function of focusing light if it were opaque and uncurved.
Similarly, the thick, long bones in our legs could not support our weight if
they were soft and thin.
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Subdivisions of the Anatomy
₴Gross anatomy: is the study of body structures that can be
examined by the naked eye.
₴Microscopic anatomy: is the study of structures that are so
small andcan be seen only with a microscope.
•cells and cell parts, and tissues
•A knowledge of microscopic anatomy is important
because physiological and disease processes occur at
the cellular level.
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Subdivision …
Regional or Topographic anatomy:is the study of all
structures in a single body region, such as the abdomen or head,
are examined as a group.
Applied anatomy: the practical application of anatomical
knowledge to the diagnosis and treatment of diseases.
Ultrastructural anatomy:the ultramicroscopic study of
structures too small to be seen with a light microscope.
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Subdivision …
Developmental anatomy: traces the structural changes that
occur in the body throughout the life span and the effects of
aging.
oexplore how body structures form, grow, and mature.
©Embryology: is the study of how body structures form and
develop before birth.
©knowledge of embryology helps you understand the complex
design of the adult human bodyand helps to explain birth
defects, which are anatomical abnormalities that occur during
embryonic development and are evident after birth.
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Subdivision …
Pathological anatomy:deals with the structural changes in
cells, tissues, and organs caused by disease.
Briefly, it is the study of structural changes caused by
diseases.
used primarily for medical diagnosis and scientific research.
Radiographic anatomy: is the study of internal body structures
by means of X-ray studies and other imaging techniques.
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Subdivision …
Comparative anatomy: is the study of similarities and
differences in the anatomy of different species.
It is closely related to evolutionary biology and phylogeny (the
evolution of species).
Surface anatomy: is the study of shapes and markings (called
landmarks) on the surface of the body that reveal the underlying
organs.
⃙It deals with anatomical features that can be studied by sight,
without dissection.
⃙Some have everyday names like the palm of the hand, the sole of
the foot, and the nape of the neck.
⃙used to identify the muscles that bulge beneath the skin in weight
lifters, and clinicians use it to locate blood vessels for placing catheters,
feeling pulses, and drawing blood.
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APPROACHES TO STUDY ANATOMY
I.Systemic approach
In systemic approach all the organs with related functions are studied
together.
Classification is based on function (structures that have a common
function studied together) about 11 systems are found in human body.
E.g. Circulatory, Respiratory, Integumentary, Skeletal, …
II. Regional approach
Deals with several systems located in a particular region of the body.
all structures in a single body region, such as the abdomen or head, are
examined as a group.
E.g. Limb (Upper & Lower) Back, Abdomen, Head, Neck …
Used mostly in dissection room and useful to physicians and surgeons.
Regional anatomy focuses on specific external and internal regions of the
body and how different systems work together in that region.
Systemic anatomy focuses on the anatomy of different organ systems, such
as the respiratory or nervous system.
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LEVELS OF STRUCTURAL ORGANIZATION OF HUMAN BODY
Life processes of the human body are maintained at several levels of
structural organization.
These include the chemical, cellular, tissue, organ, organ system, and
the organism level
The human body has many levels of structural complexity.
I.Chemical level
Includes all atoms and molecules essential for maintaining life.
oMajor atoms : C, H, O, N, Ca, K & Na
oMolecules: proteins, carbohydrates, fats, nucleic acids (DNA,
RNA) & vitamins.
Atoms unite to form molecules; molecules are building blocks of the
structures at cellular level.
II. Cellular level
Cells are the smallest living things in the body.
Cells are the basic structural and functional unit of an organism.
Cells have 2 or 3 principal parts/partition/compartments
oPlasma (cell) membrane
oCytoplasm
oNucleus
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Organization…
III. Tissue level
Tissuesaregroupsofsimilarcells(andthesubstancesurrounding
them)thatusuallyarisefromcommonancestorcellsandworktogether
toperformaparticularfunction.
4basictypesoftissues:Epithelial,Muscle,Connective&Nervous.
IV. Organ level
Organsarestructuresthatarecomposedofthreeormoredifferent
tissuesthathavespecificfunctionsandusuallyhaverecognizable
shape.
V. System level
Asystemconsistsofseveralrelatedorgansthathaveacommon
function.e.g.Digestivesystem-breakdownoffoodandabsorption.
VI. Organismic level: is the result of all of the simpler levels working in
union to sustain life.
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Level of organization
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…
At the lowest level of organization (chemical) Histochemistry&
Cytochemistry.
1.At the cellular level Cytology.
2.At the tissue level Histology.
3.At the organic level Organology.
4.At the systemic levelSystemic Anatomy.
5.At the organismic levelGross anatomy
For example:
oCell Osteocytes Muscle fibres
oTissue Osseous tissue Muscular tissue
oOrgan Bone  Muscle
oSystemic Skeletal System Muscular System
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ANATOMICAL POSITION
Anatomical position is standard, common, visual referenceposition
of a body universally used in anatomical descriptions.
Used to describe body parts & their location.
It is the position of reference for anatomical nomenclature.
Explained as follows
Body stands erect in upright position facing the observer
Feet flat on the floor together/far apart with shoulder level
Head level and the eyes facing directly forward.
Arms placed at the sides,
The palms of the hands turned forward and
The thumbs pointed away from the body.
Additionallythetermrightandleftalwaysrefertothosesides
belongingtothepersonorcadaverbeingviewednottothe
rightandleftsidesoftheviewer.
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Anatomical Terminologyterms of position &relation
Most anatomical terms are based on ancient Greek or Latin
words.
⃙For example, the arm is the brachium and the thigh bone is the
femur.
Standard directional terms are used by medical personnel and
anatomists to explain precisely where one body structure lies in
relation to another.
Directional terms indicate the relationship of one part of the body
to another.
Anatomical terminology is less wordyand confusing.
Most often used are the paired terms superior/inferior,
anterior/ventral, posterior/dorsal, medial/lateral, and
superficial/deep…
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Term of position and relation.
1.Superiorabove.
2.Inferiorbelow.
3.Cranial(rostral,cephalic)nearertothehead.
4.Caudalnearertothetail
5.Anteriorinfront.
6.Posteriorbehind.
7.Ventralinthedirectionoftheabdomen.
8.Dorsalinthedirectionoftheback.
9.Medialnearertothemidline.
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Termofpositionandrelation…
10. Lateral to the side.
11. Median at the median plane.
12. Proximal upper.
13. Distal lower.
14. Palmaron the side of the palm of the hand.
15. Plantar on the side of the sole of the foot.
16. Superficial nearer to the body surface.
17. Deep nearer to the center of the body.
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BODY PLANES AND SECTIONS
Planes are imaginary flat surfaces that are used to divide the body or
organs to visualize interior structures.
The body is divided by the following planes (imaginary flat surfaces)
in different sections.
1. Sagittal Plane
A vertical plane that divides the body or an organ into right and left
sides.
Midsagittal (median)plane:
oIf the plane passes through the midline of the body or organ
and divides it into equal right and left sides.
Parasagittal plane:
oIf the sagittalplane does not pass through the midline but
instead divides the body or an organ into unequal right and
left sides.
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Body plane…
2. Frontal (coronal) plane
Divides the body or an organ into anterior (front) and posterior
(back) portions.
3. Transverse (cross-sectional or horizontal) plane
Divides the body or organ into superior (top) and inferior (bottom)
portions.
The above planes are all at right angles to one another.
4. Oblique plane
Passes through the body or organ at an angle between the
transverse plane and vertical plane.
When we cut organs through these planes the resulting flat
surfaces is termed as section.
E.g. transverse plane gives transverse section.
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Axesofmovements:
Themovementsofthebodyarebasedonthreemainaxes,
whichareperpendiculartoeachother.
1.Longitudinalorverticalaxis:runsfromthecenterofthehead
tothesoleofthefootinlongitudinaldirection.Itisperpendicularto
thefloor.
Medialorinternalrotation
Movements Lateralorexternalrotation
Pronation
Supination
2.Sagittalaxis:runsfromanteriortoposterioraspectofthe
bodyorviceversa.Itisparalleltothefloor.
Movements Abduction
Adduction
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3.Transverseorhorizontalaxis:runsfromrighttoleftorfrom
lefttoright.Itisparalleltothefloor.
Movements Flexion
Extension
Circumduction:isamovementtotakeplaceonallthethree
axes.
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Conceptofthemovements
1.Flexion:indicatesbendingordecreasingtheangleb/nthebonesor
partofthebody.
2.Extension:indicatesstraighteningorincreasingtheanglebetween
thebonesorpartofthebody.
3.Abduction:meansmovingawayfromthemedianplane(upperand
lowerlimbs).
oInthefingersismovingtheotherfingerawayfromthe3
rd
digitor
middlefinger.
oMovingtheothertoesawayfromthe2
nd
toe.
4.Adduction:meansmovingtowardthemedianplane(upperand
lowerlimbs).
oInfingermovingtheotherfingertowardthemedianplaneofthe
hand(3
rd
finger).
oMovingtheothertoestowardthe2ndtoe.
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5.Medial/internalrotation:bringstheanteriorsurfaceofthelimb
closertothemedianplane.
6.Lateral/externalrotation:takestheanteriorsurfaceofthelimb
awayfromthemedianplane.
7.Circumduction:isthecircularmovementthatisacombinationof
flexion,abduction,extensionandadductionandtheendofthelimb
describethecircle.
8.Opposition:isthemovementbywhichthepadofthe1
st
digit
(thumb)isbroughttoanotherdigitpad.
9.Protrusion:istheanterior(forward)movementasoccursinthe
protrudingthemandible(stickingthechinout).
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10.Retrusion:istheposterior(backward)movementasoccursin
retrudingthemandible(tuckingthechinin)
11.Protractionandretraction:istheanteriorlyandposteriorlymovement
oftheshoulder.
12.Eversion:movesthesoleofthefootawayfromthemedianplane
(turningthesolelaterally).
13.Inversion:movesthesoleofthefoottowardthemedianplane(facing
thesolemedially).
14.Pronation:isthemovementoftheforearmandhandthatrotatesthe
radiusmediallyarounditslongitudinalaxis.Sothatthepalmofthehand
facesposteriorlyanditsdorsumfacesanteriorly.
15.Supination:isthemovementoftheforearmandhandthatrotatesthe
radiuslaterallyarounditslongitudinalaxis.
Sothatthedorsumofthehandfacesposteriorlyandthepalmfaces
anteriorly.
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Body Caviy& membrane
⃙Abody cavity:
is any space or compartment, or potential space, in an animalbody.
help protect, separate, and support internal organs.
Bones, muscles, ligaments, and other structures separate the
various body cavities from one another.
Body membranes arethin sheets/layers of cells or tissues which cover
the surface of internal organs, the outside of the body and lines
various body cavities.
A membrane is a thin, pliable tissue that covers, lines, partitions, or
connects structures.
Cutaneous /dry membrane e.g. skin
Mucous membrane: GIT mucosa
Serous membrane: pleura, pericardium & peritoneum
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…
For general clinical descriptions, clinicians use four quadrants of
the abdominal cavity: right upper, right lower, left upper, and left
lower.
The four quadrants are defined by two planes:
Transumbilical plane:passing through the umbilicus and IV
disc between the L3 and the L4 vertebrae.
Median plane: passing longitudinally through the body,
dividing it into right and left halves.
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Abdominal regions and quadrants
Transumbilical
plane
Median plane
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The nine regions are delineated by four planes:
Two horizontal:
Subcostal plane: passing through the inferior border of the
10th costal cartilage on each side.
Transtubercular plane: passing through the iliac tubercles
and the body of the L5 vertebra.
Two vertical:
Midclavicularplanes: passing from the midpoints of
clavicles to the midinguinalpoints, the midpoints of lines
joining the anterior superior iliac spines and the superior edge
of the pubic symphysis.
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…
Clinicians subdivide the abdominal cavity into nine regions to
locate abdominal organs or pain sites:
Subcostalplane
Transtubercular
plane
Midclavicularplanes
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…
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.
GENERAL ANATOMY OF THE OF SKELETAL
SYSTEM (OSTEOLOGY)
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…
Without bones, you could not survive.
oYou would be unable to perform movements such as
walking or grasping, and
oThe slightest blow to your head or chest could damage
your brain or heart.
The skeletal system forms the framework of the body.
√if you are familiarity with the names, shapes, &
positionsof individual bones it will help you locate and
namemany other anatomical features.
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Skeletal system…
Osteologyis the part of anatomy devoted to the study of the
bone its formation, form, structure and functions.
The word Skeleton comes from the Greek word meaning
“Dried up Body”.
The skeleton accounts for about 18-20 %of our body weight.
It consists of bones, cartilages, joints and ligaments.
Each individual bone is an organ.
Locomotory system:is formed by bones, joints and muscles.
Bones and cartilages are passive parts and muscles
and joints are active parts of the locomotory system.
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Function of the skeletal system.
1.Formation of the supportive framework and permanent shape
of the body.
2.Protection of some soft and delicate organs.
A.Bones of the head protect the brain and the sensory
organ.
B.Bones of the thoracic wall protect intrathoracic organs like
the lungs, the heart and great vessels.
C.Bones of the vertebral column protect the spinal cord.
D.Pelvic bones protect some organs of the genitourinary
system and Gastro Intestinal tract (GIT).
3.Movement.
4.Storage of minerals and fat.
5.Production of blood cells.
6.To provide an attachment site for muscles and act as rigid
lever to move the body and its parts.
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Classification of bones
Bones are classified by their shape rather than sizeas long, short,
flat and irregular.
Is based in the three dimension of the space (length, width and
thickness)).
I.Long bones: cylindrical & are considerably longer than they
wide. E.g. The bones of the arms, legs, hands, and feet (but not
the wrists and ankles).
II.Short bones: are roughly cubed shaped. E.g. The bones of
the wrists and ankles.
III.Flat Bones: they are longer and wider than thicker (thin,
flattened and usually somewhat curved).
Forming by an inner and outer thin lamina of compact bone
(inner and outer lamellar) between which lies a spongy
substance. e.g. bones of the skull (diploe), scapula, hip bone
and ribs.
IV.Irregular Bones: they have various shapes that do not fit into
any of the above categories.
They have similar structure to short bones. E.g. bones of the
vertebral column.
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.
1.Sesamoid bone:
usually have a shape similar to a sesame seed.
They are situated at the end of long bones of the limbs. E.g.
patella or knee cap
helps the tendons to glide over the bony surfaces and
prevent excessive wear and tear.
they act alter the direction of pull of the tendons.
2.Pneumatic Bones:
they contain air filled cavities lined with mucous membrane.
e.g. maxilla, frontal, ethmoidand sphenoid bones.
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…
2.Wormian or suturalbones:
small fragments of bones between bones of the skull.
3.Heterotopic bones:
are the abnormal calcifications in soft tissues.
Short, flat, and irregular bones are all made of spongy bone
covered with a thin layer of compact bone.
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Structures of typical long bone
With few exception, all bones in the body have the same
general structure.
I.Diaphysis: also called shaft, forms the long axis of a long
bone/the shaft or long main cylindrical portion
II.Epiphysis: end of a long bone
III.Metaphyses: are the areas between the epiphysis and
diaphysis and include the epiphyseal platein growing
bones.
IV.Articular cartilage: over joint surfaces acts as friction
reducer & shock absorber
V.Medullary cavity: marrow cavity
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Membrane
Endosteum:
lining of marrow cavity and central canals of osteons
is osteogenicbone producing containing bone
depositing cells and bone destroying cells.
Periosteum:
tough membrane covering bone but not the articular
cartilage
Richly supplied by nerves and blood vessels
Secured to the underlying by perforating fibers
sharpey’sfiber
Fibrous layer dense irregular CT
Osteogeniclayer bone cells
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Structures of typical long bone
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Bone tissue
Consists of widely separated cells surrounded by large
amounts of extracellular matrix.
Has both organic and inorganic components.
Chemical Composition
oHealthy bone is half as strong as steel in resisting
compression and equally strong in resisting tension.
Bone is composed of the following:
o35% organic componentscells, fibers, and ground
substance
oThe organic substance particularly collagen, contribute the
flexibility and tensile strength that allow bone resists
stretching and twisting.
o65% inorganic componentsminerals, mostly calcium
phosphate and calcium carbonate
oProvides bones hardness
oBone is not completely solid since it has small spaces for
vessels and bone marrow
Spongy bone has many such spaces
Compact bone has very few such spaces
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Classification of the Bones
AccordingtotheirLocation.
A)AxialSkeleton:
Thisislocatedaroundthelongitudinalaxisofthebody.
i.e.mostofthebonesoftheaxialskeletonconstitutedthe
centralbodycoreofthebody,theaxis.
Thisgroupiscomposedof80Bones
B) Appendicular Skeleton:
This is composed of bones found in the limbs and their
corresponding girdles forming a total of 126 bones.
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Based on gross observation bone has two different
structures:
Compact bone
Dense outer layer that looks smooth and solid to the
naked eye.
outer layer provides strength.
Makes up the shaft of long bones and the external layer of all
bones
Resists stresses produced by weight and movement
Spongy (cancellous)
consists of trabeculae (a honeycomb of small needle like),
containing marrow for blood cell production or fat storage.
It forms most of the structure of short, flat, and irregular
bones, and the epiphyses of long bones.
Spongy bone tissue is light and supports and protects the
bone marrow.
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According to their microscopic appearances.
1.Non -lamellar, Immature or Woven Bones: The term woven
denotes that it has a network of randomly oriented large
collagen fibres in its matrix.
2.Lamellar Bones: All mature bones are Lamellar.
According to their developmental origin.
1.Membranous (mesenchymal, dermal).
2.Cartilaginous (Chondral).
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Blood and Nerve Supply of Bone
Nutrient arteries:
enter through nutrient foramen
supplies compact bone of diaphysis & red marrow
Metaphyseal a:
supply the metaphysis and are a branch from the nutrient
artery
Periosteal arteries:
supply periosteum and are branches of Nutrient and
epiphyseal aa
Epiphyseal aa.:
supply red marrow & bone tissue of epiphyses
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Innervations of bones
Blood vessels of bones are accompanied by many nerve
fibers most of which are vasomotor.
Some sensory fibers are also end in the periosteum and
adventitia of blood vessels.
Some of these sensory fibers to the periosteum are pain fibers,
due to which the periosteum is specially sensitive to tearing
and tension.
The vasomotor nerves serve for constriction and dilation of
the blood vessels.
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BONE FORMATION
All embryonic connective tissue begins as mesenchyme.
Bone formation is termed osteogenesisor ossificationand begins
when mesenchymalcells provide the template for subsequent
ossification.
Prior to week 8
Embryonic skeleton is comprised of hyaline cartilage and fibrous
membranes
Week 8 and beyond
Bone tissue begins to develop
Majority of fibrous or cartilaginous structures eventually replaced
with bone
Fibrousmembrane: membrane bone(Intramembranous
ossification)
Hyaline cartilage: cartilage bone (Endochondralossification)
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Intramembranous ossification
Forms the flat bones of the skull, the mandible and clavicle.
An ossification center forms from mesenchymal cells, they convert to
osteoblasts and lay down osteoid matrix.
The matrix surrounds the cell and then calcifies as the osteoblast
becomes an osteocyte.
The calcifying matrix centers join to form bridges of trabeculae that
constitute spongy bone with red marrow in between.
On the periphery the mesenchyme condenses and develops into the
periosteum
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Endochondral ossification
Involves replacement of cartilage by bone and form most of the
bones of the body.
The first step in endochondralossification is the development of
the cartilage model.
I.Development of Cartilage model
Mesenchymalcells form a cartilage model of the bone during
development.
Growth of cartilage model in length by chondrocyte cell
division and matrix formation ( interstitial growth) in width by
formation of new matrix on the periphery by new
chondroblasts from the perichondrium (appositional growth)
Cells in mid region burst and change pH triggering
calcification and chondrocyte death
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Endochondralossification…
Development of Primary Ossification Center
Perichondrium lays down periosteal bone collar
Nutrient artery penetrates center of cartilage model
Periosteal bud brings nutrient artery and vein and osteoblasts
and osteoclasts to center of cartilage model
Osteoblasts deposit bone matrix over calcified cartilage
forming spongy bone trabeculae
Osteoclasts form medullary cavity
Development of Secondary Ossification Center
blood vessels enter the epiphyses around time of birth
spongy bone is formed but no medullary cavity
Formation of Articular Cartilage
cartilage on ends of bone remains as articular cartilage.
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BONE GROWTH
Growth in Length
Bone grows in length occurs at the epiphyseal or growth plate
The activity of the epiphyseal plate is the only means by which
the diaphysis can increase in length.
When the epiphyseal plate closes, is replaced by bone, the
epiphyseal line appears and indicates the bone has completed its
growth in length.
Epiphyseal plate or cartilage growth plate
Cartilage cells are produced by mitosis on epiphysealside of
plate
Cartilage cells are destroyed and replaced by bone on diaphyseal
side of plate
Between ages 18 to 25, epiphysealplates close.
Cartilage cells stop dividing and bone replaces the cartilage
(epiphysealline)
Growth in length stops at age 25
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Zones of Growth in Epiphyseal Plate
I.Zone of resting cartilage anchors growth plate to bone
II.Zone of proliferating cartilage rapid cell division (stacked
coins)
III.Zone of hypertrophic cartilage cells enlarged & remain in
columns
IV.Zone of calcified cartilage thin zone, cells mostly dead
since matrix calcified
Osteoclasts removing matrix
Osteoblasts & capillaries move in to create bone over
calcified cartilage
V.Ossification zoneis a region of transformation from
cartilage tissue to bone tissue.
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Growth in Thickness
Bone can grow in thickness or diameter only by appositional
growth
Two processes
Osteoblasts beneath periosteum secrete bone matrix onto
external bone surface
Osteoclasts on endosteal surface remove bone
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Bone Remodeling
Bones are not inert structures within the human body; they
continue to change over the course of a lifespan
Remodeling:is the ongoing replacement of old bone tissue by new
bone tissue.
Remodeling entails the resorptionof old or damaged bone, followed
by the deposition of new bone material.
Remodellingprotects the structural integrity of the skeletal system
and metabolically contributes to the body's balance of calcium and
phosphorus.
Old bone is constantly destroyed by osteoclasts, whereas new bone
is constructed by osteoblasts.
Continual redistribution of bone matrix along lines of mechanical
stress.
e.g. distal femur is fully remodeled every 4 months
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Fracture and Repair of Bone
A fracture is any break in the continuity of a bone.
Healing is faster in bone than in cartilage due to lack of blood
vessels in cartilage
Healing of bone is still slow process due to vessel damage.
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Fracture repair involves
I.Formation of fracture hematoma
Damaged blood vessels produce clot in 6 -8 hours, after bone cells
die
Inflammation brings in phagocyticcells for clean-up duty
New capillaries grow into damaged area
II.Formation of fibrocartilagenous callus formation ~3 weeks
Fibroblasts invade the procallus& lay down collagen fibers
Chondroblasts produce fibrocartilage to span the broken ends of the
bone
III.Formation of bony callus
Changes to spongy bone that joins 2 broken ends of bone
Lasts 3-4 months
IV.Bone remodeling
oCompact bone replaces the spongy in the bony callus
oSurface is remodeled back to normal shape
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Osteoporosis
is (bone porous condition) low bone mass due to deterioration and
bone reabsorption is faster than bone deposition.
Fractures occur easily, especially in the vertebrae, femur, or hip.
The basic problem is that bone resorption(breakdown) outpaces bone
deposition (formation).
In large part this is due to depletion of calcium from the body—more
calcium is lost in urine, feces, and sweat than is absorbed from the
diet.
Bone mass becomes so depleted that bones fracture, often
spontaneously, under the mechanical stresses of everyday living.
For example, a hip fracture might result from simply sitting
down too quickly.
Osteoporosis primarily affects middle-aged and elderly people, 80%
of them women.
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Osteoporosis
Older women suffer from osteoporosis more often than men for two
reasons:
I.Women’s bones are less massive than men’s bones
II.production of estrogens in women declines dramatically at
menopause, while production of the main androgen,
testosterone, in older men diminishes gradually and only slightly.
Estrogens and testosterone stimulate osteoblastactivity and
synthesis of bone matrix.
Besides gender, risk factors for developing osteoporosis include a
family history of the disease,
European or Asian ancestry,
thin or small body build,
an inactive lifestyle,
cigarette smoking,
a diet low in calcium and vitamin D,
more than two alcoholic drinks a day, and
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Anatomy, Bone Markings
Bone markings are projections and depressions found on bones.
The surface features of bones vary considerably, depending on the
function and location in the body.
Bone markings are important to the identification of individual
bones and bony pieces and aid in the understanding of functional
and evolutionary anatomy.
They are used by clinicians and surgeons, especially orthopedists,
radiologists, forensic scientists, detectives, osteologists, and
anatomists.
The functionality of bone markings:
⃙joints formation to produce movement or lock bones in place
⃙Provide structural support to muscle and connective tissue.
⃙Provide circumferential stabilization and protection to nerves,
vessels, and connective tissue.
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Bone markings…
There are three general classes of bone markings:
Articulations
Projections
holes.
An articulation is where two bone surfaces come together to form
joints.
A projection is an area of a bone that projects above the surface of
the bone.
•Used for attachment points for tendons and ligaments.
•size and shape is an indication of the forces exerted through the
attachment to the bone.
A hole is an opening or groove in the bone that allows blood vessels
and nerves to enter the bone.
•size and shape reflect the size of the vessels and nerves that
penetrate the bone at these points.
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There are two Categories of bone markings.
A.ProjectionsorProcesses:
Whichgrowoutfromthesurfaceoftheboneprovidesasitefor
theattachmentofstructureslikeligamentsandtendonsandhelp
intheformationofjoints.
B.Depressions/cavities/openings:Whichareindentations.
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Projection as site of muscle attachment:
Crest:araised or prominent part of the edge of a bone.
Spine:a sharp, slender, often pointed projection.
Trochanter:a very large, blunt, irregularly shaped process.
Tubercle:small round projection.
Tuberosity:a large tubercle/moderate prominence
Epicondyle:raisedareaonacondyle
ProjectionsthathelpintheformationoftheJoints:
Condyle:aroundprojection.
Head:roundedorexpandedportioncarriedonanarrowneck.
Facets:Asmooth,flatsurfacethatformsajointwithanotherflat
boneoranotherfacet
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Depression commonly seen in bones:
⃙Fissure: a narrow, slit like opening.
⃙Foramen: opening though a bone.
⃙Fossa, Pit or Fovea: a Shallow depression in a bone.
⃙Meatus or Canal: a tube-like channel that extends within the bone,
provide passage and protection to nerves, vessels, and even sound.
⃙Sinus: a depression within a bone filled with air and lined with a
mucous membrane.
⃙Notch or incisures: a depression in the margin of bones.
⃙Ramus: arm like bars of bone that forms an angle with the main part of
the bone.
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RELATED CLINICAL TERMS
Bone graft: Transplantation of a piece of bone from one part of a
person’s skeleton to another part where bone has been damaged /lost.
The graft, often taken from the crest of the iliac bone of the hip,
encourages regrowth of lost bone.
Bony spur: An abnormal projection on a bone due to bone overgrowth;
is common in aging bones.
Ostealgia:Pain in a bone.
Osteomyelitis( “bone and marrow inflammation”): Bacterial infection
of the bone and bone marrow.
The pathogen enters bones either from infections in surrounding
tissues or through the bloodstream, or follows a compound bone
fracture.
Pathologic fracture: Fracture occurring in a diseased bone and involving
slight or no physical trauma.
An example is a broken hip caused by osteoporosis.
The hip breaks first, causing the person to fall.
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Classification of bones based on their locations
206 named bones of the human skeleton are grouped in to
axial and appendicular skeletons in adults.
At birth, the skeleton consists of approximately 270 bones.
Axial skeleton
Forms long axis of the body
80 bones (skull, hyoid bone, auditory ossicles, vertebral
column, thoracic cage)
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ClassificationoftheBones
AccordingtotheirLocation.
A)AxialSkeleton:Thisislocatedaroundthelongitudinalaxisofthe
bodythatismostofthebonesoftheaxialskeletonconstitutedthe
centralbodycoreofthebody,theaxis.
This group is composed of 80 Bones constituted by:
1-Skull a) Cranium ----8
b) Face ---------14
2-Hyoid -------------------1
3-Auditory Ossicles -----6
4-Vertebral Column -----26
5-Thorax a) Sternum ----1
b) Ribs -----24
Total 80
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B) Appendicular Skeleton: This is composed of bones found in the
limbs and their corresponding girdles forming a total of 126 bones:
1-Shoulder Girdle a) Clavicle -----2
b) Scapula -----2
2-Upper Limb a) Humerus ------2
b) Ulna ----------2
c) Radius -------2
d) Carpals -------16
e) Metacarpals -10
f) Phalanges ---28
3-Pelvic Girdle Coxal, Hip, Pelvic or Innominate bones---2
4-Lower Limb a) Femur -----------2
b) Tibia -----------2
c) Fibula ---------2
d) Patella ----------2
e) Tarsals -------14
f) Metatarsals ---10
g) Phalanges ----28
Total 126
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Cartilage
Cartilage isa strong, flexible connective tissue that protects joints and
bones.
Is a semi-rigid but flexible avascular connective tissue found at
various sites within the body
Consists of cells (chondrocytes) in lacunae
Matrix is gel like and contains collagenicand elastic fibers
Has no blood vessel, it receives nutrients through diffusion
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Types of cartilage
1. Hyaline cartilage
oFirm and somewhat flexible
oMatrix contains many collagenicfibers
oFound at end of long bones (articular cartilage), in nose and
at the ends of ribs
2. Fibrocartilage
Matrix contains wide rows of thick collageneousfibers
Able to with stand tension and pressure
Found in menisci(knee joint) and discs between vertebrae
3. Elastic cartilage
Matrix contains elastic fibers
Very flexible
Found in epiglottis and ear flaps
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Arthrology
∞a branch of anatomy concerned with joints or articulations.
∞the study of how bones are joined to permit (or prevent)
movement.
A joint or articulation:
∞is the arrangement whereby separate bone or cartilage are
attached each other or it is a place where rigid elements of the
skeleton meet.
∞is the relation of two or more bones or cartilages to one another
at their region of contact.
In most of the joints bones are joined to bones, but some of them
join bones to cartilages, cartilages to cartilages and teeth to their
bony sockets.
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Structural Classification
∞In the formation of a joint, the structure found b/n the adjoining
ends of the bones is either a cavity or connective tissue.
∞The cavity separates the bone ends while the connective tissue
interconnects them.
Therefore:
∞The articulating ends of bones in some joints are separated by a
fluid containing articular cavitywhich is enclosed by a synovial
membrane, i.e. the ends are discontinuouswhich renders them a
free movement. Such joints are grouped as
1. synovial joints, freely moveable joints or diarthrosis.
∞It includes the following varieties.
Hinge joint
Pivot joint
Ball and socket joint
Gliding (plane) joint
Saddle joint
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Structural classification…
Adjoining ends of articulating bones can be attached to each other
by an interposed connective tissue without a remarkable
separation.
In such joints the ends of the bones are said to be continuous, due
to which there is little or no movement.
Constituted by:
I.Fibrous joints: when the tissue b/n the articulating ends of bone
is a dense fibrous connective tissue.
II.Cartilaginous joints: where the tissue separating the articulating
ends is cartilage
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Classification based on axes or degrees of freedom of movement
oSynarthrosis(immovable)joints
oAmphiarthrosis(slightlymovable)joints
oDiarthrosis(freelymoveable)joints
1. Synarthrosis
Sutures
Synchondrosis
Gomphosis
2. Amphiarthrosis
⃙Symphysis
⃙Syndesmosis
⃙Some synovial joints
3. Diarthrosis
Uniaxial joints
Biaxial joints
Multiaxialjoints
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The first two are mainly restricted to the axial skeleton while the third
dominants in the limbs.

Fibrous joints
Fibrous joints are classified into three types.
A.Syndesmosis:
Bones are interconnected by bundles of dense
collagenous or elastic connective tissue.
The fibrous connective tissue b/n the bones can be
organized as an interosseous membrane or a ligament.
e.g. interosseous membranes of the forearm and the leg,
ligamentum nuchae, distal tibiofibularjoint.
Such joints are slightly moveable.
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Syndesmosis
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B. Sutures
The immovably interconnected flat bones of the skull are joined
by short collagen fibers trapped b/n their opposing edges.
These sutures help the compression of fetal head during
delivery and allow free growth of the brain.
The sutures ossify after birth and the bones become fused by
bony fusion or synostosis.
e.g. Joints between bones of the skull.
Type of Suture joints
Serrate suture saw like articulation e.g. sagittal suture
Squamous suture margin of the bone overlaps with that of
articulating bone e.g. squamous suture
Plane suture margins of articulating bones are fairly smooth
e.g. median palatine suture
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Fibrous joints…
C. Gomphosis:
This is the fixation of the teeth in their alveoli or sockets by
collagenous fibers (dento-alveolar articulation) forming a
synarthrotic(immoveable) joint.
All the fixing ligaments around the root of a tooth form the
periodontal ligament.
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Cartilaginous joints
The cartilaginous joints include transitional stages in complete bony
fusion and joints which retain at least a modified cartilage throughout
life.
There are two types of cartilaginous joints:
A.Synchndrosis:
(Primary cartilaginous joints) bones are temporarily and
immovably interconnected by a hyaline cartilage until a complete
bony continuity occurs.
Such joints are found in the growth centers, e.g. epiphyseal plate,
articulation of the first rib with the sternum…
Synchondrotic joints ossify later in life usually at around the age of
25 years.
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…
Symphsis:
Secondary cartilaginous joints, bones are permanently
interconnected by a fibrocartilagecoated with a hard hyaline
cartilage.
This is a slightly movable type of cartilaginous joint.
All midline joints of the body are said to be symphysis.
E.g. pubic symphysis, manubrio-sternal symphysis and
intervertebral joints.
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,
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Cartilaginous joints
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Synovial joints
Most common and important one
Joint is freely movable
Synovial joints are characterized by the following basic features:
1.Articular head (male part of a joint) the convex end of bone usually
covered by a hyaline cartilage but sometimes by a fibrocartilage.
2.Articular fossa (Socket, Female part of a joint) a concave surface into
which the head fits. It is similarly covered by an articular cartilage.
3.Articular (Synovial) cavity a thin capillary space b/n the articulating
ends of bones and the articular capsule
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Synovial joints…
Articular capsule encloses the joint all around and it consists of two
layers.
a.An outer or fibrous layer (stratum fibrosum):
Consists of dense irregular connective tissue composed of collagen and
elastic fibers, hence also called fibrous capsule.
This layer is reinforced or strengthened by ligaments and is continuous
with the periosteumof the adjoining bones.
It is free of blood vessels but contains receptors concerned with joint
position and some sensory fibers conducting pain impulses.
b. An inner or synovial layer (stratum synovial):
Consists of loose CT composed of elastic fibers.
The inner surface of the synovial membrane is lined by fibrocytesand
macorophages(not by epithelium).
This layer contains non-myelinatednerve fibers.
Besides lining the inner surface of the articular capsule it covers all the
internal surfaces of a joint not covered by cartilage.
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Synovial joints…
Synovial fluid (synovia):
produced and absorbed by the synovial membrane in to or out of the
articular cavity.
It serves as:
A sliding (slippery) lubricant material so that there will be a
reduced friction b/n the articulating ends of bones.
A transport medium for the nutrition of the articular cartilage,
which has no blood vessels.
The synovial fluid is formed by the fibrocytesof the synovial
membrane (transudate).
It contains few glycoproteins (mucin), hyaluronic acid …
Hyaluronic acid is a glycosaminoglycan forming the gelatinous material
in tissue spaces that acts as cement substance.
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Synovial joints…
Articular cartilage
Is hyaline cartilage, covering articulating surfaces of bones in a
synovial joint.
The articular cartilage is nourished by diffusion from the synovial
fluid and gets an additional nutritional supply from the subchondral
vascular plexus.
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Classification of Synovial joints
Structurally based on the number of articulating bones.
1.Simple joint: when only two bones participate in the
formation of a joint. e.g. shoulder joint.
2.Compound joint: when more than two bones take part in the
formation of a joint. e.g. elbow joint.
3.Complex joint: when discs and menisci are involved. e.g.
knee joint.
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Types of synovial joints
oPlane joints allow gliding or sliding movement (uniaxial) e.g. b/n
scapula and clavicle b/n carpal and tarsal bones
oHinge jointspermit flexion and extension only (uniaxial) e.g. elbow,
knee and interphalangeal joints
oCondyloid jointsallow movement in two direction (biaxial) e.g.
radiocarpal joint of the wrist and MCP joint
oSaddle jointsopposing surfaces of bones are like a saddle (biaxial)
e.g. trapeziometacarpal at the base of the thumb (CMC joint of the
thumb)
oBall and socket jointsallow multidirectional movement (multi axial
joint) e.g. shoulder and hip
oPivot jointsallow rotation (uniaxial joint) e.g. at atlantoaxial joint,
proximal radioulnar
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Other structures associated with synovial joint:
Intervertebral Discs (IVD) and Menisci
oIVDsare the spongy cushions that separate the bones of the spine.
oA meniscus is a crescent-shaped fibrocartilaginousanatomical
structure that, in contrast to an articular disc, only partly divides a
joint cavity.
oE.g. knee joint
oDiscand meniscusare structures found within the articular cavity
consisting of connective tissue of fibrocartilage.
oe.g. temporomandibular joint, intervertebral joint, where as menisci divide
it partly
oIVDdivide an articular cavity completely whereas meniscus divide it
partly.
oImportant for directing of a given movement in a joint & for the
uniform distribution of pressure on the bones
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…
Synovial bursae
Are small flattened fibrous bag filled with synovial fluid
Found b/n the joints and their surrounding muscles, tendons, and
ligaments that move on each other
Reduce friction
Two types
Some of them communicate with the articular cavity
(communicating bursae) and therefore directly affected by diseases
of the joint and others are non-communicating bursae having no
direct communication with the articular cavity.
Articular labrum (lip)
oArticular labrum enlarges the articular fossa of the socket so that
the articular head of a bone correctly fits into its socket to form a
stable joint. E.g. glenoidallabrum in the shoulder joint, acetabular
labrum in the hip joint.
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Ligaments
oAre CT structures that hold the body together
oTherefore two major types of ligaments are distinguished:
1. Those that connect the viscera together
2. Those that connect bones together
oThose ligaments joining bones are of three types:
a. Reinforcing (Strengthening) ligs: providing support
and strength to the articular capsule.
b. Guiding (directing) ligs: determine the type and
direction of movement in a given joint.
c. Restricting ligs: they limit the extent of a joint
movement.
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Some clinical terms related to bones and joints
Joints are usually injured by tensional and compressionalforces
applied on them.
Therefore, there are some terms related to these injuries.
1.Contusion:injury by increased compression.
2.Distortion:injury by increased tension.
3.Ligament or capsular rapture.
4.Dislocation (Luxation or subluxation) when bones of a joint are
forced out of a ligament, commonest site being the shoulder joint.
5.Rapture and herniation of discs and menisci usually due to
excessive compression.
6.Sprain when the ligaments reinforcing a joint are over stretched of
torn.
7.Osteitisinflammation of a bone.
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8. Osteochondristisinflammation of a bone and its cartilage.
9. Osteomyelitisinflammation of a bone and its marrow.
10.Osteoarthritis (Osteoarthrosis) degenerative disease of bone and
articular cartilage.
11.Osteosarcomamaligamentcancer of a bone.
12.Osteomalaciaadult rickets
13.Osteoporosis atrophy of skeletal tissue in old age.
14.Bursitis Inflammation bursae ,e.g. Housemaid’s knee or
subcutaneous pre patellar bursitis, students elbow of olecranon
bursitis.
15.TendosynovitisInflammation of a tendon and its synovial sheath
at the level of joints, also called tendovaginitis.
16.Arthritis disease of the joints, which can be caused by infection
(e.g. Pyogenicathrists, lyme’sdisease) or degenerative process like
osteoarthritis.
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The muscular system

.
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Introduction
Myology (Sarcology):
is science concerned with muscles and their accessory parts like
tendons, aponeurosis & fasciae.
Muscle is from a Latin word meaning “little mouse,” a name given
because flexing muscles look like mice scurrying beneath the skin.
Muscle is made up of proteins and water
Muscles are organs that are capable of contraction, which is
important for movement, stabilizing body positions, storing and
moving substances within the body and generating heat.
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Muscle functions
1. Motion.
Skeletal muscle attaches to the skeleton and moves the body by
moving the bones.
Skeletal muscles help to move the body or its appendages.
Contraction of cardiac muscles pumps blood to the body
All involuntary body movements performed by smooth muscles
The muscle in the walls of visceral organs produces movement
by squeezing ﬂuids and other substances through these hollow
organs.
2. Maintenance of posture.
At times, certain skeletal muscles contract continuously to
maintain posture, enabling the body to remain in a standing or
sitting position.
The skeletal system offers form and stability to the body
Skeletal muscles maintain posture & support around flexible
joints.
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Muscle Function
3. Joint stabilization.
4. Heat generation.
Muscle contractions produce heat that plays a vital role in
maintaining normal body temperature at 37°C (98.6°F).
Involuntary contractions of skeletal muscles, known as shivering,
can increase the rate of heat production.
Body temperature is remarkable consistent.
Metabolism with in the cells releases heat as end product
Rate of heat production increases immensely during exercises
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Muscle tissue special functional characteristics
1. Contractility.
One signiﬁcant characteristic is that muscle contracts forcefully.
Muscle cells shorten and generate a strong pulling force as they
contract.
2. Excitability.
Nerve signals or other factors excite muscle cells, causing electrical
impulses to travel along the cells’ plasma membrane.
These impulses then stimulate the cells to contract.
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3. Extensibility.
is the ability of muscular tissue to stretch, within limits, without
being damaged.
The connective tissue within the muscle limits the range of
extensibility and keeps it within the contractile range of the
muscle cells.
4. Elasticity.
is the ability of muscular tissue to return to its original length
and shape after contraction or extension.
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TYPES OF MUSCLES
a.Muscles can be classified based their location:
Skeletal
Cardiac
Smooth.
b.According to their microscopic appearance
Cross striated
Non-striated
c.According to their function or innervations
Voluntary
Involuntary
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Skeletal muscle form and structure
⃙Is packaged in to skeletal muscle (that attach to & move the skeleton)
⃙As the name indicate these muscles are attached to the skeleton by
a dense regular connective tissue(tendon or aponeurosis).
⃙Skeletal muscle pass from one bone to another across one or more
joints so that contraction of the muscle results in movement at these
joints.
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Skeletal muscle form and structure
•But there are also similar cross striated muscles not attached to the
skeletal. e.g.
Mimic muscle (muscle of facial expression) which are partly
inserted to the skin of face
Extrinsic muscle of the eye
Muscles of the tongue
Muscle of the larynx
Muscle of the pharynx
Muscle of the upper esophagus
•There are about 640 skeletal muscles in the human body constituting
about 40% of the body weight.
•Skeletal muscle are innervated by voluntary or somatic nerves which
arise either from cranial or spinal nerves.
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Basic feature of a skeletal muscle
Connective tissue investment
CT surrounds and protects muscle tissue
oFascia:
oBroad band of fibrous CT that supports & surrounds muscle
and other organs of the body
Three layers of CT extend from deep fascia to further protect and
strengthen skeletal muscle
√Epimysium: surrounds the whole muscle (group of fascicles)
√Perimysium: surrounds the fascicles(group of muscle fibers)
√Endomysium: surrounds each muscle fiber
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Anatomy of skeletal muscles
Skeletal
muscle fiber
(cell)
Muscle
Fascicle
Surrounded
by
perimysium
Surrounded
by
endomysium
endomy
sium
perimysium
Skeletal
muscle
Surrounded
by epimysium
Epimysium
tendo
n
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Nerves and Blood Vessels
In general, each skeletal muscle is supplied by one nerve, one artery &
one or more veins.
Each muscle fiber in a skeletal muscle is contacted by one nerve
ending, which signals the fiber to contract such a contact is called
neuromuscular junction.
A skeletal muscle fiber cannot contract unless it is stimulated by a
nerve impulse.
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Muscle attachments
Skeletal muscle is connected to the bone by a tendon and extend
from one bone to another.
When such muscle contracts, it causes one of these bones to move
while the other one remains fixed.
±The less movable attachment of a muscle is called origin, whereas
the movable attachment is the insertion.
±i.e. Thus, the insertion is pulled to ward the origin
®In the muscles of limbs, the origin lies proximal to the insertion.
®The fleshy thickened portion of a muscle is referred to as its belly.
®Some muscles are not attached to bone of both ends.
®Some muscles have more than one origin.
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Muscle attachments
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Types of skeletal muscle fibers
Based on two characteristics:
How they manufacture energy(ATP)
How quickly they contract
Muscle fibers are divided into three general classes:
Slow Oxidative Fibers(red)
Fast Glycolytic Fibers(white)
Fast Oxidative Fibers (Intermediate)
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Criteria Slow Oxidative
fibers
Fast Oxidative
fibers
Fast Glycolytic
fibers
Structural characteristics
Fiber diameterSmallest Intermediate Largest
Myoglobin
content
Large amountLarge amountSmall amount
Mitochondria Many Many Few
CapillariesMany Many Few
Color Red Red-Pink White/Pale
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Slow oxidative fibres:
are thin, so they do not generate much power.
e.g. postural muscles of the lower back regions.
Fast glycolytic fibers:
©appear pale because they contain little Hgb.
©2x the diameter of SOF
©Contain more myofilamentsand generate much more power
©Contain few mitochondria and capillaries but large glycosomes
containing glycogen as a fuel.
©E.g. muscles of the upper limb
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Fast oxidative fibers
®Intermediate in their characteristics.
®Like FGF they contract quickly; like SOF they are oxygen
dependent and have high myoglobin content, a large
mitochondria, and a rich supply of capillaries.
®They are fatigue resistant but less than SOF.
®Speed of contraction is b/n FGF and SOF.
®The diameter of fiber is also intermediate
®More powerful than SOF but not as powerful as FGF.
E.g. muscles of the lower limbs
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Cardiac Muscle Tissue
Muscle tissue of the heart wall.
The contraction of cardiac muscle pumps blood through the blood
vessels.
Striated like skeletal muscle.
Cardiac muscle fibers are smallerthan skeletal muscle fibers and
branched longitudinally.
Contain one (occasionally two) centrally located nuclei.
Ends of adjacent cells are connected through an intercellular
junctional complexcalled the intercalated disc.
No significant regeneration of cardiac muscle after damage,
repaired by scar formation (fibroblasts).
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Cardiac muscle tissue
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Smooth Muscle Tissue
Found in the walls of visceral organs such as the stomach,
respiratory tubes, urinary bladder, uterus & intestines…
Each smooth muscle fiber is a spindle shaped cell, with one
centrally located nucleus.
Are non-striated.
The contraction of smooth muscle is slow, sustained and resistant
to fatigue.
Actively divide and regenerate.
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Smooth Muscle Tissue
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Comparison of the three muscle tissues
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Morphological types of muscle
Based on various shape or form and orientation of their fibers
skeletal muscles are classified as follow:
1.According to their form and shape
a.Fusiform (spindle shaped) e.g. Sartorius
b.Flat muscle e.g. Muscles of anterior abdominal wall
c.Quadratic muscle e.g. Quadratus lumborum muscle
d.Triangular muscle e.g. Temporalis muscle
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Morphological types of muscle…
2. According to the number of heads
a.Biceps e.g. biceps brachii, biceps femoris
b.Triceps e.g. triceps brachii, triceps surae
c.Quadriceps e. g. quadriceps femoris
3. According to the number of bellies
Some times two or more bellies are interconnected by an
intermediate tendons.
a.Digastric
b.Omohyoid
c.Rectus abdominis
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Muscle Architecture (Arrangement of Fascicles)
Skeletal muscles may be classified based on fiber arrangement
The major types of fiber arrangement are:
1. Parallel:
Strapthe long axes of the fiber run parallel to the long axis of
the muscle itself. E.g. Sternocleidomastoid muscle, Sartorious, &
Rectus abdominus
Fusiformspindle shaped with an expanded central belly. E.g.
Biceps brachii
2. Convergentfan shaped muscle
The origin is broad and the fascicles converge toward the tendon
of insertion. E.g. pectoralismajor
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3. Pennate
®Feather shaped the fibers are short and attach obliquely to a
tendon that runs the whole length of the muscle
oIf the fibers insert in to only one side of the tendon the muscle is
unipennatee.g. Flexor pollicislongus.
oIf the fibers insert in to the tendon from both sides the
arrangement is bipennatee.g. Rectus femorismuscle.
oMultipennatearrangement looks like many feathers situated side
by side, with all their feathers inserting into one large tendon e.g.
deltoid
4. Circular(Sphincter):
Surround a body openings or orifice e.g. orbicularisoris&
orbicularisoculi
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Muscle Architecture (Arrangement of Fascicles)
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√For muscles to create a movement, they can
only pull, not push
√Muscles in the body rarely work alone, & are
usually arranged in functional groups
surrounding a joint
√A muscle that contracts to create the desired
action is known as an agonistor prime
mover
√A muscle that helps the agonist is a synergist
√A muscle that opposes the action of the
agonist, therefore undoing the desired action
is an antagonist
Interaction of
Skeletal Muscle
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Function of muscle
•Muscle do not function alone, that is they act together in groups.
•Based on their function and innervations muscle are group as
follows.
I. Genetic muscle group
⃙They develop from the same embryological source, therefore all of
them are innervated by the same nerve.
⃙E.g. Muscle of facial expression (mimic muscle) developed from
second brachial arch and innervated by facial nerve.
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II. Functional muscle groups:
are groups of muscle with similar function that act together. E.g. flexors,
extensors, abductor, adductor, and rotators.
have different embryological origin and possibly innervated by different
nerves. Within this group
A. Agonist or primary movers.
Some muscles are constantly active in initiating and maintaining a
particular movement.
referred to as agonist or primary movers. E.g. brachialis muscles in the
flexor of elbow.
B. Synergists
Some groups act together with or assist the activity of the agonist
these are known as synergists.
C. Antagonists:
⃙Make the contrary movement to the synergist.
⃙If synergists and antagonists act together on a given joint they will inhibit
or lock the movement and stabilize the joint.
⃙A single muscle may be involved in several movement and
play different roles i.e. it may be a prime mover, synergist,
fixator or antagonist at different times.
.
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Nerve and blood vessel of skeletal muscle
Due to the high energy and oxygen demand skeletal muscles are
rich in blood vessels.
The flow of blood through these vessels raised during muscular
activity by dilation of the vessels.
The change in the flow of blood through these vessels is regulated
by the autonomic motor nerves that innervate the smooth muscle
cells in the wall of blood vessels.
They are also supplied by motor and sensory nerve fibers.
Fibers of the motor nerves are connected to a number of muscle
fibers at a myoneuraljunction called motor end plate.
Muscle fibers that are innervated by a single motor neuron build-
up a motor unit.
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⃙The sensory fiber carry proprioceptive impulse (deep sensation) from
the receptor (E.g. muscle and tendon spindle) to the central nervous
system.
oProprioception:perception or awareness of the position and
movement of the body.
⃙Nerves and vessels enter a muscle at its hilum that lies at or near the
middle of the muscle.
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Structure associated with muscle (accessory structures )
⃙Muscle form the active part of the locomotors system.
⃙Muscle is supported by other associated structures like tendons,
aponeurosis, fascia, bursae, and tendon receptor
organs(proprioceptors) and sesamoid bones
1.Tendons and Aponeurosis
A.Tendon:
⃙a fibrous cord or band, mainly made from collagen fibres, that
connects a muscle to bone or other structures. or
⃙is a highly organized connective tissue joining muscle to bone,
capable of resisting high tensile forces while transmitting forces
from muscle to bone.
The dense, regularly arranged collagenous tissue is made up of
fibers, cells of various shapes and ground substance.
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Accessory structures…
B. Aponeurosis:
a fibrous sheet or expanded tendon, giving attachment to flat
muscles, serving as origin or insertion.
Both tendons and aponuerosisare composed of dense
collagenous connective tissue.
The collagen fibers of tendons or aponeurosis are connected to
muscle fibers at junctions called musculotendinous
(myotendinous) junctions.
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Tendons vs. Aponeurosis
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Accessory structures…
The long tendons of the leg and arm muscles are covered by a tendon
sheath (Vagina tendinis), specially at places where they change their
running course or direction around a bony prominence.
A tendons sheath consists of:
a.A fibrous outer layer (vagina fibrosatendinis) –composed of
collagen and elastic fiber .
b.An inner loose connective tissue contain blood vessels and
nerves.
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2. Fascia
From (Latin: "band") is a band or sheet of connective tissue,
primarily collagen, beneaththeskin that attaches, stabilizes,
encloses, and separates muscles and other internal organs.
Fascia consists of a dense collagenous connective tissue sheath
covering a single muscle, group of muscles, an organ, a body part
(e.g. arm, leg ) or the body as a whole.
i.e. fascia is an envelop of collagenous tissue covering whole
body.
Beneath the skin the various structures that make up the body
are held together by a connective tissue called fascia.
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Types of fascia
There are three maintypes of fascia:
SuperficialFascia, which is mostly associated with the skin;
DeepFascia, which is mostly associated with the muscles, bones,
nerves and blood vessels; and.
Visceral (or Subserous)Fascia, which is mostly associated with the
internal organs
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2. Fascia…
⃙Fascia of muscles does not only covered muscles but also separates
different muscles and group of muscles.
⃙The fascia of the body is divided in to superficial and deep.
oThe superficial fascia
•is fat containing subcutaneous tissue found b/n the muscle and
overlying skin.
•Its thickness and fat content varies in distribution depending on age,
sex and diet.
•It contains small blood vessel, nerves, and some muscles (muscles in
the face).
•In place where movement b/n the skin and under lying structure
undesirable(e.g. scalp, sole of the foot, palm of the hand) it is fused
with the deep fascia by bundle of collagen fiber.
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The deep fascia
Contains many compactly arranged collagen fibers often
indistinguishable to the aponeurosis in wrapping material
surrounding muscle or other organ forming a tough inelastic
sheath.
Function:
⃙It ensheathes muscles
⃙Helps as an attachment for muscles
⃙Separates muscle groups by forming intramuscular septae
⃙In the region of the wrist and ankle it forms retinaculathat hold
tendons crossing these joints in place.
The deep fascia includes the palmar and plantar fasciae which are
mainly protective in function.
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Fascia…
Fasciae of muscles are again of two types
a.Single fascia covers a single muscle and separates it from its
neighbors.
b. Group fascia covers muscle groups that have similar functions
and separates them from other groups.
Some group fasciae can extend to the underlying bones .
Such extension of fascia, usually in the limb that lie b/n groups of
muscles form Intermuscular septae.
oseptae serve as origins and insertions for muscles, whereby
they are also reinforced.
Fascia also form a protective covering around muscles, so that
infection can not spread b/n adjacent muscles or group of muscles
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…
3. Synovial bursae
•They are found at places where:
a tendon rubs against a bone, a ligament, other tendon, a muscle
the skin moves over a bony prominence
they help in the uniform distribution
act as padding against injury caused by pressure.
•They may develop in response to friction and facilitate movement
by the reduction of friction.
4. Sesamoid bone
These are found in some tendons increasing the lever effect and
prevent the compression of tendons b/ n the articular ends of
bones.
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…
5. Muscle and tendon receptor organs(proprioceptors)
a.Muscle spindle(neuromuscular spindle) –controls the length of
a muscle i.e. it is stimulated by the stretch of a muscle.
b.Tendon spindle (Golgi tendon organ) –controls muscle tone.
c.Golgi mazzonibodies (found in the articular capsule ) and
paciniancorpuscles for the determination of joint position
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Cross-section through a muscle
There are two types of muscle cross-section.
1.Anatomical cross section:
is a cross section at the middle of a muscle perpendicular to its
longitudinal axis,
It is a structural type of cross section by which the internal
component of a muscle can be studied.
2.Physiological cross section-
is the sum of cross section of all the fibers in a given muscle.
Corresponds to the power of a muscle, which depends on the
size and number of fibers.
The more the number of fibers and the thicker their size is the
powerful that the muscle will be.
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MuscularHypertrophy
oThe muscle growth that occurs after birth occurs by enlargement of
existing muscle fibers, called muscular hypertrophy rather than by
muscular hyperplasia, an increase in the number of fibers.
oMuscular hypertrophy is due to increased production of myofibrils,
mitochondria, sarcoplasmic reticulum, and other organelles.
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oMuscular atrophy is a wasting away of muscles.
oIndividual muscle fibers decrease in size as a result of
progressive loss of myofibrils.
oMuscular atrophy that occurs because muscles are not used is
termed disuse atrophy.
oDenervation atrophy… occurs when the nerve supply to a
muscle is disrupted or cut, the muscle undergoes denervation
atrophy.
oMyalgiaPain in or associated with muscles.
oMyomaA tumor consisting of muscle tissue.
oMyomalaciaPathological softening of muscle tissue
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MEDICAL TERMINOLOGY
MyositisInflammation of muscle fibers (cells).
Volkmann’s contracturePermanent shortening (contracture) of a
muscle due to replacement of destroyed muscle fibers by fibrous
connective tissue, which lacks extensibility.
Hypotoniarefers to decreased or lost muscle tone. Such muscles
are said to be flaccid.
•Flaccid muscles are loose and appear flattened rather than rounded.
Hypertonia refers to increased muscle tone and is expressed in two
ways: spasticity or rigidity.
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Intramuscular Injections
Intramuscular (IM) injection is penetration of the skin and
subcutaneous layer to enter the muscle itself.
Intramuscular injections are preferred when:
⃙rapid absorption is desired
⃙larger doses than can be given subcutaneously are indicated
⃙the drug is too irritating to give subcutaneously.
The common sites for intramuscular injections include the:
⃙gluteus mediusmuscle of the buttock
⃙lateral side of the thigh in the midportionof the vastuslateralis
muscle
⃙the deltoid muscle of the shoulder.
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Intramuscular Injections
Muscles in these areas, especially the gluteal muscles in the
buttock, are fairly thick, and absorption is promoted by their
extensive blood supply.
To avoid injury, intramuscular injections are given deep within
the muscle, away from major nerves and blood vessels.
IM injections have a faster speed of delivery than oral
medicationsbut are slower than intravenous infusions.
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Classification of Muscles
Muscles of the Axial Skeleton
oInclude those responsible for facial expression, mastication, eye
movement, tongue movement, respiration; and those of the
abdominal wall and the pelvic outlet.
Muscles of the Appendicular Skeleton
oIncludes muscles of the pectoral girdle, arm, forearm, wrist,
hand, pelvic girdle, thigh, leg and foot.
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Skeletal
muscles
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Circulation
The continuous movement of blood throughout the body, driven by the
pumping action of the heart.
On average, it takes about45 secondsfor blood to circulate from the
heart, all around the body, and back to the heart again.
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Function of the Circulatory System
•Formation of blood transportation network
oHeart pumps blood
oBlood carries nutrients, oxygen, hormones and waste products to
and from the cells
oRegulate body temperature
•Drainage of surplus tissue fluid and leaked plasma proteins to the
bloodstream, as well for the removal of debris from cellular
decomposition and infection
•Absorption of dietary fat
•Formation of a defense mechanism of the body
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Components of the Circulatory System
The circulatory system is subdivided into:
a. Cardiovascular system
•blood
•heart
•blood vessels
b. Lymphatic system (vessels that carry a fluid called lymph)
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Functions of Blood
•Transport of:
Gases, nutrients, waste products
Processed molecules
Regulatory molecules
•Regulation of pH and osmosis
•Maintenance of body temperature
•Protection against foreign substances
•Clot formation
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Composition of Blood
•Blood is composed of:
•Plasma 55 %
•Formed elements (45%)
•Erythrocyte
•Leukocyte
•Platelets
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Plasma 55%
Erythrocyte 45%
Buffy coat
Centrifuge
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•After centrifuge the massive formed element laying at the base is
erythrocyte
•Hematocrit: percentage of blood volume that contain erythrocyte
Average 45 %
In male 47%±5%
In female 42% ±5%
In newborns 42%-68%
•Buffy coat lie b/n erythrocyte and plasma containing leukocyte and
platelets
•Plasma makes topmost part accounting 55%
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Blood Cell Formation
•Hematopoiesisor hemopoiesis: process by which blood cells are
formed
•Begins in the early embryo continues throughout life.
•Bone marrow is the site of blood cell formation
•Bone marrow: occupies the interior of all the bones
•Red bone marrow: actively generate blood cells
•Yellow bone marrow: dormant but become active in emergencies.
It contains many fat cells
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•At birth, all marrow in the skeleton is red.
•In adults, red marrow remains:
•between the trabeculaeof spongy bone throughout the axial
skeleton and girdles
•in the proximal epiphysis of each humerus & femur
•Yellow marrow occupies all other regions of the long bones of
the limbs.
•The replacement of red marrow with yellow marrow in the limbs
occurs between the ages of 8 and 18 years.
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Cell Lines in Blood Cell Formation
•All blood cells arise from one cell type, the blood stem
cell.
•Stem cells divide continuously:
•to renew themselves
•to produce lines of progenitor cells that lead to the
various blood cells
•The two types of progenitor cells that arise directly
from blood stem cells are:
Lymphoid stem cells: give rise to lymphocytes
Myeloid stem cells: which give rise to all other
blood cells.
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Hematopoiesis
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Some important terms related to the circulatory system
1. Plexus:a network of interjoining venous vessels(also
applied to nerves and lymphatic vessels). E.g.
Venous plexus of the scalp.
Pharyngeal venous plexus.
Suboccipitalvenous plexus.
Oesophageal venous plexus.
Rectal venous plexus.
2.Sinus:achannelforthepassageofbloodorlymph,without
thecoatsofanordinaryvessel,e.g.cerebralmeninges/dural
venoussinus
3. Sinusoid:very wide capillary found in the liver and endocrine
glands, spleen etc.
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Terms related to the circulatory system…
4. Collateral circulation:isalternate or “backup” blood vessels in your
body that can take over when another artery or vein becomes blocked
or damaged.
This is a circulation maintained by small anastomosing vessels when
the main vessel is obstructed, so that the blood supply to an organ
would be constant.
The lumen of these small collateral vessels increases in diameter
due to the increased volume to be transported.
Collateral circulation provides alternative routes for blood flow.
A collateral circulation can be adequate (sufficient) or inadequate
(insufficient).
oadequate: E.g. vessels of the GIT
oinadequate: E.g. coronary arteries
Yared Asmare(Asst Prof.) 236

Terms related to the circulatory system…
The coronary arteries, even though they form anastomosis the
collateral circulation in them is inadequate, therefore they are said to
be functional end arteries.
End arteries are the only supply of oxygenated blood to a tissue or
organ.
Other examplesto such arteries are vessels of the brain, lungs,
liver, kidneys, spleen and metaphysis of long bones.
When an artery has no collaterals or forms no anastomosis with other
vessels it is known as end artery, e.g. central retinal artery.
The blockage of a functional end artery or an end artery results in the
ischemia, infarctionand then necrosisor deathof the concerned
tissue.
Yared Asmare(Asst Prof.) 237

Terms related to the circulatory system…
5. Anastomosis:a communication between arteries, veins and
lymphatic vessels. E.g. portocavalanastomosis
6. Venae comitantes:arteries are usually accompanied by veins and
lymphatic vessels sharing a common inelastic connective tissue sheath.
While a one-to-one artery to vein relation applies for many large
vessels; two veinsaccompany the smaller arteries.
These two veins accompanying a single artery are called venae
comitantes.
Yared Asmare(Asst Prof.) 238

Terms related to the circulatory system…
7. Neurovascular bundle:vascular bundles contain their own vasomotor
nerve networks, but in addition they may be accompanied by major
nerve trunks forming a neurovascular bundle.
E.g.
Neurovascular bundle of the neck (common carotid artery, internal
jugular vein and vagusnerve).
Neurovascular bundle of the thigh (femoral artery, vein and nerve).
Innervation of blood vessels
Blood vesselsare predominantly innervatedby sympathetic
nervesthat mainly cause vasoconstriction, but to a lesser extent by
parasympatheticnerve, which are vasodilators.
Yared Asmare(Asst Prof.) 239

•Blood vessels tubular structures, with particular named
layers from innermost to outermost:
Tunica interna/intima
Tunica media
Tunica externa/adventitia
•Functions:
Distribution of blood
Exchange of materials with tissues (nutrient, oxygen, waste)
Return of blood to the heart
Transportation of hormones to their target organs
240Yared Asmare(Asst Prof.)

•Tunica externa
–Outermost layer
–CT with elastinand
collagen
–Strengthens, anchors
•Tunica media
–Middle layer
–Circular smooth muscle
–Vasoconstriction/dilation
•Tunica intima
–Innermost layer
–Endothelium
–Minimize friction
•Lumen
General Characteristics of Blood Vessels
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General Structure
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Types of Vessels
•Arteries carry blood awayfrom the heart
Elastic arteries
Muscular arteries
Arterioles
•Veinscarry blood towardsthe heart
•Capillariesthe most important part of the vascular system;
site of exchange of materials
Continuous
Fenestrated
Sinusoidal
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244Yared Asmare(Asst Prof.)

Arteries
Elastic /Conducting/Arteries
•Thick-walled arteries near the heart
•e.g. pulmonary artery, aorta and common carotid artery
•Large lumen allows low-resistance conduction of blood.
•Contain lots of elastinin all three tunics.
•Walls stretch and recoil to propel blood
•Withstand and regulate large blood pressure fluctuations.
245Yared Asmare(Asst Prof.)

Muscular (Distributing) Arteries
•Medium sized vessels
•Tunica media more smooth muscle; less elastin
•Smooth muscle layers constitute 3/4 of wall
thickness
•Major area of vaso-constriction & dilation to regulate
blood flow
•E.g. femoral a, splenica…
246Yared Asmare(Asst Prof.)

Arterioles
•Smallest arteries; lead to capillary beds
•Diameter of 0.3 mm or less
•Close to capillaries single layer of muscle spiralling
around the endothelial lining
•Regulates blood flow to capillary
Metarterioles
•Short vessels connect arterioles to capillaries
•Muscle cells form a precapillarysphincter about
entrance to capillary
247Yared Asmare(Asst Prof.)

Capillaries
•Smallest vessels –diameter just large enough for a red blood
cell
•Walls consist of tunica intimaonly
(i.e. layer of endothelium)
•Thinness facilitates exchange of materials
•Thoroughfare channel -metarteriolecontinues through capillary
bed to venule
•Precapillarysphincters control which beds are well perfused
•Only 1/4 of the capillaries are open at a given time
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Control of Capillary Bed Perfusion
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Control of Capillary Bed Perfusion
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Types of Capillaries
•Continuous
endothelial cells have tight junctions with intercellular clefts
(allow passage of solutes)
•e.g. occur in most tissues skeletal muscles, skin, and the
central nervous system.
•Fenestrated
organs that require rapid absorption or filtration;
endothelial cells have filtration pores (fenestrations)
allow passage of small molecules
e.g. kidneys, small intestine
•Sinusoids
irregular blood-filled spaces; some have extra large
fenestrations, allow proteins and blood cells to enter
e.g. liver, bone marrow, spleen
251Yared Asmare(Asst Prof.)

Fenestrated
Continuous
Sinusoidal
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Capillary Exchange
•Only occurs across capillary walls between blood and
surrounding tissues
•Routes for exchange of materials across endothelial cells
Through diffusion
Intercellular clefts
Fenestrations
Through transcytosis
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•Most tissues and organs have a rich capillary supply, not all
do. For example,
•Tendons and ligaments are poorly vascularized.
•Epithelia and cartilage contain no capillaries receive by
diffusion from the nearby connective tissue
•Cornea and the lens have no capillary supply at all and
are nourished by the aqueous humor
254Yared Asmare(Asst Prof.)

Veins
Venules
•Are formed when capillary beds unite.
•They merge to create veins
Veins
•Thin tunica media
•Thick tunica externaconsisting of collagen fibers and
elastic networks.
•Capacitance vessels (blood reservoirs) that contain
65% of the blood supply.
255Yared Asmare(Asst Prof.)

Vascular Anastomoses
Interconnection of two or more vessels
Provides collateral circulation
Venous anastomoses are more numerous than arteries
Arterial anastomoses are common around joints
Vasa vasorum vessels of the vessels
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Venous Return
•Factors aiding venous return against gravity:
1.Large lumen which offers little resistance.
2.Valvesto prevent backflow
3.Muscular“pump” –skeletal muscles “push” blood toward the
heart.
4.Respiratory“pump” –pressure gradient sucks blood into
thorax
5.Pumping action of neighboring artery
6.Body movements
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Factors Aiding Venous Return
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Control of Vessels
•It is the responsibility of the vasomotor centre in the medulla
•Sympathetic innervation
•Parasympathetic innervation
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Lymphatic System
It is part of the circulatory system, it is the complementary way of the
veins.
It is composed of lymph, lymphatic vessels, lymph nodes and other
lymphatic organs (e.g. isolated lymphatic follicles, spleen, thymus).
Returns tissue fluid to the heart.
Functionsofthelymphaticsystem:
1.To return water and proteins from the interstitial fluid to the
blood.
2.To transport fat absorbed from the GIT to the blood.
3.To defend the body (both cellular and humeral defense)
(phagocytosis and production of antibodies).
4.Haemopoiesis, production of cells like lymphocytes and
monocytes.
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261
Lymph :a transparent, usually slightly yellow, liquid found within
the lymphatic vessels, collected from the tissue and has the same
constituents as blood plasma.
Lymphatic vessels.
Lymphatic System Lymph nodes.
Lymphatic organs.
Lymphatic vessels:which transport fluid that has escaped from the blood
vessels back to the blood.
Lymphoid tissues and organs: which help provide the body’s resistance
and immunity to disease.
Lymphatic capillaries
Lymphatic vessels Afferent vessels.
Efferent vessels.
Small and large vessels.
Lymphatic trunks.
Lymphatic duct
Yared Asmare(Asst Prof.)

Lymphatic system…
1.Lymphatic capillaries:
Drain the tissue fluid.
Similar to the blood capillaries their wall consists of endothelial cells lying
on a basement membrane, but pericytes are absent.
Very fine capillaries show fenestrations, otherwise, there are scattered
pores that allow the entrance of blood cells and some particles.
2. Afferent and efferent vessels:
lead the lymph in to and away from the lymph nodes respectively.
Their thin wall does not contain muscle cells, the flow in them is
assisted by external pressure, e.g. muscle contraction.
They contain numerous valves that prevent the back flow of lymph
or help in the unidirectional flow of lymph through the lymph
nodes.
As afferent lymphatic vessels approach lymph nodes, they give rise
to a number of branches, which enter the nodes at various sites
over their convex surfaces.
A small number of efferent lymphatic vessels leave the nodes at
their hila.
Yared Asmare(Asst Prof.) 262

Lymphatic system…
3. Small and large vessels:
They transport the lymph in the direction of the heart and have
numerous valves that are only few centimetres apart.
Part of the vessel between two neighbouring valves is called
valvularsegment.
Their tunica media contains spirally arranged smooth muscle cells.
Therefore,transportationoflymphinthemisdonemainlybythe
contractionoftheirsmoothmusclecells,whichareinnervatedby
autonomicnerves.
Accordingtotheirpositionlymphaticvesselsaredividedintotwo:
A.Superficial:foundintheskin,subcutaneoustissueandonthe
superficialfascia.
B.Deep:Foundunderthesuperficialfasciaaccompanyingblood
vessels.
Thelargestlymphaticcollectingvesselsconvergetoform
lymphatictrunks.
Yared Asmare(Asst Prof.) 263

Lymphatic system…
For the drainage of lymph, the following four factors are important:
1.Muscle pump: in the afferent and efferent vessels.
2.Rhythmic contraction of the smooth muscle cells in the
media: in the small and large lymphatic vessels.
3.Suction of the heart: in the lymphatic trunks.
4.The negative pressure in the thorax during inspiration and
the negative pressure in the abdomen during expiration.
Yared Asmare(Asst Prof.) 264

Lymphatic system…
4. Lymphatic Trunks:
formed by the union of largest lymphatic vessels (e.g. lumbar,
intestinal, bronchomediastinal, subclavian and jugular).
I.Lumbar trunks:
paired trunks lie along the sides of the aorta in the inferior
abdomen.
receive all lymph draining from the lower limbs, the pelvic, and
from some of the anterior abdominal wall.
II.Intestinal trunk:
unpaired trunk lies near the posterior abdominal wall in the
midline.
receives fatty lymph (chyle) from the stomach, intestines, and
other digestive organs.
Yared Asmare(Asst Prof.) 265

Lymphatic system…
III.Bronchomediastinaltrunks:
Ascendingnearthesidesofthetrachea,
pairedtrunkscollectlymphfromthethoracicvisceraandthoracic
wall.
IV.Subclaviantrunks:
Locatednearthebaseoftheneck,
pairedtrunksreceivelymphfromtheupperlimb.
alsodraintheinferiorneckandthesuperiorthoracicwall.
V.JugularTrunks:
Locatedatthebaseofeachinternaljugularvein.
Thesepairedtrunksdrainlymphfromtheheadandneck.
Yared Asmare(Asst Prof.) 266

Lymphatic Vessels…
5. Thoracic duct:
begins in the abdomen as a sac, the cisterna chyli, after it passes
the diaphragm it ascends through the thorax and enters the
junction of the left internal jugular and the left subclavian veins (the
left venous angle).
collects the lymph from inferior limbs, abdomen, left half of the
thoracic cavity, left upper limb and left side of the head and neck.
6. Right lymphatic duct:
drains the lymph of the right side of the head and neck, right upper
limb and right half of the thoracic cavity.
Yared Asmare(Asst Prof.) 267

The Lymphoid Organs include:
The lymph nodes.
The spleen.
The thymus.
The tonsils.
The aggregated lymphoid follicles in the small intestine (peyer’s
patches), vermiform appendix.
Lymph nodes
These are round, oval or flattened nodular structures found
usually embedded in a fatty tissue being surrounded by their own
connective tissue capsule.
There are about 500 lymph nodes in the human body ranging
from 1 to 25 mm in diameter.
They contain a slight indentation, the hiluswhere vessels enter or
leave the node.
Yared Asmare(Asst Prof.) 268

Regional Lymph nodes:
⃙The cranial nodes.
⃙The cervical nodes.
⃙The tracheobronchial nodes.
⃙The Axillary nodes.
⃙The Iliac nodes.
⃙The inguinal nodes.
⃙Head
Occipital
Retromandibular
Preauricular
Parotid
⃙Facial(infraorbital, Buccal, mandibular)
⃙Neck
Submandibular
Submental
Superficial cervical
Deep cervical
Yared Asmare(Asst Prof.) 269

Regional Lymph nodes…
Upper limblymph nodes
Superficial
Deltoidopectoral(Anterior)
Deep
Axillary (lateral)
Pectoral
Central (intermediate)
Subscapular(posterior)
Subclavicular (medial) lymph nodes
Lower limb lymph nodes
⃙Popliteal
⃙Superficial inguinal
⃙Deep inguinal
⃙Abdomen and pelvis
⃙External iliac
⃙Common iliac
⃙Internal iliac
⃙Sacral lymph nodes
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271
Abdomen and pelvis
Celiac
Gastric
Hepatic
Pancreaticolienal
Lumbar (Rt. & Lt)
Lateral aortic
Retroaortic
Superior mesenteric (Mesenteric, Ileocolic, Mesocolic)
Inferior mesenteric
Thorax
Parietal Visceral
Sternal Anterior mediastinal
Intercostal Posterior mediastinal
Phrenic (Diaphragmatic) Tracheobronchial
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Lymphatic system…
TissuescontainingNOlymphcapillaries:
1.Theepithelium.
2.Allbradytrophictissue.E.g.cartilage,cornea,lens.
3.Thebonemarrow.
4.Parenchymaoftheliverandthespleen.
5.Thebrain.
Similaritiesbetweenvenousandlymphaticvessels:
1.Flowinthesamedirectionfromthetissuetotheheart.
2.Havevalves.
3.Followtheveinsanddividedinsuperficialanddeepvessels
Differencesbetweenvenousandlymphaticvessels:
1.Theyhavelymphnodes.
2.Thelymphaticcapillarieshaveonlyonesideopen,theotherisclosed.
3.Flowlymph.
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273
The Digestive System
The organs of the digestive system can be divides into:
1.The Alimentary canal.
2.Accessory digestive organs: teeth, tongue, and gall bladder.
3. Accessory Digestive Glands:
Parotid
Large glands Submandibular.
Sublingual
a) Salivary Glands
Labial.
Small glands Bucal.
b) The Liver.
c) The Pancreas Lingual.
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274
Digestive process:
1.Ingestion:the process of taking food into the mouth.
2.Propulsion:which is composed of swallowing (voluntary) and
peristalsis (involuntary).
3.Mechanical digestion:includes chewing, churning food in the
stomach and segmentation or rhythmic local constrictions of the
intestine.
4.Chemical digestion: a process in which complex food molecules are
broken down to their building block by the help of enzymes.
5.Absorption:the transportation of digested end products from the
lumen of the alimentary canal into the blood and lymphatic
capillaries in its wall.
6.Defecation:the elimination of indigestible substances in the form of
feces.
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275
The alimentary canal:
is a muscular digestive tube that winds through the body, in which
food is propelled.
It is continuous at both ends with the skin covering the body surface.
This begins with the lips at the mouth and passes through the neck,
thorax, abdomen and pelvis to end at the anus.
In the cadaver the alimentary canal is about 9 m (30 feet) long.
The organs of the alimentary canal are:
⃙The Mouth.
⃙The Pharynx.
⃙The Esophagus.
⃙The Stomach.
⃙The Small intestine (small bowel).
⃙The large intestine (large bowel).
⃙The anus (terminal opening).
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276
The small intestine(small bowel)has three parts: duodenum,
jejunum , ileum
Large intestine: Caecum , Appendix, Ascending, Transverse,
Descending, Sigmoid Colon, Rectum, Anal canal
The accessory glands:
oproduce lubricating and moistening fluid, digestive enzymes
and some of them participate in the further breakdown of
absorbed nutrients so that they can be used for energy
production or stored for latter use.
Yared Asmare(Asst Prof.)

The Urinary System
Removes excess water, salts and wastes of protein metabolism
from the blood while returning nutrients and chemicals to the
blood.
Maintains fluid and electrolyte balance in the tissue fluids.
It is composed of paired bilateral organs and unpaired median
organs.
The paired bilateral organs are kidneys and ureters, while the
unpaired median organs are composed of the urinary bladder and
the urethra.
Urine is formed by the kidneys and transported to the ureters,
which open into the urinary bladder where it will be temporarily
stored.
It is released to the exterior from the bladder through the urethra.
Yared Asmare(Asst Prof.) 277

Urinary system…
Therefore based on its function, it is divided into two parts:
1. Urine forming part: the kidneys
2. Urine transporting or conveying part:
ureter
bladder
Urethra
Yared Asmare(Asst Prof.) 278

Genital system
Each sex has:
1.A symmetrical pair of reproductive or sex glands that
produce sex cells (spermatozoa and ova).
2.Two different pairs of passages through which the germ cell
move to the exterior of the body.
3.Accessory glands.
4.External genitalia.
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280
The male reproductive organs consist of the:
Testis and Epididymis(situated in the scrotum).
Ductusdeferentes(contained in the spermatic cord).
The seminal vesicles, the ejaculatory ducts, the prostate, the
bulbourethralglands and penis.
-Testes
-Epididymis.
Essential -Ductus deferentes.
-Ejaculatory duct.
Functional -Urethra/ Penis.
division.
-Seminal vesicles.
Accessory -Prostate.
-Bulbourethralglands.
Yared Asmare(Asst Prof.)

-Testes
-Epididymis
Internal -Ductus deferentes.
-Spermatic cord.
-Ejaculatory duct.
Location -Seminal vesicles.
-Prostate.
-Bulbourethral glands.
External -Penis.
-Scrotum.
•Function of the male reproductive system:
1. Spermatogenesis.
2. Store and transport the gametes.
3. Performance the sex acts.
4. Hormonal regulation of the male sexual functionn.
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Female Genital Organs
Thefemalegenitalorgansarecomposedof:
2ovaries,2uterinetubes,uterus,vagina,vulva
Classification of the female genital organs
Functional
Essential Accessory
Ovaries Pudendum
Uterine tubes glands
Uterus Mons pubis
Vagina Labia majoraLabia minora
Clitoris
Vestibule of the vagina
Greater vestibule glands
Bulb of the vestibule
Lesser vestibular glands
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283
Ovaries.
Internal Uterine tubes.
Location Uterus.
Vagina
External Pudendum
glands.
Besides, the breasts are also considered as
secondary female sexual organs)
Yared Asmare(Asst Prof.)

RESPIRATORYSYSTEM
The respiratory system includes the lungsand a branching
system of tubes that link the sites of gas exchange with the
external environment.
The trillions of cells making up the body require a continuous
supply of oxygen to carry out vital functions.
We can survive only a few minutes without oxygen.
As cells use oxygen, they give off carbon dioxide a waste
product of cellular respiration which the body must eliminate
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Respirationis a term used to describe two different but
interrelated processes: cellular respiration and mechanical
respiration.
Cellular respiration: is the process in which cells derive
energy by degradation of energy rich organic molecules such
as glucose.
Mechanical respiration:
is the process by which oxygen required for cellular
respiration is absorbed from the atmosphere into the blood
vascular system and the carbon dioxide is excreted into the
atmosphere.
occurs within the respiratory system
RESPIRATORYSYSTEM
Yared Asmare(Asst Prof.) 285

RESPIRATORYSYSTEM
Yared Asmare(Asst Prof.) 286

Introduction
The major function of the respiratory system is to supply the
body with oxygen and dispose of carbon dioxide.
To achieve this function four distinct processes, collectively
called respiration occur in the body.
Pulmonary ventilation
External respiration
Transport of respiratory gases
Internal respiration
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Introduction
Pulmonary ventilation
Air must be moved in and out of the lungs so that the gases
in the air sacs (alveoli) of the lungs are continually changed
and refreshed
This air movement is commonly called ventilation or breathing
External respiration
Gas exchange (oxygen loading and carbon dioxide
unloading) must occur between the blood and the air-filled
alveoli of the lungs
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Introduction….
Transport of respiratory gases
Oxygen and carbon dioxide must be transported between the
lungs and tissue cells of the body
This is accomplished by the cardiovascular system, which
uses blood as the transporting fluid
Internal respiration
At the systemic capillaries, gas exchanges (oxygen unloading
and carbon dioxide loading) must be made between the blood
and tissue cells
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Anatomy of the respiratory system
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The Respiratory System
Classification of the Respiratory System
According to the location.
a.Upper respiratory tract: nose, nasal cavity, paranasalsinuses, pharynx.
b.Lower respiratory tract : larynx, trachea, bronchi & lungs
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292
Functionally
the nose.
the nasal cavity.
the paranasalsinuses.
A) conducting portion the pharynx.
the larynx
the trachea.
the bronchi and bronchioles.
b) Transitional portion Terminal bronchioles
respiratory bronchioles
alveolar ducts
c) Respiratory portion alveolar sacs
alveoli
Yared Asmare(Asst Prof.)

Functional division…
1.Conducting portion:Comprise the air conducting tubes that connect the
external environment with the portion of the lungs
2.Transitional portion:Connects the conducting and respiratory portion. It
has both conduction and respiratory functions
3.Respiratory portion:this is part where exchange of gases between the
inspired air and the blood takes place.
Functions of the respiratory system
1.Warming, humidification and filtration of the inspired air.
2.Sensation of the smell by nose.
3.Production of the voice by the larynx.
4.Regulation of the acid base balance of the body.
Yared Asmare(Asst Prof.) 293

The Nervous System
Like the CPU of a computer, the nervous system is the
master controlling systemof the body.
It is designed to constantly and rapidly adjust and respond
to stimuli the body receives.
The human nervous system is by far the most complex
system in the body histologically and physiologically and is
formed by a network of many billion nerve cells (neurons),
all assisted by many more supporting glial cells.
Each neuron has hundreds of interconnections with other
neurons, forming a very complex system for processing
information and generating responses.
294Yared Asmare(Asst Prof.)

The Nervous System …
£Both the nervous and endocrine systems have the same
objective:
oto keep controlled conditions within limits that maintain life.
£The nervous system regulates body activities by
responding rapidly using nerve impulses; the endocrine
system responds by releasing hormones.
Neurology deals with normal functioning and disorders
of the nervous system.
A neurologist is a physician who diagnoses and treats
disorders of the nervous system.
295Yared Asmare(Asst Prof.)

Basic function of nervous system
1.Sensation
Monitors changes/events occurring in and
outside the body.
Such changes are known as stimuliand the
cells that monitor them are receptors.
2.Integration
The parallel processing and interpretation of
sensory information to determine the
appropriate response
3.Reaction
Motor output.
oThe activation of muscles or glands (typically
via the release of neurotransmitters (NTs))
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297Yared Asmare(Asst Prof.)

The Nervous System
Functions of the nervous system:
1.Regulate, coordinate and control the functions and activities of
each organ in the body.
2.Initiate and control movement.
3.Process and conduct impulses from the sense organs.
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299
Division of the nervous system.
1.Topographically Central Nervous System (CNS).
Peripheral Nervous System (PNS).
2. Functionally Somatic (voluntary) Nervous System
Autonomic (involuntary) Nervous System
The central nervous system:
a.The brain (encephalon):located in the cranial cavity.
b.Spinal cord (medulla spinalis):found in the vertebral canal.
Thebrainandspinalcordarecontinuousatthelevelofthe
foramenmagnum.
Bothofthemdevelopfromtheectodermalneuraltube.
Yared Asmare(Asst Prof.)

The nervous system…
The interior of the CNS is organized into grey and white matter:
1.Greymatter or substance:Consist mainly of nerve cell bodies (corpus
neuronal), with their dendrites and synaptic contacts.
2.White matter or substance:is composed of myelinatednerve fibres, glial
cells (it has a white color due to the presence of lipid material in the myelin
sheaths).
Types of cells:
1.The neuron.
2.The neuroglia.
Neuron:is the structural and functional unit of the nervous system.
It is an excitable cell specialized for the reception of stimuli and
conduction of the nerve impulse.
Neuron has a cell body, and processes (dendrites and an axon) that carry
impulses to and away from that cell body, respectively.
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Classifications of Neurons
Neurons vary widely in morphologyand location.
They can be classified according to either their structureor
their function.
Neurons can be classified according to structure (the number of
processes extending from the cell body.)
Multipolar possess more than two processes
Numerous dendrites and one axon, most neurons in brain
and spinal cord
Bipolar possess two processes
Rare neurons found in some special sensory organs,
Retina of eye
Unipolar (pseudounipolar) possess one short, single
process
Start as bipolar neurons during development, located in
posterior root ganglia or sensory root of spinal nerves and
ganglia of cranial nerves
301Yared Asmare(Asst Prof.)

302Yared Asmare(Asst Prof.)

Functional Classification of Neurons
•According to the direction the nerve impulse travels
•Sensory (afferent) neuronstransmit impulses toward
the CNS
•Virtually all are unipolarneurons
•Cell bodies in gangliaoutside the CNS
•Short, single process divides into
•The central process runs centrally into the CNS
•The peripheral process extends peripherally to
the receptors
•Motor (efferent) neurons
•Carry impulses away from the CNS to effector organs
•Most motor neurons are multipolar
•Cell bodies are within the CNS
•Form junctions with effector cells
303Yared Asmare(Asst Prof.)

Interneurons (association neurons) most are multipolar
Lie between 2 neurons
Confined to the CNS
Facilitate communication between sensory and motor
neurons
304Yared Asmare(Asst Prof.)

Functional classification of the nerves:
1.Afferent(sensory,centripetal)fibres:thosethatcarryimpulsesfromperipheral
receptortothecentralnervoussystem.
a)Somaticafferent(somaticsensory)fibres:thesecarryimpulsesfromthe
peripheralreceptor(skin,skeletalmusculatureandbones)tothecentralnervous
system.
b)Visceralafferent(visceralsensory)fibres:carryimpulsesfromtheinternal
organstothecentralnervoussystem.
2.Efferent(motor,centrifugal)fibres:thosethatcarryimpulsesfromtheC.N.Sto
themusclesorglands.
a)Somaticefferent(somaticmotor)fibres:carryimpulsesfromtheC.N.Stothe
skeletalmuscles(exceptthepharyngealarchmusculature).
b)Visceralefferent(visceralmotor)fibres:carryimpulsesfromtheC.N.Stothe
smoothmuscleofthebody,cardiacmuscleandglands(includingpharyngealarch
muscles).
Yared Asmare(Asst Prof.) 305

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307
Type of
neuroglia
Oligodendrocyteproduce myelin
C.N.S
Astrocytes the largest neuroglialcell, supporting
function
Ependymal cells form epithelium on the lining of
the cavity of brain
Microglia Phagocytic cell
Schwann cells myelin production P.N.S
N.B Nerve cells ,Unlike other cell are unable to multiply i.e. they are post
mitotic cell.
Only their nerve process and axons increase in size.
Nerve cells(neurons) can be classified in to , i.e. multipolarbipolar, unipolar
and pseudounipolar, based on their process
Neuroglia:
Non excitable cells, they form the major component of nervous tissue.
They serve in supporting, insulating and nourishing the neuron.
Yared Asmare(Asst Prof.)

Structure of a Nerve
•A nerve is a cable-like bundle of parallel axons.
•Like a muscle, a nerve has three successive
connective tissue wrappings.
Endoneuriuma delicate layer of loose
connective tissue
Perineuriuma cellular and fibrous connective
tissue layer that wraps groups of axons into
bundles called fascicles
Epineuriuma superficial connective tissue
covering
•This thick layer of dense irregular fibrous
connective tissue encloses the entire nerve,
providing both support and protection
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309Yared Asmare(Asst Prof.)

Collection of neuronal cell bodies out side the
CNSGanglia
Collection of neuronal cell bodies with in the
CNS Nuclei
There are two types of ganglia
I. Autonomic ganglia
motor ganglia (pre and post ganglionic neurons
of ANS synapse)
II. Craniospinal
sensory ganglia associated with most cranial
nerves and dorsal roots of spinal nerves
310Yared Asmare(Asst Prof.)

Brain (Encephalon)
Its weight
400 gmin new born
800 gmat age of one year
1200 gmat age of four years
1400 gmat age of 21 years
1300 gmat age of 60-80 years but why the weight
decrease here?
Yared Asmare(Asst Prof.) 311

Cranial nerves
Thereare12pairsofcranialnervesthatcarryafferentandefferent
signalsbetweenthebrainandotherpartsofthebody.
Theyareattachedtothebrainorbrainstemandpassinandoutof
thecranialcavitythroughforaminainthebaseoftheskull.
Allthecranialnervesserveonlyheadandneckstructuresexceptthe
vagusnerve,whichextendstothethoraxandabdomen.
I.Olfactory nerve: sensory nerve of smell.
II.Optic nerve: sensory nerve of vision.
III.Oculomotor nerve: motor and autonomic nerve to the eye
muscles.
IV.Trochlear nerve: motor to the eye muscles.
V.Trigeminal nerve: mixed, sensory to the face and motor to the
chewing muscles.
VI.Abducensnerve: motor to the eye muscles.
Yared Asmare(Asst Prof.) 312

Cranial nerves…
VII. Facial (Intermediofacial) nerve: mixed, motor to muscles of the face,
sensory to the tongue, autonomic to some glands.
VIII. Vestibulocochlear(statoacustic) nerve: sensory nerve for hearing and
equilibrium.
IX.Glossopharyngealnerve:mixed,sensorytothetongueandpharynx,
motortostylopharyngeusmuscleandautonomictotheparotidglands.
X.Vagusnerve:mixed,sensorytothepharynxandlarynx,motorto
musclesofthesoftpalate,pharynx,larynxandautonomictothethoracic
andabdominalviscera.
XI.Accessorynerve:amotornerveconsistingofcranialandspinalparts.
Itscranialpartisincorporatedintothevagusnervewhileitsspinalpart
innervatessternocleidomastoidandtrapeziusmuscles.
XII.Hypoglossalnerve:motortomusclesofthetongue.
Yared Asmare(Asst Prof.) 313

…
Outofthemixedcranialnerves,fourofthemcontainautonomic
(parasympathetic)component,theseare:
Oculomotor
Facial
Glossopharyngeal
Vagus.
Spinal nerves
Thereare31pairsofspinalnervesthatareattachedtothespinal
cordasventralanddorsalnerveroots.
Theventralanddorsalrootfibresjoineachotherinornearthe
intervertebralforaminatoformthespinalnerveproperthatconsistof
bothsensoryandmotorfibres.
Yared Asmare(Asst Prof.) 314

Spinal nerves…
Just proximal to the fusion with the anterior root each dorsal root
contains an enlargement containing the sensory spinal (dorsal root)
ganglion, which is usually located at the level of each intervertebral
foramina.
A spinal ganglion contains the cell bodies of the first neurons of the
sensory pathway, which are pseudounipolarcells with central and
peripheral processes.
The spinal nerves consist of the following pairs.
8 pairs of cervical nerves
12 pairs of thoracic nerves
5 pairs of lumbar nerves
5 pairs of sacral nerves
1 pair of coccygeal nerves
Yared Asmare(Asst Prof.) 315

Differences between cranial and spinal nerves
1.Cranialnervesdonotshowsegmentaldistribution.
2.Spinalnervesaremixedwhileonlysomeofthecranialnerveshavea
mixedquality.
3.Thespinalnervesenterthespinalcordseparatelyasventralordorsalroot
butcranialnervesenterorleavethebrainatitsbasalregionexceptthe
trochlearnervethatleavesitdorsally.
Thesomatic(voluntary)nervoussystem:isthepartofthenervous
systemconcernedwiththeinnervationofvoluntarystructures,skeletal
muscle.
Theautonomic(visceralorvegetative)nervoussystem:isthepartofthe
nervoussystemconcernedwiththeinnervationoftheinvoluntarystructures,
suchastheheart,smoothmuscleandglandswithinthebody.
Theautonomicnervesaredividedintotwoparts:
1.Sympathetic.
2.Parasympathetic
Yared Asmare(Asst Prof.) 316

Autonomic nervous system
The involuntary effectors including smooth muscles, cardiac
muscles and glands ,are regulated by autonomic nervous
system.
Although the autonomic nervous system (ANS) is composed of
portions of both the central and peripheral nervous system, it
functions independently and with out a person`s conscious
control.
Responsible for maintaining homeostasis
317Yared Asmare(Asst Prof.)

Sympathetic Division
⃙Originate from T1-L2 & innervate viscera and glands
⃙Activated during exercise, excitement, and emergencies
⃙Prepare the body for emergency condition “ fight or flight”
318Yared Asmare(Asst Prof.)

Sympathetic nerves
The nerve fibres from the lateral horns enter the paired paravertebral
sympathetic ganglia and the unpaired prevertebral(abdominal)
ganglia.
The paravertebral ganglia lie in the sympathetic trunk located on both
sides of the vertebral column extending from the base of the skull to
the sacrum.
The paravertebral ganglia are interconnected by interganglionicfibres.
Fibres from the prevertebralganglia form plexuses that supply the
abdominal and pelvic organs.
Yared Asmare(Asst Prof.) 319

Sympathetic nerves…
The sympathetic fibres from the lateral horn leave the spinal cord
through the anterior root as the white communicatingfibreswhich
enter the paravertebral ganglia.
Then they rejointhe spinal nerves by way of grey communicating
fibres or rami (Rami communicansgriseus)and carried by the spinal
nerves to their areas of innervation.
Yared Asmare(Asst Prof.) 320

Parasympathetic nerves…
Theparasympatheticnervesarisefromthebrainstemand
sacralpartofthespinalcord.
ThecranialoutflowareviatheIII,VII,IXandXcranialnerves
thatsupplythehead,visceraoftheneck,thorax,foregutand
midgut.
ThesacraloutflowisfromS2-S4spinalcordsegmentthrough
thepelvicsplanchnicnervesthatsupplyhindgutandpelvic
viscera.
Yared Asmare(Asst Prof.) 321

Concerned with conserving energy “rest and digest”
322Yared Asmare(Asst Prof.)

ANS…
The sympathetic and parasympathetic innervations are usually
antagonistic.
For it is involved in Fright, Fight and Flight reaction, sympathetic
innervation is energy consuming where as parasympathetic
innervation is energy conserving because it is engaged in response and
repair reaction.
The sympathetic nerves have a relatively short preganglionic fibres
extending between the spinal cord and a sympathetic ganglion but
longer postganglionic fibres extending from a sympathetic ganglion to
an effector (gland, muscle or viscera).
In contrary, the parasympathetic nerves have a longer preganglionic
fibres lying between its origin and a parasympathetic ganglion found
near or within the effectors, while their postganglionic fibres is short
and extends from the ganglion to the structure to be innervated.
Yared Asmare(Asst Prof.) 323

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327Yared Asmare(Asst Prof.)

Reflex Arch
•The reflex:is a fast response to changes in the internal and external
environments to maintain homeostasis, it is arapid and automatic
motor response to stimuli.
•Homeostasisis a process by which the body equilibrium is maintained.
•The reflexes are mediated by chains of neurons called reflex arch.
•A reflex arch contains two or more neurones over which impulses are
conducted from a receptor to the brain or spinal cord and then to an
effector.
•Component of the Reflex arch:
1.The receptor.
2.The sensory neuron.
3.The integration center.
4.The motor neuron.
5.The effector. Yared Asmare(Asst Prof.) 328

Reflex Arch
1.The receptor:this is the site where the stimulus acts and is transformed
into nerve impulse.
Its role is to respond to changes in the internal or external
environments by initiating an impulse in a sensory neurone.
2.The sensory neuron:this transmits the afferent impulses to the C.N.S.
3.The integration center:lies in the C.N.S can be a single synapse between
the sensory and motor neurons or multiple synapses in more complex
reflex.
Here the impulse may be inhibited, transmitted or re-routed.
4.The motor neuron:this conducts efferent impulses from the integration
center to an effector.
5.The effector:organ of the body, muscle or gland that responds to the
efferent impulses by contracting or secreting.
This response is called reflex action or reflex.
Yared Asmare(Asst Prof.) 329

The interneurons are of two types:
1.Excitatory interneurons:intensify the impulse to be conducted.
2.Inhibitory interneurons:reduce or slow down the impulse
intensity.
Reflexes carried out by the spinal cord are called spinalreflexes.
Those reflexes causing skeletal muscle contraction are called
somatic reflexes
Those reflexes that cause contraction of smooth and cardiac
muscles and secretions by glands are called visceral or autonomic
reflexes.
Yared Asmare(Asst Prof.) 330

Different types of ganglia:
1.Craniospinal(somatic) ganglia:they belong to the somatic nervous
system, these ganglia are found as:
a.Relay stations of cranial nerves.
b.Spinal ganglia in the dorsal root of the spinal cord (dorsal root
ganglia).
These contain pseudounipolarcells except the vestibulocochlear
nerve that contains bipolar nerve cells.
2.Autonomic or vegetative ganglia: that belong to the autonomic
nervous system. These ganglia appear in the form of:
A.Paravertebral
B.Prevertebral
C.Vegetative ganglia of cranial nerves
•These usually contain multipolar nerve cells and pseudounipolar.
Yared Asmare(Asst Prof.) 331

Sensory Function
The sense organs contain receptors where an impulse (excitation)
can be initiated and conducted to the respective centre.
Mechanical or other stimuli taken up from the internal and
external environments are transduceby receptors in to electrical
signals and these signals carried to the centre by afferent
neurones.
Yared Asmare(Asst Prof.) 332

Classification of Receptors…
II. Classification according to the site of signal reception:
a.Exteroception
b.Proprioception
c.Interoception
A.Extroceptors:that respond to stimuli arising outside the body. They
help the body to react to stimuli in the external environment.
Extroceptors are subdivided into:
1.Surface (contact) receptors.
2.Teloreceptors.
1.Surface (cutaneous, superficial or contact) receptors:to these
belong the extroceptors, which react to stimuli in the environment
like pressure, pain, temperature, etc. e.g. receptors in the skin.
2.Teloreceptors: respond to stimuli or objects separated from the
body. e.g. visual and auditory receptors.
Yared Asmare(Asst Prof.) 333

…
B. Deep receptors (Proprioceptors):
Found associated with muscles, tendons and articular capsule.
They react to changes in posture (body position), pressure and
movement.
They react to changes that occur in muscle length, muscle tone
and position of joints and send information to the CNS about the
position of the concerned body part.
C. Interoceptors:
Are found in the viscera and blood vessels.
They respond to visceral stimuli like distension of the stomach and
changes in the pH of the blood.
Yared Asmare(Asst Prof.) 334

…
III. According to the type of signal (stimulus) they receive
1.Chemoreceptors: they react to chemical stimuli like a change in the
partial pressure of oxygen in the blood.
e.g. carotid body, aortic body.
2.Photoreceptors: they react to light stimuli and are found in the
retina as rods and cones.
3.Audioreceptors: they react to acoustic or sound stimulus and found
in the organs of hearing.
4.Thermoreceptors:
5.Presso-receptors (Baro-receptors): they are stimulated by changes
in blood pressure and found in the wall of blood vessels, e.g. carotid
sinus
6.Mechanoreceptors
Yared Asmare(Asst Prof.) 335

Yared Asmare(Asst Prof.) 336

Generally, sensory nerve endings can be encapsulated or unencapsulated.
The unencapsulatedones appear in the form of expanded free
nerve ending consisting of terminal branches of sensory nerves.
The encapsulated ones are nerve endings surrounded by a
structurally modified non-neural tissue.
•The capsule serves as a mechanical filter to modify stimuli before
they reach the sensory ending and plays a barrier role, which is
important to regulate the composition of fluid surrounding the
sensory ending.
•The capsule with the sensory nerve ending it surrounds
commonly forms a corpuscle
•e.g. Meissner’scorpuscles, paciniancorpuscles, etc.
Yared Asmare(Asst Prof.) 337

Synapse
Synapse is an area of specialised contact between neurons or neuron
and other non-neural cells where the Information is relayed.
It is derived from the Greek term “synapsis” which means union.
Synapse is responsible for a unidirectional transmission of impulse
from one neuron to another or from a neuron to an end organ.
Generally, this is a functional contact of a nerve cell to a nerve cell or
to effector organs like muscles and glands.
Synapses are found in both the somatic and autonomic nervous
system.
Yared Asmare(Asst Prof.) 338

Classification of synapses
1.According to the mechanism of impulse conduction:
a.Chemical
b.Electrical synapses.
a.Chemical synapses:
•Most of the synapses in human beings are chemical synapses, where
a chemical transmitter substance called neurotransmitter is
involved.
•These substances are synthesised in the cytoplasm of the
presynaptic neuron and stored in the synaptic vesicles of the
presynaptic ending.
•In such synapses, the membranes of the presynaptic &postsynaptic
neurones are separated by a narrow gap of about 20 nm called
synaptic cleft.
Yared Asmare(Asst Prof.) 339

Classification of synapses…
When an impulse reaches the presynaptic ending, the transmitter is
released from the vesicles into the synaptic cleft and transmits the
signal to the postsynaptic neuron.
In this case, the conduction of impulse is unidirectional.
b. Electrical synapses: are common in invertebrates but may also occur
in the CNS of mammals.
There is a narrow gap junction of about 2 nm containing small
channels extending between the opposing membranes for the direct
transmission of impulse by ionic flow.
Yared Asmare(Asst Prof.) 340

2. According to the localisation of the synapses:
a.Synapses between nerves (neuroneuronalsynapses) :
This is a synaptic contact between two neurons.
There are three types of neuroneuronalsynapses.
1.Axo-dendritic: between an axon and a dendrite.
2.Axo-somatic: between an axon and a perikaryon.
3.Axo-axonic: between two axons.
Yared Asmare(Asst Prof.) 341

…
b. Neuromuscular (myoneuralsynapses): this describes the contact
between a neuron and muscle cell.
c. Neuroepithelialsynapses (Neuroglandularsynapses): a contact
between an axon and the plasmalemmaof glandular cells and
plurivacuolarfat cells.
3. According to their function:
a. Excitatory synapses
b. Inhibitory synapse
Yared Asmare(Asst Prof.) 342

343
Endocrine system
Yared Asmare(Asst Prof.)

.
The endocrine system is a series of ductless glands that secrete
messenger molecules called hormones into the circulation.
The circulating hormones travel to distant body cells and signal
characteristic physiological responses in those cells.
Through its hormonal signals, the endocrine system controls and
integrates the functions of other organ systems in the body.
In its general integrative role, the endocrine system resembles the
nervous system, with which it closely interacts.
344Yared Asmare(Asst Prof.)

.
However, because hormones travel more slowly than nerve impulses,
the endocrine system tends to regulate slow processes, such as growth
and metabolism, rather than processes that demand rapid responses,
such as the contraction of skeletal muscle.
•Some major processes controlled by the endocrine system are:
growth of the body and of the reproductive organs,
the mobilization of body defenses against stress,
maintenance of proper blood chemistry, and
control of the rate of oxygen use by the body’s cells.
•The scientiﬁc study of hormones and the endocrine glands is called
endocrinology.
345Yared Asmare(Asst Prof.)

.
•The endocrine cells of the body are partly contained within “pure”
endocrine organs and partly within organs of other body systems.
•The purely endocrine organs are:
the pituitary gland at the base of the brain;
the pineal gland in the roof of the diencephalon;
the thyroid and parathyroid glands in the neck; and
the adrenal glands on the kidneys (each adrenal gland is actually
two glands, an adrenal cortex and an adrenal medulla).
346Yared Asmare(Asst Prof.)

.
Organs that belong to other body systems but also contain a large
proportion of endocrine cells include the pancreas, the thymus, the
gonads, and the hypothalamus of the brain.
Because the hypothalamus produces hormones in addition to
performing its nervous functions, it is considered a neuroendocrine
organ.
Numerous other organs, for example the heart, digestive tract,
kidneys, and skin, also contain scattered or small pockets of cells that
secrete hormones.
The usual action of hormones is to speed up or slow down cellular
process in the target tissue
347Yared Asmare(Asst Prof.)

. Control of Hormone Secretion
•The various endocrine cells of the body are stimulated to make and
secrete their hormones by three major types of stimuli : humoral,
neural, and hormonal stimuli.
•Endocrine glands that secrete their hormones in direct response to
changing levels of ions or nutrients in the blood are said to be
controlled by humoral stimuli (humoral relating to the blood and other
body ﬂuids). This is the simplest endocrine control mechanism.
348Yared Asmare(Asst Prof.)

•For example, the cells of the parathyroid gland directly monitor the
concentration of calcium ions (Ca2+) in the blood and then respond to
any decline in this concentration by secreting a hormone that acts to
increase blood calcium levels.
•The secretion of a few endocrine glands is controlled by neural stimuli.
•For example, sympathetic nerve ﬁbers stimulate cells in the adrenal
medulla to release epinephrine and norepinephrine during ﬁght-or-
ﬂight situations.
349Yared Asmare(Asst Prof.)

.
•Many endocrine glands secrete their hormones in response to
hormonal stimuli received from other endocrine glands; that is, certain
hormones have the sole purpose of promoting the secretion of other
hormones.
•For example, the hypothalamus of the brain secretes some hormones
that stimulate the anterior part of the pituitary gland to secrete its
hormones, which in turn stimulate hormonal secretion by other
endocrine glands: cortex, and the gonads.
350Yared Asmare(Asst Prof.)

351Yared Asmare(Asst Prof.)

•The skin(cutis, cutaneous layer, integument) and its derivatives
like hair, nail, glands (sweat, mammary, sebaceous) constitute
the integumentary system.
•Heaviest single organ of the body both in weight (15-20% of total
body weight) and surface area (presenting 1.5–2 m
2
of surface to
the external environment in adults)
•Best indicators of general health
Yared Asmare(Asst Prof.) 352
Integumentary System

Function of the Skin
•Protection
Mechanical abrasion
Barrier to pathogen (provides immunologic information)
Glycolipid-impermeability
Melanin-UV light
•Temperature regulation
Physical exercise & warm temperature
•Excretion
Water, sodium salts, urea, and nitrogenous wastes
•Sensory perception
•Formation of vitamin D
•Non-verbal communication
353Yared Asmare(Asst Prof.)

Cont’d
©Sensation.The skin is the largest sensory organ in the
body, and contains a range of different receptors for touch,
pressure, pain and temperature.
©As there is regional variation in structure, sensory
receptors are most numerous in skin which has most
physical contactwith solid objects in the environment the
soles and palms, and the ventral surfaces of fingers and
toes
Yared Asmare(Asst Prof.) 354

???
Yared Asmare(Asst Prof.) 355

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