POWER POINT PRESENTATION ON SKELETAL SYSTEM

NOTES ON SKELETAL SYSTEM

1. THE HUMAN
SKELETAL SYSTEM
POT 131: ANATOMY & PHYSIOLOGY 1

2. THE SKELETAL SYSTEM
•Consists of bones and joints, along with
cartilage and ligaments associated with
joints.

3. The Human Skeleton
•It is an endoskeleton – lies within the soft tissues of the
body
•Living structure capable of growth, adaptation & repair
•Consists of several bones: both fused & individual
•Average adult has 206 bones
•Serves as a framework that offers:
–Support
–Protection
–Mineral Reservoir (Calcium)
–Hemopoiesis
•In an adult, makes up about 14% of total body weight

4. Classification of Bones
•Variety of classification schemes:
Based on macroscopic appearance
–Compact
–Spongy/ Cancellous/ Trabecular
Based on their developmental origin
–Intramembranous
–Endochondral
Based on shape
–Long
–Short
–Flat
–Irregular etc

5. Long Bones
•Mainly bones of the limbs: e.g. humerus, femur
•Have a long axis – longer than wide
•Characterised by
–a central region or shaft (diaphysis)
– two ends (epiphyses)
•Proximal epiphysis
•Distal epiphysis

6. Long Bones
•Diaphysis is formed of a
hollow cylinder of compact
bone surrounding a
medullary cavity
–(yellow bone marrow cavity)
•The medullary cavity
serves as a fat storage site
•The medullary cavity is
lined by a thin connective
tissue layer – endosteum

7. Long Bones
•The central regions of
the epiphyses is
spongy bone and this
contains the red bone
marrow
•Outer surface of
epiphyses formed of
compact bone

8. Bone Marrow

9. Long Bones
EPIPHYSEAL PLATE
•In children & young adults, it separates the
epiphysis and diaphysis
•Made of cartilage
•Provides the means for bones to increase in length
•In adults when skeletal growth has been completed,
the cartilage is replaced by bone leaving a junction
called the epiphyseal line

10. Diagram of a long bone (femur)
Each bone irrespective of shape, source of formation and function is clothed
by a tough fibrous connective tissue material called PERIOSTEUM

11. Bones
Short bones
•Do not have a long axis
•e.g. Carpal (wrist) & tarsal (ankle) bones.
Flat bones
•Thin/ flat bones
•e.g. cranial bones, scapula, ribs, sternum
Irregular bones
•Various shapes, do not fit in any of above
•e.g. Vertebrae, pelvic girdle

12. Organisation of The Human
Skeleton

13. Divisions of the skeleton

14. THE AXIAL SKELETON
•Comprises of
–Skull (including the ossicles & hyoid bone)
–Vertebral column
•Cervical vertebrae (7)
•Thoracic vertebrae (12)
•Lumbar vertebrae (5)
•Sacrum (1)
•Coccyx (1)
–Thoracic cage
•Ribs (24)
•Sternum (1)

15. THE APPENDICULAR SKELETON
•Comprises of
–Pectoral Girdle (Scapula (2), Clavicle (2))
–Upper Limb
•Humerus, Radius , Ulna
•Carpals (16), Metacarpals (10)
•Phalanges (28)
–Pelvic Girdle (Os coxae)
–Lower Limb
•Femur, Tibia, Fibula, Patella
•Tarsals (14), Metatarsals (10)
•Phalanges (28)

16. The Skull
•The skull is made up of 22 bones (+ auditory
ossicles & hyoid bone = 29 bones)
•All bones except the mandible are connected by
immovable joints (sutures)
• Skull bones can be divided into 2 broad groups:
•Cranial Bones (have direct contact with meninges)
»Frontal, Occipital, Parietal, Temporal, Sphenoid, Ethmoid
bones
•Facial Bones (have no direct contact with meninges or brain)
»Maxilla (above the upper jaw), Mandible (below the lower
jaw), Palatine, Nasal, Zygomatic (around the socket) etc

18. The Skull

19. Skull of newborn

20. The Vertebral Column
•Also called the backbone or spine or spinal column
•Consists of a chain of individual bones (vertebrae)
connected, one above the other separated by
cartilaginous intervertebral discs.
•Usually slightly S-shaped.
•Functions include:
»Support the skull and trunk
»Protects the spinal cord
»Intervertebral discs act as shock absorbers of the vertebrae
»Provides attachment for the limbs, thoracic cage

21. Vertebral Column
•Made up of 33 vertebrae:
7 Cervical vertebrae (neck)
12 Thoracic vertebrae (thorax/chest)
5 Lumbar vertebrae (lower back)
5 Sacral vertebrae (base of the spine, fuse to form the sacrum in adults)
(3-5) Coccygeal vertebrae (end of the spine, fuse to form the coccyx)
Coccyx

22. The Thoracic Cage
•Consists of the sternum, ribs and the thoracic
vertebrae
•The sternum (breastbone) is an elongated flat bone
that forms the midline portion of the anterior wall of
the thorax.
•Sternum has 3 parts:
•Manubrium (broad superior part)
•Body or Gladiolus (longest part, middle part)
•Xiphoid process (small, pointed inferior end)

23. THE THORACIC CAGE

24. The thoracic cage
•12 pairs of ribs which articulate with 12 thoracic
vertebrae.
•First/Superior 7 pairs are directly (individually)
connected to the sternum by costal cartilage
•Superior 7 pairs of ribs thus called TRUE RIBS
•The rest are called FALSE RIBS
•Ribs 8 – 10 are only indirectly connected to the sternum (attach to
costal cartilage of rib 7)
•Ribs 11 & 12 lack any connection to the sternum and are called
FLOATING RIBS
•The thoracic cage serves to protect vital organs and provide
attachment for the upper limb/girdle and muscles

25. THE THORACIC CAGE

26. Bone fracture

27. OTHER SPECIFIC BONES

28. Upper Limb Bones
Humerus & Radius and Ulna
•Humerus
–Long bone of upper arm
•Radius
–Long and narrow bone of
forearm
–Lateral to ulna
•Ulna
–Long and narrow bone of
forearm
–Medial to radius

29. Upper Limb Bones
Hand (carpals, metacarpal & phalanges)
For each hand
•Carpals
–8 short bones of the wrist
•Metacarpals
–5 narrow and elongated
bones of the palm
•Phalanges
–14 bones of the digits

30. Pelvis
•Comprises
–Sacrum
–Coccyx
–Hip bone/ os coxae
•Hip bone
–Large flattened
–Irregular shaped
–Comprises:
•Ilium
•Ischium
•Pubis

31. Lower Limb Bones
Femur •Largest and longest bone
in human body

32. Lower Limb Bones
Tibia and Fibula •(Patella – knee cap)
•Tibia and Fibula form the lower
part of the leg
•Tibia:
–2
nd
largest bone in the human
body
–Medial to fibula
•Fibula
–3
rd
largest bone in the human
body
–Lateral side of tibia

33. Lower Limb Bones
Foot (tarsal, metatarsals and
phalanges)
For each foot
•Tarsals:
–7 bones
–Thick and short
–Most proximal
•Metatarsals:
–5 bones
–Elongated, “parallel”
–In between tarsals and
phalanges
•Phalanges
–14 bones
–Smaller, slightly elongated
–Distal bones of the foot

34. JOINTS

35. JOINTS
•The study of joints falls under arthrology (the
scientific study of joints).
•A joint or articulation is a point where two or more
bones meet.
•Some joints are moveable, others are not
•Classification based on
•Structure
•Function (Degree of movement)
•Number of bones involved

36. Classification based on:
Number of Bones Involved
1.Simple Joint: Occurs
between 2 bones
•Shoulder Joint (humerus
and scapula)
•Hip Joint (femur and os
coxae)
2.Compound Joint:
More than 2 bones
involved
•Elbow Joint (humerus,
radius & ulna)

37. Functional Classification
(Degree of Movement)
1.Synarthrosis: Permits (little or) no movement
•Sutures of the skull
2.Amphiarthrosis: Slightly moveable joint
•Intervertebral discs
3.Diarthrosis: Permits a variety of movements (freely
moveable)
•Shoulder, hip, elbow, knee

38. Structural Classification
•Based on the way the bones
are held together
1.Fibrous Joint –
–Bones are joined together by
fibrous tissue
–Collagen fibres emerge from
matrix of one bone and
penetrate into matrix of another
–3 types:
•Sutures
•Gomphosis:between a tooth and the
jaw
•Syndesmosis: between tibia and
fibula

39. Structural Classification

40. Structural Classification
3.Synovial Joints –
–Allow for much movement
–Characteristics are
•Articulating surfaces are covered by hyaline cartilage
•Bones are separated by a cavity that contains a slippery
lubricant (synovial fluid)
•A capsule encloses the cavity and retains the fluid
•Capsule lined by a serous membrane which secretes the fluid
(synovial membrane)
•6 types of synovial joints

41. Synovial Joints

42. Types of Synovial Joints
1.Gliding or Plane Joints
2.Hinge Joints
3.Pivot Joints
4.Condyloid or Ellipsoidal Joints
5.Saddle Joints
6.Ball-and-Socket Joints

43. Gliding or Plane Joints
•Allow only gliding or sliding movements
•Essentially flat articulating surfaces
•Multiaxial
•eg. carpals of the wrist

44. Hinge Joints
•Act like a door hinge
•Allowing flexion and extension in just one plane
•Uniaxial
•eg. elbow and knee

45. Pivot Joints
•Rotational joints allowing rotation of one bone about
the other
•Uniaxial
•eg. joint between atlas and axis

46. Saddle Joint
•Joint in which each bone surface is saddle-shaped
•Multiaxial joints
•E.g. Carpal and metacarpal joint

47. Condyloid or Ellipsoidal Joint
•Oval shaped end of one bone fits into the elliptical
cavity of another.
•Biaxial
•Between metacarpals and phalanges

48. Ball and Socket Joint
•Multiaxial
•Permits radial movement in almost any direction.
•hips and shoulders