THE SKELETAL SYSTEM POWER POINT. (2).pptx

skeletal system

1. THE SKELETAL SYSTEM PRESENTED BY MR MPONDELA AARON

2. General objective At the end of the lecture / discussion, students should be able to gain knowledge and understanding of the skeleton

3. Specific objective Define terms used in the skeletal system Describe a bone and its composition Outline the growth and development of the bone Describe the axial and appendicular skeleton

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5. THE BONE A bone is a dense connective tissue which form the skeleton. Composition A bone is composed of; 25% of water 30% of organic material ( cartilage) 45% inorganic material

6. Function The bones which form the skeleton perform five functions; They constitute the frame work for the body. They provide the body with support and protection They contribute in body movement They save as a store room for calcium, phosphorus, sodium and magnesium. They save as a site for blood cell formation

7. Types of Bones There are two types of bone tissue described; Compact bone tissue; which to the naked eye appears to be solid structure but when examined under a microscope the structural units(osteon) can be seen. Cancellous bone tissue; which to the naked eye appears like a sponge hence it is also called sponge bone . Red bone marrow is always present within cancellous bone.

8. Classification of Bones Bones can be classified into four varieties according their shape; Long bones Short bones Flat bones Irregular bones

9. Bone Classification

10. Distal epiphysis Proximal epiphysis diaphysis yellow marrow epiphyseal line periosteum compact bone spongy bone Endosteum hyaline cartilage Anatomy of a Long Bone Sharpey’s fibers

11. Cont..... Long Bones; the long bones provide the frame work of the limbs ranging from the short terminal phalange of the little finger to the femur. Long bones consist of ; Shaft or diaphysis; mainly composed of compact bones with a central canal known as medullary canal. In adult life this canal is filled with adipose tissue called yellow bone marrow.  2 extremities or epiphysis; composed of a thin layer of compact bone tissue containing red bone marrow.

12. Cont....... Short Bones; the short bones have no uniform shape. The cube like bones of the wrist and ankle are examples of short bones. Flat Bones; flat bones are those with surfaces roughly parallel and close to each other as in the sternum, scapular and most skull bones. The flat bones form the wall of the major body cavities and protect their content.

13. Cont...... Irregular Bones; bones that fit non of the above categories are called irregular bones. The vertebrae with projections extending from their bodies are good examples.

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16. STRUCTURE OF BONES The tissues which form the bone are; Bone tissue Hyaline cartilage Fibrous tissue Adipose tissue Bone Tissue; as stated there are two types of bone tissues compact and cancellous bone tissue.

17. Hyaline Cartilage this is a bluish white translucent tissue which is smooth like a glass. It is found at the extremities of long bones and wherever there is a movable joint. This tissue is sometimes referred to as articular cartilage and it allows the bones to glide freely on each other.

18. Fibrous tissue; a sheet of fibrous adheres to all surface of each bone except smooth areas where joints are formed. It provides a protective covering which help in the nourishment and growth of the bone. It is called periosteum. Through it ran small blood vessels carrying food, calcium and oxygen to the cells.

19. adipose tissue consist of red and yellow bone marrow. Red bone is the fatty tissue found in the spaces within cancellous bone tissue. It is from this tissue that blood cells are formed, develop and mature before they are released into the blood stream. Infants up to the age of 5 years have red bone marrow in the medullary canal of their long bones, which is gradually replaced by yellow bone marrow which contains more fat cells and few blood cells.

20. GROWTH AND DEVELOPMENT The development of bones begins before birth and is not complete until 25 years of life. It is influenced by action hormones and by the amount of calcium, phosphate and vitamin D in the diet. Development of long Bones; Long bones develop from rods of cartilage. The process consist of complicated series of changes causing the destruction of cartilage and it is replaced by bone tissue.

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22. Four Types of Bone Cells Osteoprogenitor cells stem cells derived from mesenchyme which produce other stem cells and osteoblasts Osteoblasts produce new bone, and once osteoblasts become entrapped in the matrix they produce and secrete, they differentiate into osteocytes Osteocytes mature bone cells Osteoclasts: not derived form osteoprogenitors Related to macrophages Formed from multiple cells; are multinucleated are involved in bone resorption

23. CONT....... From this primary of ossification the diaphysis or shaft of the bone is formed and ossifications splits upwards and down wards. After birth secondary centres of ossification appear in the parts of the bone. From these centres, ossification splits upwards, sidewards, and down wards. Bone grows in length at the epihyseal cartilage or plate which is found between each epiphysis and diaphysis. The development of shaft in

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25. Development of other Bones Short, flat and irregular bones develop from membrane with exception of sesamoid bones which develop from tendon. The process begins from one or more primary centre of ossification.

26. THE SKELETON The skeleton is the bone frame work of the body and is divided into two main parts the axial and appendicular skeleton . The axial skeleton consist of the bones of the upper right or axis of the body(skull, vertebral column and thoracic cage). The appendicular skeleton consist of shoulder girdles and upper limbs, the pelvic girdle and the lower limbs which are appendages of the body.

27. Axial Skeleton

28. The Cranium; The cranium is the bone box which contains and protects the brain. The cranium consist of 8 bones; 1 frontal bone, which form the forehead and roof of the cranium. 2 parietal bones; which form the sides and top of the skull. 2 temporal bones; which lay on each side of the skull. 1 occipital bone; which forms the back and part of the base of the skull.

29. CONT....... 1 sphenoid bone; which has a shape of a bat with its wings out stretched and it occupies the middle portion of the base of the skull. On the superior surface of the body of the bat there is a little depression called sella turcica or Hypophyseal Fossa in which the pituitary gland rest. 1 ethmoid bone; this is an irregular bone which occupy the anterior part of the base of the skull and help to form the orbital cavity, nasal septum, and lateral holes of the nasal cavity.

30. The Face; There are 4 bones which form the skeleton of the face; 2 Zygomatic or Check Bones; which form the prominence of the check and part of the floor and lateral hole of the orbital cavity. 2 Maxilla Bones or Upper Jaw: form the upper jaw, anterior part of the hard palate( roof of the mouth), lateral hole of the nasal cavity and part of the floor of the orbital cavity.

31. CONT........ 2 Nasal Bones; these are two small flat bones forming greater parts of the lateral and superior surfaces of the bridge of the nose. 2 Lacrimal Bones; these are two small bones in posterior and lateral position to nasal bones which form part of the middle hole of the orbit. Each Lacrimal bone is pieced by a foramen for the passage of nasal Lacrimal ducts(tears)

32. CONT...... 1 Vomer; it is a thin flat bone extending upwards from the middle of the hard palate to separate the two nasal cavities. 2 Palatine Bones; these are two L shaped bones. There horizontal part unity to form the posterior part of the hard palate and the perpendicular parts projects upwards to form part of lateral walls of the nasal cavity. 2 Inferior Conchai or Turbinated Bones; each concha is a long scroll shaped bone forming part of the lateral wall of the nasal cavity.

33. CONT..... 1 Mandible; this is the only moveable bone of the skull, two rami each having a condyloid process which attach to the temporal bone and coronoid process for attachment of muscles and ligament. At birth the frontal bone consist of two parts separated by a Frontal Suture, but their union is usually complete by the 8 th year of life.

34. Cont....... The joint which form between the frontal bone and parietal bone is held by the Coronal Suture . The junction between the two parietal bones is the Sagittal Suture. The Lambdoidal Suture joins the parietal bones to the occipital bone . At birth ossification is not complete and there are two very marked membranous part called Fontanels

35. CONT........ Anterior Fontanel is diamond shaped membranous part situated at the junction of the Frontal, Coronal and Sagittal sutures. It is the largest and is not fully ossified until the child is twelve to eighteen months old. The Posterior Fontanel is a smaller triangular shaped membranous part at the junction of the Lambdoidal and sagittal suture. It is usually ossified six weeks to three months after birth. Another suture found between parietal and temporal bones is called Squamous Suture.

36. SINUSES Many of the bones which make up the skeleton of the skull contain sinuses. All of these sinuses are in communication with the upper air passage and are lined with ciliated mucus membrane. The sinus saves two important purpose; Give resonance to the voice. Lighten the bones thus making it easier for head to balance on top of the vertebral column.

37. Cont...... The Maxillary Sinuses; is the largest and lies in the check bone lateral to the lower half of the nose. The Ethmoid Sinuses; these are much smaller spaces, several in number and lie between the upper nasal cavity and orbit. The Sphenoid Sinuses; situated towards the back of the nasal cavity roof. The Frontal Sinuses; lies above the inner half of the orbit.

38. THE VERTEBRAL COLUMN It consists of 24 separate and moveable irregular bones plus the sacrum consisting of 5 fused bones and the coccyx consisting of 4 fused bones. The 24 separate bones are divided into three groups; Cervical vertebrae (7) Thoracic vertebrae (12) Lumbar vertebrae (5) The vertebrae has certain characteristics in common but each group has its own special distinguishing features.

39. Common Characteristics Of Vertebrae Body; the body lies in front of and takes the weight. Its size varies with the situation of the vertebrae. b). Neural Arch; the neural arch enclose a large foramen (vertebrae foramen) which contains the spinal cord.

40. SPECIAL FEATURES OF DIFFERENT VERTEBRAI A) Cervical Vertebrai; each transverse process exhibits a foramen through which a vertebral artery passes upwards to the brain. The Spinous processes are forked or lifted at the ends giving attachment of muscles and ligaments. Atlas; this first cervical vertebral consists of a ring of bone with two short transverse processes. its superior surface articulates with the condyles of the occipital bones of the skull, the nodding movement of the head takes place at this joint.

41. Cont....... Axis; second cervical vertebral the body is small and has an upward projecting process called odontoid process. This tooth like process articulates with the atlas and the movement at this joint is rotational(side to side) Thoracic Vertebral; there Spinous process are long and points downwards so that they partly overlap each other. They articulate with the ribs and so presents two half facets on each lateral surface of the body and one articular surface on each transverse process.

42. Cont......... Lumbar Vertebral; there bodies are the largest and their vertebral foramina are the smallest. Their spinous process are short, flat and projects straight back.   Sacrum; consists of five vertebrai fused to form a wedge shaped bone with a concave anterior surface. Its upper part or base articulates with the fifth lumbar vertebral, laterally it articulates with the two os coxal at sacral- iliac joint to form the pelvis or pelvic girdle. At its inferior tip, it articulates with the coccyx.

43. cont....... Coccyx; this consists of four terminal vertebral fuse together to form a very small triangular bone. Its broad base articulates with the tip of the sacrum.

44. The vertebral column is not straight but presents four curves. Primary curvature; when the fetus is in the uterus it lies curved up with the vertebral column bent so that the head and knees are more or less touching. This position shows the primary curvature of the column which is concave anteriorly. THE CURVES OF THE VERTEBRAL COLUMN.

45. Cont...... Secondary Curvature; after birth the first curve is maintained until at about three month old, when the child can control the movement of his head. The control of the head causes the development of the first secondary curve, the cervical curve. At the age of about 12- 18 months the child begins to walk, that is forming the second secondary curve, The lumber curve. Both cervical and lumber curves are convex anteriorly. The primary curves (concave) which remain are the thoracic and sacral curves.

46. Movements of the Vertebral Column The movements between the individual bones of the vertebral are very limited. However, the movements of the column as a whole are quite extensive and include; flexion or bending forwards , extension or bending backwards, lateral flexion or bending to the sides, rotation or turning round.

47. Functions of Vertebral Column Protection, especially for delicate spinal cord, which lies within it. Support , it supports the skull and forms an axis giving attachment to other parts of the skeleton. Movement , it permits a wide range of forwards, backwards, side to side and twisting movement.

48. THE THORACIC CAGE The bones of the thoracic cage (thorax) are sternum, ribs and thoracic vertebral. Sternum; or breast bone is a flat bone which can be felt under the skin in the middle of the chest. The sternum is described in three parts manubrium(handle) body(blade) and the xiphoid( point) Ribs ; there are twelve pairs of ribs which form the boney lateral walls of the thoracic cage. The first seven pairs are known as true ribs

49. Cont....... The remaining five pairs are called false ribs. The first three pairs of false ribs( 8 th , 9 th and 10 th pairs) are attached by their coastal cartilage to the coastal cartilage immediately above so that they are only indirectly attached to the sternum. The last two pairs (of false ribs) have no anterior attachment and are therefore called floating ribs. All twelve pairs of the ribs articulate posteriorly with the thoracic vertebrae.

50. Cont........ Thoracic vertebrai; the twelve vertebrae have already been described.

51. Appendicular Skeleton

52. APPENDICULAR SKELETON The shoulder girdle and upper limbs. Each shoulder girdle consists of the following bones; 1 scapula , 1 clavicle . Each upper limb consists of; 1 humerus, 1 ulna, 1 radius, 8 carpal bones, five metacarpal bones, 14 phalanges.

53. Cont......... Clavicle/ collar bone; is a long bone with a double curve. its rounded medial extremity articulates with the manubrium of the sternum at the sterno clavicular joint, its flattened lateral extremity forms the acromio- clavicular joint with the acromion process at the scapular.

54. Cont....... Scapular or shoulder blade; is a flat triangular shaped bone which lies on the chest wall posterior to the ribs and separated from them by muscles. shallow articular surface called the glenoid cavity, which together with the head of the humerus form the shoulder joint. Projecting laterally from the superior boarder of the bone is the coracoid process which gives attachment to the muscles and ligaments.

55. Cont........ At its posterior surface the scapula has the a spinous process which projects beyond the lateral angle of the bone as the acromion process which overhangs the shoulder joint and articulates with the clavicle.

56. The Humerus; This is a long bone which form the upper arm. It consists of a proximal end , head, neck , shaft and distal end. Between the neck and the shaft are two roughened projections of bone, the greater and lesser tuberosity and between them is a deep groove called bicipital groove which houses one of the two tendons of the biceps muscle

57. CONT...... The distal end of the bone presents two articular surfaces. The rounded capitellum laying laterally and the more rectangular trochlea medially. The fossa immediately above the articular surface is called the coronoid fossa, and the corresponding fossa on the posterior surface from the articular surfaces one on each side are the medial and lateral epicondyles.

58. CONT....... The ulna; the proximal end of the ulna presents two articular fossae (notch) and two process; the trochlea notch is a semi lunar fossa which articulates with the trochlea of the humerus. The proximal extremity of this notch is called olecranon process which forms the point of elbow and fits into the olecranon fossa of the humerus when the arm is straight. At the distal extremity of the trochlea notch there is the coronoid process which in turn fits into the coronoid fossa of the humerus when the arm is bend.

59. CONT....... The Radius; The proximal end and head of the radius disc shaped and flat on top with a very shallow depression which articulates with the capitellum of the humerus. The circumference of the head articulates with radio notch of the ulna. The distal end of the bone is expanded. it articulates with the carpal bones to form the wrist joint and with the ulna to form the inferior radio- ulna joint.

60. Carpal Bones(Bones of the wrist) These are 8 in number and arranged in two rolls of four. Their names from without inwards are enumerated bellow; Proximal row; scaphoid, lunate, triquetral and pisiform. Distal row; trapezium, trapezoid, capitates and hamate. These bone s are all closely fitted together and held in position by ligament. The proximal row is associated with the wrist joint and the distal row forms joint with the metacarpal bones.

61. Metacarpal Bones or Bones of the Hand These are five in number and form the structure of the palm of the hand. They are not given names but are numbered from the thumb side inwards. They are long slender bones, their proximal end articulate with the carpal bones and the distal ends articulate with the phalanges.

62. Phalanges or Bones of the Fingers There are 14 in number and are arranged so that there are three in each finger and two in the thumb.

63. THE PELVIC GIRDLE AND LOWER LIMBS The bones which make up the pelvic girdle or pelvis are 2 os coccyx and 1 sacrum The bones of the lower extremity are; Femur Tibia Fibular Patellar Tarsal bones (7) Metatarsal(5) Phalanges(14)

64. Hip Bones; 2 in number each hip bone consists of three separated bones the ileum, ischium and pubis. These three bones fuse to form one large irregular bone. On its outer surface it has a deep depression called accetebulum which with the head of the femur forms the one hip joint. In front and below the accetebulum there is the obturator foramen which in life which in life is occluded by the membrane.

65. CONT........ Sacrum; this is the bone of the vertebral column. Femur or Thigh Bone; The proximal extremity of the femur consists of a head, neck, greater and lesser Trochanters the head almost spherical in shape and fits into the accetebulum of the hip bone to form the hip joint.

66. Tibia or Shine Bone; This is the medial of the two bones of the leg. Its proximal extremity is broad and flat and presents 2 condyles for articulation with the condyles of the femur at the knee joint(medial and lateral condyles) lateral condyles presents an articulation with the head of the fibular at the superior tibia- fibular joint. The distal extremity is smooth and flat where it forms the ankle joint with the talus.

67. CONT....... The lateral aspect of the distal end articulates with the fibular and the inferior tibia- fibular joint. Fibular ; this is a long slender lateral to the tibia in the leg. Its head articulates with the lateral Condyle of the tibia and its lower extremity of the tibia but projects beyond to form the lateral malleolus and takes part in the ankle joint formation.

68. Patellar ; This is a sesamoid bone associated with the knee join. It is roughly triangular in shape and lies with the apex pointing downwards. Its anterior surface is in the patellar tendon and its posterior surface articulate with the patellar surface of the femur at the knee joint.

69. Tarsal or Ankle Bone; These are seven in number. The talus articulates with the tibia and fibula at the ankle joint the calcaneum or heel bone is roughened for attachment of muscles which move the ankle joint. The navicular is situated on the medial aspects of the foot distal to the talus. The medial intermediate and lateral cuneiform and the cuboid form a row of bones from within outwards, which articulates with the other 3 tarsal bones proximally and with the 5 metatarsal bones distally.

70. Metatarsal Bones; These are five in number and form the greater part of the dorsum of the foot and their proximal ends with the phalanges. They don’t have individual names but are numbered from within outwards. Toes; these are 14 in each foot and are arranged in a similar manner to those in the fingers i.e. 2 to the great toe and 3 to each of the other toes.