The Skeletal System

1. The Skeletal System • Parts of the skeletal system • Bones (skeleton) • Joints • Cartilages • Ligaments • Two subdivisions of the skeleton • Axial skeleton • Appendicular skeleton

2. Functions of Bones • Support the body • Protect soft organs • Allow movement due to attached skeletal muscles • Store minerals and fats • Blood cell formation

3. Bones of the Human Body • The adult skeleton has 206 bones • Two basic types of bone tissue • Compact bone • Homogeneous • Spongy bone • Small needle-like pieces of bone • Many open spaces Figure 5.2b

4. Classification of Bones on the Basis of Shape Figure 5.1

5. Classification of Bones • Long bones • Typically longer than they are wide • Have a shaft with heads at both ends • Contain mostly compact bone • Example: • Femur • Humerus

6. Classification of Bones Figure 5.1a

7. Classification of Bones • Short bones • Generally cube-shape • Contain mostly spongy bone • Example: • Carpals • Tarsals

8. Classification of Bones Figure 5.1b

9. Classification of Bones • Flat bones • Thin, flattened, and usually curved • Two thin layers of compact bone surround a layer of spongy bone • Example: • Skull • Ribs • Sternum

10. Classification of Bones Figure 5.1c

11. Classification of Bones • Irregular bones • Irregular shape • Do not fit into other bone classification categories • Example: • Vertebrae • Hip bones

12. Classification of Bones Figure 5.1d

13. Anatomy of a Long Bone • Diaphysis • Shaft • Composed of compact bone • Epiphysis • Ends of the bone • Composed mostly of spongy bone

14. Anatomy of a Long Bone Figure 5.2a

15. Anatomy of a Long Bone • Periosteum • Outside covering of the diaphysis • Fibrous connective tissue membrane • Sharpey’s fibers • Secure periosteum to underlying bone • Arteries • Supply bone cells with nutrients

16. Anatomy of a Long Bone Figure 5.2c

17. Anatomy of a Long Bone • Articular cartilage • Covers the external surface of the epiphyses • Made of hyaline cartilage • Decreases friction at joint surfaces

18. Anatomy of a Long Bone • Epiphyseal plate • Flat plate of hyaline cartilage seen in young, growing bone • Epiphyseal line • Remnant of the epiphyseal plate • Seen in adult bones

19. Anatomy of a Long Bone Figure 5.2a

20. Anatomy of a Long Bone • Medullary cavity • Cavity inside of the shaft • Contains yellow marrow (mostly fat) in adults • Contains red marrow (for blood cell formation) in infants

21. Anatomy of a Long Bone Figure 5.2a

22. Bone Markings • Surface features of bones • Sites of attachments for muscles, tendons, and ligaments • Passages for nerves and blood vessels • Categories of bone markings • Projections or processes—grow out from the bone surface • Depressions or cavities—indentations

23. Formation of the Human Skeleton • The process of bone formation is called ossification. • In embryos, the skeleton is primarily hyaline cartilage • During development, much of this cartilage is replaced by bone • Cartilage remains in isolated areas • Bridge of the nose • Parts of ribs • Joints

24. Types of Bone Cells • Osteocytes—mature bone cells • Osteoblasts—bone-forming cells • Osteoclasts—bone-destroying cells • Break down bone matrix for remodeling and release of calcium in response to parathyroid hormone • Bone remodeling is performed by both osteoblasts and osteoclasts

25. Bone Fractures • Fracture—break in a bone • Types of bone fractures • Closed (simple) fracture—break that does not penetrate the skin • Open (compound) fracture—broken bone penetrates through the skin • Bone fractures are treated by reduction and immobilization

26. Types of Fractures • Comminuted – breaks into many fragments. • Common in aged brittle bones • Compression – bone is crushed. • Common in porous bones (ex) osteoporosis • Depressed – broken portion is pressed inward • Typical of skull fractures

27. Types of Fractures • Impacted – broken ends are forced into each other • Commonly occurs when one falls and attempts to break the fall with outstretched arms. • Spiral – ragged, occurs when excessive twisting forces cause break • Common with sports fractures. • Greenstick – incompletely breaks, like a green twig breaking • Common in children because they have more collagen in their matrix and are more flexible • d

28. Common Types of Fractures Table 5.2

29. Repair of Bone Fractures • Hematoma (blood-filled swelling) is formed • Break is splinted by fibrocartilage to form a callus • Fibrocartilage callus is replaced by a bony callus • Bony callus is remodeled to form a permanent patch

30. Hematoma Externalcallus Bonycallus ofspongybone Internalcallus(fibroustissue andcartilage) Newbloodvessels Healedfracture Spongybonetrabecula Bone remodeling Hematomaformation Fibrocartilagecallus formation Bony callusformation Stages in the Healing of a Bone Fracture Figure 5.5

31. Hematoma Hematomaformation Stages in the Healing of a Bone Fracture Figure 5.5, step 1

32. Hematoma Externalcallus Internalcallus(fibroustissue andcartilage) Newbloodvessels Spongybonetrabecula Hematomaformation Fibrocartilagecallus formation Stages in the Healing of a Bone Fracture Figure 5.5, step 2

33. Hematoma Externalcallus Bonycallus ofspongybone Internalcallus(fibroustissue andcartilage) Newbloodvessels Spongybonetrabecula Hematomaformation Fibrocartilagecallus formation Bony callusformation Stages in the Healing of a Bone Fracture Figure 5.5, step 3

34. Hematoma Externalcallus Bonycallus ofspongybone Internalcallus(fibroustissue andcartilage) Newbloodvessels Healedfracture Spongybonetrabecula Bone remodeling Hematomaformation Fibrocartilagecallus formation Bony callusformation Stages in the Healing of a Bone Fracture Figure 5.5, step 4

35. The Axial Skeleton • Forms the longitudinal axis of the body • Divided into three parts • Skull • Vertebral column • Bony thorax

36. The Axial Skeleton Figure 5.6a

37. The Axial Skeleton Figure 5.6b

38. The Skull • Two sets of bones • Cranium • Facial bones • Bones are joined by sutures • Only the mandible is attached by a freely movable joint

39. Human Skull, Lateral View Figure 5.7

40. Eight bones of the Cranium • Frontal - forehead • Parietal (paired) – top of the skull • Temporal (paired) - temples • Occipital – back of skull • Sphenoid – forms floor of cranial cavity • Ethmoid – forms roof of nasal cavity

41. Human Skull, Superior View Figure 5.8

42. Human Skull, Inferior View Figure 5.9

43. Human Skull, Anterior View Figure 5.11

44. Fourteen Facial Bones • Maxillae – upper jaw • Mandible – lower jaw • Palatine (paired) – • Zygomatic(paired) – cheekbones • Lacrimal (paired) – inside of eye, outside of nose • Nasal (paired) – bridge of noes • Vomer (paired) – median line of nasal cavity, means “plow” • Inferior Conchae (paired) – curved bones projecting from the side walls

45. The Hyoid Bone Figure 5.12

46. The Hyoid Bone • The only bone that does not articulate with another bone • Serves as a moveable base for the tongue • Aids in swallowing and speech

47. The Vertebral Column • Each vertebrae is given a name according to its location • There are 24 single vertebral bones separated by intervertebral discs • 7 cervical vertebrae are in the neck • 12 thoracic vertebrae are in the chest region • 5 lumbar vertebrae are associated with the lower back

48. The Vertebral Column • Nine vertebrae fuse to form two composite bones • Sacrum (5) • Coccyx (4)

49. The Vertebral Column Figure 5.14

50. The Vertebral Column • The spine has a normal curvature • Primary curvatures are the spinal curvatures of the thoracic and sacral regions • Present from birth • Secondary curvatures are the spinal curvatures of the cervical and lumbar regions • Develop after birth