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Skeletal System Axial Skeleton

Skeletal System Axial Skeleton. Anatomy Chapter 7. Axial skeleton. axis- center consists of the center bones of the body 80 bones 3 major regions: skull vertebral column thoracic cage. Skull. most complex structure mostly flat bones has about 85 named openings

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Skeletal System Axial Skeleton

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  1. Skeletal SystemAxial Skeleton Anatomy Chapter 7

  2. Axial skeleton • axis- center • consists of the center bones of the body • 80 bones • 3 major regions: • skull • vertebral column • thoracic cage

  3. Skull • most complex structure • mostly flat bones • has about 85 named openings • 22 bones, usu interlocked along suture lines • 8 cranium bones • 14 facial bones

  4. Cranium • helmet • encloses and protects the brain, provides areas for muscle attachment for head movements and chewing • held together by sutures- immovable joints

  5. 8 bones

  6. frontal- forehead • parietal- largest part (2) • occipital- external occipital protuberance foramen magnum occipital condyles • temporal (2)- Latin- temporum- time passing external auditory meatus mastoid process styloid process- (stake-like) zygomatic process

  7. Frontal Occipital

  8. Temporal

  9. 5. sphenoid- (spheno-wedge) helps form base of cranium, sides of skull, floors and sides of orbits; keystone sellaturcica- Turk’s saddle 6. ethmoid bone- forms most of bony area of nasal cavity & eye orbits cribiform plates cristagalli- cock’s comb

  10. Sphenoid

  11. Facial bones • 14 bones- 13 immovable; 1 movable • Fxn: form basic shape of face, provide attachment for muscles, contain cavities for special sense organs, provide openings for air & food, & secure teeth

  12. 1. Maxillae • keystone bone of the face • form upper jaw, roof of mouth, floors of orbits and nasal cavity

  13. Cleft palate

  14. 2. Zygomatic bones • form cheekbones

  15. 3. Mandible • horseshoe shaped body

  16. Sinuses • fxn: • warm and humidify air • lighten skull • enhance resonance of voice • sinus infections

  17. Fontanels • aka soft spot • allows for movement through birth canal • close up by 2 years of age

  18. Vertebral Column • ~ 28” long in adults • 26 irregular bones adults • infants 33 bones • separated by intervertebral discs

  19. Cervical Vertebrae C1 – atlas nod yes; up and down m’ment C2- axis shake no; side to side m’ment 7 vertebrae

  20. Thoracic Vertebrae • Larger than cervical • Articulate with ribs • 12 vertebrae

  21. Lumbar Vertebrae • biggest vertebrae • bears most of body’s weight • small of back • 5 vertebrae

  22. Sacrum and Coccyx • sacrum- 5 fused vertebrae • form base of column • coccyx- lowest part of column • 4 fused bones

  23. Thoracic Cage • includes ribs, thoracic vetebrae, sternum, costal cartilages • fxn: support pectoral girdle, protect viscera, aid in breathing

  24. Ribs • 12 pairs (usually) • join to a thoracic vertebra • 1st 7 ribs are TRUE RIBS- join sternum directly by their costal cartilages • next 5 pairs are FALSE RIBS- cartilage doesn’t reach sternum directly • next 2 (3) pairs are FLOATING RIBS- no cartilaginous attachment to sternum

  25. usu break at greatest curvature • middle ribs commonly fractured

  26. Sternum • aka breastbone • ~ 6” long • xyphoid process doesn’t completely ossify until about 40 years old

  27. Hyoid Bone • Only bone in body that doesn’t articulate w/ other bones • Enables us to talk

  28. Smallest bones of body

  29. Spongy & Compact bone

  30. Ossification • process of bone developing • bones form by replacing existing connective tissue in either of 2 ways: 1. intramembranous ossification- formation of bone directly on or within fibrous membranes

  31. simplest, most direct type of bone development • osteoblasts form bone tissue • skull & clavicles formed this way

  32. 2. endochondral ossification • replacement of hyaline cartilage shapes by bone tissue • endo= within chondro= cartilage

  33. growth takes place at the epiphyseal plates on the long bones

  34. most bones of body form this way • more complex method • by age 25 all bones are ossified • clavicle- last bone to stop growing • bone REMODELING occurs continuously thru-out life

  35. Male vs Female • Skull: mastoid process, size of skull, forehead, weight • Limbs

  36. Pelvic cavity: wider in females, pubic arch > 90o

  37. Joints • aka articulation • bind parts of skeletal system • make bone growth possible • allow parts of skeleton to change shape during childbirth • enable body to move during muscle contraction • 230 joints in body

  38. 3 classifications: • immovable • slightly movable • freely movable

  39. Fibrous • basically NO movement • bones lie in close contact w/ each other • ex: sutures in skull

  40. Cartilaginous • hyaline cartilage connects bones • slightly movable

  41. Synovial Joints • freely movable • synovial fluid reduces friction • joint capsule • menisci- • bursae • 6 types

  42. Ball and Socket • wider range of motion • hip • shoulder

  43. Condyloid • condyle fits into elliptical cavity • variety of m’ments in different planes; rotational m’ment not allowed

  44. Gliding Joint (plane) • most joints in wrists & ankles • allow sliding & twisting motion

  45. Pivot joints • cylindrical bone rotates • rotation around central axis

  46. Hinge joint • allows for flexion and extension

  47. Saddle Joint • variety of m’ment

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