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Axial Skeleton

Axial Skeleton . Honors Anatomy & Physiology. Skull A. 22 bones B. Cranium - houses and protects the brain 1. Frontal – forms forehead and orbits of eyes 2. Parietal (2)– right and left; forms sides and roof of skull.

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Axial Skeleton

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  1. Axial Skeleton Honors Anatomy & Physiology

  2. Skull A. 22 bones B. Cranium - houses and protects the brain 1. Frontal – forms forehead and orbits of eyes 2. Parietal (2)– right and left; forms sides and roof of skull

  3. 3. Temporal (2) – right&left; forms temple, cheek, ear openings a) Temporal fossa b) Mastoid process c) Zygomatic process d) External auditory meatus e) Styloid process

  4. 4. Occipital – back of skull a) Foramen magnum – spinal cord passes through here 5. Sphenoid – fills space between orbital plates a) Sellaturcica– depression in upper surface for pituitary gland 6. Ethmoid– forms roof of nasal cavity

  5. 7. Sutures – unite bones of the cranium a) Coronal suture: between frontal and parietal bones b) Sagittalsuture: between right and left parietal bones c) Lambdoidalsuture: between parietal and occipital bones d) Squamoussuture: between temporal and parietal bones

  6. 8. Fontanels a) Fusion of the cranial bones is not complete at birth, so a space between bones remains b) 6 fontanels at birth c) Fused by 2 yrs. of age

  7. C. Facial Bones – guard and support the eyes, ears, nose, and mouth 1. Nasal bones (2) – bridge of nose 2. Vomer– forms central nasal septum 3. Maxilla (2) – upper jaw bones a) Fusion occurs before birth (1) Non-fusion results in cleft lip/cleft palate b) Forms roof of mouth, walls of nose, floor of orbitals

  8. 4. Mandible – lower jawbone a) Ramus b) Mental foramen 5. Zygomatic(2)- cheek bones a) Zygomatic arch 6. Lacrimal(2) – forms medial wall of eye socket; tear duct passes through

  9. 7. Palatine (2) – forms back roof of mouth and floor of nose; L-shaped 8. Inferior turbinate (2) – forms curved ledge inside side wall of nose D. Ear Bones 1. Malleus- hammer 2. Incus- anvil 3. Stapes - stirrups

  10. E. Hyoid Bone – U-shaped bone in the neck at the base of the tongue; only bone that does not touch another bone F. Cranial Sinuses 1. Cavities within the cranium 2. Functions as resonance chambers in voice production 3. Decreases weight of skull 4. Lined with mucous membrane

  11. II.Vertebral Column A.Spinal Curvature 1.Cervical, thoracic, lumbar, and sacral curvatures 2.Primary Curves – appears late in fetal development a)Thoracic and sacral curves b)Accommodation curves - Accommodate the thoracic and abdominopelvic organs c)Present in the newborn – the only curves present

  12. 3.Secondary Curves a)Lumbar and cervical curves b)Compensation curves - Shifts the trunk weight over the lower limbs c)Appear several months after birth (1)Cervical curve – develops when infant can hold head upright (2)Lumbar curve – develops with ability to stand (3)Both curves become accentuated with walking and running

  13. 4. All 4 curves developed by 10 years of age 5. Abnormal Spinal Curves a) Kyphosis– Exaggerated thoracic curvature - Humpback b) Lordosis– Exaggerated lumbar curvature - Swayback c) Scoliosis – Abnormal lateral curvature

  14. B. Vertebral Anatomy 1. Vertebral Body – transfers weight along the axis of vertebral column 2. Vertebral Arch a) Surrounds each vertebral canal b)Vertebral canal – canal for spinal cord

  15. c) Spinal process – project posteriorly, can be seen and felt along spine d) Transverse process – project laterally on both sides – muscle attachment sites 3. Articular processes a) Superior b) Inferior

  16. C. Vertebral Articulations 1. Articular facet – involved in joint D. Intervertebral discs – fibrocartilage discs for cushioning E. Intervertebral foramen – gaps between pedicles permit passage of nerves F. Vertebral Regions 1. Cervical Vertebrae a) Function –Support the weight of the head

  17. b). 7 Cervical Vertebrae (C1 – C7) (1) C1 – Atlas (a) Function – Permits nodding – “YES” (b) Structure (i) Lacks a body (ii) Lacks a spinous process

  18. (2) C2 – Axis (a) Function – permits rotation of head – “NO” (b) Structure – see Table 7.17 (i) Dens process – Bony projection to which atlas is bound (c) Shaken Baby Syndrome (i) Dislocation of the dens (ii) Crushing damage to spinal cord

  19. (3) C3 – C6 (a) (b) Forked spinous process cradles strong ligaments of head (4) C7 – Vertebrae prominens (a) Function -– transition vertebrae between cervical and thoracic curves (b) Structure - Broad tubercle that can be felt at base of neck

  20. 2. Thoracic Vertebrae a) 12 vertebrae (T1 – T12) b) Function (1) Rib facets provide articulation with ribs c) Structure – see Table 7.17 (1) Vertebral body is heart- shaped

  21. 3. Lumbar Vertebrae a) 5 vertebrae – L1 – L5 b) Function (1) Bears most of the weight of the body c) Structure – see Table 7.17 (1) Large, oval vertebral body (2) Massive spinous processes provide increased surface area for large muscle attachment

  22. 4. Sacrum a) Function (1) Protection of reproductive, digestive, and excretory organs (2) Attaches axial skeleton to appendicular skeleton b) Structure (1) Fusion of 5 sacral vertebrae (2) Triangular, curved bone

  23. 5. Coccyx a) Function (1) Attachment site for ligaments (2) Attachment site for muscle that constricts the anal opening b) Structure (1) Fusion of 3-5 coccygeal vertebrae (2) Slightly movable to assist in childbirth

  24. III. Thorax A. 25 bones and cartilage B. Functions 1. Protects and supports heart and lungs 2. Serves as attachment point for muscles involved in a) Respiration b) Position of vertebral column c) Movements of the pectoral girdle and upper extremity

  25. C. Sternum - breastbone 1. Manubrium a) Articulates with clavicle and 1st rib b) Jugular notch – shallow indentation 2. Body a) Individual costal cartilages form rib pairs 2 – 7 are attached 3. Xiphoid process a) Diaphragm and rectus abdominis muscles attach here

  26. D. Costal Cartilages 1. Hyaline cartilage 2. Connects ribs to sternum in 1 – 7 and to anterior rib (#7) in 8 - 10 E. Ribs (12 pairs) 1. Attached posteriorly with vertebrae and anteriorly with costal cartilage 2. True ribs: a) 1st seven pairs b) Direct connection-each costal bone connects directly to sternum with its own piece of cartilage

  27. 3. False ribs: a) Pairs 8 – 10 b) Indirect connection – cartilage from each of these three costal bones fuses together before fusing with cartilage on rib 7 4. Floating ribs: a) Pairs 11 – 12 b) No costal cartilage c) NO connection to sternum

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