The skeletal system

1. The skeletal system

2. Axial skeleton (80) Skull Cranium 8 Face 14 Hyoid 1 Ossicles 3 Vertebral column 26 Thorax Sternum 1 Ribs 24 Appendicular (126) Pectoral girdles 2 clavicles, 2 scapulae Upper limbs 2 humerus, 2 radius, 2 ulna 16 carpals, 10 metacarpals, 28 phalanges Pelvic girdle 2 hip bones (coxae) Lower limbs 2 femurs, patellae, tibias, fibulas 14 tarsals, 10 metatarsals, 28 phalanges Bones of the adult skeletal system

3. Bones can be classified by shape

4. Bone surface markings (table 5.1) • Raised areas where “pulling” occurs • Depressions where compression occurs • Major types of markings • Depressions and openings • Joints, pathways for blood vessels and nerves • Processes • Attachment points for ligaments and tendons

5. Examples of bone markings

6. The skull • 8 cranial bones • Protects the brain • Supports blood vessels, nerves, etc. • Attachment sites for muscles • 14 facial bones • Framework of face • Support openings to digestive, respiratory systems • Attachment sites for muscles

7. Sutural (Wormian) bones • Located within sutures of certain cranial bones • Number varies among individuals

8. Importance of multiple views

9. How is the skull held together? • Immovable joints (sutures) • Are movable during infancy and childhood • Often named according to the bones they join • Frontozygomatic, e.g. • Directional (frontal, sagittal) • Shape (lambdoid, squamous) • Only ossicles and mandible are movable

10. Cavities of the skull • Cranial • Orbits • Nasal • Paranasal sinuses

11. Functions of paranasal sinuses • Lined with mucous membranes • Resonating chamber

12. Major bones of the cranium • One frontal bone • Forehead • Roofs of orbits • Paired parietal bones • Attachment sites for meninges • Temporal bones • Zygomatic process • Mastoid process • External auditory meatus • Petrous portion (middle and inner ear)

13. Occipital bone • Foramen magnum • Occipital condyles (atlanto-occipital joints) • Nuchal lines: attachments sites for muscles

14. Sphenoid bone articulates with all other cranial bones Sella turcica protects the pituitary gland

15. Ethmoid bone • Lateral masses separate nasal cavilty from orbits • Roof- cribriform plate • Perpendicular plate- nasal septum • Crista galli- attachement site • Conchae facilitate respiratory function and sense of smell (inferior nasal conchae are separate bones)

16. 14 facial bones

17. Maxillae • Articulate with all facial bones except mandible • Contributes to orbits, nasal cavity and hard palate

18. Facial bones, continued • Zygomatic bones (cheekbones) • Lacrimal bones (orbits) • Palatine bones roof of mouth, part of nasal cavity and orbits • Inferior nasal conchae • Vomer forms part of nasal septum

19. Mandible

20. Orbits

21. Fontanels • Allow for flexibility and growth • Anterior fontanel is the most prominent and last to close (ossify)

22. Hyoid bone does not articulate with any other bone

23. Vertebral column Kyphosis Lordosis Scoliosis

24. 26 bones in adult cervical vertebral column • 7 cervical • 12 thoracic • 5 lumbar • Sacrum has 5 fused vertebrae • Coccyx has 4 fused vertebrae

25. Lumbar and thoracic vertebrae lumbar thoracic

26. Cervical vertebrae

27. Sacrum and coccyx

28. Thoracic cage

29. Articulation of ribs with vertebrae

30. Summary • Axial skeleton consists of skull, ossicles, hyoid, vertebral column, sternum and ribs • Skull is composed of cranial and facial bones • Hyoid bone supports tongue and does not articulate with another bone • Vertebral column protects spinal cord • Thoracic cage protects vital organs