Lecture 6 Skeletal System Axial Skeleton 1 The

Lecture 6 Skeletal System: Axial Skeleton 1

The Complete Skeleton • Axial skeleton –Skull –Hyoid bone –Vertebral column –Thoracic (rib) cage • Appendicular skeleton –Limbs –Girdles Fig. 7. 1 2

Superior and Posterior Views of Skull or Cranium Fig. 7. 5 • External occipital protuberance – Ligamentum nuchae: Helps keep head erect • Nuchal lines: Neck muscle attachment 3

Lateral View of Skull Fig. 7. 6 • Temporal lines (temporalis muscle) • Mandible – Condyle – Coronoid process for temporalis muscle 4

Frontal View of Skull Frontal bone Parietal bone Temporal bone Ethmoid bone Lacrimal bone Zygomatic bone Maxilla Sphenoid bone Nasal bone Perpendicular plate of ethmoid bone Vomer Inferior nasal concha Mandible Fig. 7. 4 • Optic foramen (optic nerve) • Lacrimal groove (tears from eye to nasal capsule) 5

Inferior View of Skull Hard palate Maxilla Palatine bone Temporal process of zygomatic bone Zygomatic process of temporal bone Vomer Sphenoid bone Zygomatic arch Styloid process Mandibular fossa Temporal bone Jugular foramen Mastoid process Occipital condyle Carotid canal Foramen magnum Occipital bone External occipital crest Inferior nuchal line Superior nuchal line External occipital protuberance Fig. 7. 8 • • Foramen magnum Occipital condyles Jugular foramen, carotid canal Hard palate - maxilla and palatine Fig. 7. 8 6

Hyoid Bone and Auditory Ossicles • Hyoid bone – Unpaired – No direct bony attachment to skull – Attachment point for some tongue muscles – Attachment point for neck muscles that elevate larynx during speech and swallowing Fig. 7. 26 • Auditory ossicles – Malleus, incus and stapes 7

Vertebra • Parts – – – – Body Vertebral foramen Vertebral arch Superior and inferior articular processes Transverse process Articular facets for rib Spinous process Fig. 7. 29 8

Vertebral Column • Regions – – – Fig. 7. 28 Cervical (7 vertebrae) Thoracic (12 vertebrae) Lumbar (5 vertebrae) Sacral bone (1) Coccygeal bone (1) 9

Cervical Vertebrae • Atlas – First vertebra – ‘yes’ motion • Axis Fig. 7. 30 – Second vertebra – Dens or odontoid process – ‘no’ motion 10

Thoracic and Lumbar Vertebrae Table 7. 5 11

Sacrum and Coccyx Fig. 7. 31 12

Review Question The spinal cord passes along the vertebral column through the _______ and enters the skull through the _____. (a) Spinous process, mandibular fossa (b) Body, occipital condyles (c) Superior and inferior articular processes, jugular foramen (d) Vertebral arch, carotid canal (e) None of the above is correct 13

Thoracic Cage and Sternum • Parts – Thoracic vertebrae – Ribs (12 pair) • True • False – Sternum (manubrium, body) Fig. 7. 32 14

Points to Remember • Two major components of the human skeleton: – Axial skeleton arranged along the medial axis – Appendicular skeleton connects to the axial skeleton • Skull consists of: – 22 bones (single and paired) – 6 auditory ossicles (3 each side) and 1 hyoid • Vertebral column consists of: – – – Cervicals (7) Thoracics (12) Lumbars (5) Sacrum (5, fused) Coccyx (3 -5, fused) • Rib cage has true (bone) ribs and false (cartilage) ribs 15

Questions? 16