Chapter 5

1. Chapter 5 Axial Skeleton 3 parts: skull, vertebral column, bony thorax

2. Skull: cranium and facial – all but one joined by sutures • Cranium: 8 large flat bones – 2 paired – rest single • Frontal • Parietal (pair) • Meet at sagittal suture • Coronal suture – btw parietal and frontal

3. Temporal (pair) – meet parietal at squamous suture • External acoustic meatus – canal to eardrum • Styloid process – inferior to acoustic meatus – neck muscle attachment • Zygomatic process – joins cheek bone • Mastoid process – posterior and inferior to acoustic meatus • Mastoid sinuses – air cavities • Jugular foramen – allow passage of jugular vein

4. Occipital – joins parietal at lamboid suture • Foramen magnum – large opening for spinal cord • Occipital condyles – sit on 1st vertebra • Sphenoid bone – butterfly shaped – floor of cranial cavity • Sella turcia – depression that holds pituitary • Foramen ovale – opening for cranial nerve to mandible • Optic canal and superior orbital fissure – allow nerves for eye

5. Ethmoid bone – anterior to sphenoid • Roof of nasal cavity and medial walls of orbits • Crista galli – outer brain covering attaches • Cribriform plates – allow nerves through

6. Facial: 14 bones – 6 paired – 2 single • Maxillae (maxillary bones) • Upper jaw – keystone of face • Alveolar margin – holds teeth • Palatine processes – anterior portion of hard palate • Paranasal sinuses – openings – drain into nasal passage

7. Palatine bones • Posterior to palatine processes • Posterior part of hard palate • Failure to fuse = cleft palate • Zygomatic bones – cheekbones • Lacrimal bones • Fingernail size • Medial wall of orbit • Grooved for tear passage

8. Nasal bones - bridge of nose • Vomer – single – nasal septum • Inferior Nasal Conchae • Project from lateral walls of nasal cavity • Mandible – single • Lower jaw • Only free movable joint of skull – meets temporal bones • Body – horizontal part • Rami (ramus) – upright bars

9. Hyoid bone • Suspended in midneck region • 2cm above larynx • Held by ligaments – touches no other bones • Body and 2 pairs of horns (greater and lesser) • Movable base for tongue • Fetal skull • Fontanels – soft spots • allow compression during birth

10. Vertebral column (spine) • Before birth – 33 vertebrae • 9 fuse to form sacrum and coccyx • 24 single vertebrae • 7 cervical – neck • 12 thoracic – back • 5 lumbar – lower back • Vertebrae separated by intervertebral discs • Cushion and absorb shock

11. Primary curvature • In thoracic and sacral – present from birth • Secondary curvature • Cervical – appears when baby begins to raise head • Lumbar – appears when baby begins to walk

12. Vertebrae • Parts • Body (centrum) – weight bearing – faces anterior • Vertebral arch – joining of lamina and pedicle • Vertebral foramen – canal for spinal cord • Transverse processes – projection off arch • Spinal processes – projection off posterior • Superior and inferior articular processes • Lateral to vertebral foramen • Joints w/ other vertebrae

13. Cervical – C1 – C7 • 1st – atlas – no body • Depressions in transverse processes to receive occipital condyles • Allow nodding • 2nd – axis – acts as a pivot • Dens – pivot point • All have transverse foramen for cranial nerves

14. Thoracic – T1 – T12 • Costal facets – receive ribs • Have long spinous processes • Lumbar – L1 – L5 • Short, chunky spinous processes • Sacrum – 5 fused vertebrae • Alae – wings – articulate w/ hips • Median sacral crest – fused spinous processes • Sacral foramen – openings • Sacral canal – for spinal cord – ends @ sacral hiatus • Coccyx – 3-5 fused vertebrae – tailbone

15. Bony Thorax – thoracic cavity • Sternum – breastbone • Fusion of manubrium, body, and xiphoid process • 7 ribs attach • Jugular notch – upper border of manubrium • Sternal angle – where manubrium and body meet • Xiphisternal joint – where body and xiphoid process meet • Sternal puncture – w/draw hematopoietic tissue

16. Ribs – 12 • True ribs – 1st 7 – attach to sternum • False ribs – next 5 • 3 – attach to ribs by costal cartilage • 2 – floating – don’t attach to anything • Intercostal space – btw ribs – filled w/ muscle