1. CHAPTER 7 “The Axial Skeleton #2” Course objectives:Define and identify the bones of the axial skeleton
2. Vertebral column composed of 26 irregular bones. These bones provide a solid support structure, but are also remarkably flexible.
3. Regions of the Vertebral Column – Cervical − neck region 7 vertebrae – Thoracic – thorax region 12 vertebrae – Lumbar – lower back 5 vertebrae – Sacral – low, low back 1 vertebrae (5 fused) – Coccygeal – tail bone 1 vertebrae (4 fused)
4. Spinal Curvature Thoracic and sacral are concave (i.e. backward) Primary curves since they developed first. Cervical and lumbar curves are convex (i.e. forward) and secondary curves.
5. Vertebral column
6. Vertebrae Individual vertebrae are found in the cervical, thoracic and lumbar regions of the vertebral column. There are significant differences between the vertebrae in each of these regions that you should know.
7. Cervical vertebrae – C1- C7 Body is oval; spinous process is short (except C-7) and sometimes split; Large vertebral foramen Transverse foramen for vertebral artery to brainstem. C1 is Atlas articulates (atlanto-occipital joint) with occipital bone of skull -allows “yes” motion of head C2 is Axis characterized by peg-like process called “dens” or odontoid process which interlocks with atlas (atlanto-axial joint) -allows sideward rotation or “no” motion of head.
8. Cervical VertebraeAtlasAxis
9. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Atlanto/axial joint Atlas (C1vertebra) Articular facet of dens Dens Transverse ligament Axis C2 vertebrae)(c) Axis and atlas, posterosuperior view
10. Cervical Vertebrae
11. Thoracic vertebrae T1- T12 Body is roughly heart shaped Demifacets for rib articulation Vertebral foramen are circular Spinous process long and points inferiorly The thoracic vertebra look like a giraffe’s head when viewed from the lateral view!
12. Thoracic vertebrae T1- T12
13. Lumbar Vertebrae L1-L5 Pedicles and laminae are short and thicker Spinous processes are short, flat and hatchet shaped Vertebral foramen is triangular Inferior and superior processes lock the adlacent vertebrae together for strength and stability. The lumbar vertebra look like a Moose’s head!
14. Lumbar Vertebrae L1-L5
15. Sacral Vertebrae S1-S5 Sacral vertebrae consists of 5 fused vertebrae fully fused by 30 years of age Women sacrum is shorter, wider and more curved Connects the spine to the pelvic girdle at the sacroiliac joint. Sacral canal is continuation of vertebral canal.
16. Sacrum and CoccyxAnt. ViewPost view
17. Coccyx Vertebrae Co1-Co4 Coccyx is Greek for “cuckoo” Consists of 4 fused vertebrae Fuse between 20 and 30 years Tailbone is vestige of tail - Men it points anteriorly - Women it points inferiorly
18. Cervical and Thoracic vertebrae
19. Lumbar vertebrae
20. Additional structures of the vertebral column Intervertebral discs Present between all vertebrae C2- L5/S1; Composed of fibro cartilage Two regions of disc: - nucleus pulposis – central core of disc - annulus fibrosis - outer covering of fibro cartilage Function: -discs permit various movements -provide shock absorbing functions for vertebral column
23. Vertebral Ligaments(1). Anterior and posterior longitudinal ligaments hold vertebral column together along with trunk skeletal muscles -prevent hyper-extension and hyper-flexion of the vertebral column.(2). Shorter ligaments connect adjoining vertebrae together. -There are 3 of these ligaments the ligamentum flavum, the supraspinous ligaments and the interspinous ligaments.
24. Vertebral Ligaments
25. Bony Thorax Consists of ribs attached to the vertebral column and sternum True ribs R1-R7 attach directly to sternum False ribs R8-R10 attach indirectly Two floating ribs R11 & R12 The Sternum consisting of: - manubrium - body - Xiphoid process
26. Bony Thorax
27. Ribs1. true ribs – the first (superiormost) seven pairs of ribs R1-R7 are directly connected to the sternum via costal cartilage. - are called vertebrosternal ribs.2. false ribs – the remaining five pairs of ribs. There are two types of false ribs.  vertebrochondral ribs -- rib pairs #8, #9, and #10 are connected by a single band of costal cartilage to the inferior portion of the sternum. Unlike the first seven pairs of ribs they do not have their own individual attachments.  floating or vertebral ribs – rib pairs #11 and #12 are connected only to the vertebral column, they have no anterior connection to the skeleton.
28. All ribs articulate with vertebral column. The head of the rib articulates at a demifacet on the body of the vertebrae, while the tubercle of the rib articulates at a facet on the transverse process.
29. Sternum “breast plate” Anterior central portion of thorax Only bony attachment of axial skeleton to appendicular skeleton via clavicle. Consists of Manubrium, Body and Xiphoid process Key landmarks: calvicular notches, jugular notch “suprasternal notch”, sternal angle.
30. SternumThe sternal foramen is an anomaly and occurs in ~ 4-10% of the population. It can be mistaken for a bullet puncture in cases of traumatic death.
31. Hyoid bone Lies inferior to the mandible Is not attached to skeleton by bony means Helps movement of base of tongue