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 Vertebrae
Atlas
Axis

9. Atlanto/axial joint Atlas (C1vertebra) Articular facet of dens
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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 Coccyx
Ant. View
Post 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

19. Cervical and Thoracic vertebrae

20. Lumbar vertebrae

21. 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

22. Vertebra and vertebral disc
Spinous process
Articular facet
Vertebral foramen
Transverse process
Body
Nucleus pulposus
Annulus fibrosus

23. Herniated Intervertebral discs
Spinal cord
Dorsal root ganglion

24. 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.

25. Vertebral Ligaments

26. 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

27. Bony Thorax

28. Ribs
1. 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.

29. All ribs articulate with vertebral column
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.

30. 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.

31. Sternum
The 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.

32. Hyoid bone Lies inferior to the mandible
Is not attached to skeleton by bony means
Helps movement of base of tongue

33. Hyoid bone