1. The Vertebral Column
The Back Bones

2. Vertebral Column Function
Serves as the central support of the body.
Extends from the skull to the coccyx.
Is formed from 26 irregular bones.
Surrounds and protects the spinal cord.

3. Structure
At birth, the vertebrae has separate bones, but 9 of them eventually fuse. (sacrum and coccyx)
Of the 24 vertebral bones:
7 are cervical (neck) vertebrae
12 are thoracic vertebrae
5 are lumbar (lower back) vertebrae

4. Structure
Single vertebrae are separated by intervertebral disks which are made of dense cartilage. They cushion and absorb impact from motion.
In young people the disks are about 90% water and are spongy and compressible.
In older people, the disks become harder and more dense.

5. Normally, the vertebral column has an S-shape.

6. Primary and Secondary Curvatures
The thoracic and sacral curvature is referred to as primary curvatures, because they were present at birth.
Secondary curvatures developed in the cervical region when the baby begins to hold his head up and in the lumbar region when the baby begins to walk.

7. Abnormal spinal curvatures can sometimes occur:
Kyphosis – a posterior curvature in the thoracic area that usually results from bone demineralization
Lordosis – an exaggerated anterior curvature in the lumbar area (AKA sway back)
Scoliosis – any lateral pull on the spine

10. Typical Vertebral Structure
All vertebrae bones have similar structures. The following features are common to all:
1. body – the disk-like, flattened, weight- bearing part; faces anterior
2. vertebral foramen – the opening through which the spinal cord passes

11. Typical Vertebral Structure
3. transverse process – 2 lateral projections from the vertebral arch (in the thoracic area, ribs articulate here)
4. spinous process – a single projection from the posterior part of the vertebral arch

12. Body
Vertebral foramen
Transverse process
Spinous process

13. Cervical Vertebrae Identified as C1 – C7
Forms the neck region of the spine. The first two bones have special names.

14. The atlas (C1) has no body, has depressions to receive the base of the occipital bone; allows nodding
The axis (C2) has a large upright process that hooks into C1; allows side to side motion

15. Thoracic Vertebrae Identified as T1 – T12
Typical shape, but has a long spinous process that hooks downward
Lateral view looks like a giraffe’s head

16. Lumbar Vertebrae Identified as L1 – L5
Have very large block-like bodies, are the sturdiest of the vertebrae
Has a short spinous process
Lateral view looks like a moose’s head

17. Sacrum and Coccyx The sacrum is formed by the fusion of 5 vertebrae
Has a sacral canal where spinal cord ends
Forms the posterior wall of the pelvis
The coccyx is the tip or “tailbone” made up of 4 fused bones

19. The Bony Thorax
The Rib Cage

20. Bony Thorax Function
Made up of the sternum, the ribs, and the thoracic vertebrae
Referred to as the thoracic cage, it protects the organs of the thoracic cavity:
Heart
Lungs
Major blood vessels

21. The Sternum AKA the “breastbone”
Is attached to the first 7 pairs of ribs
Is formed from the fusion of 3 bones:
manubrium
body
xyphoid process
Manubrium
Body
Xyphoid process

23. Ribs There are 12 pairs of ribs (both ♂ and ♀)
True ribs – ribs 1 -7, attach to the sternum with costal cartilage
False ribs – ribs either attach indirectly to the sternum with shared cartilage, or are not attached at all
Floating ribs – the last 2 pair of false ribs, are not attached to the sternum at all

24. The Bony Thorax
True Ribs
False Ribs
Floating Ribs

25. Name these parts: