Essentials of Anatomy and Physiology

120 The Skeletal System

1 2 3 4 5 6 7 1 2 3 4 5 6 7 8 9

10

11

12

1

2

3

4

5

Coccyx

Sacrum

Lumbar

vertebrae

Thoracic

vertebrae

Cervical

vertebrae

Intervertebral

discs

• Articular surface
  for ilium
  
  
  • 
    
    
    
    • 
      
    
    
    
    
  
  
  
  

Vertebral body

Vertebral

canal

Spinous process

Facet for rib

• Transverse process


• 
  


• 
  

Odontoid process

• Vertebral canal

Spinous process

of axis

Facets of atlas for occipital condyles

D

1st Lumbar

C

7th Lumbar

B

Atlas/Axis

A

Figure 6–10. Vertebral column. (A) Lateral view of left

side. (B) Atlas and axis, superior view. (C) 7th thoracic

vertebra, left lateral view. (D) 1st lumbar vertebra, left lat-

eral view.

QUESTION:Compare the size of the individual thoracic

and lumbar vertebrae. What is the reason for this differ-

ence?

All of the vertebrae articulate with one another in
sequence, connected by ligaments, to form a flexible
backbone that supports the trunk and head. They also
form the vertebral canal, a continuous tunnel (lined
with the meninges) within the bones that contains the
spinal cord and protects it from mechanical injury.
The spinous and transverse processes are projections
for the attachment of the muscles that bend the verte-
bral column. The facets of some vertebrae are small
flat surfaces for articulation with other bones, such as
the ribs with the facets of the thoracic vertebrae.

The supporting part of a vertebra is its body; the

bodies of adjacent vertebrae are separated by discs

of fibrous cartilage. These discs cushion and absorb

shock and permit some movement between vertebrae

(symphysis joints). Since there are so many joints,

the backbone as a whole is quite flexible (see also Box

6–3: Herniated Disc).

The normal spine in anatomic position has four

natural curves, which are named after the vertebrae

that form them. Refer to Fig. 6–10, and notice that the

cervical curve is forward, the thoracic curve backward,