350 THE SPINAL cozr.u.v. 



The smooth places where the articulating processes join 

 are called Facets. 



Observe on each side of the body of the vertebra a facet 

 where the head of the rib articulated. There is also a facet 

 on the transverse process where the tubercle of the rib artic- 

 ulated. 



The first vertebra, the Atlas, has no body. The second 

 vertebra is the Axis. It has a peg, called the Odontoid Process, 

 which represents the body of the atlas. In shaking the head, 

 the atlas, with the head, turns on the axis. In nodding the 

 head, the head simply rocks back and forth on the atlas. It 

 might, therefore, be claimed that it ought to mean more to 

 say "no" than to say "yes/' because in saying "no" one 

 actually puts some " backbone " into it. 



The seven Cervical vertebrae (neck) have holes through 

 their sides, or transverse processes, for the passage of blood 

 tubes. 



The twelve rib-supporting vertebrae are the Thoracic ver- 

 tebras. 



The next five are the Lumbar. The Sacrum is composed of 

 five vertebrae grown together, and the remaining four are com- 

 bined in the Coccyx. 



Let the eye slowly review the whole spinal column, noting 

 what the vertebrae have in common. Note also their differ- 

 ences. 



In most articulated skeletons there are pads of felt be- 

 tween the vertebrae. These take the place of the Inter-ver- 

 tebral Cartilages, which are a form of connective tissue, possess- 

 ing the elasticity of cartilage and the toughness of fibrous 

 connective tissue, such as ligament and tendon. These inter- 

 vertebral cartilages serve both to keep the vertebrae apart 

 and to hold them together. When we bend the shoulders to 

 the right, the right edges of these cartilages are compressed, 



