Chap. V] THE SKELETON 65 



Cervical, in the neck 7 



Thoracic, in the thorax 12 



Lumbar, in the loins 5 



Sacral, in the pelvis 5 



Coccygeal, in the pelvis ..... 4 



The vertebrae in the three upper portions of the spine are 

 separate and movable throughout the whole of life, and are known 

 as true vertebrse. Those found in the sacral and coccygeal re- 

 gions are, in the adult, firmly united, so as to form two bones, five 

 entering into the upper bone, or sacrum, and four into the ter- 

 minal bone of the spine, or coccyx. They are known as false 

 vertebrae, and on account of their union the number of vertebrae 

 in the adult is twenty-six. The bodies of the vertebrae are piled 

 one upon another, forming a strong, solid pillar, for the support 

 of the cranium and trunk, the arches forming a hollow cylinder 

 behind for the protection of the spinal cord. Viewed from the 

 side, it presents four curves which are alternately convex and 

 concave. The two concave ones are called primary curves because 

 they exist in foetal life 



and are designed for spinous rrocr., i'"^^CC' 



the accommodation 1\*^^~ ^ *' 



of viscera. The other L^^ "' m 



two are called second- 

 ary or compensatory 

 curves because they AHicuiar./ ^ 



Process ~ ))!» miiir 



enable the child to as- \ m 



sume the erect atti- Trausverse^:^/ ^im\\<i '^^.^^m 



1 Process , 



tude. 



The vertebrae. — 



Each vertebra con- ^o'* 



sists of two essential Fig. 42. — A Ckrvical Vertebua. 



parts, an anterior 



solid portion or body, and a posterior portion or arch. Each 

 arch has seven processes : four articular, two to connect with bone 

 above, two for bone below ; two transverse, one at each side, and 

 one spinous process, projecting backward. 



Cervical vertehros. — In the cervical region of the vertebral col- 

 umn the bodies of the vertebrae are smaller than in the thoracic, 

 but the arches are larger. The spinous processes are short, and 



F 



