20 



THE HUMAN BODY. 



a body and an arch. They have projections called pro- 

 cesses, to which muscles are attached. When they are 

 joined in position, the arches to- 

 gether constitute the spinal canal, 

 and the bodies form a solid col- 

 umn for support. Between the 

 bodies are cushions of a tough and 

 elastic substance called fibre-car- 

 tilage. Each is about one-fourth 

 of an inch thick, and is firmly 

 united to the bone above and 

 below. They serve as springs in 

 the column, and allow a twisting 

 motion. 



Fig. 4. 



A VERTEBRA. 1. Body. 2. Pro- 

 3. Spinal canal. 



E- o 



The sacrum is a wedge-shaped 

 bone, which fits in between the 

 hip-bones. 



The coccyx is the end of the column, and is a small, 

 curved bone, commonly in two or more pieces, which are 

 united by joints. 



