IKEITABILITY 



105 



much more freedom than there is in the trunk. Move- 

 ment between any two vertebrae is restricted by the unit- 

 ing ligaments, but there are so 

 many vertebras that though each 

 one moves but slightly, the column 

 as a whole is capable of bending 

 considerably (Fig. 62). 



The Shoulder Girdle.— About 

 the spinal column as an axis the 

 other bones are arranged so that 

 the body has a two-sided symmetry. 

 It is surmounted by the head and 

 to it are attached two bony girdles 

 each of which carries a set of ap- 

 pendages (Fig. 63). The shoul- 

 der girdle consists of two shoulder 

 blades which lie one on each side 

 of the back, two collar bones which 

 lie at the base of the neck in front, 

 and the breast bone to which the 

 collar bones are attached. The 

 upper end of the arm bone fits into 

 a shallow cup at the upper outer 

 end of the shoulder blade. 



The Pelvic Girdle.— The pelvic 

 girdle consists of two broad flaring 

 bones joined together by ligaments 

 in front and united to the spine by 

 ligaments in the back. The upper 

 end of the leg bones fits into a hollow 



The Ribs, — The ribs encircle the body and enclose 



Fig. 62.— Side view of the 

 spinal column. (From 

 Martin.) 



