106 



PHYSIOLOGY 



the heart and lungs. They are united to the vertebrae 

 behind and to the breast bone in front and furnish sup- 



Fig. 63.— The skeleton of the trunk seen from the front, showing the shoulder girdle 

 composed of the collar bone(C) and the scapula (5), and the pelvic girdle com- 

 posed of the sacrum and the innominate bones (Oc). (From Martin.) 



port for the shoulder girdle and the arm muscles. As 

 they are not rigidly fastened they are capable of move- 

 ment which aids breathing (Fig. 64). 



Appendages. — The legs and arms are each divided 



