LECTURE III. 123 



dergoes no change ; but if the hands be 

 brought either forwards or backwards, the 

 weight proportionately preponderates, and 

 the whole body moves upon the base of the 

 vertebral column. The extent of motion 

 of the shoulder joint in the directions that 

 have been mentioned, greatly augments the 

 sphere of motion of the arm and hand. 



The joint of the shoulder is kept from 

 approaching the front of the chest by the 

 collar bone, which is nearly strait, though 

 projecting a little forwards towards its 

 middle, so as to give a slight convexity of 

 outline to the top of the chest and bottom 

 of the neck. The end of the collar bone, 

 which rests upon the sternum, is bulky, and 

 of a somewhat triangular form, but it rests 

 in a thick bed of cartilage, which prevents 

 its shape from being apparent. The scapu- 

 lar end of the collar bone is flat, and con- 

 nected in an horizontal direction with a 

 like-shaped projection of the blade bone, 

 which forms the end of the shoulder. 



When the trunk is bowed forwards, the 



