PHYSIOLOGY. 



The pelvis. 



/ 



43. The last division of the body comprehends the upper 



and lower extremities), The upper consist of the shoulder, 

 arm, fore-arm, and hand. (~The bones composing the shoulder 

 are two, the clavicle, or collar bone, and the scapula, or the 

 blade bonej |jThe clavicle, named from its resemblance to a 

 key, resembles the italic s, and extends across the upper part 

 of the chest, from the shoulder to the breast bone, and it 

 serves not only to sustain the upper extremity and connect 

 it with the chest, but also to prevent its falling forward upon 

 the thorax, and to afford a fixed point for steadying the arm 

 in the performance of its various actions. 



44. f The scapula, or shoulder blade, is a large, flat, trian- 

 gular bone placed upon the upper and back part of the chest, 

 and extends from the second to the seventh ribs. It lies em- 

 bedded in muscles, and has no connection with any other 

 bone except the clavicle at a single point. It is separated 

 from the thorax by a double layer of muscles, on which it is 

 placed as on a cushion^ fit serves for the attachment of six- 

 teen muscles which go o the ribs, the bone of the tongue, 

 the arm, the head, and the spine. It thus serves not only as 

 a support, but a fulcrum for every action of the superior 

 extremity. 



