146 DESCRIPTION OF THE SKELETON. 



carpal bones/ and phalanges g, forming the wrist, 

 hand, and fingers. 



The scapula is the broad flat bone lying at the 

 upper part* of the back, familiarly known as the 

 shoulder-blade, and so troublesome to many young 

 ladies by its unseemly projection. It serves to 

 connect the arm with the trunk of the body, and 

 gives origin to many of the muscles by which the 

 former is put in motion. The collar-bone y extends 

 from the breast-bone outwards to the scapula. Its 

 chief use is to prevent the arms from falling for- 

 ward in front of the body ; and hence it is wanting 

 in the lower animals, whose superior extremities are 

 much closer to each other than those of man. 



The humerus or arm-bone b is adapted by a kind of 

 ball and socket joint to a corresponding surface in 

 the scapula, and hence enjoys great latitude of mo- 

 tion, and is somewhat liable to dislocation. The 

 radius and ulna de, constituting the forearm, are con- 

 nected with the humerus by a hinge-like joint, which 

 admits readily of flexion and extension, but not of 

 rotation ; and as the articulation is of a peculiar con- 

 struction, it is rarely dislocated. The movements 

 of pronation and supination, or turning round the 

 hand, are effected, not by the elbow-joint, but by the 

 radius d moving upon the ulna e, by means of joints 

 formed for this purpose. The wrist and finger 

 joints are too complicated to admit of explanation 

 here. 



The lower extremities consist of the osfemorisor 

 thigh-bone z, the patella or knee-pan /, the tibia m 

 and fibula n, or leg bones ; and the tarsal and meta- 

 larsalbones 0, and phalanges p, composing the ankle, 

 foot, and toes. 



The thigh-bone i is articulated by means of a large 

 round head deeply sunk into a corresponding hollow 

 in the pelvis at A, freedom of motion being thus 

 combined with great security. The thigh may be 

 moved backwards and forwards as in walking ; and 



