LAMENESS IN THE FORE-LEG. 27 



joiut is flexed, the flexor muscles are tightened; extension 

 of that joint is followed by tightening of the extensor 

 muscles of the foot, and consequently extension of the 

 phalangeal articulations. The action of the swinging leg 

 takes place as follows : at the moment the supporting leg 

 has finished its work it points obliquely downward and 

 backward ; now the weight borne by the one supporting leg is 

 transferred to the other one, the strained tendons and 

 aponeuroses of the first leg are relieved, the flexors and 

 their check ligament become slackened, and the phalanges 

 advance ; this is partly brought about by the action of the 

 flexors, greatly assisted by the elasticity of the fascine of 

 the fore-arm ; now the mastoido-humeralis and some of the 

 pectoral muscles also act, the extensors of the shoulder joint 

 and flexors of the elbow joint, principally the biceps brachii, 

 coraco-humeralis, antea-spinatus muscles, and the leg swings 

 forward. Thus the first half of the pendulum-like motion 

 of the swinging leg is made. While the muscles moving the 

 scapula and those extending the shoulder joint continue to 

 act, the other joints are extended. A gradually increasing 

 flexion of all joints from the elbow joint downward 

 accompanies the first half of the swinging leg. The second 

 half of the forward stride shows extension of all joints of the 

 leg. The above indicates that the function of the swinging 

 leg depends chiefly on the action of the muscles, the first 

 part of the forward stride on the muscles of the shoulder, 

 mastoido-humeralis, biceps brachii, coraco-humer.ilis and 

 "^-ntea-spinatus ; in the second half, the olecranian muscles 

 and extensors of the fore-arm assist the advancement of ths 

 leg b}^ extending all joints, and gradually change the swinging 

 leg into the supporting leg. In the supporting leg the 

 muscular elements are more or less at rest, being 



