MUSCLES OF THE THIGH. 451 



The Sleeps Flexor Cruris, 



Constitutes the outer hamstring, and is situated on the pos- 

 terior outer part of the thigh; it arises by two heads. The 

 first, called the long head, has an origin, in common with the 

 semi-tendinosus, from the upper back part of the tuberosity of 

 the ischium, by a short tendon, which, in its descent, is changed 

 into a thick fleshy belly. The other, called the short head, 

 arises, by an acute fleshy beginning, from the linea aspera just 

 below the insertion of the glutaeus magnus, and this origin is 

 continued along the lower part of the linea aspera and from 

 the ridge leading to the external condyle. 



A thick tendon is gradually formed on the outside of the 

 muscle, which, descending along the external face of the ex- 

 ternal condyle, is inserted into the superior face of the head of 

 the fibula at its point. A bursa is found between this tendon 

 and the external lateral ligament of the knee. 



This muscle flexes the leg on the thigru* 



, T/i e Se m iten dinosus, 



Is on the inside of the thigh, between the biceps andgracilis; 

 it is superficial, being immediately under the fascia, and arises, 

 in common with the biceps, from the back part of the tuberosi- 

 ty of the ischium; it also adheres, for three or four inches, to 

 the inner edge of the tendon of this the long head of the 

 biceps. 



About four inches above the knee it terminates in a long 

 round tendon, which passes behind the internal condyle and 

 the head of the tibia, and is reflected forwards to be inserted 

 into the side of the tibia, just below its tubercle and very near 

 it, being lower down than the insertion of the' tendon of the 

 gracilis. Its insertion is much connected with that of the gra- 



* Varieties. Sometimes the short head does not exist, thereby affording an 

 analogy with animals. Sometimes there is a third head, but more delicate, which 

 comes either from the tuber of the ischium or from the long head, and descend- 

 ing along the back of the leg, runs into the tendo-aehillis, corresponding there- 

 by with the arrangement of mammiferous animals.. 



