452 MUSCLES. 



cilis, and is generally divided into two slips, one above the 

 other. 



Between its origin, that of the long head of the biceps, and 

 the semimembranosus, there is a bursa : one or more are like- 

 wise found between its tendon below, that of the sartorius, of 

 the gracilis, and the internal lateral ligament of the knee. 



It flexes the leg on the thigh.* 



The Semimembranosus, 



Is at the inner side of the thigh ; its upper part is concealed 

 by the semitendinosus and the origin of the long head of the 

 biceps, and below it projects between these two muscles. It is 

 in contact with the posterior surface of the adductor magnus. 



It arises, by a thick round tendon, from the exterior upper 

 part of the tuberosity of the ischium, which tendon soon be- 

 comes flattened, and sends off the muscular fibres obliquely 

 from its exterior edge to a corresponding tendon below. The 

 latter passes behind the internal condyle and the head of the 

 tibia, and despatches a thin aponeurotic membrane under the 

 inner head of the gastrocnemius, to cover the posterior part of 

 the capsule of the knee joint, and to be fastened to the external 

 condyle. 



It is inserted, by a round tendon, into the inner and back 

 part of the head of the tibia, just below the joint. The unfa- 

 vourable insertion of this muscle is compensated for by the 

 multitude of its fibres, which gives it a great increase of 

 strength. 



A bursa exists between its tendon above and the quadratus; 

 another exists between its tendinous termination, the internal 

 head of the gastrocnemius, and the capsule of the knee. 



It flexes the leg on the thigh. 



SECT. III. MUSCLES OF THE LEG. 



These muscles are situated anteriorly, posteriorly, and ex- 

 ternally. 



* Varieties. Sometimes it is divided into three sections by two transverse 

 tendinous lines. 





