132 



DISSECTION OF THE THIGH. 



use on knee 



and hip- 

 joints, 



on pelvis, 



and femur. 



Semttendi- 

 nosus is 

 attached to 

 pelvis and 

 tibia ; 



parts in 

 contact 

 with it ; 



use on 

 knee 



and hip- 

 joints, 



on the 

 pelvis. 



Semimem- 

 branosus 

 reaches from 

 pelvis to 

 tibia ; 



parts around 

 it; 



great sciatic nerve and on the adductor magniis muscle. On the 

 inner side are the semitendinosus and semimembranosus as far as 

 the ham. Its tendon gives an offset to the deep fascia of the 

 limb. 



Action. It can bend the knee if the leg-bones are not fixed, and 

 afterwards rotate out the tibia ; and the long head will extend the 

 bent hip-joint when the knee is straight. 



The leg being supported on the ground, the long head will assist 

 in balancing and erecting the pelvis ; and the short head will draw 

 down the femur so as to bend the knee in stooping. 



The SEMITENDINOSUS (fig. 53, E) is a slender muscle and received 

 its name from its appearance. It arises from the tuberosity of the 

 ischium with the long head of the biceps, and by fleshy fibres from 

 the tendon of that muscle. Inferiorly it is inserted into the inner 

 surface of the tibia, close below the gracilis, and for a similar extent 

 (fig. 68, p. 179). 



This muscle, like the biceps, is partly covered by the gluteud 

 maximus. About its middle an oblique tendinous intersection may 

 be observed. It rests on the semimembranosus, and 011 the internal 

 lateral ligament of the knee-joint. The outer border is in contact 

 with the biceps as far as the lower third of the thigh. As the 

 tendon turns forwards to its insertion, an expansion is continued 

 from it to the fascia of the leg ; and it is attached, with the gracilis, 

 on a level with the tubercle of the tibia, the two being separated 

 from the internal lateral ligament by a bursa. 



Action. If the leg is movable, the muscle bends the knee and 

 rotates inwards the tibia. Supposing the knee-joint straight but 

 the hip-joint bent, the femur can be depressed, and the hip extended 

 by this and the other hamstrings. 



Should the limbs be fixed on the ground, the muscle will assist 

 in balancing the pelvis, or in erecting the trunk from a stooping 

 posture. 



The SEMIMEMBRANOSUS MUSCLE (fig. 53, F) is tendinous at both 

 ends, and receives its name from the membraniform appearance of 

 the upper tendon. The muscle arises from the upper and outer 

 impression 011 the ischial tuberosity (fig. 47, p. 113) ; and it is 

 inserted below into the inner and hinder part of the head of the tibia 

 (fig. 73, p. 191), and from this position one fibrous expansion is sent 

 outwards across the back of the knee-joint to the outer side of the 

 external condyle of the femur, forming thereby the strongest part of 

 the posterior ligament, and another proceeds downwards as a fascial 

 investment over the back of the popliteus muscle (fig. 52, p. 128). 



The muscle is thick and fleshy below, where it bounds the 

 popliteal space. On it lies the semitendinosus, which is lodged, 

 together with the long head of the biceps, in a hollow in the upper 

 tendon ; and beneath it is the adductor magnus. Along the outer 

 border is first the great sciatic, and then the internal popliteal 

 nerve. Between its tendon and the inner head of the gastrocnemius 

 is a large bursa. The insertion of the muscle above described will 

 be dissected with the knee-joint (p. 214). 



