252 



SEMI-MEMBRANOSUS. 



Fig. 131.* 



two muscles being closely united for several inches below their origin, [t 

 is inserted into the inner tuberosity of the tibia. 



Relations. By its superficial surface with the glu- 

 teus maximus, fascia lata, and at its insertion with the 

 synovia! bursa which separates its tendon from the ex- 

 pansion of the sartorius. By its deep surface with the 

 semi-membranosus, adductor magnus, internal head 

 of the gastrocnemius, and internal lateral ligament of 

 the knee joint, the synovial bursa common to it and 

 the tendon of the gracilis being interposed. By its 

 inner border with the gracilis ; and by its outer border 

 with the biceps. 



These two muscles must be dissected from the tube- 

 rosity of the ischium, to bring into view the origin of 

 the next. 



The SEMI-MEMBRANOSUS, remarkable for the tendi- 

 nous expansion upon its anterior and posterior surface, 

 arises from the tuberosity of the ischium, in front of 

 the common origin of the two preceding muscles. It 

 is inserted into the posterior part of the inner tuberosity 

 of the tibia ; at its insertion the tendon splits into three 

 portions, one of which is inserted in a groove on the 

 inner side of the head of the tibia, beneath the internal 

 lateral ligament. The second is continuous \vith an 

 aponeurotic expansion that binds down the popliteus 

 muscle, the popliteal fascia ; and the third turns up- 

 wards and outwards to the external condyle of the 

 femur, forming the middle portion of the posterior 

 ligament of the knee joint (ligamentum posticum 

 Winslowii). 



The tendons of the last two muscles, viz. the semi-tendinosus and 

 semi-membranosus, with those of the gracilis and sartorius, form the 

 inner hamstring. 



Relations. By its superficial surface with the gluteus maximus, biceps, 

 semi-tendinosus, fascia lata, and at its insertion with the tendinous expan- 

 sion of the sartorius. By its deep surface with the quadratus femoris, ad- 

 ductor magnus, internal head of the gastrocnemius, the knee joint, from 

 which it is separated by a synovial membrane, and the popliteal artery 

 and vein. By its inner border with the gracilis. By its outer border with 

 the great ischiatic nerve, and in the popliteal space with the popliteal 

 artery and vein. 



If the semi-membranosus muscle be turned down from its origin, the 

 student will bring into view the broad and radiated expanse of the adduc- 

 tor magnus, upon which the three flexor muscles above described rest. 

 Actions. These three hamstring muscles are the direct flexors of the 



*Tbe muscles of the posterior femoral and gluteal region. 1. The gluteus merlins. 

 2. The gluteus maximus. 3. The vastus externtis, covered in by fascia lata. 4. The 

 long head of the biceps. 5. Its short head. 6. The semi-tendinosus. 7. The semi 

 :nernbranosus. 8. The gracilis. 9. A part of the inner border of the adductor magnus. 

 10. The erige of the sartorius. 11. The popliteal space. 12. The gastrocnemius 

 muscle; its two heads. The tendon of the biceps forms the outer hamstring; and the 

 sartorius with the tendons of the gracilis, semi-tendinosus, and semi-membranosus, the 

 inner hamstring. 



