POSTERIOR FEMORAL REGION. 251 



by five openings : the three superior, for the three perforating arteries ; 

 and the fourth, for the termination of the profunda. The fifth is the large 

 oval opening, in the tendinous portion of the muscle, that gives passage 

 to the femoral vessels. 



Relations. By its anterior surface, with the pectineus, adductor brevis, 

 adductor longus, femoral artery and vein, profunda artery and vein, with 

 their branches, and with the posterior branches of the obturator vessels and 

 nerve. By its posterior surface, with the semi-tendinosus, semi-membra- 

 nosus, biceps, and gluteus maximus. By its inner border, with the gra- 

 cilis and sartorius. By its upper border, with the obturator externus and 

 quadratus femoris. 



The GRACILIS (slender) is situated along the inner border of the thigh. 

 It arises by a broad, but very thin tendon, from the body of the os pubis, 

 along the edge of the symphysis, and from the margin of the ramus of the 

 pubes and ischium ; and is inserted, by a rounded tendon, into the inner 

 tuberosity of the tibia, beneath the expansion of the sartorius. 



Relations. By its inner or superficial surface, with the fascia lata, and 

 below, with the sartorius and internal saphenous nerve ; the internal sa- 

 phenous vein crosses it, lying superficially to the fascia lata. By its outer 

 or deep surface, with the adductor longus, brevis, and magnus, and the 

 internal lateral ligament of the knee joint, from which it is separated by a 

 synovial bursa, common to the tendons of the gracilis and semi-tendinosus. 



Actions. The iliacus, psoas, pectineus, and adductor longus muscles 

 bend the thigh upon the pelvis, and, at the same time, from the obliquity 

 of their insertion "1fitirthe~Tesser trochanter and linea aspera, rotate the en- 

 tire limb outwards ; the pectineus and adductors adduct the thigh power- 

 fully ; ancTfrom the manner of their insertion into the linea aspera, they 

 assist in rotating the limb outwards. The gracilis is likewise an adductor 

 of the thigh ; but contributes also to the flexion of the leg, by its attach- 

 ment to the inner tuberosity of the tibia. 



Posterior Femoral Region. 

 Biceps, Semi-tendinosus, Semi-membranosus. 



Dissection.- Remove the integument and fascia on the posterior part 

 of the thigh by two flaps, as on the anterior region, and turn aside the glu- 

 teus maximus from the upper part ; the muscles may then be examined. 



The BICEPS FEMORIS (bis, double, xspaXi}, head) arises by two heads, 

 one by a common tendon with the serni-tendinosus ; the other muscular 

 and much shorter, from the lower two-thirds of the external border of the 

 linea aspera. This muscle forms the outer hamstring, and is inserted by a 

 strong tendon into the head of the fibula ; a portion of the tendon is con- 

 tinued downwards into the fascia of the leg, and another is attached to the 

 outer tuberosity of the tibia. 



Relations. By its superficial or posterior surface with the gluteus maxi- 

 mus and fascia lata. By its deep or anterior surface with the semi-mem- 

 branosus, adductor magnus, vastus externus, the great sciatic nerve, pop- 

 liteal artery and vein, and near its insertion with the external head of the 

 gastrocnemius, and plantaris. By its inner border with the semi-tendi- 

 nosus, and in the popliteal space with the popliteal artery and vein. 



The SEMI-TENDINOSUS, remarkable for its long tendon, arises in common 

 with the long head of the biceps, from the tuberosity of the ischium ; 'he 



