MEDIAL SIDE OF THE THIGH 277 



The fibres which spring from the rami of the pubis and 

 ischium act like the fibres of the other adductor muscles, that 

 is, they adduct the thigh, rotate it laterally, and help to flex 

 the hip joint, but the fibres which arise from the tuberosity of 

 the ischium and are inserted, by tendon, into the adductor 

 tubercle of the femur extend the hip joint. 



Dissection. Detach the adductor magnus from its origin 

 from the pubic and ischial rami, in order that the obturator 

 externus muscle and the obturator artery may be more fully 

 examined. 



M. Obturator Externus. The obturator externus is 

 a flat, fan-shaped muscle, which is placed over the anterior 

 aspect of the obturator foramen of the hip bone. It 

 springs from the medial half of the membrane which closes 

 the foramen, and also from the medial and lower part of its 

 bony margin (Figs. 119, 128). It passes backwards and 

 laterally, below and behind the neck of the femur and the 

 capsule of the hip joint, and ends in a stout tendon which 

 obtains insertion into the trochanteric fossa (Figs. 121, 122). 

 This tendon will be examined in the dissection of the gluteal 

 region. The obturator externus is supplied by the posterior 

 division of the obturator nerve. It is a flexor of the hip joint 

 and an adductor and lateral rotator of the thigh. 



Art. Obturatoria. The obturator artery appears in the 

 thigh through the upper part of the obturator foramen of 

 the hip bone. It at once divides into two terminal branches, 

 which diverge from each other and form an arterial circle 

 upon the obturator membrane, under cover of the obturator 

 externus. The muscle must therefore be detached in order 

 that the vessels may be followed. Both branches give twigs 

 to the neighbouring muscles, whilst the posterior branch 

 sends an articular twig through the acetabular notch into 

 the hip joint. When the joint is opened this twig may be 

 followed, in a well-injected subject, along the ligamentum 

 teres into the head of the femur. 



Mm. Psoas Major and Iliacus. Both the psoas major and 

 the iliacus muscles arise within the abdomen, and they enter 

 the thigh posterior to the inguinal ligament. A tendon 

 appears on the lateral side of the psoas major, and into this 

 the fibres of the iliacus are for the most part inserted. The 

 conjoined tendon of the ilio-psoas is implanted into the lesser 

 trochanter of the femur, but a certain proportion of the fleshy 



i 18 a 



