2i 4 INFERIOR EXTREMITY 



is a gap between the two portions of the muscle, and is 

 situated in the distal third of the thigh. 



The adductor magnus has a double nerve supply. The 

 fibres which spring from the pubic arch are supplied by the 

 posterior branch of the obturator nerve. Those which arise 

 from the ischial tuberosity are supplied by the sciatic nerve. 



Dissection, The adductor magnus should now be detached from its 

 origin, 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 (Fig. 81, p. 212). It proceeds posteriorly 

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

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

 obtains insertion into the fossa trochanterica (Fig. 78, p. 

 209). This tendon will be examined in the dissection of the 

 glutaeal region. The obturator externus is supplied by the 

 posterior division of the obturator nerve. 



Art. Obturatoria (Obturator Artery). 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. This 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 incisura acetabuli 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 Magnus and Iliacus. These muscles arise 

 within the abdomen and enter the thigh posterior to the 

 inguinal ligament. A tendon appears on the lateral side of 

 the psoas magnus, 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 fibres of the iliacus obtain 

 direct insertion into the body of the femur distal to that 

 prominence (Fig. 78, p. 209). 



