35 



sattorius and the pectineas (PI. V, 63). Note the relation of this gland 

 to the large artery (A. femoraHs) beneath it and to the inguinal ligament. 

 Dissect between the pectineus and the adductor magnus, on one side, and 

 the deep inguinal lymph gland and the A. and V. femoralis, on the other. 

 Transect the pectineus a little below its middle and draw aside the distal 

 portion. Carefully remove any connective tissue or fat from the space 

 between the pectineus and the adductor magnus and find the small nerves 

 that enter each of these muscles. Dissect between the adductor magnus 

 and the semimembranosus; transect the adductor magnus close to its 

 pelvic attachment and draw up the muscle sufficiently to expose the M. 

 obturator externus which is directly beneath the proximal portion of the 

 adductor magnus. Find the A. obturatoria (and large vein) where it emerges 

 from beneath the posterior border of the M. obturator externus, close to 

 the ventral surface of the ischiiim. The posterior portion of the M. 

 obturator externus must now be cut close to its origin and drawn aside in 

 order to expose the A. obturatoria, after it passes through the obturator 

 foramen. About 5 cm. from the posterior edge of the foramen the artery 

 gives off a large branch which runs along the ventral surface of the ischium 

 to the ischial arch where it divides into several branches, of which one goes 

 to the crus penis close to its attachment to the ischium. The extrapelvic 

 portion of the A. obturatoria also gives off a branch to the ventral surface 

 and one to the dorsal surface of the penis. About 5 cm. peripheral to these 

 two branches a much larger branch is given off to the semimembranosus. 

 Further dissection of the obturator artery must be deferred until the over- 

 lying muscles have been dissected. 



N. obturatorius (Pl.V, 49; PI, VII, 16) originates from the 4th and 5th lumbar 

 nerves; frequently however, it receives a branch from the 6th lumbar 

 nerve. The nerve extends directly to the anterior part of the obturator 

 foramen. It lies just beneath the peritoneum and for some distance accom- 

 panies the obturator artery and vein; the nerve and blood-vessels then 

 diverge from each other, the nerve passing through the anterior part of 

 the obturator foramen and the blood-vessels through the posterior part. 

 Reflect the proximal portion of the M. gracilis and the large branch of the 

 N. obturatoris that supphes it will be seen on the proximal portion of the 

 muscle extending transversely toward its posterior border. Upon drawing 

 aside the proximal portion of the M. pectineus the branches of the N. 

 obturatorius to it and to the adductor magnus may be seen. Upon 

 drawing the adductor magnus from the obturator externus the branch 

 of the obturator nerve that passes through the M. obturator externus, 

 near its anterior border, and enters the adductor magnus, may be seen. 



