Obturator nerve

The obturator nerve arises from the ventral divisions of the second, third, and fourth lumbar nerves; the branch from the third is the largest, while that from the second is often very small.

It descends through the fibers of the Psoas major, and emerges from its medial border near the brim of the pelvis; it then passes behind the common iliac vessels, and on the lateral side of the hypogastric vessels and ureter, which separate it from the ureter, and runs along the lateral wall of the lesser pelvis, above and in front of the obturator vessels, to the upper part of the obturator foramen.

Here it enters the thigh, through the obturator canal, and divides into an anterior and a posterior branch, which are separated at first by some of the fibers of the Obturator externus, and lower down by the Adductor brevis.