Unlike in the upper limb where most structures pass between the neck and limb through a single axillary inlet, in the lower limb, there are four major entry and exit points between the lower limb and the abdomen, pelvis, and perineum (Fig. 6.14). These are: the gap between the inguinal ligament and pelvic bone, the greater sciatic foramen, the obturator canal (at the top of the obturator foramen), and the lesser sciatic foramen.