Ischial- lesser sciatic notch

Medial view (deep surface), right side

Medial view (deep surface), left side

Medial view (deep surface), right and left respectively

The lesser sciatic notch of the ischium forms part of the wall of the lesser sciatic foramen. The remainder of the wall is formed by the ischial spine, the sacrotuberous and sacrospinous ligaments. The lesser sciatic foramen is inferior to the pelvic diaphragm and the ischial spine. This foramen provides communication between the perineum and the gluteal region. The pudendal nerve, internal pudendal vessels, and the nerve that serves the obturator internus muscle pass through this foramen to reach the perineum. Also, the tendon of the obturator internus muscle passes through this foramen to reach the gluteal region of the lower limb.