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Lesser Sciatic Notch

incisura ischiadica minor

The lesser sciatic notch is a smaller notch below the ischial spine on the posterior border of the ischium, between the ischial spine superiorly and the ischial tuberosity inferiorly. It is converted into the lesser sciatic foramen by the sacrospinous and sacrotuberous ligaments. The obturator internus tendon exits the pelvis and turns sharply around the lesser sciatic notch, changing direction by approximately 90 degrees to reach the greater trochanter.

Region: Pelvis & Hip

Clinical Relevance

Clinical Notes

The lesser sciatic notch is the pulley around which the obturator internus tendon hooks to reach the trochanteric fossa, making it analogous to the trochlea of the superior oblique in the eye. The pudendal nerve and internal pudendal artery exit the pelvis through the greater sciatic foramen, encircle the sacrospinous ligament, and re-enter the perineum through the lesser sciatic foramen — explaining why sacrospinous ligament fixation for vault prolapse risks pudendal nerve injury at the lesser sciatic notch level.

Pathology

Common Injuries & Conditions

Pudendal Nerve Injury at Sacrospinous Ligament

Sacrospinous ligament colpopexy for vaginal vault prolapse risks injury to the pudendal nerve as it encircles the lesser sciatic notch adjacent to the ligament fixation suture, producing perineal pain and sexual dysfunction managed by placing sutures lateral to the ischial spine and no deeper than 2 cm from the ligament's ischial attachment.