Obturator Nerve, Posterior View

Description

Originating from the anterior divisions of L2 to L4 of the lumbar plexus, the obturator nerve descends along the medial border of psoas major, then tracks inferomedially toward the pelvic brim. From a posterior perspective with the bony pelvis and proximal femora exposed, the sacrum sits midline with the hip bones lateral, and the course of the nerve can be followed as it hugs the inner surface of the ilium before entering the obturator canal at the superior margin of the obturator foramen. Distal to the canal, it divides into anterior and posterior branches separated by obturator externus and adductor brevis, then continues along the medial thigh adjacent to the adductor compartment. Deep and deliberate. Clinically, this relationship to the pelvic ring and obturator foramen is the point. Obturator neuropathy most often presents as medial thigh pain with weakness of hip adduction, and it can follow pelvic fracture, obturator hernia, or surgical dissection during pelvic lymphadenectomy and retropubic approaches where the nerve is at risk near the obturator vessels. The posterior layout also helps clarify why obturator nerve blocks are performed with attention to the obturator canal and why incomplete blocks occur when the anterior and posterior divisions are not both addressed. Designed for gross anatomy teaching of the pelvis and medial thigh, the illustration also suits orthopaedic and pelvic surgery texts discussing the obturator foramen, acetabular and pubic rami fractures, and nerve injury patterns contrasted with the nearby sciatic nerve. It is equally appropriate for pain medicine or regional anesthesia references that need a clear bony landmark view for obturator nerve block technique and expected motor findings. Anatomical accuracy verified by SciePro's Medical Advisory Board.