Obturator Internus, Gross Anatomy

Description

Arising from the pelvic (internal) surface of the obturator membrane and the surrounding bony margins of the obturator foramen, the obturator internus is rendered as a thick muscular sheet lining the lateral wall of the male pelvis. Its fibers converge posteriorly and inferiorly toward the lesser sciatic notch, where the tendon makes a sharp turn to exit the pelvis and course laterally toward the greater trochanter of the proximal femur. Adjacent landmarks in this lateral pelvic view include the ilium and ischium, the sacrum posteriorly, the lower lumbar vertebrae superiorly, and the femoral head seated in the acetabulum. Spatially, the muscle lies medial to the hip joint capsule while its tendon passes posterior to the joint on its way to the femur. Understanding obturator internus anatomy matters because it is both a deep hip external rotator and a key reference in peritrochanteric pain syndromes often grouped under deep gluteal pain, where obturator internus and the obturator internus bursa can be symptomatic and mistaken for intra-articular hip pathology. That right-angle bend at the lesser sciatic notch is the mechanical hinge point. Pelvic surgeons also use the obturator internus as a landmark along the lateral pelvic wall during transobturator approaches and when orienting to the ischiorectal fossa, where inadvertent deviation can place the pudendal neurovascular bundle at risk near the ischial spine. Ideal for gross anatomy teaching on the pelvis and hip, this artwork supports lecture slides, dissection guides, and atlas plates that need a clear lateral relationship between obturator internus, the acetabulum, and the proximal femur. It also fits orthopedic and sports medicine materials discussing deep external rotators, hip stability, and extra-articular sources of hip pain. Anatomical accuracy verified by SciePro's Medical Advisory Board.