Pectineus

Description

Centered in the superomedial anterior thigh, the pectineus lies deep to the fascia lata and forms a flat, quadrangular muscle that bridges the pelvis to the proximal femur. Its fibers arise from the pecten pubis and superior ramus of the pubis, then run inferolaterally to insert on the pectineal line of the femur just inferior to the lesser trochanter. Laterally, the iliopsoas approaches the femur toward the lesser trochanter, while medially the adductor longus and adductor brevis occupy the medial compartment. The femoral artery and vein descend anterior to the pectineus at the base of the femoral triangle, separated from its deep surface by fascia and the femoral sheath. A key landmark. Clinical work in the groin often hinges on this relationship: pectineus contributes to the floor of the femoral triangle, so the vessel bundle you palpate or cannulate is immediately superficial to it and the adjacent pectineal fascia. During exposure for common femoral endarterectomy, femoral hernia repair, or lymph node dissection, the pectineal (Cooper’s) ligament on the superior pubic ramus sits just superior and medial to the muscle’s origin, and the lacunar ligament lies close by, a tight space where bleeding and nerve irritation become real risks. Variant innervation matters too, since pectineus may receive a branch from the femoral nerve with additional input from the obturator nerve, which can muddy localization of groin pain and adductor weakness. Orthopaedic anatomy teaching benefits from this view when distinguishing hip flexors from adductors and when tracing the transition from pelvis to femur at the pectineal line. It also fits surgical atlases, emergency medicine training on femoral vascular access, and radiology captions that orient ultrasound or CT anatomy at the femoral triangle. Anatomical accuracy verified by SciePro's Medical Advisory Board.