Semimembranosus, Gross Anatomy

Description

Posterior lower-limb anatomy is presented in a male specimen with the semimembranosus highlighted along the posteromedial thigh. Proximally, its broad tendon arises from the superolateral impression of the ischial tuberosity, lying deep and medial to the biceps femoris and deep to the more cordlike semitendinosus. Distally, the muscle belly narrows into a tendon that passes posterior to the medial femoral condyle and inserts on the posterior aspect of the medial tibial condyle, with expansions blending into the oblique popliteal ligament over the posterior knee capsule and bordering the medial side of the popliteal fossa. This posterior perspective matters because semimembranosus is a common pain generator at the posteromedial knee, where its insertion, capsular expansions, and the semimembranosus bursa sit close to the medial collateral ligament, the posterior horn of the medial meniscus, and the pes anserinus region (often confused in referral patterns with semitendinosus and gracilis). Small changes in tendon course with knee flexion alter its relationship to the medial gastrocnemius and popliteal vessels, which is why posteromedial corner injuries, hamstring avulsions, and semimembranosus tendinopathy can present with deep, activity-related pain that mimics meniscal pathology. A key landmark. Use this artwork for teaching hamstring compartment anatomy in gross anatomy, kinesiology, or orthopedic physical examination labs, and for illustrating posteromedial knee pain, proximal hamstring injury patterns, or surgical discussions of the oblique popliteal ligament and posterior capsule in sports medicine and arthroscopy publications. Anatomical accuracy verified by SciePro's Medical Advisory Board.