Semimembranosus (Musculus semimembranosus)
Educational content only — not medical advice.
Anatomy
The deepest hamstring, lying beneath the semitendinosus in the medial posterior thigh. Named for its broad membranous origin from the ischial tuberosity; its tendon inserts into a groove on the medial tibial condyle behind the medial ligament.
Origin & insertion
Origin: ischial tuberosity (superolateral facet). Insertion: groove posterior to the medial tibial condyle, with tendinous expansions to the medial meniscus and tibia.
Action
Knee flexion and medial rotation; hip extension.
Innervation
Tibial nerve — anterior division of the sciatic nerve
Clinical notes
Its tendinous expansions tether the medial meniscus, drawing it posteriorly during flexion — explaining combined medial-ligament and meniscus injuries. In adolescents, its apophyseal origin may avulse at the ischial tuberosity.
Related structures
Educational references
FAQ
What is the role of the Semimembranosus?
The deepest hamstring, lying beneath the semitendinosus in the medial posterior thigh. Named for its broad membranous origin from the ischial tuberosity; its tendon inserts into a groove on the medial tibial condyle behind the medial ligament.
Why is the Semimembranosus clinically important?
Its tendinous expansions tether the medial meniscus, drawing it posteriorly during flexion — explaining combined medial-ligament and meniscus injuries. In adolescents, its apophyseal origin may avulse at the ischial tuberosity.
Source & license
BodyParts3D, © The Database Center for Life Science licensed under CC Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/). license details