Muscle
Semitendinosus
Medial hamstring ending in a long tibial tendon
High-yield
It reaches the pes anserinus alongside sartorius and gracilis. Unlike semimembranosus, which attaches behind the medial tibial condyle, semitendinosus continues around toward the upper medial tibial shaft.
Overview
Semitendinosus shares a proximal attachment with the long head of biceps femoris, then runs down the back of the thigh above semimembranosus. Its long distal tendon curves toward the inner upper tibia.
Reference facts
- Origin
- Ischial tuberosity and the shared proximal tendon/aponeurosis with the long head of biceps femoris
- Insertion
- Upper anteromedial tibial shaft as part of the pes anserinus
- Action
- Extends the hip, bends the knee and turns the flexed leg inward
- Innervation
- Tibial division of the sciatic nerve, with L5-S2 commonly used as the hamstring root summary
- Blood supply
- Mainly profunda femoris perforators, with regional inferior gluteal and popliteal muscular contributions
Mnemonic
Follow its long tendon from the back of the thigh around to the inner tibia. At the pes anserinus, semitendinosus is the posterior member beside sartorius and gracilis.
Clinical correlation
Its tendon is one option for an anterior cruciate ligament autograft. Techniques may use semitendinosus alone or combine it with gracilis; graft choice depends on the reconstruction and patient rather than one universal standard.
Frequently asked questions
What does the semitendinosus do?
The semitendinosus extends the hip, bends the knee and turns the flexed leg inward.
What nerve innervates the semitendinosus?
The semitendinosus is innervated by the tibial division of the sciatic nerve, with L5-S2 commonly used as the hamstring root summary.
Where does the semitendinosus attach?
The semitendinosus originates from the ischial tuberosity and the shared proximal tendon/aponeurosis with the long head of biceps femoris and inserts on the upper anteromedial tibial shaft as part of the pes anserinus.
What is the blood supply of the semitendinosus?
Mainly profunda femoris perforators, with regional inferior gluteal and popliteal muscular contributions.