Semimembranosus is the most medial of the three hamstring muscles. Chronically tight hamstrings are often a contributary factor to lower back pain and knee pain.
- Ischial tuberosity.
- Posterior part of the medial condyle of the tibia.
- Hip extension.
- Knee flexion.
- Internal rotation of the hip when the knee is flexed.
- Tibial part of the sciatic nerve.
- Bending the knee to step over something.