Semimembranosus Muscle

Semimembranosus

Action – flexion of knee, extension of hip
medial rotation of knee (tibia) when knee is flexed

Origin – ischial tuberosity

Insertion – medial tibial condyle (posterior medial aspect)

Nerve – sciatic nerve, tibial division (L5, S1, S2)

Semimembranosus is one of three hamstring muscles. It is medial (towards the inside of your thigh) and lies below another hamstring muscle – semitendinosus. It can be felt when tensing the hamstrings deep to the semitendinosus tendon.

Semimembranosus is the largest hamstring muscle. In some people the distal fibres blend into the proximal fibres of the gastrocnemius medial head.

The hamstring group are used when walking, running or lifting from the ground with straight legs. Semimembranosus also plays an important role in knee stability.

Injury or dysfunction in the semimembranosus muscle can cause pain or discomfort in the back of the thigh, lower buttock or inner knee regions, and sometimes can be associated with low back pain. Common injuries include hamstring strains/tears, particularly when performing ballistic activity (sprinting, kicking, hurdling) without proper warm-up.

Hip or knee joint pain referral or nerve related pain, may need to be differentiated from injury to the hamstrings. Consult your local Myotherapist to help with differentiating.

Strengthening

Standing upright with feet shoulder width apart, hold a barbell, kettlebell or pair of dumbbells of an appropriate weight with an overhand grip in front of your thighs with straight arms. With knees slightly bent and keeping a straight back, hinge forward at the hips and lower the weights while keeping them close to your legs until about the mid shin level. Pause, then squeeze your glutes to bring the hips forward and return to the starting upright position.

Stretching

Sitting on the ground with one leg out in front and the other bent out to the side. With your foot on the inside of the straight legs knee. Lean forward (keeping a straight/neutral back) to feel a nice stretch down the back of the straight leg.

Rotate legs outwards to favour the medial hamstrings (semitendinosus and semimembranosus). You can use a towel to make the stretch stronger.

Self Treatment

Sitting on a firm table or chair with your legs hanging off the edge. Place a ball under your right hamstring, where you feel it is tight. Slowly lift your foot, extending your knee a few times. Then move the ball onto the next tender spot along the muscle. Alternatively, not extending the knee, you can use your hands and body weight to push your thigh onto the ball with more pressure. When you feel the discomfort dissipate, move onto the next spot.