What is the semimembranosus muscle?
The semimembranosus muscle is a muscle located in the back of the thigh. It is one of the three muscles comprising the hamstrings group, which also includes the biceps femoris and the semitendinosus. The semimembranosus muscle originates on the ischial tuberosity of the pelvis and inserts on the medial condyle of the tibia. It is primarily responsible for knee flexion and medial rotation of the lower leg and also plays a role in hip extension. It is located deep to the semitendinosus muscle and it is the most medial muscle of the hamstrings group. (1)
Origin, insertion and function
Origin:
- Ischial tuberosity of the pelvis
Insertion:
- Medial condyle of the tibia
Function:
- Knee flexion
- Medial rotation of the lower leg
- Hip extension
- Assists in stabilizing the knee joint
The semimembranosus muscle is located deep in the back of the thigh, it starts in the pelvis and attaches to the shin bone. It is the most medial muscle of the hamstrings group, which helps in bending the knee and turning the lower leg inwards. It also assists in straightening the hip.
Common signs of a weak semimembranosus muscle
Here are a few signs that your semitendinosus muscle is weak:
- Difficulty or pain during knee flexion exercises
- Difficulty or pain during hip extension exercises
- Difficulty or pain during medial rotation of the lower leg
- Weakness or instability in the knee joint
- Increased risk of knee or hamstring injury
- Difficulty in walking or running
- Pain in the back of the thigh
- muscle imbalances in the thigh
- Poor posture or gait
- Weakness or imbalance when compared to other muscles in the hamstrings group
- Difficulty performing activities that require knee flexion, medial rotation and hip extension.
Exercises that strengthen the semimembranosus
Here are some exercises that will help make your semimembranosus muscle stronger:
Hamstring Curl:
- Lie face down on a hamstring curl machine with your legs extended.
- Flex your knees and curl your heels towards your glutes, keeping your hips on the pad.
- Slowly lower your legs back to the starting position.
Stiff-Legged Deadlifts:
- Stand with your feet hip-width apart, holding a barbell or dumbbells in front of your thighs.
- Keep your knees slightly bent and hinge forward from the hips, lowering the weight towards your toes.
- Keep your back straight and abs tight.
- Slowly return to the starting position.
Glute Bridge:
- Lie on your back with your knees bent and your feet flat on the floor.
- Drive your hips upward, squeezing your glutes as you lift your hips towards the ceiling.
- Lower your hips back to the starting position.
Single-Leg Deadlifts:
- Stand on one leg and hinge forward from the hip, keeping the other leg lifted behind you.
- Reach towards the ground with the weight held in front of your thigh.
- Slowly return to the starting position.
Seated Leg Curl:
- Sit on a leg curl machine with your legs extended.
- Flex your knees and curl your heels towards your glutes.
- Slowly lower your legs back to the starting position.
Swiss ball leg curl:
- Lie face down on a swiss ball with your legs extended behind you, with your feet resting on the floor.
- Flex your knees and curl your heels towards your glutes, keeping your hips elevated on the ball.
- Slowly lower your legs back to the starting position.
It’s important to note that you should always consult a healthcare professional before starting any new exercise program, and to always use proper form and technique when performing exercises.