What does hamstring muscle do

You probably talk about these muscles all the time, but you may not fully understand where they are or what they do. The hamstrings include three large muscles that run along the back of your thighs. They extend from your pelvis to the top of the bones of your lower leg. The hamstring muscles -- including the biceps femoris, semimembranosus and semitendinosus -- play an important role in activities such as walking, running and jumping.

The hamstrings function to bend your knees and move your hips backward. The main function of your hamstrings is to bend your knees. This movement is performed during daily activities such as walking, running, climbing stairs and jumping. Your hamstrings also help rotate your lower leg.

Two hamstrings attached to the inside of your knee rotate your lower leg inward. The third hamstring, attached to the outer border of your knee, rotates your lower leg outward.

Mild hamstring strains can be treated at home. But you should see a doctor if you can't bear any weight on your injured leg or if you can't walk more than four steps without significant pain. The hamstring muscles are a group of three muscles that run along the back of your thigh from your hip to just below your knee.

These muscles make it possible to extend your leg straight behind your body and to bend your knee. When any one of these muscles stretches beyond its limit during physical activity, injury can result.

Returning to strenuous activities before your hamstring muscles are completely healed might cause an injury recurrence. As part of an overall physical conditioning program, regular stretching and strengthening exercises can help minimize your risk of hamstring injury.

Try to be in shape to play your sport; don't play your sport to get in shape. If you have a physically demanding occupation, regular conditioning can help prevent injuries.

Ask your doctor about appropriate conditioning exercises. Mayo Clinic does not endorse companies or products.

Advertising revenue supports our not-for-profit mission. This content does not have an English version. Become acquainted with each of the hamstring muscles , including where they attach and what they do. The hamstrings are a group of four muscles: long head of the biceps femoris, short head of the biceps femoris, semitendinosus, and semimembranosus. Each hamstring crosses two joints—the hip and the knee.

This means when they contract they can either take your lower extremity back behind you called hip extension or bend the knee called knee flexion. The biceps femoris muscle is one of the big, long muscles at the back of your thigh. The other one is the semitendinosis; the biceps femoris is lateral, or toward the outside relative to the semitendinosis. The biceps femoris has two heads—a long and a short. At the hip, both the long and short heads rotate the thigh outwardly and extend it backward.

At the knee, they flex and laterally rotate the joint. Of all the hamstring muscles, the biceps femoris is the biggest contributor to hip extension.

The long head of the biceps femoris originates on the inner side of your sitting bones, which are little knobs of bone that are technically called the ischial tuberosities. The ischial tuberosities are located on the underside of your pelvis. You likely can feel them when you sit down. The short head of the biceps femoris originates on three places on the femur i.

Note that the short head of the biceps femoris is the only part of the hamstring muscle group that does not cross two joints. It's actually missing in some people. Both the long and short head of the biceps attach on the lower leg, also in three places: The head of the fibula bone, the outer called lateral condyle of the tibia bone, and the fascia of the leg.

The multitude of attachment sites on the lower leg may make for more tears here than in the other hamstring muscles. The semitendinosus is another long, big hamstring muscle. At first glance, it is situated medially, or toward the inside of the back of the thigh, relative to the biceps femoris. The semitendinosus originates at the inner side of your sitting bone. As with the other hamstring muscles, the semitendinosus muscle crosses the knee. It attaches at the upper part of your tibia bone the shin bone on the inner, or medial side.