What Are The Three Muscle Groups For Hamstrings?

Your hamstrings are a hard-working group of muscles. As major muscles involved in locomotion, they are active when you walk, run, cycle, climb stairs or even pick up your kids. They tend to work with your glutes and quadriceps to perform multi-joint motions. The hamstrings are actually three different muscles that lie along the back of your thighs, and are commonly injured in athletes and avid exercisers.

Biceps Femoris

The biceps femoris originates with the other two muscles on the pelvis. It attaches to the ischial tuberosity on the lower border of the pelvis, the protuberance that you feel when you are sitting down. It then travels down the back of the femur and attaches to the fibula and lateral, or outside, condyle of the tibia. The biceps femoris works to extend your thigh at the hip joint, which is to push it straight back. It also works to bend, or flex, the knee as it crosses both the hip and knee joints.

Semimembranosus

The semimembranosus is smaller than the biceps femoris, but works together with it to extend the thigh and flex the knee. It also originates on the ischial tuberosity on the upper outer surface compared to the biceps femoris and semitendinosus. The semimembranosus then travels vertically along the back of the femur to insert on the medial condyle of the tibia, opposite the biceps femoris.

Semitendinosus

The semitendinosus is the last of the three hamstring muscles. It is located medial to the other two, closer to the inner thigh area. It also originates on the ischial tuberosity, on the lower, medial surface sharing a tendon with the biceps femoris. It travels down with the semimembranosus to insert on the medial condyle of the tibia. The semitendinosus works to extend the thigh and flex the knee, along with the biceps femoris and semimembranosus.

Hamstring Muscle Concerns

A hamstring injury can occur to one of the muscles, or all three. You can pull, or strain, the muscle or have a partial or full tear of the muscle. Most of the hamstring injuries occur at the thicker part of the muscle, or where the muscle fibers join the tendon fibers, according to the American Academy of Orthopaedic Surgeons. Overloading the hamstrings, muscle fatigue, tightness, muscular imbalance and poor conditioning are all risk factors for hamstring injuries. Adequately train the hamstrings for your chosen activity, and warm up and stretch properly to reduce your risk of injury.