Major Muscle Groups

Hamstrings

Where are they?

The Hamstrings attach to your pelvis on one end and your tibia or fibula on the other. This stretches them across two joints, making them very long and powerful.

Hamstrings play a strong role in squatting below parallel, jumping, and running

What muscles make up the hamstrings?

- Semitendinosus

- Semimembranosus

- Biceps femoris

Semitendinosus

The semitendinosus helps to extend (straighten) the hip joint and flex (bend) the knee joint. It also helps medially rotate the tibia on the femur when the knee is flexed and medially rotate the femur when the hip is extended. It counteracts forward bending at the hips as well.

Origin - Ischium

Insertion - Tibia

Semimembranosus

The semimembranosus helps to extend (straighten) the hip joint and flex (bend) the knee joint.

It also helps medially rotate the knee: the tibia medially rotates on the femur when the knee is flexed. Medially rotates the femur when the hip is extended. The muscle can also aid in counteracting the forward bending at the hip joint.

Origin - Ischium

Insertion - Tibia

Biceps femoris

It consists of two parts: the long head as the attachment from the ischium and the short head attached to the femur bone. The long head is a part of hamstring muscle group which occupy posterior section of the thigh.

Biceps femoris muscle is important for knee flexion, internal and external rotation, and hip extension

Hamstring muscles - 3D anatomy tutorial