The muscles composing the hamstring group has its anatomical location in the posterior region of the thigh (back of the legs). The hamstrings musculature is formed by three important muscles and these include the biceps femoris, semitendinosus, and semimembranosus. The primary function of the hamstrings is to facilitate flexion of the leg, along with medial and lateral rotation which is important for activities such as jumping, pedaling, walking, and running.
Exercise Guides For Your Hamstrings!
The biceps femoris originates in the sciatic region of the pelvis and has its insertion in the fibula (lateral bone of the leg) and is divided into two parts which includes the long head and the short head. The long head of the biceps femoris crosses the knee joint and has a motor action on this joint. Because it originates in the sciatic region of the pelvis, the long head of the biceps femoris also crosses the hip joint which will have motor action on the hip as well.
The short head of the biceps femoris muscle has its insertion at the fibula and its origin is in the distal part and posterior face of the femur bone. The short head of the femoral biceps only crosses the knee joint, so its motor action is only on the knee joint. The biceps femoris, both in its long and short heads, is located more laterally in the posterior face of the thigh.
Movement Produced By The Long and Short Head of the Biceps Femoris
The motor action of the biceps femoris (both on the long and the short head) will be engaged when contracting and flexing the knee. However, the long head of the femoral biceps, in addition to flexing the knee, also has the ability to produce movement when the hip is extended, so it is considered a biarticular muscle.
Function, Origin, and Insertion of the Semimembranosus Muscle
The semimembranosus is a muscle that is also located in the posterior region of the thigh and its origin is in the sciatic region of the pelvis and is very close to the area where the long head of the biceps femoris is located. Its insertion is located on the posterior aspect of the tibia, just behind the tibial plateau.
The semimembranous muscle crosses both the hip joint and the knee joint. The motor actions are knee flexion and hip extension along with the long head of the biceps femoral. The semimembranosus muscle is also biarticular.
Anatomic Location and Function of the Semitendinosus
The semitendinosus muscle is also located in the posterior region of the thigh and is composed of the biceps femoris and the semimembranosus which make up the overall area of the hamstrings. The semitendinosus is above the semimembranosus and this muscle presents a thinner tendon that crosses and has its insertion on the tibia in its distal face, and below the tibial plateau, which also occurs with the semimembranosus. The origin of the semitendinosus is also in the sciatic region of the pelvis.
The femoral, semimembranosus and semitendinosus muscles cross the knee joint, and due to their anatomical characteristics, these three muscles of the hamstrings include knee flexors and hip extensors. They are stronger muscles in the muscular action of flexing the knees and extending the hip and are very important muscles in the lower body.
Main Characteristics and Motor Action of The Hamstrings
If the hip is flexed, and the hip joint moves forward, there will be a stretching of the hamstrings, and if the knees are extended, this elongation will be even greater. The more flexed the hip becomes, the greater the force of traction of the hamstrings to flex the knee because a greater physiological arc of the action occurs to work on the knee joint.