The human leg consists of many different components, some of which work alone and others which work in conjunctions with other muscles and tendons to perform vital tasks which enable us to move about.

The biceps femoris muscle is located on the back or posterior section of the human thigh. As the name of the muscle implies by using the word “Bi” the muscle consists of two sections, one of these sections is the long head and forms a part of the hamstrings group of muscles.

There are two heads of origin for the Biceps Femoris muscle. These are the long head and the short head. The long head arises from the inner and the lower impression on the posterior section of the tuberosity of the ischium by means of a tendon which it shares in common with the semitendinosus and also from the lower section of the ligament known as the sacrotuberous ligament. The short head arises from the lateral lip of the linea aspera in the middle of the adductor magnus and the vastus lateralis. It extends in an upward manner to almost as high as the insertion point of the gluteus maximus muscle.

The long head fibers form what is known as a fusiform belly in slides of cna training which passes in an oblique downward and lateral ward direction, travelling across the sciatic nerve and ending its journey in an aponeurosis which provides cover to the posterior surface of the muscle and also receives the fibers of the short head. It is this aponeurosis which then becomes contracted into a tendon gradually and this tendon is inserted into the lateral side of the fibulas head and also by a small sized slip into the lateral condyle of the human tibia.

At the point of insertion the tendon is divided into two sections. These sections embrace the fibular collateral ligament of the knee joint. A thin expansion is given off to the fascia of the leg from the posterior border of the tendon. The tendon of insertion of the muscle forms what is known as the lateral hamstring and the common peroneal nerve makes it decent along the medial border.

Both the long head and the short head of the Biceps Femoris muscle play their part in performing knee flexion. Due to the long head originating in the pelvis the long head is also responsible for playing a part in the extension of the hips. The long head of the muscle is weaker in knee flexion during hip extension because of an active insufficiency. The long head is also a weaker hip extender when the knee is flexed due to this same reason. When the knee is in a semi flexed position the muscle rotates the leg slightly outward because of the oblique direction it holds.

There are some possible variations to the muscle. The short head may instead be completely absent just the same as there may be additional heads which arise from the ischial tuberosity, the linea aspera and also the medial supracondylar ridge of the femur as well as from various other areas. A slip may also pass to the gastrocnemius.