Biceps femoris muscle

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The biceps femoris is a muscle of the posterior thigh. As its name implies, it has two heads, one of which (the long head) forms part of the hamstrings muscle group.

It has two heads of origin;

• one, the long head, arises from the lower and inner impression on the back part of the tuberosity of the ischium, by a tendon common to it and the semitendinosus, and from the lower part of the sacrotuberous ligament;
• the other, the short head, arises from the lateral lip of the linea aspera, between the adductor magnus and vastus lateralis, extending up almost as high as the insertion of the gluteus maximus; from the lateral prolongation of the linea aspera to within 5 cm. of the lateral condyle; and from the lateral intermuscular septum.

The fibers of the long head form a fusiform belly, which passes obliquely downward and lateralward across the sciatic nerve to end in an aponeurosis which covers the posterior surface of the muscle, and receives the fibers of the short head; this aponeurosis becomes gradually contracted into a tendon, which is inserted into the lateral side of the head of the fibula, and by a small slip into the lateral condyle of the tibia.

At its insertion the tendon divides into two portions, which embrace the fibular collateral ligament of the knee-joint.

From the posterior border of the tendon a thin expansion is given off to the fascia of the leg. The tendon of insertion of this muscle forms the lateral hamstring; the common peroneal nerve descends along its medial border.

[edit] Variations

The short head may be absent; additional heads may arise from the ischial tuberosity, the linea aspera, the medial supracondylar ridge of the femur, or from various other parts.

A slip may pass to the gastrocnemius.

[edit] Additional images

Cross-section through the middle of the thigh.

The popliteal, posterior tibial, and peroneal arteries.

Back of left lower extremity.

[edit] External links

• LUC bfem
• GPnotebook -865402803
• UWash - long head
• UWash - short head
• SUNY Labs 14:06-0100
• SUNY Labs 14:st-0402

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.