Biceps Femoris · What Is It, Location, Action, and More

The biceps femoris is a long muscle in the posterior compartment of the thigh responsible for movement at both the hip and knee joints. Along with the semitendinosus and semimembranosus, the biceps femoris makes up the hamstrings muscle. The muscles of the hamstring border the popliteal fossa, which is a triangular space behind the knee. The lateral border of the popliteal fossa is created by the biceps femoris. 

The innervation (i.e., nerve supply) differs between the long head and short head. The long head is innervated by the tibial portion of the sacral nerve (L5-S2), while the short head is innervated by the common fibular, or peroneal, division of the sacral nerve (L5-S2).

The inferior gluteal artery, popliteal artery, and perforating branches from the inferior gluteal and profunda femoris arteries supply blood to both the long head and short head of the biceps femoris.

The biceps femoris muscle is located in the posterior compartment of the thigh, also known as the hamstrings. The hamstrings are made up of three separate muscles: the semimembranosus, semitendinosus, and biceps femoris. The biceps femoris has two heads, a short head and a long head, that originate from different locations but share the same insertion site. There, they join to form the biceps femoris tendon. The biceps femoris tendon then joins with the lateral collateral ligament to insert at the lateral aspect of the head of the fibula (i.e., outer lower leg bone). The two heads originate at different locations, with the long head originating at the ischial tuberosity, and the short head originating at the linea aspera of the femur (i.e., thighbone). The ischial tuberosity is a rounded portion of the ischium, or part of the pelvic bone. Comparatively, the linea aspera of the femur is a lip, or ridge, at the posterior shaft of the femur.

The biceps femoris is responsible for movement at both the hip joint and knee joint. At the hip, the long head of the biceps femoris allows for thigh extension and external rotation. Whereas at the knee, the biceps femoris allows for knee flexion and lower leg external rotation. The biceps femoris muscle also stabilizes the pelvis.

The biceps femoris muscle, located in the posterior portion of the thigh, is composed of a long head that originates from the ischial tuberosity and a short head that originates at the linea aspera of the femur. The biceps femoris inserts at the lateral head of the fibula. The biceps femoris muscle alongside the semitendinosus and semimembranosus form the hamstrings muscle. These muscles are responsible for thigh extension, knee flexion, and external rotation of both the hip and leg.