Inferiorly, the aponeurosis condenses to form a tendon which predominantly inserts onto the lateral side of the head of the fibula.

The tendon of insertion of this muscle forms the lateral hamstring; the common fibular (peroneal) nerve descends along its medial border.

[6] The long head of the biceps femoris is a weaker knee flexor when the hip is extended (because of active insufficiency).

When the knee is semi-flexed, the biceps femoris in consequence of its oblique direction rotates the leg slightly outward.

Avulsion of the biceps femoris tendon is common in sports that require explosive bending of the knee as seen in sprinting.