The outer hamstring
Biceps femoris · musculus biceps femoris
The outer hamstring, which bends the knee and straightens the hip.
What it does
The biceps femoris has two heads, one from the sit bone and one from the femur, that join into a tendon on the head of the fibula. It bends the knee, straightens the hip and turns the lower leg outwards when the knee is bent.
Surprising fact
Its long head is the most commonly torn hamstring, usually as a sprinter's leg reaches forward at top speed.
Why it matters
Hamstring strains are among the most common injuries in running sports. Strength training that lengthens the muscle under load has been shown to reduce them.
Nearby
Read more
Sources
Drafted with AI help; awaiting a human fact-check against these sources.
Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.