The biceps femoris is the big muscle at the back of the thigh.

biceps femoris
The word 'ceps' means 'heads', so 'biceps' means that the muscle has two heads. There is a long head, and a short head. The long head forms part of the hamstrings muscle group.


Knee flexors

Both heads of the biceps femoris are knee flexors, and the long head also helps to extend the hip.


The muscles of the knee

Learn the names of the main knee muscles.



Physical principles demonstrate that the biceps femoris muscle relative to the other hamstring muscles exerts the most force: implications for hamstring muscle strain injuries. Dolman B, Verrall G and Reid I. Muscles Ligaments Tendons J. 2014 Jul-Sep; 4(3): 371–377.

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