Final answer:
The biceps femoris is a hamstring muscle located in the posterior compartment of the thigh, which works in opposition to the quadriceps femoris group located in the anterior compartment, responsible for extending the knee.
Step-by-step explanation:
The biceps femoris is one of the three muscles in the hamstring group, located in the posterior compartment of the thigh. This muscle group's primary function is to flex the knee and extend the thigh.
The hamstring group, which includes the biceps femoris, semitendinosus, and semimembranosus, works antagonistically with the quadriceps femoris group located in the anterior compartment of the thigh.
While the hamstrings flex the knee, the quadriceps are responsible for extending it. The quadriceps femoris group comprises four muscles: rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius.
These muscles not only extend and stabilize the knee but also have a common tendon known as the quadriceps tendon (patellar tendon), which inserts into the patella and becomes the patellar ligament that attaches to the tibial tuberosity.