Final answer:
A torn hamstring typically involves damage to the hamstring muscles, which include the biceps femoris, semitendinosus, and semimembranosus, all of which are responsible for knee flexion.
Step-by-step explanation:
A patient with a torn hamstring has potentially damaged the muscles that are part of the posterior compartment of the thigh. These muscles include the hamstrings: biceps femoris, semitendinosus, and semimembranosus, which all function to flex the knee. The hamstring muscles are common injury sites, particularly in athletes, and they can range from a mild strain with slight discomfort to a severe tear that causes significant pain, stiffness, and bruising.