What is the primary function of the quadriceps?

The primary function of the quadriceps is extension at the knee. The quadriceps muscle group, located at the front of the thigh, consists of four muscles that work together to straighten the knee joint during activities such as walking, running, jumping, and squatting. When the quadriceps contract, they pull on the patella (knee cap), which in turn causes the knee to extend.

In contrast, the other choices refer to movements that do not involve the quadriceps directly. Plantarflexion of the ankle is primarily performed by the calf muscles, while elbow flexion involves the muscles in the upper arm, such as the biceps. Knee flexion is executed mainly by the hamstring muscles located at the back of the thigh, which serve to bend the knee. Understanding these specific muscle functions is crucial for designing effective training and rehabilitation programs.