Which of the following muscles is involved in extending the leg?

The vastus medialis is a key muscle involved in extending the leg. This muscle is part of the quadriceps group, which is primarily responsible for knee extension. The quadriceps muscle group is located at the front of the thigh and includes the vastus lateralis, vastus intermedius, vastus medialis, and the rectus femoris. When these muscles contract, they work together to straighten the knee joint, allowing for movements such as kicking or standing up from a seated position.

Understanding the role of the vastus medialis within the quadriceps is crucial, as it not only facilitates knee extension but also helps stabilize the patella (kneecap) during movement. This stabilization is particularly important for maintaining proper knee alignment and function.

In contrast, the other muscles listed primarily serve different functions. The gluteus minimus is mainly involved in hip abduction and medial rotation, the tensor fascia latae helps stabilize the hip and knee during movement but does not extend the leg, and the sartorius is involved in flexing, abducting, and laterally rotating the hip, as well as flexing the knee, rather than extending it.