Which muscle group is primarily responsible for knee extension?

The quadriceps femoris muscle group is primarily responsible for knee extension. This group consists of four muscles: the rectus femoris, vastus lateralis, vastus intermedius, and vastus medialis. Their primary function is to work together to extend the knee joint, which is crucial during various activities such as walking, running, squatting, and jumping.

The quadriceps are located at the front of the thigh and play a key role in maintaining stability and control of the knee. When the quadriceps contract, they pull on the patellar tendon, which subsequently pulls on the tibia, resulting in the extension of the knee.

In contrast, while the hamstrings are responsible for knee flexion and the gastrocnemius assists in knee flexion and plantarflexion of the ankle, they do not contribute to the extension of the knee. The sartorius, although involved in flexing the hip and knee, does not play a primary role in knee extension either. Thus, the quadriceps femoris stands out as the definitive muscle group for this particular action.