Identify the major muscle group allowing for the movement at the knee joint to occur.

Identify the knee joint: The knee joint is a hinge joint that connects the thigh bone (femur) to the shin bone (tibia).

Understand the movement: The primary movements at the knee joint are flexion (bending the knee) and extension (straightening the knee).

Identify the major muscle groups:

• Quadriceps: This group of muscles is located at the front of the thigh and is primarily responsible for knee extension. The quadriceps consist of four muscles: the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius.
• Hamstrings: This group of muscles is located at the back of the thigh and is primarily responsible for knee flexion. The hamstrings consist of three muscles: the biceps femoris, semitendinosus, and semimembranosus.

Conclusion: The major muscle groups allowing for the movement at the knee joint to occur are the quadriceps for extension and the hamstrings for flexion.