Answer
Answer: Extension of the leg at the knee joint.
Work Step by Step
The qudriceps femoris is essentially a four-in-one anterior thigh muscle. The four components are the rectus femoris, the vastus lateralis, the vastus medialis, and the vastus intermedius. The origins are the femur and the anterior iliac spine. Distally (inferiorly) attachment is by the quadriceps tendon to the patella, and by way of the patellar ligament to the tibial tuberosity. When all four components contract together the leg is extended at the knee joint. Contraction of rectus femoris alone flexes the thigh at the hip joint
