Definition: The Rectus femoris muscle is one of the four quadriceps muscles that sits in the middle of the front of the thigh. It is responsible for knee extension and hip flexion.
The rectus femoris attaches from the pelvis to just below the knee (on the patellar tendon.) The other muscles of the quadriceps include the vastus medialis, the vastus intermedius and the vastus lateralis.
It is considers one of the muscles that make up the hip flexors; a group of muscles that bring the legs and trunk together in a flexion movement.
The muscles that make up the hip flexors include:

