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42 m a s s a g e & b o d y w o r k m a r c h / a p r i l 2 0 2 0 RECTUS FEMORIS Attachments • Origin: Anterior inferior iliac spine (AIIS) and upper rim of acetabulum • Insertion: Tibial tuberosity via the patellar tendon Actions • Flexes the hip • Extends the knee Innervation • Femoral nerve • L2–4 FUNCTIONAL ANATOMY education The rectus femoris bisects the front of the thigh between the sartorius and tensor fasciae latae. It is one of four quadriceps muscles, but the only one that crosses the hip joint and the most superficial of the four. The fibers of the rectus femoris are feather-shaped or bipennate. Muscle fibers on each side attach obliquely to a central tendon. This configuration accommodates a higher number of muscle fibers in a given area compared to parallel fiber arrangements, thus increasing potential force production. The fiber configuration is a clue to this muscle's function as a prime mover for hip flexion and knee extension. Functionally, the rectus femoris pulls the femur forward at the hip while kicking out the lower leg during the swing phase of gait. This places the heel of the swinging leg in position to contact the ground and accept the weight of the body during the stance phase. This two-joint motion is also used in activities such as flutter kicks for swimming or kicking a ball forward. At the hip, the rectus femoris assists muscles like the psoas, iliacus, sartorius, and tensor fasciae latae in flexion. Because of its origin at the anterior inferior iliac spine, the rectus femoris also has some ability to tilt the pelvis anteriorly. The rectus femoris, vastus lateralis, vastus intermedius, and vastus medialis form the quadriceps group and together straighten the knee during standing and lifting with the legs. All three vastus muscles are much more powerful than the rectus femoris in this action. Rectus Femoris By Christy Cael