Muscle of the Month: Rectus Femoris

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by Devin Sarno, NSCA-CPT

Location: The Rectus Femoris is the biggest muscle of the quadriceps muscle group, and is located on the anterior (front) side of the upper leg between the hip and knee.

Attachments (where the muscle starts and ends):

Origin: Anterior inferior iliac spine and ilium above acetabulum, or essentially the front of the pelvis/hip

Insertion: Quadriceps tendon to patella, via ligamentum patellae into tubercle of tibia, or the knee


The Rectus Femoris extends the leg at the knee and flexes the thigh at the hip. Basically, any time that you are performing an action where your knee is moving closer to your hip or your shin is moving toward a parallel position with your thigh, you are likely activating your rectus femoris. However, the muscles will be less active in knee extension if it is already shortened into hip flexion; and in the same fashion it is weaker in hip flexion when it is shortened due to the knee being extended.

Exercises that use this muscle:

  • Squat variations
  • Lunge variations
  • Step-ups
  • Leg Press
  • Leg Extensions

Summary: Given that the rectus femoris is main muscle of the quadriceps, it plays an extremely important role in your everyday life in helping support your frame. It is also frequently a prime mover in any sort of kicking or squatting motion that you may utilize throughout the day. The other three muscles in the quadriceps that work with the Rectus Femoris are the Vastus lateralis, the Vastus Intermedius, and Vastus Medialis. The main opposing muscles, or antagonists, are the muscles in the hamstring that include: Biceps Femoris, Semimembranosus, and Semitendinosus.