Beginners Rectus Femoris Muscle: Function and Anatomy How this quad muscle helps with hip flexion By Elizabeth Quinn Elizabeth Quinn Elizabeth Quinn is an exercise physiologist, sports medicine writer, and fitness consultant for corporate wellness and rehabilitation clinics. Learn about our editorial process Updated on June 21, 2022 Medically reviewed Verywell Fit articles are reviewed by board-certified physicians and nutrition and exercise healthcare professionals. Medical Reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Erin Pereira, PT, DPT Medically reviewed by Erin Pereira, PT, DPT LinkedIn Erin Pereira, PT, DPT, is a board-certified clinical specialist in orthopedic physical therapy. Learn about our Medical Review Board Print MedicalRF.com / Getty Images Table of Contents View All Table of Contents Anatomy Function Injuries Exercises The rectus femoris muscle is one of the four quadriceps muscles. It is located in the middle of the front of the thigh. The rectus femoris' function is two-fold: It is responsible for knee extension and thigh flexion, and it is the main muscle that can flex the hip. Anatomy of the Rectus Femoris The rectus femoris attaches from the pelvis to just below the knee joint (the patellar tendon). The other muscles of the quadriceps include the vastus medialis, the vastus intermedius, and the vastus lateralis. The rectus femoris muscle connects to bone at two places (this connection is called a head). The first head, called the straight or direct head, is located on the outer hip. The other, known as the reflected head, starts above the hip socket. It meets the patellar tendon at the kneecap (patella). The blood supply comes from a vital artery in the upper thigh called the lateral femoral circumflex artery. It gets its signal from the brain via the femoral nerve. The rectus femoris is part of the muscle group called the quadriceps in the upper thighs. Specifically, it is located on the anterior portion of the thigh muscle (in the very front). It runs from the pelvis to the knees and is the most superficial muscle, closest to the surface of the skin. Rectus Femoris Function In sports, the rectus femoris is used powerfully when you kick a football or soccer ball. It is also used in cycling. It is one of the muscles that make up the hip flexors, which are a group of muscles that bring the legs and trunk together in a flexion movement. The muscles that make up the hip flexors include: Psoas major Illiacus Rectus femoris Pectineus Sartorius It also extends the leg at the knee. It can extend the knee powerfully when the hip is extended. But if the hip is flexed, such as when you are sitting, the rectus femoris is weaker in extending the knee and the other quads have to do the work. The same is true if the knee is extended; in that case, the rectus femoris can only flex the hip weakly and the other hip flexors have to go to work. The synergist muscles for the rectus femoris (the ones that have similar function, like flexing the hip) are the gluteus maximus, piriformis, obturator externus, obturator internus, and the superior and inferior gemelli. The hamstrings are the antagonist muscles to the rectus femoris. That means they produce the opposite action. Injuries Overuse of the rectus femoris in sprinting or kicking can cause a strain, leading to pain in the groin. You may also feel pain when walking downstairs. Acute tears or strains can happen in activities such as jumping, sprinting or kicking, and these usually happen at the patellar tendon. You might feel a sharp pain extending to the knee or be unable to fully straighten the knee. Sitting too much can tighten and shorten the hip flexors, as can wearing high heel shoes. Enjoying running and fitness walking develops the hamstrings, the antagonist muscles to the rectus femoris, and you can have a relative imbalance if those are your chief physical activities. Keeping the rectus femoris (and all the quad muscles) strong and flexible can help prevent imbalance and injury. Exercises for the Rectus Femoris Squats and lunges, with your body weight or with barbell or dumbbells, will exercise the rectus femoris. Machine exercises include the leg extension and upright leg press. If your chief cardio activities are walking or running, it is good to include exercises for the quads in the rest of your fitness program. Squats Verywell / Ben Goldstein Squats can be done almost anywhere, which make them a great exercise to do on the go. You can use your body weight or, for an additional challenge, hold dumbbells while you perform this exercise. Standing hip-width apart, bend at the knees, keeping your torso upright. As you stand upright, push through the heels, and end with a slight pelvic thrust as you activate your glutes. Perform 12 squats, rest for a moment or do another exercise, and then repeat the set of 12. Add more reps or more sets as your muscles gain strength. Lunges Verywell / Ben Goldstein Lunges are another excellent exercise for the rectus femoris. Stand shoulder-width apart and bring one leg forward, bending at the knee. Your other leg will dip down so your shin is parallel to the ground. Push through your heel to come back to a standing position. Start with two sets of 12 and increase as you gain fitness. A Word From Verywell Maintaining the strength of your rectus femoris muscles will help prevent injury and preserve your range of motion. If you have any concerns about how your rectus femoris muscle is performing, or if you experience significant pain in the front of your thigh, talk to a healthcare professional. Targeted exercise and stretching can keep this important muscle functioning optimally. Was this page helpful? Thanks for your feedback! Get exercise tips to make your workouts less work and more fun. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit 9 Sources Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Landin D, Thompson M, Reid M. Actions of two bi-articular muscles of the lower extremity: A review. 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Patellar tendon tear. Daly C, Persson UM, Twycross-lewis R, Woledge RC, Morrissey D. The biomechanics of running in athletes with previous hamstring injury: A case-control study. Scand J Med Sci Sports. 2016;26(4):413-20. doi:10.1111/sms.12464 Ema R, Sakaguchi M, Akagi R, Kawakami Y. Unique activation of the quadriceps femoris during single- and multi-joint exercises. Eur J Appl Physiol. 2016;116(5):1031-41. doi:10.1007/s00421-016-3363-5 Additional Reading Zhu XF, Zhang XC. Clinical anatomy and mechanical tensile properties of the rectus femoris tendon. Int J Clin Exp Med. 2015;8(12):22286-92.