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What are the Quadriceps Muscles?


Updated July 03, 2012

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Question: What are the Quadriceps Muscles?

Recently I was out for a walk and I started feeling pain in my knee. I went to my doctor who prescribed physical therapy to help strengthen my quadriceps muscles. What are my quadriceps muscles, and what do they do?


The quadriceps are a group of muscles on the front of your thighs. As you may guess from the name, there are four distinct muscles that make up the quadriceps muscles. These muscles are called the vastus intermedius, the vastus medialis, the vastus lateralis, and the rectus femoris.

What Does the Quadriceps Do?

If you sit in a chair and straighten your knee a few times, you can see and feel the quadriceps in action on the front part of your thigh. When your quads (as they are often called) contract, they straighten your leg at your knee joint. Since the quadriceps extend over the kneecap (patella), they also help to keep your kneecap in its proper position in a groove in the end of your thigh bone.

Common Injuries to the Quadriceps

Injury to the quadriceps muscles can occur. Sometimes, the muscle tears off the bone just below the knee cap, resulting in a dislocated kneecap. This is almost always the result of trauma, such as a sports injury or fall. If this occurs, surgery is often performed to repair the torn quadriceps. After surgery, you may have to wear a knee brace and attend physical therapy to return to normal activity and function.

If you have knee pain or swelling from an injury or if you have arthritis, the quadriceps sometimes stops working properly. This may result in a condition called patella femoral stress syndrome. This happens when the quads are unable to help keep the kneecap in its proper position.

Your quadriceps may become weakened due to spinal cord injury or stroke (a condition called paresis). Low back pain may result in a pinched nerve that may cause weakness in the quads. This is usually a severe condition, and you should see your doctor right away to assess the situation and get the proper treatment.

Loss of Function from Injured Quadriceps

If you injure your quadriceps muscle or muscles, you may have difficulty with functional mobility. You may be surprised to learn that your quadriceps muscles help you move around in bed. They contract to help you scoot your bottom while lying down, and they can help you roll in bed.

The quadriceps muscles also are very active when rising from a chair. They help to straighten the knee, which is essential to rise up from a sitting position. The quads are also a major muscle group responsible for walking up and down stairs.

As you may have guessed, the quadriceps muscle group is also essential for walking and running. The quads help keep you moving forward while walking and running, and they prevent you from falling when standing still. Weakness in the quads may result in gait abnormalities, and you may require an assistive device like a cane or walker to help with normal walking if your quads are not working properly. Your physical therapist can help you decide which device is right for you.

Can I Perform Exercises for My Quadriceps?

If you suffer an injury to your quadriceps, your doctor may refer you to physical therapy to help improve functional mobility and to improve the strength and flexibility of the quadriceps. Your physical therapist can offer suggestions for the correct exercises for you to perform to help your specific condition.

Basic knee mobility exercises focus on quadriceps strength and mobility, and stretching exercises for the quadriceps help improve flexibility of the muscle group.

The main types of exercises that you can perform to help improve the function of your quadriceps include:

  • Strength: Since the quadriceps muscles cross both the hip and the knee, exercises that involve the knee and the hip are essential to improving the strength of the quads. Simple knee strengthening exercises will target the quads, and advanced hip strengthening exercises will also include quite a bit of quadriceps work.

  • Flexibility: There are many easy stretches to do to improve the flexibility of your quadriceps muscles. Basic quadriceps stretching can be done, and the towel quadriceps stretch is a great way to improve the flexibility of this muscle group.

  • Balance and proprioception: Balance and proprioception exercises often focus on the quadriceps since these are essential in keeping you upright and balanced. Basic balance exercises can also help to prevent falls.

An injury to your quadriceps can be a painful experience. A visit to your physical therapist may be the key to helping you improve the function of your quadriceps to get you back to normal functional mobility quickly and safely.

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