Quad Muscles

What are quad muscles?

Your quad muscles, or quadriceps femoris, are a group of leg muscles at the front of your thigh. Together, they contain more mass than any other muscle group in your body. You use these thigh muscles to perform a variety of movements, including kicking, running, jumping and walking. Your quads are voluntary muscles, meaning you control how they move and work.

In the past, experts believed there were four quad muscles. In Latin, the root “quad” means “four or fourth.” But recently, they discovered a fifth muscle in this group.

What is the purpose of your quad muscles?

The main purpose of your quad muscles is to help you straighten your knee. But they also:

• Absorb force when your heel hits the ground
• Flex your hip
• Help maintain correct posture and balance
• Move and stabilize your patella (kneecap)
• Regulate your gait (the way you walk)

Where are the quads located?

Your quad muscles are on the front of your thigh, above your knee and below your hip. Quad tendons attach them to your pelvis, hip bones, femurs (thigh bones) and kneecaps.

How are the quadriceps structured?

The five quad muscles are:

• Rectus femoris. This muscle has two heads originating from your hip bone and pelvis. It stretches down to your kneecap. It’s the only quad muscle that spans your hip joint and knee joint.
• Vastus intermedius. This muscle lies in the middle of your thigh, beneath your rectus femoris. Like the other vastus muscles of your quads, its primary purpose is extending your knee.
• Tensor of the vastus intermedius. The most recently discovered quad muscle, it’s a slanted muscle that sits between your vastus lateralis and vastus intermedius.
• Vastus lateralis. This muscle connects your thigh bone to your kneecap. It runs along the outside of your thigh. It’s the largest of the five quad muscles.
• Vastus medialis. This muscle also connects your thigh bone to your kneecap. It runs along the inside of your thigh. It’s the smallest of the quad muscles.

All five of these muscles have heads that merge into a single tendon, the quadriceps femoris tendon. This tendon attaches them to your kneecap.

What are the quad muscles made of?

Your quads contain lots of tiny, elastic muscle fibers. These fibers help your thigh muscles contract, or tighten. The fibers are red and white, giving the muscles a striped appearance.

What conditions and disorders affect the quadriceps?

The most common quadriceps femoris injuries are strains, or “pulled quads.” A strained quad muscle is the result of overstretched muscle fibers. Thigh strains can range from mild — slight overstretching — to severe, meaning your quad tendon completely tears away from your kneecap (quad tendon tear).

Other quad muscle injuries include:

• Contusions. Quadriceps contusions are usually the result of a direct blow to the front of your thigh. You may develop a bruise or a hematoma (when blood pools under your skin).
• Cuts (lacerations). Open wounds that break the skin of your thigh can damage your quad muscles or tendon. A cut may be the result of a fall, car accident or traumatic sports injury.
• Tendonitis. Inflammation of the tendons that connect your quad muscles to your kneecap or hip can cause thigh pain. Tendonitis can irritate muscles and put additional pressure on them.

What are the symptoms of quad muscle injuries?

Quadriceps muscle injuries may cause:

• A tearing or popping sensation
• Severe pain and swelling
• Bruising
• A noticeable indentation above your kneecap
• An inability to straighten your knee
• Cramping
• Tenderness
• A drooping or sagging kneecap
• Trouble walking

What are the risk factors for quad muscle injuries?

Quad muscle injuries are common in athletes who run, jump and kick. This includes sprinters and people who play soccer, football, rugby, basketball and softball.

You’re also at risk for quad muscle injuries if you:

• Are over age 40
• Have certain health conditions that can weaken tendons
• Have had a previous quad injury
• Have quad muscle fatigue
• Have weak quads or hamstrings
• Use corticosteroids or some other medications that can lead to side effects, like tendon damage

How can I keep my quads healthy?

Take care of your quad muscles by:

• Not pushing through hip, leg or knee pain
• Resting your quadriceps muscles between workouts or prolonged periods of exertion
• Properly stretching and warming up your quad muscles before and after engaging in activity

When should I call my healthcare provider?

Contact your healthcare provider right away if you:

• Can’t move your leg or walk
• Experience numbness in your hips, legs or knees
• Have severe, sudden pain anywhere in your legs