Quad Muscles

What are quad muscles?

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

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.

Your quads are vulnerable to injuries, such as contusions (bruising) from blows to the front of your thigh. These muscles also handle a lot of strain from your hip and knee joints, so quad strains or “pulled quads” can occur.

Your quad muscles are skeletal muscles. They’re voluntary muscles, meaning you control how they move and work. Some other muscles in your body, such as those in your heart, are involuntary. This means they work without you having to think about it.

What is the purpose of the 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 the hip.
• Help maintain correct posture and balance.
• Move and stabilize the patella (kneecap).
• Regulate your gait (the way you walk).

Where are the quad muscles 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, femur (thigh bones) and kneecaps.

How are the quad muscles structured?

The five quad muscles are:

• Rectus femoris: This muscle has two heads, originating at your hip bone and pelvis. It stretches down to your knee cap. It’s the only quad muscle that spans the hip joint and knee joint.
• Vastus intermedius: This muscle lies in the middle of your thigh, beneath the rectus femoris. Like the other vastus muscles of the 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 the vastus lateralis and vastus intermedius. Researchers are still studying its function.
• Vastus lateralis: This muscle connects your thigh bone to your kneecap. It runs along the outside of your thigh. It’s the largest and strongest 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 the kneecap.

What are the quad muscles made of?

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

What conditions and disorders affect the quad muscles?

The most common quad muscle injuries are strains.A strained quad muscle is the result of overstretched muscle fibers. Thigh strains usually affect the rectus femoris since this muscle spans two very mobile joints.

Thigh strains can range from mild to severe:

• Grade 1: The muscle fibers overstretch or tear slightly. You may feel mild thigh muscle pain or see some swelling, but you can still use your leg.
• Grade 2: These are more serious quad muscle tears. They can cause significant pain and loss of strength. You might not be able to put weight on your leg.
• Grade 3: The quad tendon ruptures, meaning it completely tears away from your kneecap, or the muscle tears away from the tendon. You can’t use your leg due to severe pain and swelling. You might see a defect under your skin if you have a torn quad muscle.

Other quad muscle injuries include:

• Contusions: Quadriceps contusions are usually the result of a direct blow to the front of your thigh. You might develop a bruise or a hematoma (a type of bruise that causes blood to pool under the skin and tissue damage). Severe contusions can lead to myositis ossificans (bone tissue that forms inside a muscle).
• Lacerations: An open wound that breaks the skin of your thigh can damage your quad muscles or tendon. A laceration might be the result of a fall, automobile accident or a 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. It can also lead to reduced mobility in your knee, thigh or hip.

How common are quad muscle injuries?

Quad muscle injuries aren’t that common. One study of college athletes suggests that thigh strains occur in about 1 out of 10,000 athletes. Hamstring injuries, affecting the muscles at the back of the thigh, tend to be more common.

Who gets 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 pain if you:

• Are over age 40.
• Have certain health conditions that can weaken tendons, such as multiple sclerosis, diabetes, gout or rheumatoid arthritis.
• Have had a previous quad injury.
• Have quad muscle fatigue.
• Have weak quads or hamstrings.
• Use corticosteroids or some other medications, which can weaken muscles and tendons.

How can I keep my quad muscles healthy?

Take care of your quad muscles by:

• Not pushing through hip, leg or knee pain.
• Resting your quad muscles between workouts or periods of exertion.
• Stretching and warming up your quad muscles before activity.

When should I call my healthcare provider?

Contact your healthcare provider right away if you:

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