Quadriceps Muscles

Written By: Chloe Wilson, BSc(Hons) Physiotherapy
Reviewed by: KPE Medical Review Board

Quadriceps Muscles: Anatomy, Function & Common Injuries from knee-pain-explained.com

The quadriceps muscles are a group of four muscles found on the front of the thigh, aka the quadriceps femoris group.

The quads work together to straighten the knee and play an important role in activities such as walking, running, getting up from a chair and climbing stairs.

Here we will look at the anatomy of each of the quadriceps muscles, how they work, the quadriceps femoris functions and common injuries.

Quadriceps Anatomy

The quadriceps femoris group comprises of four muscles, rectus femoris, which originates from above the hip, and three vastus muscles, each originating from various places on the shaft of the femur, thigh bone.

  • Rectus Femoris: is the most superficial of the quadriceps muscles
  • Vastus Lateralis: is on the outer side of the thigh, 
  • Vastus Intermedius: runs down the middle of the thigh and 
  • Vastus Medialis: is found on the inner side of the thigh
Quadriceps Muscles Anatomy: Rectus Femoris, Vastus Medialis, Vastus Lateralis & Vastus Intermedius

The four quadriceps muscles pass down the front of the thigh and then join together near the knee to form the quadriceps tendon aka ligamentum patellae.

The quads tendon flows around the patella (kneecap) before finally attaching to the tibial tuberosity, by which time it is known as the patellar tendon.

The tibial tuberosity is the knobbly bit on the front of the shin bone that you can feel about 1cm below the kneecap.

Quadriceps Origin and Insertion

For those of you who want to know more detailed quadriceps anatomy, let’s have a quick look at where each muscles comes from and goes to:

Rectus Femoris: originates via two heads from the pelvis, the anterior inferior iliac spine and just above the hip socket on the ilium. Inserts onto the patella and tibial tuberosity.

Vastus Medialis: originates from the intertrochanteric line and the medial side of the femur including the medial intermuscular septum and medial supracondylar line. It attaches to the medial border of the patella, the tibial tuberosity and the medial condyle of the tibia

Vastus Intermedius: originates from the upper two-thirds of the femur, linea aspera and lateral supracondylar line. It forms the deep aspect of the quadriceps tendon inserting onto the tibial tuberosity

Vastus Lateralis: originates on the front of the femur from the intertrochanteric line and inferior border of the greater trochanter. It inserts onto the lateral margin of the patella and the tibial tuberosity

If you really want to get into the nitty gritty detail of quadriceps anatomy, use the links above to find out more .

Nerve Supply

Quadriceps femoris is supplied by the femoral nerve, root value L2, L3 & L4.

Quadriceps Muscles Function

The main function of the quadriceps muscles is to straighten the knee. As rectus femoris originates above the hip on the pelvis, it can also independently bend the hip.

Here are some examples of what activities rely on quadriceps femoris function

  1. Kicking A Ball: Rectus femoris comes into play when there is a need for combined hip flexion and knee extension

  2. Walking: The quadriceps muscles extends the leg as it swings forwards and then stops the knee from bending when the heel strikes the floor

  3. Patella Control: Vastus medialis is most active in the final stages of knee extension controlling the movement of the patella

  4. Stepping Activities: such as stair climbing

  5. Squats: the quads control the downward movement when squatting

  6. Standing On One Leg: all four muscles work statically to provide stability

  7. Lifting The Leg Off The Bed: Rectus femoris works particularly strongly when raising a straight leg

Fun Fact: When simply standing, there is actually very little action in the quadriceps muscles, which is why if someone knocks your knee from behind, the knee suddenly collapses

Common Types of Quadriceps Injury

The quadriceps muscles are prone to a number of different injuries including:

  1. Tendonitis: Inflammation of the quadriceps tendon either above the kneecap, quadriceps tendonitis, or below the kneecap, patellar tendonitis

  2. Quadriceps Strain: aka pulled quad, where some of the muscle fibers are torn

  3. Quadriceps Tendon Rupture: The combined quadriceps femoris tendon partially or completely tears usually just above where it inserts onto the patella

  4. Quadriceps Contusion: a traumatic blow to the anterior thigh resulting in a deep bruise

  5. Quadricep Tightness: Tightness in one or more of the quadriceps muscles can cause hip, knee and foot problems and is often due to underlying muscle weakness

  6. Quadriceps Atrophy: Weakness and wasting in the quadriceps femoris group 

Quadriceps Exercises

Quadriceps exercises are a great way to improve the strength, definition and flexibility of the thigh muscles which make a real difference to daily activities such as climbing stairs, getting out of a chair and kicking a ball.

Quadriceps Stretches: Exercises for stretching quads muscles effectively, and simple tests to check if you have tight quads

Quads Strengthening: Exercises to strengthen the quadriceps muscles, from beginners to advanced

You can find out loads more about how best to exercise the quadriceps muscles using the links above e.g. top tips, best ways to stretch & how to progress strengthening.

Page Last Updated: Sept 09, 2020
Next Review Due: Sept 09, 2022

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