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What is the Vastus Intermedius?

Alex Paul
Alex Paul

The vastus intermedius muscle is located in the thigh and makes up part of the quadriceps muscle group. Its main action is to extend the knee and hence it is used in a number of different activities including going up stairs and cycling. Due to its location in the middle of the thigh, it has an important role to play in stability of the lower body and is commonly involved in injuries and other leg problems.

The origin of the vastus intermedius muscle is on the lateral surface of the upper femur. From this point it runs down the middle of the thigh and inserts at the patella via the quadriceps tendon. It also inserts to the tibial tuberosity through the patella tendon. The innervation of the muscle is through the femoral nerve.

Side lunges strengthen and tone the thighs -- including the vastus intermedius -- and other leg muscles.
Side lunges strengthen and tone the thighs -- including the vastus intermedius -- and other leg muscles.

As a muscle of the thigh, the vastus intermedius is important in a number of different daily activities. Any movement that requires extension of the leg will heavily use the muscle. For this reason if it isn’t functioning correctly or is too weak then the muscle can cause knee pain.

There are a number of different exercises that can be used to strengthen the vastus intermedius. For example, squats work all the quadriceps muscles although it’s important that they are performed correctly to avoid injury. Knee extension machines are also commonly used to build up muscle strength in the quadriceps group.

The primary function of the vastus intermedius is to extend the knee.
The primary function of the vastus intermedius is to extend the knee.

It’s also important for the muscle to be flexible otherwise it can put excess pressure on the knee joint. A basic quadriceps stretch usually focuses on the vastus intermedius. To perform this stretch the stretcher should stand on one leg and gently pull the foot towards the gluteal muscles until a stretch is felt. This position should be held for around 30 seconds before being released. A tight vastus intermedius is thought to be a common cause of tendinitis in both the quadriceps and patella tendons.

The vastus intermedius is used when extending the leg.
The vastus intermedius is used when extending the leg.

The other three muscles which make up the quadriceps are the vastus medialis, vastus lateralis and the rectus femoris. Although the vastus intermedius makes up part of the quadriceps group, it is the deepest of the four muscles and is located beneath the rectus femoris. These four muscles are essential for the stability of the kneecap. For example, the vastus medialis and lateralis pull on opposite sides of the patella and need to be balanced in order for the knee to track properly.

Discussion Comments

irontoenail

@pleonasm - Personally I think that losing weight is the best thing you can do for that muscle. It's where you bear a lot of the weight that gets put on your knee. I know when I weighed more, it would often be sore after climbing up a hill or after some kind of exercise where I had to use my knees a lot.

Once, after completing a really long and difficult hike, which was very steep in places, it was so stiff and sore I could hardly get out of bed the next day.

But now that I've lost weight, it hardly ever troubles me. When you think about how much weight is thrust down every time you walk, it's hardly surprising that being overweight can lead you to vastus intermedius injury.

pleonasm

@Iluviaporos - It's a really good idea to do that stretch. I used to use my bicycle to go everywhere and sometimes on very bad roads, and that muscle would inevitably be the one to start aching, which makes every rotation a chore when you are on a bike. I found the best thing to do was to be vigilant about going vastus intermedius exercises and stretches after every ride.

Still I was riding so much it did hurt my knees a bit for a while, even though I stretched. I think it didn't help that I was overweight.

lluviaporos

The stretch where you stand on one leg, as is described by the article, is one of the basic stretches that you should try to do after any kind of exercise to help your muscles to relax.

I would suggest holding onto the frame of a door or something like that to keep up upright though, if you aren't used to doing the stretch.

Oh, and don't fall into the trap of thinking because 30 seconds is good, that 60 seconds must be even better. Although it helps to repeat the stretch several times, it actually doesn't make much difference how long you hold it once you've passed 30 seconds.

I read a study on this recently in fact, where they put together all their research on different sports stretching. Anything below 20 seconds doesn't do much, and anything about around 30 seconds doesn't add anything, so 30 seconds is the best time to hold a stretch.

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    • Side lunges strengthen and tone the thighs -- including the vastus intermedius -- and other leg muscles.
      By: z3zo
      Side lunges strengthen and tone the thighs -- including the vastus intermedius -- and other leg muscles.
    • The primary function of the vastus intermedius is to extend the knee.
      By: Dirima
      The primary function of the vastus intermedius is to extend the knee.
    • The vastus intermedius is used when extending the leg.
      By: CandyBox Images
      The vastus intermedius is used when extending the leg.
    • Knee pain can be caused by the vastus intermedius muscle being weak or not functioning properly.
      By: evgenyatamanenko
      Knee pain can be caused by the vastus intermedius muscle being weak or not functioning properly.