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.
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.
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 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.
