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Functions of the vastus lateralis muscle

Functions and anatomy of the vastus lateralis muscle shown with 3D model animation.

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Hello everyone! It's Megan from Kenhub here, and in today's tutorial, we're going to be talking about the functions of the vastus lateralis muscle. Before finding out more about this muscle, what it does and how it moves, let me show it to you first. Here is, on your screen, the vastus lateralis in all its glory. So the vastus lateralis is part of the quadriceps femoris muscle group which is the muscle you can see now. The quadriceps femoris is the main muscle of the anterior compartment of the thigh that allows you to stand, walk, climb, jump, run and squat. Making you an athlete is no easy feat so the quadriceps femoris is one of the largest muscles of your entire body.

Now let's get back to the vastus lateralis and learn more about it. We'll remove this big muscle – the rectus femoris – which partially covers the vastus lateralis so that we can see it a bit better. The vastus lateralis, as the name suggests, is located laterally right here. In order for the vastus lateralis to perform its functions, it needs a nerve supply. This is provided by the femoral nerve which you can now see highlighted on your screen. This nerve forms part of the lumbar plexus and arises from the second, third and fourth lumbar segments.

The vastus lateralis is the largest and most powerful muscle of the quadriceps femoris group so make sure you take extra good care of it. Similar to any muscle in your body, the vastus lateralis has origin and insertion points from which it pulls in order to create movements. As you can see from this anterior view, the muscle originates from the greater trochanter and the lateral lip of the linea aspera of the femur and joins the quadriceps the tendon. In turn, this common tendon inserts into the tibial tuberosity via the patellar ligament.

Let's rotate the model so we can see the vastus lateralis from the lateral side. Here is the muscle and here are the same attachments once again but seen from a lateral perspective – the greater trochanter and the lateral lip of the linea aspera of the femur, the quadriceps tendon, the patellar ligament and the tibial tuberosity.

Now that you've seen where the vastus lateralis attaches, I'm sure you know the joint moved by this muscle. Exactly, it's this one over here – the knee joint. This hinged joint is where the femur of the thigh and the tibia of the leg meet – the two bones onto which this muscle is attached.

Let's look closer at the movements of the knee joint that the vastus lateralis is involved in. There is one major movement the vastus lateralis takes part in which is extension of the knee joint. Now, let's look at this movement in slightly more detail and visualize it with the help of our friend on the screen.

The easiest way to see this action is to first place the model in a sitting position like so. As you are well aware by now, the vastus lateralis is part of the quadriceps femoris muscle group which is an extensor of the knee. Therefore, when the quadriceps femoris contracts as you see now, the vastus lateralis is involved in bringing the lower leg up otherwise known as knee extension. As you can imagine, there are many times when you need to extend your knee every day, like standing up for a much needed study break, perhaps, as well as walking, climbing or doing sports to help you stay fit, and the vastus lateralis is involved in all of them.

So there you have it, the function of the vastus lateralis muscle. Thanks for watching and see you next time.

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