Video: Gluteus maximus muscle (3D)

And the award for the largest muscle in the human body goes to – Gluteus Maximus!

Wow! This is so unexpected. First of all, I want to thank the Academy – I mean, Anatomy – the sacrum, the coccyx, gluteal surface of the ilium, sacrotuberous ligament, gluteal tuberosity of the femur. This award is for you!

The nerves and joints that make my functions possible, you know…you are…thank you! All my life…

Nothing worse than those acceptance speeches that drags on, but in fairness, the gluteus maximus has a lot to boast about. It is probably the most well-known muscle in the body after all. Let's find out more as we explore the functions of the gluteus maximus muscle.

So before we talk about the functions of the gluteus maximus, let's first familiarize ourselves with the anatomy of this muscle. As we can see from our impressive model here, the gluteus maximus is the largest and most prominent of the four superficial gluteal muscles. In fact, it is the largest muscle by volume in the entire human body. The gluteus maximus creates the shape of the buttocks.

An important step in understanding the functions of the gluteus maximus is learning the bones and tissues it attaches to and the joints that it crosses. If we take a closer look, we can see that the gluteus maximus originates from the lateroposterior surface of the sacrum and the coccyx as well as the gluteal surface of the ilium posterior to the posterior gluteal line. It then slopes across the gluteal region at a roughly 45-degree angle to insert at the iliotibial tract and the gluteal tuberosity of the femur.

Now that we've learned the origin and insertion sites of the gluteus maximus, we can easily work out the joints that it crosses. It attaches to the ilium, part of the hip bone, and the femur of the bone of your thigh; therefore, it crosses the hip joint. This means that the gluteus maximus acts on or performs movements at the hip joint.

We're about to see that the gluteus maximus has several functions, but in order to carry out its actions, it needs a nerve to tell it what to do and when. The gluteus maximus is innervated by the inferior gluteal nerve which is formed by the L5, S1, and S2 nerve roots of the sacral plexus.

As I previously mentioned, the gluteus maximus acts on the hip joint, but what movements does it actually perform? We're going to discover there as many as five different functions, none of which aren’t working. Let's check them out.

So the first and most important function of the gluteus maximus is extension of the thigh at the hip joint. This is responsible for producing up to 75 percent of the power behind this movement with the rest coming mainly from the posterior thigh muscles. As we can see here, extension of the thigh at the hip joint involves increasing the angle between the trunk and the thigh.

If we repeat this movement, we can see how this movement fits into our everyday lives. One way we can get our gluteus maximus working is by squatting just like our 3D model is doing now. The gluteus maximus extends the thigh at the hip joint to push you back upwards into an upright position.

Another way to demonstrate extension at the hip joint is when you drop something and need to pick it up. We can see the angle between the trunk and the thigh increase as the trunk is raised back to an upright position. This is why squatting and dead lifting are the exercises of choice when you want to firm up your glutes.

We can also hyperextend the hip joint. This kind of movement may be seen when footballers swing their leg back to take a good kick at the ball.

Okay, so let's move on to the second movement of the gluteus maximus – the external or the lateral rotation of the thigh at the hip joint. As we can see from our animation, external rotation of the thigh involves rotation of the thigh outwards away from the midline of the body. If we keep with the football theme, this is the movement required to kick a football with the side of your foot.

Next, we're going to talk about a movement performed specifically by the superior part of the gluteus maximus – abduction of the thigh – of course, once again, occurring at the hip joint. As we can see from our model, abduction describes the movement of the thigh away from the midline of the body. Conversely, the inferior part of the gluteus maximus assists with adduction of the thigh at the hip joint. Adduction describes the movement of the thigh towards the midline of the body.

Finally, the gluteus maximus functions to stabilize and balance the pelvis while standing, walking, or running. It does this by tensing the iliotibial tract which it attaches to.

So that brings us towards the end of our tutorial on the functions of the gluteus maximus. But before you leave, let's summarize what we covered today.

The first function of the gluteus maximus we saw was extension of the thigh at the hip joint which involves increasing the angle between the trunk and the thigh. This is the movement we perform when squatting to achieve our dream booty. Next, we had a lateral rotation of the thigh at the hip joint which involves rotation of the thigh outwards away from the midline of the body.

We then looked at functions performed by different parts of the muscle. We saw that the superior part of the gluteus maximus abducts the thigh or moves it away from the body whereas the inferior part adducts the thigh or moves it towards the body. Finally, the gluteus maximus functions to stabilize the pelvis throughout these movements. It also tenses the fascia lata.

And that's it! We're done and dusted for this tutorial. Thanks for watching and feel free to check out our other 3D muscle function videos and lots more at kenhub.com. See you next time!