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Functions and anatomy of the gluteus medius muscle shown with 3D model animation.
You may not remember it, but learning to walk took you a long time. That’s because being bipedal is no easy feat and it takes more than a little bit of time to get it right. In this tutorial, we’re going to discuss the gluteus medius muscle, which is one of the most important muscles for maintaining an upright posture and balance while walking.
Before we look at what this muscle does and how it helps us to walk upright, let’s first have a look at the anatomy of the gluteus medius muscle. We’re going to be focusing on the gluteal region, so let’s zoom in for a closer look. Our gluteus medius is one of the four superficial gluteal muscles and sits in between the gluteus maximus, which is this muscle here, and the tensor fascia lata, which is here.
The fourth superficial gluteal muscle is the gluteus minimus, which is situated deep to our gluteus medius despite being a part of the superficial layer. Because the gluteus minimus and medius have a similar structure and is similarly positioned, they have identical functions, so make sure to check out our video on the gluteus minimus once you’ve gone through this one.
So the gluteus medius is a broad and thick muscle, originating from the gluteal surface of the ilium, just between the posterior and anterior gluteal lines, which you can see here. The muscle fibers then run inferiorly to converge into a flat tendon that attaches to the lateral surface of the greater trochanter. The gluteus medius connects the pelvis to the femur by crossing over the acetabulofemoral joint or hip joint for short. As the name suggests, this joint is formed by the articulation of the femoral head and the acetabulum of the pelvis.
Of course, no muscle is an island and this muscle needs some innervation, right? Well, the gluteus medius muscle gets its commands via the superior gluteal nerve, which is this nerve here. It originates from the sacral plexus, specifically, from the posterior divisions of L4, L5, and S1. Once innervated, the gluteus medius can contract to perform three main functions.
Let’s jump straight into our first one, which describes the role of the gluteus medius as a strong abductor of the thigh at the hip joint. This means when muscle fibers contract, they can pull the thigh away from the midline of the body raising the leg laterally. It’s also important in helping to return the thigh back to their neutral position when adducted. That explains why one of the best exercises to activate your gluteus medius is walking laterally while under resistance. Walking laterally involves abduction of the hip joint so the gluteus medius muscle is definitely being put to work here.
The second function of the gluteus medius muscle is internal rotation of the thigh at the hip joint when in a flexed position. This means that the thigh is being rotated towards the center of the body. This function is carried out by the anterior most fibers of the gluteus medius as they have a greater mechanical advantage for this type of movement compared to their posterior counterparts.
To give you an example of this type of movement, let’s look at the classic bear crawl exercise. Believe it or not, that our gluteus medius helps to internally rotate our hip joint during each advancing stride forwards. Who knew?
Now, let’s move on to the third and final function of the gluteus medius muscle, which is stabilization of the pelvis. In our animation, the model is standing on their right leg. If we were to take the weight off our left foot, this causes the pelvis to drop on the opposite side by means of adduction at the right hip joint. To counteract this instability, our right gluteus medius contracts and causes the ipsilateral hip to abduct and return to the neutral or balanced position. This simple, but essential function keeps our pelvis balanced during the gait cycle, and failure of this function to occur perhaps due to nerve injury is known as the Trendelenburg gait.
So that’s the functions of the gluteus medius covered, let’s have a quick recap before we finish.
We first learned that the gluteus medius muscle is a strong abductor of the thigh at the hip joint by contracting to pull the femur away from the midline of the body. We then saw that the specific shape of the gluteus medius allows it to perform internal rotation through contraction of its anterior most fibers when the hip is in a flexed position. And finally, we demonstrated the role of the gluteus medius muscle in stabilization of the hip joint during the gait cycle.
That’s it for me for this tutorial. Remember to check out our other 3D muscle function videos for lots more 3D anatomy like this. See you there!