Hello everyone! This is Joao from Kenhub. Welcome to another tutorial. This time, I'm going to be talking about the muscles of the hip and thigh. Now, keep in mind that what I’m going to be doing is I'm going to be talking about this specific muscle groups that you find within the hip and thigh regions.
Now, when you’re learning anatomy in your school, you know that we separate all these muscles so we can learn them better, so we divide them into groups. We usually do so by locating them either where they’re located specifically, either anteriorly, posteriorly, inferiorly and so on, or by innervations, and also by function. But here I'm going to keep it simple, so I'm going to do it by location, so where you can exactly find them within the hip and thigh regions. That way you can also connect the dots and use this material for your studies no matter where you are.
Now, let’s start with the very first group. This is known as the hip muscles. Now, the hip muscles can be even further divided into two groups. These are the hip muscles, none other than that. The hip muscles are a group of four muscles that we’re going to see that are specifically either located in the region that we could consider the hip region. So that’s why we’re going to see them there. And they have a lot of functions that are related to the hip joint as well.
Now, the other group that we needed to subdivide further is known as the gluteal muscles, and the gluteal muscles are the muscles that you find on the gluteal region or the buttock region.
The other ones, then, are the thigh muscles, and the thigh muscles can be divided into three groups. The first one is an anterior group that is, of course, located on an anterior surface. You’re going to see also some muscles located on a medial position. And of course a posterior set or group of thigh muscles.
Now, let’s talk about the very first group of muscles that I mentioned in the beginning. This is the hip muscles. There are four that we need to look at. The first one is this large muscle seen here, highlighted in green. This is known as the psoas major. Now, located a bit more laterally, you find another muscle and this one is known as the iliacus.
Now, an interesting thing, very important point, is that both the psoas major and the iliacus usually are distinguished as one muscle, and this muscle is known as the iliopsoas. As you can see, both the psoas major and the iliacus, they are found on the posterior abdominal wall. And then this two will join forces right here and pass through the inguinal canal and attach right here on this part of the femur known as the lesser trochanter.
Now, the last muscle or the fourth muscle is known as the psoas minor. This is a very small muscle compared to the other muscles that we talked about, and sometimes, it’s not mentioned because between 40-70% of people do not have this muscle.
As I’ve promised, I'm going to be adding a few things that you need to know about every group of muscles that we’re going to be discussing on this tutorial. And for the hip muscles, you need to know that these are the powerful flexors of the thigh at the hip joint, very important thing.
Now, moving on to the second group of muscles, the gluteal muscles. You need to know that this group is comprised of nine specific muscles that we’re going to be looking at.
Now, the very first one, I would say that is a famous muscle, because it defines the buttocks with, of course, a layer of fat, and this is the gluteus maximus. And as you can see here on this image, you notice that it’s located a bit more superficially compared to the muscles that we’re going to be seeing after… or right now.
Now, this muscle here that you’re seeing, highlighted in green, is known as the gluteus medius, as if I were to remove the gluteus maximus, so now, this is what you see right under it. If you were to remove the gluteus medius, you can expose another muscle that is seen right now and is known as the gluteus minimus.
The fourth gluteal muscle is this really long muscle known as the tensor fascia latae. And as you can see, it’s really long because it goes from the hip all the way down to the tibia.
Now, the fifth one is known as the piriformis, as you can see here, located posterior when you’re looking at the pelvis but a bit more deeply when you compare it to the gluteus maximus, minimus, and even medius.
Now, the other muscle that is still a gluteal muscle or part of this group is known as the obturator internus muscle. Notice here that I have both the English and Latin terminologies, and throughout this tutorial, I just kept one because usually you do not translate muscles names from Latin into English. But in some cases there are slight changes like this one here, and I'm going to show both ways of writing the names of these muscles.
Now, the next muscle is a group of two muscles, as you can see here. The first one is highlighted in green and is known as the inferior gemellus muscle. And of course if you have an inferior gemellus muscle, you have to have a superior gemellus muscle. This is the one seen here, now, highlighted in green and is sitting on a superior perspective when compared to the inferior gemellus muscle.
Now, the last muscle of this group has the shape of a square and if you guess, well, this is then named the quadratus femoris muscle.
Now, I would like to add a few words on the gluteal muscles. The first thing is that they’re responsible for extending and abducting the limb at the hip. And keep in mind that the muscles that are able to do that are mainly the gluteus maximus, minimus, and medius.
Now, in terms of the tensor fascia latae, this muscle is able to act on the hip and helps keep the knee joint extended. That’s thanks to that really large or broad tendon that it has.
Now, the deep muscles of the… or the deep gluteal muscles are able to also act on the hip, but this time, as lateral rotators of the thigh.
Now, an important and crucial function of the gluteal muscles is that they’re able to assist in stabilizing the hip joints. So very important function of these muscles on one of the, I would resay, most important joints of your body.
Now, still on the gluteal muscles, I would like to talk about the blood supply, and blood reaches these muscles thanks to the superior and the inferior gluteal arteries.
In terms of nerve supply, these muscles are supplied by the nerves from the sacral plexus. So you can see here a few on this image that contribute to the innervation of the gluteal muscles.
Now, let’s move on to another group of muscles, this time, of the thigh, and let’s talk about the anterior compartment or the anterior thigh muscles. And this group of muscles has six in its total.
Now, the first one is the sartorius muscle as you can see here. And the other one is a group of muscles that come together to form the quadriceps femoris. So usually you can talk about the quadriceps fermoris or distinguish this muscle as one large muscle. But you need to know that it’s formed by four muscles namely these listed here that we’re going to talk about right about next.
So the quadriceps femoris is comprised of this one here that’s found on the most posterior surface—oh, sorry—anterior surface of this muscle and is known as the rectus femoris. Now, if we remove the rectus femoris, we’re going to be able to see the other three a bit better, and of course, this one here, found more laterally is known as the vastus lateralis. Now, in the middle you’re going to find another vastus, and this is known as the vastus intermedius. And to the medial side, you’re going to find, of course, another vastus, and this is known, of course, as the vastus midialis.
Now, a few words on the muscles that we just talked about of the anterior thigh, and the first thing you need to know is that they are primarily extensors of the leg at the knee. But they also have secondary functions namely the sartorius and the rectus femoris that can act as or they can flex the thigh at the hip.
In terms of blood supply of the anterior thigh muscles, you know that these are supplied by the femoral and the deep femoral arteries, as you can see here, highlighted in green.
In terms of nerve supply, these muscles are supplied by the femoral nerve, as you can also see here, highlighted in green.
Now, moving on to the next group of muscles located a bit more medially, for that reason we’re going to call it, then, the medial thigh muscles, and this group of muscles is comprised of seven structures or seven muscles and is also known as the adductor muscles of the thigh or simply as the adductors of the thigh.
Now, the first one that you need to know is known as the obturator externus muscle, and you can see it here, highlighted in green. Now, the other one is known as the pectineus muscle, and this one is known as the gracilis. And the gracilis is an exception within this group of medial thigh muscles. I'm going to tell you why.
If you notice, the medial thigh muscles are attaching or inserting here on the femur as you can see, and this will definitely play a major role on the functions that these muscles are going to have within the thigh and also the hip. But the gracilis goes all the way and inserts here on the tibia, which will, then, influence as well the functions that this muscle is able to perform within the thigh and even the leg. But we’re going to look at it a little bit later on on this tutorial.
Moving on now to the next set of muscles, these are the adductors, so muscles that have adductor in their names. And there are four. The first one is seen here, is known as the adductor brevis. And if you have a brevis—brevis means “short” in Latin—you’re going to have then a longus. So an adductor longus.
And another adductor is a great adductor because it’s a large adductor. We’re going to call it then the adductor magnus. An important differentiation here is this part or this portion of the adductor magnus that can sometimes be distinguished as a different muscle known as, of course, the adductor minimus.
A few words on the medial thigh muscles, the first thing that you need to know is that they, of course, act as the adductors of the thigh at the hip. This is their primary function, let’s say. But they’re also able to flex and rotate the thigh, especially thanks to the gracilis that is able to perform some of these functions, some of these secondary functions.
Now, in terms of blood supply, the blood reaches these muscles through the obturator artery and the deep femoral artery. As you can see here, the deep femoral artery is highlighted here in green.
In terms of innervation of the medial thigh muscles, the innervation… the main innervation is done by the obturator nerve. But some muscles receive additional fibers from the femoral nerve and also the tibial nerve. And these muscles are the pectineus, which receives from the femoral nerve that is highlighted here in green, and the adductor magnus that receives its nerve supply from the tibial nerve that you can see here also on the right. This is the tibial nerve, highlighted in green.
It’s time for us to move on to the last group of muscles that we’re going to discuss on this tutorial, the posterior thigh muscles, of course, found on the posterior compartment of the thigh, and they are three—three muscles of the posterior thigh.
Now, the first one that you’re seeing here is known as the biceps femoris. And the second one is this one known as the semitendinosus, and you have another one with a similar name that is known as the semimembranosus. But look here that they are slightly different, and the semitendinosus right here is located on the top, let’s say, of the semimembranosus.
A few words on the posterior thigh muscles is that they are mainly flexors of the leg acting on the knee, and they’re also extensors of the thigh at the hip, except the short head of the biceps femoris.
In terms of blood supply of the posterior thigh muscles, the blood will reach these muscles thanks to the femoral and deep femoral arteries, as you can see here—both arteries highlighted in green.
Lastly I would like to talk about the innervation of the posterior thigh muscles, and the nerve supply comes from, then, the tibial nerve, which is a division of the sciatic nerve. And you can see it here, highlighted in green.
Now, there is an exception though. The short head of the biceps femoris is innervated by the common fibular or also known as the common peroneal nerve, which is also a division of the sciatic nerve. You can see here this common peroneal nerve highlighted in green.