Bones, ligaments and joints of the hip bone and the thigh.
Hello everyone! This is Joao from Kenhub. Welcome to another tutorial, another training unit, and this time we’re going to be learning about the pelvis and the femur, more specifically about the bony elements of the femur. So we’re going to be dealing with osteology of the femur. And also, a specific part of the pelvis that we’re going to be dealing here is the hip bone. So we’re going to talk about all the bony elements related to the hip bone.
Now, keep in mind that throughout this tutorial, what I'm going to be doing is I'm going to provide you and show you exactly where all the bony elements of the femur and the hipbone are. And I'm going to give you more information so you can have... that way you will have a solid foundation on these topics. So when you go to an exam or in your profession, you know these topics very well. Now, to tie this up, I'm going to end this tutorial talking about the ligaments that connect the femur and the hip bone.
Now, moving on, and I want to do some clarification here, a very important thing is to define what is the bony pelvis—an important thing to clarify before we go on and talk about the rest. What you need to know about the bony pelvis is this structure that you can see here on the screen right now with other elements as well. You have the two femurs here and the vertebral column as well, but the bony pelvis is this structure right here that consists of two hip bones, which we will focus on this tutorial—keep in mind. And another two elements or two bones are the sacrum—this bone that you can see right here, which we will talk about in a different tutorial and also a different training unit. But as you can see, this is also part of what is known as the bony pelvis. And the... Let’s say the fourth element, since we have four in total, will be the coccyx. And the coccyx is this bone here joining the tip of the sacrum. We’re also going to talk about it in a different tutorial and training unit.
But now, we’re going to be focusing, like I said, on the hip bone—very important. And the very first thing you need to know about the hip bone, it’s also comprised of three bones. Three bones... or the hip bone consists of three bones. The first one is this one that you can see here. It’s highlighted in green like all our training units and all our tutorials. So you have a similar process, learning process. And this bone right here is the largest one that you find on the hip bone and is known as the ilium. Now, the second one is this one here, also highlighted, and this is known as the ischium (iskiŭm) or ischium (ishiŭm). You can pronounce it both ways. I’ve heard it both ways, so I think it’s accepted as both ways. Now, the third bone is this one here—very famous, I would say, bone. It is known as the pubic bone.
Now, that I just briefly introduced the three main components of the hip bone, it is time for us to talk about a structure where they all meet, and this is known as the acetabulum. Now, the acetabulum, as I mentioned, is a cavity formed by the synostosis of these three bones. So this is the meeting point of these three bones: the ilium, the pubic bone, and of course, the ischium.
Now, still on the acetabulum, I want to add something important here that this is the socket for the hip joint. So this serves as the socket point or the socket attachment, let’s say, for the hip joint. As you know, the hip joint is a ball-and-socket joint, and for that matter, you’re going to have a ball portion. That is the head of the femur as you can see here. And of course, the socket portion where this head will attach will, then, be the acetabulum. And this is, of course, forming one of the most important joints of the human body.
Now, moving on, I want to talk about a few structures that you find in the or within the acetabulum, and the first one is this moon-shaped structure that is known as the lunate surface. And the lunate surface works as the articular surface of the acetabulum. And as you notice here, it’s surrounding the acetabulum. And another important thing that you need to know is that it’s covered in cartilage—very important point.
Now, moving on to another structure, this is known as the margin of the acetabulum. And this margin is bordering the acetabulum, as you can see here, or it’s bordering the acetabular fossa. You can say that. And it is interrupted here by this notch, as you can see here, that is known, of course, as the acetabular notch.
Moving on to another structure and not to be confused with the margin of the acetabulum, this is known as the acetabular lip. And this is a fibrocartilaginous collar on the rim of the acetabulum, as you can see here, that is surrounding the margin of the acetabulum—very important thing.
Now, it is time for us to talk about the different elements that you find within the bones of the hip bone. And the first one, you probably guessed, this is the ilium. And the ilium is divided into two parts: the body and the wing. Now, the wing is this flat-shaped portion here that does look like a wing, and that’s why we call it. We simplify things in anatomy. Now, the body is the central part of the ilium that is located near the acetabulum, so this portion right here. And it is also part of the iliac portion of the acetabulum like we talked about on the previous slides.
Now, moving on to the different elements that we find within the ilium, the first one is a line and is known as the arcuate line. And this is a smooth, rounded border on the internal surface of the ilium. And this arcuate line is marking, as you can see here, the border between the body and the wing of the ilium.
Now, the other structure is known as the gluteal fossa or gluteal surface, and it is an external surface of the wing of the ilium. And the extremities of this gluteal surface serve as the origin points of the different gluteal muscles—so very important.
The other one is known as the iliac fossa. This time, this is found internally, so this is in the internal surface of the ilium, and it is a large, smooth, and concave surface that you find on the ilium.
The other structure that we need to talk about is known as the iliac crest, and this is the superior border of the wing of the ilium. And as you can see here on this image, it’s stretching from the spine here known as the anterior superior iliac spine that is stretching all the way to the posterior part to another spine known as the posterior superior iliac spine. Now, important thing about the iliac crest is that it serves as an origin and insertion points for certain muscles—very important thing. So it’s an attachment point for muscles including a very important one that you know, and is very important, and large muscle of your body known as the latissimus dorsi.
Moving on to another structure, this is known as the iliac tuberosity. And the iliac tuberosity is a roughened area behind the iliac fossa, as you can see here on this image. And it serves as attachment point to the sacroiliac ligaments.
Moving on to another structure, this is known as the auriclular surface. And like the name indicates, this is ear-shaped surface which articulates with the sacrum. It is covered in fibrocartilage—very important point to know about this auriclular surface.
One important thing about the ilium is that is has four different spines located in four different positions within the ilium. Now the first one is the one that you see here. This is known and as I already talked about this is the anterior superior iliac spine. And it is a bony projection that marks the anterior limit of the iliac crest like I also talked about on the previous slides. And it is the origin for the sartorius muscle.
The next spine is known as the posterior superior iliac spine. And this is a posterior bony process at the posterior and of the iliac crest. Now, it’s shorter than the anterior—important thing to notice. And it serves as attachment for the oblique portion of the posterior sacroiliac ligaments and multifidus.
The other spine is known as the anterior inferior iliac spine, and this is a bony process at the anterior margin of the ilium. Now, this serves as the origin point for the rectus femoris muscle.
Now, moving on to the last spine that you find within the ilium and this is known as the posterior inferior iliac spine. Now, the posterior inferior iliac spine is found right on the superior end or edge of this really important structure that we will talk about known as the greater sciatic notch. Now, just at the tip you find this spine.
Now, these are all the bony elements that we need to cover on this tutorial for the ilium, and we need to move on to another bone of the hip bone. This time is the pubic bone. And the pubic bone is known to have three main structures: the body, the superior ramus, and the inferior ramus. Now, the superior ramus is this portion right here that you can see here that is located just above the obturator foramen, which is this large opening here that we will also briefly talk about later on. But this is where you find the superior ramus. Now, of course, the inferior ramus will be this portion right here that it is between the symphisis and the suture line with the ischium, which we will talk about as well later on.
Like I promised, let’s start then with the obturator foramen, this large opening that you find here between the pubis and the ischium. Now, this is really important to mention, especially on this tutorial, because this is where a lot of nerves, important nerves and blood vessels, will pass through. So this is a very important foramen in your body.
Now, the other structure that you find within the pubic bone is known as the symphyseal surface. Now, this is a surface of the superior ramus of the pubis that will—or the pubic bone—that will unite with the opposite surface through a midline cartilaginous joint forming this structure right here that you can see on this image. This is known as the pubic symphysis or the symphysis pubis—adding the name right here. So this structure is very important as well. And of course, the participating structure of the pubic bone will be the symphyseal surface.
Another structure will be then the pubic tubercle and this is a protuberance that is located on the medial portion of superior ramus and the anterior and lateral to the symphysis, so right here on the superior surface of the symphyseal surface. Now, this is where the inguinal ligament will attach to.
Moving on to another structure, this time we’re talking about the iliopubic eminence. This is a flat prominence at the proximal portion of the pubic bone. It marks the union of the pubic bone and the ilium as you can see right here, so two bones being united at this portion here at this iliopubic eminence, this elevation right here.
Now, let’s talk about another structure, and this one is the obturator crest. Now, the obturator crest extends, as you can see here on this image, from the pubic tubercle all the way to the acetabulum—so from the pubic tubercle here all the way to the acetabulum forming this crest. And it is the origin point for the pubofemoral ligament, very important origin point for this ligament.
Now that we just covered all the bony elements that we find within the pubic bone, it is time for us to move on to the third and last bone of the hip bone. And this is, as you probably guessed already, this is the ischium. Now, the ischium is also divided into two portions: the body and the ramus. And the body is this portion right here located just behind the obturator foramen. This is the obturator foramen like we talked about—this large opening. Now, the ramus of the ischium is going to be found right here just below the obturator foramen.
Now, still on the ramus of the ischium, I want to add an important point here that the anterior portion of the ramus of the ischium is going to meet right here with another ramus but this time the inferior ramus of the pubic bone like we talked about before. So this is a meeting point for the pubic bone and the ischium.
Now, moving on to another strucuture of the ischium, this time, the ischial (ishial) spine or the ischial (iskial) spine. And the ischial spine is a bony prominence, as you can see here, between two sciatic notches: the greater sciatic notch right here and the lesser sciatic notch; and this is the ischial spine just in between those two notches. Now, an important structure because it serves as an attachment point for some muscles including this one that I'm showing you right here, this one highlighted in green. And you can see clearly it attaching to the ischial (iskial) spine or the ischial (ishial) spine.
Since we’ve been talking about these structures, it makes sense to talk about them in a little bit more detail now. And let’s start of course with the greater sciatic notch. And this is a large notch that you find between the posterior inferior iliac spine, right here, and goes all the way down to the ischial spine that we talked about previously. Now, an important thing that you need to know is that once you add this ligament here, this important ligament that is known as the sacrospinous ligament, then this notch will become what is known as a foramen. And this foramen is then used by a lot of important structures to pass through including the piriformis muscle and this structure that you see here highlighted in green—very important nerve known as the sciatic nerve. So this is passing through that foramen that is formed by this ligament and the greater sciatic notch.
Let’s move on to the other notch, and this time it’s going to be the lesser sciatic notch. And the lesser sciatic notch exists between the ischial spine, as you can see here, and extends all the way to another structure that we’re going to talk about next known as the ischial tuberosity, right here. Now, it also converts into a foramen once this ligament is present, this large ligament that is known as the sacrotuberous ligament. Also the sacrospinous ligament, which is also present here, will help to convert this lesser sciatic notch into a foramen—important thing to add as well. Now, the structures passing through this foramen include the obturator internus muscle, the nerves that supply the muscle and internal and pudendal vessels and nerves, just for your information.
Moving on to another structure, the last structure of the ischium, this is the tuberosity of the ischium and this is a ischial (iskial) or ischial (ishial) process at the lower end of the lesser sciatic notch. Like I mentioned before, here, the lesser sciatic notch will extend up to the tuberosity of the ischium, and of course, this is the structure that we are highlighting right now.
Now that we just finished talking about all the bony elements that we find on the hip joint, it is time to move on to another bone, this time, located a little bit further down, and this is the femur. Now, the femur is the largest tubular bone that you find on your body and it is also known as the thigh bone. And in terms of elements, let’s start with the very first one. It is known as the head of the femur. Now, I already talked a little bit about this element and what you need to know is this is the ball part of the ball-and-socket hip joint. Now, this is going to be articulating with this portion here of the hip joint known as the acetabulum—very important part.
Now, another part that I want to highlight on the head of the femur is this depression right here that is used for the attachment of this ligament that is cut right here. This is the head of the femur ligament. And this is a very important ligament because this helps the connection between the two bones, helps strengthen this connection.
Now, moving on to another part, the largest portion of the femur, this is known, of course, as the body or the shaft of the femur.
Moving on to the next one, this time, we’re going to talk about the neck of the femur. And this is the portion that you find between the head right here and this other portion that we’re going to talk about next known as the greater trochanter. As I promised, moving on to the greater trochanter, this is a large prominence on the superior lateral aspect of the femur shaft. And it’s used for several things, especially attachment of different muscles, including the gluteus medius that you can find here on this image and is attaching here to this greater trochanter—and also others like the gluteus minimus and the piriformis muscles.
If you have a greater trochanter, you have to have, of course, a lesser trochanter. And the lesser trochanter is a small prominence that you find on the posterior medial aspect of the proximal femur shaft. And it serves as an attachment to a very important muscle known as the iliopsoas muscle.
Now, between the two trochanters, you find a line. This line is known as the intertrochanteric line. It’s a rough anterior line between the shaft, as you can see here, and the neck of the femur that is hidden behind these ligaments right here. And this line is running as well from the greater trochanter all the way down to the lesser trochanter. Now, on the posterior side, you find, as well, another line, let’s say, but this time called the intertrochanteric crest that is also between the neck of the femur and the shaft and runs, as well, from the greater trochanter all the way down to the lesser trochanter.
Now, enough about lines; let’s move on to (oh no!) another line. And this line is known as the linea aspera. In Latin, this means rough line, and it is indeed a rough double line on the posterior aspect of the femur. And this is an important line because it serves as insertion and attachment points for many muscles including the gluteus maximus. As you can see here, the gluteus maximus is inserting, as well, on the linea aspera.
Now, the next structures that we need to cover on the femur are these that you find on the distal portion of this bone right here. You have a lateral one and also a medial one. And these are called the condyles. So you have a medial condyle of the femur and a lateral condyle. Between these two structures there is another structure known as the intercondylar fossa, as you can see here. And this is, of course, separating these two femoral condyles, and it’s a posterior notch as you can see here. It’s found on the posterior side of the femur.
Now, moving on to the other structures here now, this time, we’re going to talk about bony elevations that we find on the aspects of the different condyles. And the one that we see here is known as the medial epicondyle—important thing. The medial epicondyle is a bony elevation that you find on the medial aspect of the medial condyle. And also on this medial epicondyle, you will find a very important structure known as the adductor tubercle. And this is this tiny elevation that you find right here, this is a small process that is located above the medial epicondyle. And it’s very useful because it’s a point for attachment or insertion point for the adductor magnus muscle seen here, highlighted in green. If you follow here, here is where it’s attaching on this adductor tubercle found medially.
Now, the last structure that I want to talk about on the femur is known as, then, the lateral epicondyle. And this is, of course, a bony elevation that is found on the lateral aspect of the lateral condyle.
Now that I’ve discussed all the bony elements of the femur, it is time to move on to the last topic of this tutorial, and this is the ligaments—now, the ligaments that connect the femur to the hipbone or vice versa. Now, the first one that we’re going to talk about is one that I discussed briefly when I talked about the head of the femur, and this is, of course, the ligament of the head of the femur. Now, this ligament extends, as you can see here, from this portion here of the acetabular notch, all the way to this depression here on the head of the femur.
Now, moving on to another ligament, this one; you can see a little bit better on the anterior portion here. You can still see it a bit on the posterior portion but just a tiny bit. And this is known as the iliofemoral ligament. This is a strong anterior ligament, as I mentioned, of the hip joint capsule which extends from the ilium all the way to the intertrochanteric line that we talked about. See why this is important to talk about all these bony elements: because this is a point of attachment for this specific ligament.
Now, moving on to the other ligament, this is known as the ischial (iskial) or ischial (ishial) femoral ligament. And it starts into the orbicular zone from the posterior margin of the acetabulum. It is also attached to the anterior margin of the greater trochanter and the intertrochanteric line. So as you can see, it goes all the way to the front, to the intertrochanteric line, and starts here on this acetabular margin.
Moving on to the other ligament, this time is the pubofemoral ligament. And this ligament arises medially, as you can see here, from the joint capsule of the pubic bone and extends to the orbicular zone and to the part of the femur proximal to the lesser trochanter. So it goes all the way closer to the lesser trochanter. The last ligament that we need to briefly talk about is known as the transverse acetabular ligament, and you can guess by the name that this is a ligament that is bridging the acetabular notch and completes the articular surface for the head of the femur, helping it stabilize and stay inside the acetabulum.