Lower Limb Anatomy PDF

All right, in this recording, we are going to cover most of the lower limb. We are going to look at the bones and then the muscles of the thigh and the hip joint as well. So here's the lower limb. It's going to be comprised of our oscoxa or a pelvic bone here. We have one bone in the leg or in the t...

All right, in this recording, we are going to cover most of the lower limb. We are going to look at the bones and then the muscles of the thigh and the hip joint as well. So here's the lower limb. It's going to be comprised of our oscoxa or a pelvic bone here. We have one bone in the leg or in the thigh, excuse me, the femur, two bones in the leg, and then we have tarsals, metatarsals, and phalanges for the feet. One thing I do want you to note is in this image, you can see that the pelvis here, the pelvic bones, are actually tilted more anteriorly than one might think, and this is kind of an important aspect of this arrangement here. The other thing to note is that the lower limb really does mirror the upper limb in terms of its muscles and its organization. All right, so here's the pelvic girdle, which means we're including the sacrum in this. The pelvic girdle is also going to include what we call the oscoxa, right? So the oscoxa is going to be both of these bones, so paired, and it can be divided into three different portions. We have the ilium here in blue, the pubis here in green, and then the ischium here at the bottom. So originally, these are going to be three different bones that will ossify and join together during development. All right. So now we are looking at this anterior view of the pelvis here, right? So some of the really important landmarks I am going to point out here. One is going to be the anterior superior iliac spine. That's because there's an inferior one, and then there's two posteriorly as well, right? So the ASIS is where many of our muscles that work on the lower limb are going to attach, so specifically those that are in the thigh. We can also see the acetabulum here on these two sides here. That is where the head of the femur is going to sit and make our hip joint. We also have this right here, our pubic symphysis is going to be where these two bones meet. This is going to be one of those fibrous joints that we covered way in the beginning of this material here. One last thing I want to point out here is the optorator for ramen. We have two muscles associated with these as well as a thick fascia, and this is going to be a location where we have a neurovascular bundle go through. All right. Here is our lateral view. It's a really weird bone, so take a minute to kind of get your orientation. We are looking again at the acetabulum here. That is where the head of the femur, of course, sits within. Here you can see the head of the femur has been pulled out, but we have all the soft tissue still on here. Here is that optorator for ramen again from this side. If we go more posteriorly here, two important landmarks are going to be the greater sciatic notch and the lesser sciatic notch. Those are going to really be separated by the ischial spine here, which is going to have a ligament attached to it. These two notches are going to help create these for ramen that, again, important neurovascular bundles for the pelvis and perineum, will travel through. Again, we're going to see them again, and I think in terms of this view, that's pretty much it. If we look down on the ossococcus or the pelvic girdle here, we can see the pelvic inlet. This is really going to define the superior boundary of the pelvic cavity. All right. Moving on to our femur, we can see that the femur is going to articulate and sit within the acetabulum here. We are looking at a right femur, the posterior aspect here. The head, of course, is always going to point medially. Two structures that will be important for muscle attachment sites are going to be the greater trochanter, like the greater tuberosity is going to sit laterally on the bone. We can also see it from the front as well, see right there. Then the lesser trochanter is really going to be prominent posteriorly here. We also have this inter trochanteric crest, another point of attachment for muscles. If we come down here, we can see that the head is always going to help us determine the medial versus lateral side, because it's always going to be medial. This is our medial condyle, lateral condyle, and this is going to be the surface that articulates with the superior aspect of the tibia, as we can see there, and help create the knee joint. We're going to look at the leg bones here. Here's the tibia, and here is the fibula. The tibia is bigger, and it's medially located, and it's really going to hold most of the weight here. It is going to really make up the medial aspect of your ankle joint, versus the fibula that's going to make up the lateral aspect. If we look down here, we have these two kind of prominences on either side here. They are going to have a special name. They're going to be the lateral for the fibular side, malleolus versus the medial malleolus. This is kind of the sides of our ankle joint. We can kind of see right here, here's one of our tarsals, the big tarsal that we actually will flex and extend using. Here's that medial malleolus. This is going to be the opposite foot than this here, and this is going to be our lateral malleolus. The lateral, again, is going to be the fibular side. Medial malleolus is going to be the medial side, so we have our left foot here. These are the bones of our right leg versus the left, so keep that in mind when you're looking at that. All right, in terms of our foot, we have, again, it looks very much like the hand in terms of how it's built. We're going to have these big, clumpy, block-like bones that are going to be our tarsals. This is where the tibia is actually going to articulate with the ankle joint here. Metatarsals are going to comprise our foot, and then we have our toes. Again, we have a proximal, intermediate, and distal phalange. Our big toe does not have a middle phalange, just like our thumb doesn't. Looking at these bones individually in terms of the tarsals, the talus is going to be the one that articulates with the distal tibia. Here's our talus. It has this nice rounded top on it. Our heel bone is actually going to be called the calcaneus. My mouse is a little bit jumpy here. There we go. There's the calcaneus. It's the largest of these bones. Then we have a series of smaller bones that make up the rest of the ankle. If we go from medial, we know this is medial because there's the big toe, to lateral, medial most is going to be the navicular. You can actually see that it's shaped like a little boat, which is why it's called the navicular. Then we have the cuboid next to that, the lateral most aspect. Then we have these three bones right here. They are just named for where they are in location to really one another. We'll have a medial cuneiform, middle cuneiform, sometimes called intermediate, and then our lateral cuneiform. Again, with a lot of our appendicular stuff, you need to identify medial versus lateral to really get the context for the bones and the muscles that we will see. Joints and muscles of the lower limb. Here we're going to take a look at some of the important information. The hip joint is really important. It's similar to the shoulder, but because all of our weight is transmitted through this one joint or two, while we are standing, it has to be really tough. It has to be strong and durable. It's designed for stability, but it also has quite a bit of movement, as we can see from this nice dancing skeleton. It might be a little obnoxious, but I like them. We want to look at the ligaments that are allowing our hip to be strong, but also fairly flexible. They're going to be called the spiral ligaments. They're really cool in their organization. This one here is going to be our ileophimoral ligament. It's coming from the inferior aspect of the ileum. There's the anterior-inferior ileic spine right here. Then we have our pubophimoral ligament that's going to cross here, spiral in this location from our pubis. That's our pubis region. Then our ileophimoral ligament is going to be this one right here. We're looking at the posterior view, which is this really prominent lesser trochanter and greater trochanter. If you're confusing trochanter with tuberosity that we see in the humerus, you can think that you're going to trot with your trochanter. Again, greater trochanter, lesser trochanter, and here are these spiral ligaments. The ileophimoral ligament right here is going to prevent hyperextension. That's really pushing your thigh posteriorly to make sure it doesn't keep going and then pop out of the socket. The pubophimoral ligament is going to really prevent overabduction. It's holding that head of the femur, the neck of the femur in place so we don't overabduct, which means rising above the midline out of our socket. These are going to be important in stabilization. I am going to outline this. I would like you to know this material here. Then we can see some other things we can really see in this image, that nice thick fascia that covers that obturator for raiment as well. Here is the real stuff. They are highlighted for you because it's difficult to really define those boundaries. ileophimoral, pubophimoral, there's our nice pubic bone. There's that obturator fascia again. We know it's anterior because we can see the pubic symphysis here. Looking at this posterior view, we have that ischio femoral ligament right there. We can still see a little bit of that ileophimoral as well. One of the things that I have highlighted here, and we're not going to really talk about it a lot, is this area right here. We're going to talk about it more or revisit it when we do the reproductive system. We have this greater sciatic for raiment, helped to be made by the greater sciatic notch. This is going to be our lesser sciatic for raiment. You can actually see this nerve passing through here. We actually have a neurovascular bundle coming out of the pelvic cavity, then back in, in these areas. That area is further defined by that sacrospinus ligament right here. I highlight it because, again, we're going to revisit it. Lower limb fascia and muscle organization, again, similar to the upper limb. I have this image in here to show you really how thick that overlying fascia is and how those compartments that we talked about before in the upper limb and now in the lower limb are really binding or compartmentalizing these muscles into these defined groups. The compartments of the thigh will be defined by this fascia lata. The anterior muscles here are going to be our hip flexors. This is going to be a little bit weird because we said they're opposite when we look at them. Our hip flexors are going to be anterior here. However, the rest of the muscles in our anterior thigh are going to be knee extensors. We can see this already extending our knee. This is going to be opposite in terms of anterior posterior from our upper limb because of that limb rotation. The medial aspect of our thigh is going to be the hip adductors. When these contract, they bring the leg down and in or the thigh down and in and lateral. We have one muscle in the lateral compartment, which is our hip abductor, helping our leg raise above the midline. When we look at the leg and what you will get to in the last recording, we are going to see an interosseous membrane again between the tibia and fibula. The anterior compartment is all going to be extensors, but we are going to call this dorsal flexion, dorsiflexion. The posterior compartment is going to be flexors and we are going to call those plantar flexors. Extensors and dorsiflexion are going to be synonymous, so keep this in mind. We will also have some adductors as well on our leg. If we look at the hip flexors, we are thinking anterior compartment, they are going to cross from inside our torso across our hip joint to attach on the femur here. They are going to allow us to flex our hip. We have the iliacus right here, it is sitting within the ilium that we saw a little bit earlier, the iliac fossa. Then we are going to have the psoas muscles here. We have a psoas minor and major, we are just going to call them the psoas. They are going to come together as the iliopsoas inferiorly here, they merge as one. Then we have up here our quadratus lumborum muscle, it is actually going to be a vertebral extensor, but it is going to be located inside our abdomen, so that is kind of a neat organization there. We have one more muscle here called the pectinius that we will associate with our hip flexors as well. It is going to be attached to that pubic ramus, our superior pubic ramus, down to the femur here. Then our sartorius sometimes will help with these muscle actions, really is going to help us laterally rotate our thigh though. We are going to get those covered, so lateral rotation means turning the leg laterally, the thigh laterally. Coming down here, we are just going to look at these from a higher view here, there is that sartorius that we talked about. The longest muscle in our body, here are our hip flexors up here, now we are looking at the knee extensors. The knee extensors are called the quadriceps femoris, four muscles all together. We have the rectus femoris, help keeping our femur erect right down the midline here. The rest of them are the vastus muscles and they are named for their location to one another, lateral, intermediate, and medial vastus muscles. Those are pretty straight forward and they are going to help extend the knee, so extensors and hip flexors up here, so they are extending and crossing the knee. We do have our lateral compartment visible here, we have one muscle in that lateral compartment that is going to be the tensor fascia latae, you are going to tensor fascia latae with this muscle because our IT band, our iliotibial band we will see again is attached here. That is going to help us bring our leg, our thigh above or away from the midline. If we go to this medial compartment here is that pectinius again, remember that is going to be one of our hip flexors here, then we have our adductor muscles, adductor longus is right here, it is going to be next to this really long muscle called the gracilis, and here is our adductor magnus, note that we are deeper here, these muscles here have been cut and pulled aside, reflected to see this adductor magnus, and you can see how that adduction actually occurs in this image, oh I almost forgot one, we have a deep muscle here called the obturator externus, if we could look or make this transparent we could see that the obturator foramen is just deep to that, we are going to cross that obturator foramen and attach on the proximal femur here. So here is the view of the anterior femur, I am not going to go through all of these but I want to help you find a few landmarks to know what you are looking at, so the ASIS is up here, the anterior superior iliac spine is up here, it is a nice landmark, we can also see this really easily recognizable long muscle, the sartorius, and then finally our tensor fasciae latae and the iliotibial band, IT band is right here, and in addition to all that we can kind of see the knee as well, so that tells us we are looking anteriorly, over here we are still looking anteriorly, the knee is a little bit more visible in this one in terms of the contrast, but we also know we are deep because we see all of these vessels, we don't want to have these vessels hanging out superficially, so we know we are deep when we see those, alright in terms of the gluteal region, our **** region, we have this very large muscle right here, this is the gluteus maximus, it is going to help with lateral rotation of our thigh, so recall we are looking at the posterior aspect here, if this contracts we are going to pull the lateral aspect of our thigh posteriorly and allow for that lateral rotation, looking deep to that we are going to have our gluteus medius muscle right here, and there you can see it underneath that thick fascia and gluteus minimus here, these are really going to also help you abduct, they are going to help that tensor fascia latae, abduct your thigh here, and they are also going to be a stabilizer muscles, they are going to help keep our hips in a straight line when we stand on one leg, so they are going to help keep our balance and stabilize our hip, if we go deep here, these muscles similar to really if we think about the rotator cuff muscles, these are going to kind of have a similar design or action right, so if we go from superior to inferior we have the piriformis, superior gemelli, obturina internus and inferior gemelli and then the quadratus femoris here, so if you can kind of think about this and I remember in a row, all of these muscles are going to attach to the posterior aspect of the greater trochanter, greater trochanter, inter trochanter crest, and the lesser trochanter, so if these contract they are going to pull the hip laterally and help with that lateral rotation right, they are also going to really help stabilize that femoral head, they're in addition to those spiral ligaments keeping everything in place, and I think this little graphic really does help show you how those are working. If we follow that obturator internus in for identification, we're going to go underneath that sacrotuberose ligament, but we also see that it's going to come in and attach internally to the obturator for raiment around it right, so the obturator for raiment would be right here, and then our quadratus femoris is nice and one really important nerve, not that all nerves are important, but one really important large nerve called the sciatic nerve running through here. This is going to innervate the posterior thigh and really all of the leg and foot right, so its branches are going to come down and innervate those anterior thigh is going to be femoral, but we want to be really careful and knowledgeable about the location of this structure, especially if we have to give or distribute or administer drugs into muscle. This is commonly done in the gluteal region just because there's a lot of muscle here, we also have nice quite a bit of padding usually as well, but if you were to inject something into this sciatic nerve it's going to have profound effects right, it's going to really impact the patient, really the entire lower limb or at least most of it right, so we have to be knowledgeable about the organization here in these muscles, so that sciatic nerve is actually going to protrude between the piriformis muscle and the superior jamellae muscle right here. All right just a few more muscles back here, we are going to have our main hip extensors, where you're extending the hip but knee flexors, so hip extensors really are going to all work together to extend the hip based on their superior attachment across the posterior hip, and then they will flex our knee because they're going to cross over our knee, we have this great acronym, beef steaks smell great to help us remember these, so beef is going to be biceps femoris, it is going to be the only one of these that attaches the laterally in the leg, that's how you know this one, steaks is semitendinosus right, there's a long tendon, semimembranosus is smell, it's a really shiny muscle and you actually see it, you can see a little bit of the shininess here, great is going to be gracilis which isn't a hip extensor or knee flexor, but it helps make the acronym right. Okay you want to get used to this image right because you got to get your bearings first, there's a big gluteus maximus here and our iliotibial band or tract, it's a nice landmark that also tells you that you're looking at the lateral aspect here, and then in addition to that we can see our biceps femoris coming down, only one of those attaching laterally in the leg, so that means this is medial semitendinosus, if we follow this muscle down carefully we see there's a really nice significant tendon down here, semimembranosus actually sits underneath it, so we think about the muscle semimembranosus, semitendinosus is going to come down here, so we see it on either side of that structure, so sometimes the b-sticks smell great and can be confusing because semimembranosus, we can really see it on either side. All right that's the end of the fourth recording.