We now begin our discussion of the lower extremity, and during this group of lectures, we'll talk about the bone, the muscles, the movement of the joint, the blood supply and the nerves. So, we begin with the bones of the lower limb. Just to be clear with this skeleton here, we're used to looking at and remind ourselves that when we speak of the lower extremity many of us use the term leg to describe it. But we're exactly the the lower extremity is divided into a thigh which goes from hip joint to knee joint. A leg which goes from knee joint to ankle joint and then from the ankle joint we go to the foot. So, if we use these terms were more exact about which part of the lower extremity we're talking about. So, our objectives here are to be able to name the parts of the pelvis. Name the bones of the lower limb, described the properties of the hip, knee and ankle joints, and describe the crucial ligaments of the knee. So, we begin with the pelvis. The pelvis is composed of the two hip bones on the right and on the left. And these hip bones have three divisions an ilium, an ischium and a pubis. And these are joined in the midline by a cartilaginous plug called the pubic synthesis. The pelvis is completed posterity by the sacrum me here and then a small set of rudimentary bones at the end of the sacrum called the toxics. The joint between the ilium and the sacrum are large joints, and these are important because they stabilize the pelvis as a circle. But they also transmit the way to the head, the upper extremity, and the trunk to the lower extremities. So, it's very important then in the transfer of of weight from the pelvis. As we see to the femur here, you see the femoral head sitting in a socket. The socket at the pelvis is called the acetabulum. So, the hip joint itself then is between the femur and the acetabulum. So, it's a posterior view. What I call your attention is how deep this joint is compared to the much more shallow shoulder joint between the humorous and the glenoid fossa. So, here's a view now of the of the acetabulum and ephemeral head sits snugly within it, reinforced by very dense joint capsule that help stabilize the joint. So, now we look we look at the femur we see it's the largest bone in the body and it transfers the weight of the trunk, and upper limbs to the knee joint here. So, we look here we can see the distal attachment of the femur to the tibia. These composed a knee joint will look at that in just a second. This is a lateral view now of the knee joint. We see the femur sitting on the tibia. And this is a relatively flat structure here. The tibial plateau is nothing like the socket that we saw at the knee joint and it needs other structures to help stabilize it. We also note the patella here. The patella is a sesamoid bone which sits in the tendon of the quadriceps femurs. And this patella here increases the strength of the of the quadriceps r for extension of the knee. But it also then articulates with the femur and has a cartilaginous surface here which which articulates with a cardiologist part of the femur. And as such is a critical part of the knee joint again which involves the femur, the patella and the tibia. We note that the fibula itself comes close to the knee joint, but does not participate in it directly. The knee joint itself in is stabilised, deepened by a set of fiber cartilaginous discs called the medial meniscus and the lateral meniscus. And they form a kind of a shallow socket which stabilizes the joint. And furthermore, we see another view here in this anterior image in which the patella has been removed for clarity here of the structures. So, patella has been taken away. We now see the meniscus and we see the ACL, the anterior cruciate ligament. This next image here is a posterior view. We see the posterior cruciate ligament. We see the anterior cruciate ligaments and we can see the medial and lateral femoral condyle where the femur sits in this shallow socket if you will created by the minus key. This shows a view now in which the femur has been removed. We're looking at the superior surface of the tibia. We can see the medial meniscus here. The lateral meniscus here and this shallow space here is where our ephemeral conned will sit. We can see the ACL, a name for its tibial attachment and the PCL posterior cruciate ligament named fritz tibial attachment. Again, ACL attaches to anterior tibia. The PCL attach is to posterior tibia. And the configuration of the joint here makes the knee joint a simple hinge joint as opposed to our air joint which is a ball, and socket joint allowing considerably more movement. Now this is a view of the leg, and now we see the tibia here and we see the fibula. We can see clearly how much thicker, more sturdy the tibia is and we see it down at the ankle joint. This is a view of the ankle joint here showing the tibia resting on the talus. So, the transfer of weight from the body goes from the pelvis to the femoral head, from the distal femur to the to the knee. And then from the knee the weight of the body is transferred principally from the tibia to the talus. So, the tibia talus joint is the main ankle joint where our weight is transferred and we see also the fibula participating a bit laterally. This is a slightly higher power view that shows how the configuration of the joint. The medial malleolus say the protuberance of the tibia. That bump that we can feel on our medial ankle and the lateral malleolus is here which is a bump we feel on our lateral ankle. And they wrap around the tail is here and together they ensure that the ankle joint is a simple hinge joint. This is a lateral view now that shows the fibula here and shows the talus, and what we can see is the talus sits principally on a bone called the calcaneus. Calcaneus is the heel bone which we can all feel as we bump our posterior foot. And this is where the much of the weight of the rest of the body is transferred down to the balconies on what's sometimes called the sub talus joint, the joint inferior to the tables. And we can see here number of carpal bones and then metacarpals, and phalanges distantly. This is a slightly better view that shows that parcel bones which we've spoken about the talus and the calcaneus. There are other carpal bones which for the most part are beyond the scope, and this course the distal to the tarsal bones. We see the the metatarsal bones and just talk to them, we see the phalanges for the second third, fourth, and fifth digits we have. There are three phalanges a proximal middle and distal phalanx for the first digit. For the great toe, we have simply approximate in distal feelings. Let's for a moment here. Which are bones of the pelvis. And again, let me remind you that these are just, these are totally upgraded self assessment questions. So, you can think about how you've done with respect to the objectives that we started with. So, feel no pressure. But think about it briefly. If you remember that excellently remember the bones that of the pelvis included the parts of the hip bone, proper helium pubis initially. And the sacrum. That's good. I ask you which are hinge joints? She said that the knee and the ankle are hinged joints. That's good there. The movement is as always there is a small amount of rotation at some of these joints, but principally, because of the way the bones and the ligaments fit together. These are thought of classically as hinge joint. Which are multi axle or in other words, ball and socket joints. He said the hip joint that's good. We talked about the fact that it's a, that we have our femoral head sitting in the acetabulum. Makes it a ball and socket joint configuration. That joint has much to do with our capabilities of movement. Okay, so, the anterior cruciate ligament runs from the posterior tibial played to the femur. True or, false. A few, if you said false, that's good. It just remind ourselves that the the crucial ligaments are named for their attachment to the tibial plate, or plateau. And the ACL, arises from the anterior tibia and extends posterity to attach to the femur. And similarly to posterior cruciate ligament rises from the posterior tibia and passes a superiorly, and entirely to attach to the femur at the ankle. The tibia rests on the. If you said tell us that's good, remind ourselves that the fibula talus joint is the ankle joint. We have our large our large distal just to be a thick bone transferring away to a broad resting place on the talus. Makes it ideal for transfer of weight as as well as a small as well as flexion and extension. The fibula is a part of the knee joint. Okay, that's false. If you recall that the knee joint itself is the the femur sitting on the tibia and patella here, moving up and down on the femur as we extend and flex our knee. We have completed the first lecture on the lower extremity in succeeding lectures will define the specific movements of the joints. I will talk about the muscles in charge of those movements and we'll talk about the blood supply, and the nerves. I look forward to seeing you in there in the next lecture
