[Music] Hi everyone, welcome to Bodyworks Prime. Today, we're going to be going over the anatomy of the popliteus muscle. On the left-hand side here, you can see the popliteus from a posterior view, and on the right-hand side, you can see the popliteus from a more lateral view. These two views help demonstrate how it's connecting onto the tibia and also onto the femur. We'll be going over the origin and insertion of the muscle in a little bit more detail later on in the video. Now, we can see the popliteus among some of the other muscles of the leg. The popliteus is a deep muscle, so deep in fact, it actually pierces the joint capsule of the knee and passes through to connect to the meniscus. We'll be going over that in a little bit more detail when we go over the origins of this muscle. This picture is really good to demonstrate where the popliteus is located in relation to the other muscles. You can see the gastrocnemius, it covers up the popliteus, and we've also got the soleus here. The origin of the soleus is just below the insertion of the popliteus. You can see a few of the other muscles of the lower leg labeled down here. So, I just want to mention about the pronunciation of this muscle as well. Some people use the pronunciation popliteus and some people say popliteus. There's nothing particularly wrong with either of these two pronunciations, they just seem to vary depending on what part of the world you're from, or perhaps who taught you about this muscle initially. Let's take a look at our first origin point, which you can see highlighted here in red on the femur. Presently, we're viewing the knee from a lateral view, from the side, and you can tell this because we've got the fibular bone here. The fibula is located on the outside of the leg. Now, the origin point for this muscle is located on the lateral surface of the lateral femoral condyle. This origin is located just below the attachment of the fibular collateral ligament of the knee. The femoral condyles are large rounded areas on the end of the femur. So, we can see the lateral femoral condyle here and then the condyle facing away from us here, that would be the medial femoral condyle. The popliteus muscle also connects to the head of the fibula, and it does so via a fibrous band, which is called the popliteofibular ligament. You can see that ligament here connecting onto the muscle and then coming down and connecting onto the head of the fibula. The popliteus muscle also connects the fibrous capsule of the knee joint, which you can see pictured right here. It's a tough and fibrous structure which encloses the knee joint itself, and the popliteus passes through this fibrous capsule round about here to connect to the lateral meniscus of the knee, which we'll be going over in just a second. But in addition to passing through this fibrous capsule, it also connects to it as well. So, the fibrous capsule of the knee joint is another origin point of the popliteus muscle. Now, we can see that origin point highlighted in red on the lateral meniscus of the knee. The meniscus is a crescent-shaped piece of cartilage in the knee joint, which helps with shock absorption and stabilization. So this would be the lateral meniscus on this side right here, and then we've got the medial meniscus on this side here. So, this would be the inside of the knee and then this would be the outside of the knee. You'll understand the reason why it originates from this lateral meniscus when we go over the actions of this muscle later on in the video. Let's move on to the insertion point next, which you can see here highlighted in blue. The popliteus muscle inserts onto the posterior surface of the tibia just above the soleal line. The soleal line is a prominent ridge found on the posterior aspects of the tibia. The soleal line gets its name because it's an origin point of the soleus muscle. So the insertion of the popliteus is going to be just above the soleal line and also just above the soleus muscle as well. The popliteus muscle is primarily innervated by the tibial nerve, which is a branch of the sciatic nerve. Here, we can see the tibial nerve highlighted in red and if you follow it upwards, you can see where it connects to the sciatic nerve. The specific nerve roots which contribute to the innervation of the popliteus muscle are L5 and S1. Let's take a look at the actions next, and our first action is one you might have heard about before, which is where the popliteus is able to assist in unlocking the knee joint. So, how that occurs is through lateral rotation of the femur. It'll be lateral rotation where the femur rotates away from the midline of the body. During medial rotation when the leg is locked out in this extended position right here, that's going to be what locks the knee joint into position, and then that lateral rotation is what can allow for knee flexion to occur. This lateral rotation of the femur in regards to the popliteus is going to happen in a closed-chain position. A closed-chain position, in this case, would be standing up straight, foot on the floor, and the knee in a locked-out position. That's going to mean that the tibia is less able to be freely moved, which is why the femur is the bone which can laterally rotate in this case. What happens when we move to an open chain position when the foot's off the ground like this and the knee slightly bent? In this case, the popliteus is able to assist with medial rotation of the tibia. A medial rotation would be rotating the tibia towards the midline of the body. The opposite of that would be lateral rotation as it rotates outwardly. So when the foot's off the ground in an open-chain position, the knee joint is bent, that's when the popliteus muscle can assist with medial rotation of the tibia. But the popliteus has another important action too, regarding the meniscus of the knee joint. Let's swap over to a different view so we can take a closer look at that. Pictured here, you can see the meniscus and the various ligaments of the knee joint. We're specifically going to be looking at the lateral meniscus here. The lateral meniscus is this crescent-shaped piece of cartilage which I'm just moving my cursor around at the moment. The popliteus helps protect the lateral meniscus of the knee by pulling it posteriorly during flexion. Posteriorly would be pulling the meniscus of the knee towards the back of the knee, so in the direction I'm just moving my cursor at the moment. By retracting the lateral meniscus posteriorly, the popliteus muscle ensures that the meniscus is moved out of the way of the articulating surfaces of the tibia and the femur during knee flexion. This prevents the meniscus from being trapped and potentially damaged by these two large bones. You may have noticed from this image that there's a medial meniscus here as well, and I want to just discuss that in a little bit more detail. The lateral meniscus is more mobile and less prone to injury than its medial counterpart, and this is likely due to the role that the popliteus muscle plays in protecting that lateral meniscus. The medial meniscus doesn't have an equivalent muscle that pierces the joint capsule and that connects to it like the lateral meniscus does. Therefore, the lateral meniscus benefits greatly from the role of the popliteus muscle. Conversely, the medial meniscus has to depend solely on adjustments in tension, compression, and torsional forces to alter its shape and position because it lacks that benefit of a dedicated supporting muscle. We've got one more action of the popliteus muscle to go over now, and that's going to be flexion of the knee joint. So the knee is extended right now, as it bends, that would be flexion. The contribution of the popliteus muscle to knee flexion is extremely low. Some of the textbooks which I've looked at in regards to this muscle describe the contribution of the popliteus to knee flexion as insignificant. So it's in no way a primary mover in flexion, but just an action to be aware of nonetheless. So, if you've enjoyed this video or you found it helpful, you know which buttons to press. Press that like, subscribe, let me know what you thought of the video in the comment as well because it really helps out the channel. Thanks again for watching everyone, I'll see you all next time.