so everyone in this video we're going to guide you through the key muscles of the knee joint we're going to look at muscles such as the quadriceps as well as key muscles like the hamstrings as well as other muscles that assist in the movement of this joint if you're ready to learn anatomy let's dive in hey everyone Khalid here welcome back to Clinical Physio let's dive into the anatomy of the knee joint and we're going to start with the quadriceps muscles so first of all when we think about the quadriceps we're actually going to look at them more globally in particular to look out where they insert distally so for simplicity the quadriceps essentially all run from around the anterior hip and the pelvis and then join together distally to a central common tendon which is the quadriceps tendon the quadriceps tendon is suggested to insert into the more superior aspect of the patella and is suggested to blend into the next structure the patella tendon which originates from the more inferior half of the patella so from the patella tendon we get the insertion point into the tuberosity of the tibia the tibial tuberosity so the key thing to remember when it comes to all four quadriceps muscles is that they insert into the quadriceps tendon which then blends in with the patella tendon which inserts into the tibial tuberosity of the tibia so you may well hear that these muscles all insert into the quadriceps tendon or the tibial tuberosity and now you understand why so now let's look at these muscles in more detail the quadriceps are made up of four key muscles we have vasis lateralis vasis intermedius vasis mediialis and the biggest over the top rectus forous so let's start with vasis lateralis which we can clearly see on the more lateral side of the anterior thigh the origin of this muscle comes from the superior half of the anterior and lateral surfaces of the feur before it goes on to insert into the quadriceps tendon and thus the tibial tuberosity as we said before we then have vasis intermedius in the middle this muscle originates also from the superior half of the anterior and lateral surfaces of the feur before like the others joining into the quadriceps tendon and thus the tibial tuberosity vasis mediialis as you can imagine is on the more medial side of the knee as the phrase suggests the origin of this muscle is from the more anterior and medial surfaces of the feur before also joining into the quadriceps tendon and the tibial tuberosity and finally the biggest of the four rectus forous now this muscle has two heads it has a straight head and a reflected head the straight head originates from the aiis the anterior inferior iliac spine not to be confused with the anterior superior iliac spine which sits a little bit more superiorly as you can imagine so that's the straight head and we can just see the reflected head over here which originates from a small groove just superior to the acetabulum referred to as the supra acetabular groove and of course this muscle runs straight down the middle of the thigh before inserting into the quadriceps tendon and thus the tibial tuberosity so the key thing about all of the quadriceps muscles is that they extend the knee that is their focal chief job as a movement provider when we think about rectus forous it originates just superiorly to the hip joint and therefore it has a weaker role in hip flexion but the key thing to think about when we think of them all as a four knee extension so now let's swap over to the posterior side of the thigh and the chief muscles in this region are the hamstring muscles now we have three of these we have from medial to lateral semimebrosinosis and I like to remember that mem is the most medial semiendinosis and biceps forous now the term biceps would suggest that this muscle has two heads and indeed it does as we can see here we have a long head and a short head the short head naturally the shorter of the two originates from a little bit deeper than the long head and we can see how this muscle originates from the lateral lip of the linear aspa of the feur however the long head of the biceps forous as well as semimebrosinosis and semmitendinosis originate from the isial tuberosity this is our sitting bone so when you're sitting down and you palpate on your buttock the hard bony prominence you can feel there is the isial tuberosity and so when patients have a proximal hamstring tendonopathy you'll commonly see them reaching for and pointing to that area the isial tuberosity as the place that they experience their pain now the hamstring muscles insert into slightly different areas the semimebbrinosis inserts into the posterior aspect of the medial tibial condile the semiendinosis inserts into the pazanserine region which is on the superior and slightly medial aspect of the tibial shaft and the biceps forous muscle has those two heads the long head and the short head and both of them join together to insert into the fibular head so basically semimebrosinosis and semmitendinos insert medially but the biceps forous inserts laterally now the key thing about the hamstring muscles is that their key role is knee flexion when we think about the knee however when we think about their origin of the isial tuberosity which sits just around the hip joint we can remember that they also have a key role at the hip which is in hip extension but when it comes to the knee the hamstring muscles are the knee flexors so finally let's talk through a couple of muscles that have secondary roles at the knee joint but as a result are really important to mention so the first two are the sartorius muscle and the graasilus muscle we can see that both of these run along the medial aspect of the thigh and both of them have a whirl in knee flexion the sartorius is a weak knee flexor but as it originates from the asis we can also imagine that it has a weaker role in hip flexion whereas the graascillus muscle also is a weak knee flexor but as we can see from its more medial position around the hip we can also remember that it has a role in hip adduction so the eagle-eyed of you will notice that the graasilus and the sartorius muscle also insert into the pazanserine region here at the superero medial tibial shaft and the other muscle which inserts into this region which we mentioned earlier was the semmitendinosis muscle so that's a really key thing when you're thinking about patients who have pain around this superero medial aspect of the tibia could it be that they have a panserine basitis where these three tendons sartorius gristillis and semmitendinosis may irritate the bersa that sits underneath it which is of course the pazanserine bersa so the next muscle to highlight is the gastro nemius muscle now of course you will remember that this muscle is a chief plant flexor at the ankle with its insertion into the Achilles tendon however it does have a role at the knee as it also acts as a weak knee flexor now the way that we can remember this is that this muscle has two heads it has a medial head which originates from the posterior medial femoral condile and a lateral head that originates from the posterior lateral femoral condile so as a result the fact that it has these two heads which originate from just superiorly to the knee joint helps us remember that it indeed has that role in knee flexion and the final muscle to mention which is really important and really specific to the knee joint is the poplatus muscle this muscle sits deep to the gastromus and it has a really interesting shape and direction that in which it runs as you can see here so it originates from the lateral femoral condile before running medially and posteriorly round the back of the knee joint before inserting into the proximal posterior surface of the tibia so the key role of the poplatus comes in the locking and unlocking mechanism of the knee by rotating the feur and the tibia which we can remember from the fact that it originates and inserts into both of those bones in order to control the position of the knee this is really important to fully allow our knee to lock into place when it is in a closed pack position of knee extension to maintain stability so everyone I really hope you've enjoyed this video if you have please support us by smashing that like button it's the number one way that you can help us with our clinical physio YouTube channel if you want more resources from us please be sure to check out our Instagram account @ clinical physio make sure you give us a follow there if you want even more resources for physiootherapists and if you want more specifically on knee anatomy check out our membership website member.clinicalphysio.com on membership you can get access to the knee anatomy boot camp for all the best anatomy teaching for the knee and of course you'll get access to other anatomy boot camps like the shoulder anatomy boot camp the foot and ankle anatomy boot camp the wrist and hand anatomy boot camp and more to help with your anatomy learning my name's Khed thank you so much for watching see you soon here on Clinical Physio