Hi everyone, welcome to Bodyworks Prime. Today, we're going to be taking a look at the anatomy of the extensor carpi ulnaris muscle. So, you can see a variety of different views of this muscle on screen now. So, you can see a medial view on your left-hand side. So, that's the side towards the pinky finger. You can see a posterior view in the middle. So, that's the back of the hand and the back of the forearm as well. And you can see a lateral view on the right-hand side. So, you can see the thumb is pointing towards us in that particular view. So, let's take a closer look at where this muscle starts and where it ends. And we'll be going over the exact anatomical names and positioning of the origin and insertion in just a moment. But I just want to keep this as a broad overview to start with. So, we've got a lateral view of the elbow on the right here. So, that would be where this muscle is starting. It's starting on the humerus. Specifically, we've got the lateral epicondyle there. So, it's crossing the elbow joint, although that's not really where its primary actions are. We'll be going over the actions in more detail later. On the left-hand side, we can see a medial view of the hand. And you can see how it's crossing the wrist joint and connecting onto the base of the pinky finger here. And the wrist joint is going to be where its primary actions are occurring. So, I just want to go over the location of the extensor carpi ulnaris in relation to a few of its neighboring muscles. So, you've got the extensor carpi ulnaris highlighted in red here, coming down, passing under the extensor retinaculum, and then connecting to the base of the pinky finger here. And just medial to it here, we have the flexor carpi ulnaris muscle. Just superior to it here, we have the anconius muscle. Lateral to it, we have the extensor digitorum muscle. And then we have this smaller muscle right here, which is also lateral to it, and that's the extensor digiti minimi muscle. And you'll notice all of these extensor muscles are passing under this fibrous band on the wrist here. And that's the extensor retinaculum. So, let's take a look at the origin and insertion next. So now, we can see the origins this muscle marks out in red. And you can see this muscle has two points of origin. Essentially, it has two heads. We got a humeral head up here on the humerus. And then we've got the ulnar head just here on the ulna. Um, so we'll start off by going over the humeral head first. The humeral head is going to connect onto the lateral epicondyle of the humerus. So, this would be the lateral side. You can see the thumb here. So, in the anatomical position, this is pointing away from the body. And then the body would be towards this side here. So, it's originating on the lateral epicondyle. And it's originating on this lateral epicondyle via the common extensor tendon. And several other forearm extensor muscles share this particular tendon. So, other muscles that share this tendon are the extensor carpi radialis brevis, the extensor digitorum, and the extensor digiti minimi. So, let's take a look at the origin of the ulnar head next. And you can see that marked out here in red. And that's on the posterior border of the ulna. And the ulnar head is originating from a common aponeurosis. And this aponeurosis is what's linked to that posterior border of the ulna. And an aponeurosis is a flat and broad tendinous sheet of connective tissue that serves as an attachment site for muscles. So, it acts in a similar way to a tendon, but usually, it covers a larger surface area. So, this is advantageous in places where tendons might be a little bit too bulky or where you might need a broader attachment site. And this broader attachment site is going to allow for a more even force distribution over a larger area compared to a localized, rope-like tendon. So, you know, we've got that more localized, rope-like tendon up here on the humerus. But then we've got that broader attachment site on the ulna via that aponeurosis. So, let's take a look at the insertion next. And we can see a view of the hand from the medial side. And we know it's the medial side because we got the pinky finger facing us here at the moment. So, we can see that insertion point marked out here in blue on this bone at the top here. And this bone right here would be the metacarpal. And in this case, it would be metacarpal number five because it's the pinky finger. So, if we're going to describe our insertion point here, it would be on the base of the fifth metacarpal. And just bear in mind that the metacarpals are the bones which are under the palm area of your hands. So, don't get confused and think that this is the part of your finger that protrudes outwards from that palm. This is a bone that'll be under the palm of your hands. So, this insertion point is really close to the wrist joint, which puts it in a really nice, advantageous position for its actions, which we'll be going over in just a moment. Pictured here, we can see the posterior interosseous nerve, which innervates the extensor carpi ulnaris from the nerve roots of C7 and C8. So, the muscle you can see in this picture here is the supinator muscle. And the reason why I've got the muscle in this picture here is because it essentially shows us where that posterior interosseous nerve begins. So, here we've got the posterior interosseous nerve. And we know that because it's emerging from the supinator muscle. This nerve right here would be a deep branch of the radial nerve. So, the deep branch of the radial nerve comes down here, penetrates the supinator muscle, and innervates it, of course. And then, as it emerges from the supinator muscle, that's the part of the nerve which we would consider as the posterior interosseous nerve. So, essentially, this nerve that's innervating the extensor carpi ulnaris, it's a branch of the radial nerve, essentially, or a continuation of it. So, let's take a look at the actions next. Now, one thing to remember when we're describing these actions is they're always going to be from the anatomical position, which is thumbs facing away from the body and the palms facing towards the front of the body. So, just like this. Essentially, that would be the anatomical position. So, we're describing all of the actions from this position. And because the extensor carpi ulnaris is connecting onto the base of the little finger right here, it should be towards the medial side. The body, as it contracts, can pull the wrist joint, or pull the little finger, should I say, and the wrist joint as well, towards the midline of the body here. And this particular action here is called adduction. So, A D duction. And the opposite of that would be A B duction, abduction, moving it away from the midline of the body. So, we got the first action: adduction of the wrist joint. Our second action, that's going to be extension of the wrist joint. So, extending the wrist backwards, just like that. And that's because the extensor carpi ulnaris is crossing the posterior side of the forearm here. So, as it contracts, it can extend the wrist. The opposite movement would be flexion of the wrist, just like that. So, the extensor carpi ulnaris is a wrist adductor and a wrist extender. So, if you've enjoyed this video or you found it helpful, you know which buttons to press. Press "Like", press "Subscribe", and let me know what you thought of the video in the comments too. It really helps out the channel. Let me know what you think of my new recording setup as well. I know some people had mentioned in comments that they were struggling to see the skeleton model when I was using it to describe particular actions. Because, obviously, the skeleton model's white, and my previous background was white as well. I've added in some colored lighting. Hopefully, that makes this pop a little bit more, so it's a bit easier to see. So, anyway, thanks again for watching, everyone. See you in the next video.