Limb Muscle Video Transcript PDF

Our final groups of muscles that we want to focus on are the limb muscles. And with a little help from some pictures of my daughter from about 15 years ago, I want to demonstrate just how specific these muscles are in the arms and in the legs. Now, we've looked at all of these other muscle groups so...

Our final groups of muscles that we want to focus on are the limb muscles. And with a little help from some pictures of my daughter from about 15 years ago, I want to demonstrate just how specific these muscles are in the arms and in the legs. Now, we've looked at all of these other muscle groups so far that have essentially been associated with the axial skeleton. So head and neck muscles. We've looked at trunk muscles. A lot of these muscles are associated with supporting giving structure to the torso and to the neck and movements of the head, movements within the torso, the ribs, that sort of thing. But if you remember, there are also a few muscles that cross from our axial skeleton to the appendicular skeleton to allow us movement of the limbs and they'll be anchored on that axial skeleton. Well, the limb muscles are contained completely within the arms and legs. Now, they also have to in certain cases overlap with that axial skeleton to a certain degree. For instance, when we look at the arms, we're going to be taking a look at the movement of the arm at the elbow, movement at the wrist, movement of the hands, the fingers. But there is some overlap with movement at the shoulder, especially when it comes to stabilization. Similarly with the legs. We're going to be looking at some of the largest muscles in your body associated with the thighs with the upper legs. Now, muscles and the legs are going to be moving at the knee joint, at the ankle joint. They're going to be responsible for movements of the feet of the toes, but they also tend to be anchored on our axial skeleton at the midline, on the pelvis for movement of the leg as a whole. So Let's move to our arm. That term brachium. Brach brachial or brachium just refers to that upper part of your arm. Up here. On the anterior side, let's remind ourselves what the location of a muscle will do. Anything on that anterior. You hold your stand in anatomical position right now. If you actually look at muscles that are on the anterior side of your upper arm, that's like this. Here's an example of an anterior muscle. The fibers are running parallel to each other. If this muscle crosses your elbow joint and you shorten it, that's going to allow you to flex at the elbow. That we have to remember with muscles as they just attach to two points and bring them closer together. Because they're on the anterior side, they're going to cause flexion. The other thing that they can actually be used for though is subnation of your forearm. Remember that really cool thing that your radius and ulna will do, where they cross over each other when you actually son and pronate your wrist. Well, we have muscles that allow us to do that that actually deviate those two bones. Here's a closer look at the specifics. The first thing we look at is your bicep racy. The biceps brainy find their bicep, we call it or bicep, but bicep means it as two heads. We actually have something referred to as the short head, and we have something referred to as the long head. But ideally, what we're looking at here are two pieces. Here's one piece, and here's the other piece, and they fuse together down here into that mean body of the muscle. And both of them are going to originate. One of them originates on the coracoid process way up here. The other one actually originates on the scapula itself. If they're both going to now insert on the other side of your elbow joint on your radius, when these muscles contract, they're going to pull your radius toward your shoulder. They're going to pull it up that way. They have that common insertion on the radial tuberosity. But because their origins are in slightly different places, they're going to perform a couple of different activities. Here's the other one. We actually have three major muscles that allow us to flex at our elbow. Bicep Bracy is one of them. The next one is this brachialis. The brachialis muscle, we can also feel that. When you flex your arm at the elbow and you actually flex that bicep, you are feeling part of your brachialis muscle as well. But this one originates on the very distal part of the humerus. So it actually doesn't start until we almost get to the end of the humerus here. That's the origin. And it inserts, once again, on the other side of the elbow. But this one inserts on the ulna rather than on the radius. But on the very proximal part of that ulna, right here, the coronoid process. But the same idea. It crosses the elbow joint. So when you contract that muscle, this part of the ulna is going to move toward the humerus, you're going to flex at the elbow. Make sense. This is actually the stronger muscle. When we look at the three muscles that flex at our elbow, this is the strongest one. It's not the one that we have the most control over, however. This is a little bit deeper. If I were to put your bicep on top of this, your bicep brachi, it would actually overlap it a little bit. This is deep to your bra. The bicep brac would be sitting right in here, and we'd actually cover it up a bit. Now, the other one that I didn't mention there, there's a third muscle called the brachio radialis, which also assists inflection at the elbow. But we'll look at that when we get a bit closer to the distal part of the arm. We Let's flip around now. Let's look at the posterior side, because you also know that muscles occur in pairs. We have antagonistic pairs. That means if I have a muscle like bicep brachy or brachialis that's there to flex at my elbow, I need another muscle that will help me extend at the elbow, that will balance that out. Here's where a muscle like tricep brachy comes in. Because it's on the posterior side, get used to this, a muscle on the posterior side of your arm, if it contracts and it pulls, that's going to move things in that posterior direction. It's going to straighten my arm back out again. It's called the tricep Bracy because this one has three heads. Remember that from naming muscles, triceps means three heads. We have a long head. We have a lateral head, and we have something called the medial head. The three of them. The first two are very easy to see. That medial head is you have to flip around and you can see it on the other side. Now, in case of the long head, it originates on your scapula. The lateral head, it originates on the humerus itself, and then the medial head also on the humerus. But they're all anchored at the very proximal either the proximal part of the humerus or the scapula, but they all insert in the same place. They all insert on the electronn. That ice cream scoop, if you remember I called it on your na. That means when you pull on that proximal end of your na, it's going to straighten the arm back out again. It's going to extend it. As we move to the forearm, the biggest thing to note is really what the muscles are associated with. So you'll notice that a majority of the muscles in the forearm, both anterior and posterior are actually associated with movements of the wrist and hand, the fingers, the palm. Now, we do, as you know, have some muscles that have crossed the elbow joint. So in particular, there's that brachio radialis. But so it is possible to have muscles associated with movement at the elbow or even the shoulder. But the majority of the muscle bodies that are located within that forearm, are the ones, as I said, that act on the wrist and the hands and the fingers. So just to help clear this all up, and we can apply this to the other limbs as well. We want to look at the relative differences between the anterior and the posterior groups, how they're going to impact what happens, what their action is going to be. This is pretty intuitive, we've already looked at this. Since muscles just pull, if a muscle is located in an anterior compartment, its action is going to be relatively limited. It's going to be acting on structures. It's going to be acting on insertion and origin points normally on that anterior aspect. Again, there's going to be a couple of exceptions, and I'll point those out. But let's look at where these muscles attach. Let's talk a little bit about what they're ultimately going to do. You'll notice for the next few slides. I'm going to mention a few nerves here and there as well. We'll look at this more when we talk about the nervous system, but I do want to focus on this idea that muscle groups or muscle compartments are generally associated with very specific nerves as well. This is probably one of the best ways to really appreciate how these muscles are arranged. This is a cross section through your arm. Here's what I'd like you to pay attention to. Notice that we can group all of these muscles together and they actually exist in groups. Now, the color might be a little bit difficult to see here. But this group of muscles that are all as the same color. This is your group of flexles. These are all on the anterior side. So we're in the forearm now. This gets a little bit more complicated. But if you remember, the muscles in our forearm are the ones that are responsible for moving everything, almost everything in our hand, our fingers, our wrists, the carpal bones, everything else. So a lot of these muscles actually cross the wrist and are responsible for finger movements in those very detailed types of activities. There are some extra ones as well. We do have at least one that crosses your elbow, and we have muscles that are associated with keeping that radius and alma together. But that group of flexor muscles. Look at them. It's a whole bunch of them in here. Because they're all grouped together in the same place on that anterior side, that's why they can all perform similar activities. These are all on the anterior side of your forearm. When they contract, they are going to be responsible for pulling your fingers and your wrist toward your forearm. On the absolute opposite, on the other side, we have the extensors. This is the extensor group here. Extensors are on the complete opposite on the other side of that radius and ulna, they are on the posterior aspect of your forearm. When they contract, you're going to get this type of activity. You're going to get things bending in the opposite direction. You're going to get your fingers being pulled back in a posterior direction and your wrist being pulled that way as well. This is very important to recognize when we look at arrangements because we're going to see the same thing in our legs. Muscles are grouped together with other muscles that do similar things. That makes sense, because in order for a muscle to do something, it has to be in the right place. Now, we do have one other group here, and on this picture is just referred to as others, but we have a group of muscles here. It's a slightly different color, and they're intermingled between the flexors and the extensors. But these give us other activities, rather than extending or flexing at the wrist. We have, for instance, that brachioradialis that I mentioned. Brachioradialis is another one of the muscles that actually crosses your elbow joint. It's responsible for partly for flexing at the elbow. But it also that radialis part, brachio radialis. It also extends very far down right to the very distal end of your forearm. But we also have muscles like this pronator. I don't want you to worry too much about the specific name of this one. But what it's telling you is, this is not an extender or a flexer. This is something that allows us to pronate. This is one of those, this is the muscle that actually allows us to do that really cool thing with our radius and alma where they cross over each other. We have one other interesting little piece in here that is also not a flexor or an extensor. We have piece of muscle here that's called the adductor polycis longus. This one allows us to adduct something. In the case of this, this allows us to adduct our thumb. A? We'll look at that more detail a little bit later on. So let's look at what gives us the ability to have some of this really fine motor control in our forearms. This is going to be potentially the hardest part for you to understand without me being there to show you, but I'll do my best, and I want you to play around with this. I'd like you to actually check this out in your textbook as well, and I'll see if I can find a couple of interesting videos to post up for this too. But let's look at these forearm flexors. So what we're looking at here is a picture of the anterior surface of your arm. Thumb and your fingers. And you can feel these. So if you put your hand on the anterior surface of your forearm and you start moving your fingers, flexing and extending them, you feel a whole bunch of muscle moving in there. And so this is where I was talking about muscle layers being very important. There's that brachio radialis that I mentioned already, that one that stretches, this actually crosses your elbow joint. It's an extra little muscle that helps to flex at the elbow and it also extends down to your wrist. But these other layers. That's just four groups of muscle here, all considered superficial. We have a pronator muscle. That pronator muscle, if you look at it, is going on an angle across. When that muscle contracts, that's the one I keep referring to that will actually allow that radius and alma to cross over each other and pull your arm to a pronated position. What with these others? Flexor carpi radialis. Well, flexer tells us right away, we know it's on the anterior side. It's going to flex something. Well, it also attaches to carpi. It must cross our wrist joint because it attaches to the carpal bones. Where is it anchored on the radius. Flexor carpi radialis. This is a muscle that's attached to our radius, it's attached to our carpal bones, and it flexes. We know everything we need to know about that muscle. We know where it is, we know what it does, and we know what it's attached to. This palmaris longus. This is as in palm, the palm of your hand. This palmaris longus, if you follow it, watch the connective tissues from this muscle stretch out and attach to the bases of my phalanges across the metacarpal bones in my hand. And then flexor carpi ulnaris. Just like that flexor carpi radialis, but this one attaches to the carpal bones and the ulna. It seems like we've got a lot of muscles doing the same thing. They're all crossing the wrist. They're all anchored on our forearm. They're all inserting on structures in my hand. But this is one of the reasons that we have so much control over what our hand can do. Right? We can move fingers individually. We can move them a little bit or a lot. We can bend just at the phalanges, we can bend between the phalanges and the metacarpals, we can bend between the metacarpals and the carpals. In order to do that, we have to have lots of different muscles. And these are the superficial ones. This is just one layer. So these give us relatively easy movement of these structures in our hand and in our wrist. Let's go down though now to the next deeper layers. Here's a situation where we actually have three layers of muscle. After that superficial layer, we have something that's called the middle layer. The middle layer is composed of this big chunk of muscle right here, this thing called the flexer digitorum superficialis. This is why I want you to focus on the names a little bit. It's a flexer, so we know it's on the forearm. Digitorum means that we have pieces that attach to the digits. Look at this, the phalanges. We have pieces of connective tissue going out to each of those digits. That's what we call our fingers. Superficialis meaning it's closer to the surface. Now, let's compare that to the really deep layer. We call this the profundus, the deepest layer is the profundus. In this really, really deep layer, if you look, we have something very similar here. This is interesting because this looks a whole lot like that flexor digitorum superficialis that we just looked at. Very similar. It has connective tissue going out to the fingers again, just like that. But this is an extra layer. You might think, why do we have two muscles doing the same thing? They're not exactly the same. This flexor digitorum profundus has one really, really important difference. And I'd have to blow this up to show you. Let me see if I can do that. No, I don't have any way to blow this up for you right now, but you can actually do it yourself. You can make the picture a little bit bigger. And here's what you want to see. Notice that all of these attachments are at that middle part of your finger, the middle phalange. When this muscle contracts, it's going to pull our fingers toward our wrist, but it's going to pull it from the middle piece. Whereas, this flexor digitorum profundus, let's follow those. These connective tissues go right past that. Here's the connection that we just looked at. This goes all the way out to the tip of our finger. Same thing here, all the way out to the tip of the finger. This muscle does the same thing. It flexes our fingers, but it's pulling from the very tip finger. Imagine now we can balance between the two of them. By using either of those muscles, can, we can pull our fingers towards our wrist, but we're pulling from a slightly different point. I can balance the amount of force. I can control how much these fingers move because I've got more than one way of doing it. That gives us a lot of that extra control that we see. At this point, I'm hoping you're starting to wrap your brain around this idea of recurring themes or these similarities that we see with respect to function and what things are attached to. For instance, posterior forearm as opposed to the anterior forearm. Think about that for what it is. You're standing in anatomical position and now consider the posterior aspect of your forearm. Think about what's going to happen if muscles in the posterior aspect of our forearm that are attached to structures in our hand, they're anchored in the forearm. If I activate these muscles, I'm going to pull something. If I'm pulling from that posterior side, for the most part, I'm going to see actions like extension. The extensors of our wrist of our fingers of the hand, the palm. Those are all located in this posterior compartment. Seriously, reach to the back of your arm right now and do that. Imagine it's a little string going from the posterior aspect of your finger, anchored somewhere in the posterior aspect of your arm, pull it. It's going to extend. We also though see that we have a couple of other things. And from that image that I showed you a little bit earlier, showed you the different groups of muscles, the extensors, the flexors, and then there's the other group. And I gave you this idea that, well, remember, we can also pronate and supinate the wrist. We do have groups of muscles that don't fall into either flexion or extension categories. We have muscles like supinators. They happen to be located in this posterior compartment as well on the forearm. We also have a few that remember our hands are the most versatile structures on our body. These are the ones where we have that huge amount of dexterity. We have that saddle joint in our thumb that gives us an advantage over all the other animals as a higher primate. We can actually oppose our thumb. We have multiple movements of the fingers, all the different types of joints in the many muscles that are attached to there. Something like thumb abduction depends on an individual muscle associated with that particular movement. Deviation of that radius and alma is associated with supernation and pronation. But the fact that radius and alma are two parallel bones, as we saw in the appendicular skeleton, there are attached at both ends of both epiphyses, but they can move with respect to each other as well. We have muscles associated with that. And with respect to the nerve thing. Now, again, we're going to look at this more closely in a little bit when we look at nerves that go to different parts of your body. But we have more major nerves going to the arm, the forearm, the wrist in the hand, than we do with just about any other part of our body as well, directly related to the fact that we have such a variety of muscles and muscle activity. And in keeping with our look at some of the clinical disorders or things that can happen, I'll give you a few examples of some potential things that can go wrong if you have a problem with the muscles or a problem with the nerves supplying those muscles, one of which is something we refer to as wrist drop. Then finally, if we flip it around and look at the posterior part of the arm. On the posterior side, this is where we want to get a muscle that will actually or groups of muscles that will extend those digits. Now we have a lot more control flexing than we do extending. We don't see nearly as many layers of muscle here. But the superficial. Here's a layer of superficial muscle here. Notice they all have tendons that are stretching out to the posterior sides of those bones, those phalanges, all the way out here, and they extend to the digits and to the metacarpals. The metacarpals that are halfway. We still have multiple attachments. We don't have quite as many as we do for the flexures. But this is what lets us balance that flexion and extension movement. For every movement that you can make in an anterior direction, you have a balancing movement that you can make in the posterior direction. Now, the names are going to be associated with what they do specifically. Let me get rid of this. You can see this more clearly. For instance, extensor digitorum. Extensor digitorum is going to extend all of these digits. All of those. Extensor indicis. Well, that refers to our index finger. This one. We have one particular extension that will come just to this index finger. Notice right now, take your index finger and notice, you have a lot more control to move your index finger independently than you do any of your other fingers. Then extensor urpi. Extensor urpi is going to be just attached to the urpal bones. It's going to allow us to extend our entire wrist back, but not specifically by pulling on the fingers. It's just pulling on the carpal bones. And within that posterior compartment then, here's where we end up with extensors for our wrist and our fingers. We also have muscles for supination of the hand, to pull it back in the other direction to straighten those bones back out. Okay? And we even have independent little pieces of muscle that will allow us to do things like a thumb. So if you look here, our thumb actually has its own separate little piece of muscle right here that you can use to abduct or pull that thumb away from the midline. And you know that we have quite a bit of control over our thumbs as well, with that special saddle joint. At this point in the nursing program. I'm guessing, I'm hoping you guys are starting to develop a pretty good appreciation for the significance of surface anatomy, like I mentioned to you a few times. Just to put it in perspective again, the idea is we don't have the ability to actually see what's going on inside of our bodies without some help with some imaging. But surface anatomy, recognizing features on the surface of the body, various areas of the body can allow us to orient ourselves to see what's going on. In many cases, it makes it a lot easier to understand how things work. Now, this particularly true when we look at muscle activity and joints and bones. For instance, you're aware that on both the anterior and posterior surfaces of your hand and your wrist, and your arm. We have quite a few structures that become more visible when we're moving them, when we're using. So just as an example, let's take a look at right here. So what I'm outlining here is something that you can see right now. If you take a look, this is the tendon of that extensor polycis longus. So translation, it's the tendon attaching the extensor psis longus muscle to your thumb. It's on the posterior aspect. It is an extensor. It allows you to extend your thumb. That's the polycis the longest part referring to, it's a longer muscle. It's also responsible for longer movements. As opposed to this other one on the other side, we also have this extensor polycis brevis running on here. You can see both of these. Look at them on the posterior aspect of your thumb. Now, a couple of things we can take from this. One is that recurring theme that here are two different muscles attached to almost the same place and the same structure. Giving us a much greater degree of movement, giving us much more control over that movement of the thumb. Take a look at your thumb. You can move it anteriorly, posteriorly, you can extend, you can flex. It almost looks like you can circumduct it. You can't really. It's not a ball and socket joint, but that saddle joint allows us to abduct and adduct. Well, those two are actually really good borders or outlines for a little area in here that's referred to as the anatomical snuff box. Silly name. Anybody who's familiar with maybe some history or some older literature, The snuff box refers to an old thing that people used to carry their snuff, their ground tobacco in. And this is stuff that people would snort for for a little tobacco buzz. But the anatomical snuff box, again, this is just historically, it's not anatomical. But it is a place where people would often there's a little indentation, and you can actually put this stuff and take a little snort of it if you want to. Sounds completely silly. But anatomically clinically, This represents an area of the body that's incredibly important when you're doing things like evaluation of injury. With certain types of fractures, certain types of injuries to the wrist to the hand. You'll often hear a description of snuff box tenderness. And this allows you to know potentially what carpal bone may have been injured or what structures around those carpal bones, ligament wise, soft tissue wise, may have been injured. Even more importantly than that, it's a landmark. It lets you know where you're at, and you can describe the location of other things based on that particular identifiable mark. We also see everybody's noticed these and maybe never really realize the significance of it, but those tendons of that extensor digitorum muscle. Now remember on the posterior side, we have less muscles than we do in the anterior side. There's less control over extension than there is over flexion. But those are the strings, they're attached to the finger here. They're anchored here or the muscle itself is here, the muscle is anchored on the forearm. When you shorten this, when you pull on it, the finger is going to come back. It's going to extend. They pop out a little bit. You actually see a little bit of a bowstring effect there. Get rid of this. Eraser. You can actually see even on your own hand, when you do extend those fingers, you get that little bit of a bowstring effect in there. Now, the surrounding tissues help to retain that and make sure it doesn't pop out very very far, but it's obvious that something is going on. You can feel those when you move your fingers as well on both sides. We have these connections. That relates to that whole idea, that muscles in the forearm. Are connected to fingers are connected to your palm to your hand as an efficient way of controlling these structures. If we were to put all those huge muscles in our actual hands, our hands would be huge, and they wouldn't have very much dexterity. Sure, they'd have a lot of strength, but you wouldn't be able to do those fine movements that we can because the muscles are located outside of the hand itself. Now we've been focusing on this idea that there are so many of these muscles located in the forearm that act on the hand. But we can't forget that the hand does contain muscles. It actually has quite a few. They just tend to be smaller, very specific groups of muscles that are responsible for very particular types of controlled movements. We refer to these things as intrinsic muscles. Just like when we're referring to intrinsic structures in a joint as opposed to extrinsic. Well, intrinsic muscles of the hand are incredibly important. They don't have the same degree of strength as those larger muscles in the forearm, the ones that cross over. But when we look at what they do, and when you start to appreciate things like when your hand actually gets fatigued when you feel stiffness in your hand, or if anybody likes that relaxing stress relieving feeling of a hand massage. If you've been writing for a long time or if you've been doing really really fine work, these muscles become fatigued quite quickly. Because they're making all of these little tiny actions over and over and over again to control movements. As an example, when we look at one particular area called the hypothenar group, hypothenar group are the ones associated with over here, that little finger. There's a group of them in there that are associated. Look at your hand right now, start moving your fingers and notice that you have a fairly higher degree of control over that thumb, of course, because there's lots of muscles associated with the thumb. But to a certain degree that little finger as well. You can take your baby finger and bring it into the center of your palm quite easily. You can touch that little finger up against all of the other fingers quite easily. It completes the package when you're making something like a fist or if you're grasping something. It's the opposite side of your thumb to help complete that grasp. But we have muscles that are referred to as short flexors. The short flexors are just what they say. They are within the hand itself. They are responsible for smaller controlled movements, not strong ones, but controlled movements of that little finger. We also have the ability to abduct on that side. Put your hand in anatomical position, your arm, and just like our thumb, we can abduct and abduct, but we can do the same quite easily with that. Our baby finger all by itself. It's much harder to move the other fingers the same way. There's not quite as much freedom of movement, although they all have unique abilities. Now, on the other aspect, the thenar group, now we're talking about muscles that are associated with that thumb itself. Now, you know that you have muscles in the forearm that are responsible for thumb movements, but we also have short flexors of the thumb within the structure of the hand. And those are obvious ones because you do have some fairly large pouches or outcroppings of muscle there that we can see and appreciate. We have abductors in here as well associated with the thumb, that can move it short distances, not a whole lot of strength, but very important for control of the position of your thumb. And this comes back to what I just told you, so just to reiterate, all of these muscles that are responsible for large, strong, repetitive movements of our hand, generating large amounts of force. These are found in the form. And it's simply associated with that idea that there's always this balance. Our hands, our fingers have a huge degree of fine motor control, fine movements. You can't generate fine controlled movements with large collections of big strong muscles. You need a bunch of little tiny ones that are contained within the hand. Those larger movements are controlled extrinsically. But the two things work together. This is the really cool part. You'll see this on the next slide. The smaller muscles that are in the hands don't just attach to the muscles, sorry to the bones themselves. Some of these smaller muscles are actually intimately associated with the connections from the larger muscles in your forearm. They may actually attach to the tendons from those larger muscles in the form to help control their movements, to help regulate their position. You'll see what I mean in just a second. This is a slightly different look. Now, when we look at orient you again, here are the tendons that are associated with a couple of those large flexor muscles in the forarm. We have that flexor digitorum superficialis. If you remember that one, we have an attachment here that middle phalange. We have the flex digitorum profundus that attaches at that distal phalange. That's what allows us to flex those in interfalngeal joints very specifically and control, balance it with the activity of the extensor digitorum, and we have a huge degree of motion and control over those fingers. But within the hand itself, we are saying these little things called lumbricles. Ubercles are multifaceted things. They perform a few different activities. They are responsible for some of the short movements of the fingers. Actually bringing the fingers closer together in a lateral and medial direction, spreading them apart. They are actually a balance of both short flexions and short extension from these lumbarcles, but they also attach to the flexor tendons. So those big flexor tendons that are running out there that we just looked at, so the profundum and the superficialis, the lumber coles can tug on those. They can reposition them. They can actually help control and regulate the movement of that, to give us a higher degree of control over those movements from the muscles in our forearm. So I don't want that sounds confusing. Again, look at it as more pieces doesn't necessarily mean more confusing. More pieces means we have more ways to regulate something. And throwing in all these little tiny pieces, they're like the little final modifications that we can use to make sure that fine control is achieved when we're trying to move our fingers and trying to manipulate our hand. And then finally, we have something called inter Oc. The name should tell you something about that. Inter osi literally between the bones. Well, we also have these in our feet and we'll see those a little bit later as well. But these interossei are interesting little fan shaped muscles. Here is an inter osseous. We see that it does connect to the finger, and we can see that we could move these fingers in both abductive and abductive directions. There's a midline here. Here's the midline. And everything on one side tends to pull away from that midline. On the other side, it pulls away from the midline as well. Responsible for deviating these fingers from that middle finger, that third one. But you see that the attachments are actually all along those metacarpal bones here. Ang the surface of those metacarpal bones, we have these little tiny interossei. That means we can also deviate and move those metacarpal bones directly, to stabilize our palm, to manipulate the position of our palm. And so abduction of the fingers results, adduction of the fingers results. We can do both because of the orientation of the muscles. Together, it's just another way of regulating those movements on a different axis, and giving us many, many different ways to perform activities and perform very fine motor movements with our hands. Many of you have probably heard of this. In terms of clinical examples, you know, I like throwing some clinical examples now and then. A lot of people talk about carpal tunnel syndrome. Many people have had it been treated for it, more embraces to help prevent it from getting worse. Surprising though, a lot of people that suffer from carpal tunnel syndrome or have been treated for it don't really actually know what it is. They know that it's something that's affecting their wrist and their fingers can get numb and sometimes there's pain, sometimes it's hard to move their fingers. But it ties into how all of this tissue is organized in the hand and in the wrist. So in this image, what we're showing, and doing a little sneak preview would jump ahead, we're showing something called the median nerve. And one of the aspects of the median nerve is, in terms of motor function, it's actually responsible for movement of we spread out here. It's actually responsible for movement of some of the structures in the hands, like the fingers, but it also has that sensory component, if you remember. So there's a division here. The median nerve is responsible for sensory information coming back from the thumb, and then number two, number three, and there's even a little bit of overlap under the fourth one over here. But mostly those first three. Whereas the ulnar nerve, slightly smaller, but the ulnar nerve is more associated with that little finger and the one next to it. Get with a little tiny bit of overlap. But what this means is, when we look at how everything is getting into your hand. Something that we haven't mentioned too much is this idea of space. We have the connections from the muscles. The tendons from all the muscles in our forehand. Sorry, our forearm, have to get out to our hand. They have to pass across the wrist across those carpal bones on both the anterior and posterior sides. We have blood vessels that have to pass there, arteries, and veins. We have nerves that have to pass across there. We have a huge amount of structures, number of structures that actually have to make it into your hand. So space is at a bit of a premium. We also mentioned that one of the other little structures, this thing here, the transverse carpal ligament. This is a wide band of tissue that does a few things. It helps keep some of those carpal bones oriented to one another because it wraps around all of them, but it also covers over structures that are passing into the hand, particularly this median nerve. What happens with repetitive use type injuries is continuous use over and over quite often associated with bad posture, or bad ergonomics, bad hand positioning. You get inflammation, you get irritation in this area. Irritation in this area around this relatively thick band of ligamentous material means that you get swelling. When that starts to happen, it's expandable. It's not like a skull, but it is rather restrictive. That swelling, that build up of fluid, that scarring that may be occurring is actually going to build up pressure within something that we call the carpal tunnel. The carpal tunnel is the little root that this median nerve takes deep to this transverse carpal ligament. You can imagine now if there's swelling there and this starts to squeeze around that median nerve, you're going to start to impair nerve function. Now, for the most part, this means sensory type things. You're going to get tingling. You're going to get loss of feedback from that tissue. But remember, this is going to have a direct impact on motor function. Even if it doesn't directly impair the muscles in your forearm that move those fingers, my brain is very funny about moving a structure if it loses contact with it. In other words, if I'm not getting sensation coming back effectively from my fingers or if I'm getting pain signals coming back from my fingers, My brain is less likely to use those structures effectively. And this is the problem with carpal tunnel syndrome. It starts off normally with some tingling, loss of sensation, little loss of coordination. Eventually, you actually start to experience some rather severe pain, and you get deficit in the movements of those fingers. And one of the ways to relieve it is, of course, to make sure that the wrist stays straight. It doesn't get irritated, you can ice it, you can take anti inflammatories. In extreme situations, though, a surgery is actually done to literally go in there. Clear out some of the extra tissue that may have built up around that carpal tunnel. This is something that's supposed to make a little bit more space and reduce impingement of that median nerve. So this is not a pathophysiology class folks. I'm not going to be testing you on the details of different syndromes, especially things like carpal tunnel syndrome, but it is very important that you recognize how these things can be related. When we look at anatomical structure, it's not just to label it, it's to understand that this is a job to do, and it's the relationship between this piece and this piece and all these other pieces that allows that to work. If I mess that up, if something is broken, if something is out of place, something is being squeezed inappropriately, it's not going to work properly. That brings us down to the lower limb. You're going to see a lot of similarities that you saw with the upper limb, and you might want to play around with this a little bit too. Remember the biggest difference with our lower limbs is what we use them for. Our upper limbs, it's all about find control. It's all about manipulating our environment, moving things around, grasping things. Whereas our lower limb is more about locomotion, supporting our weight, allowing us to jump and land and things like that. We do see similar arrangement of muscles. We still have those big groups. But you'll see that there's a little bit more stress put on the arrangement in terms of which groups of muscles have the biggest effect. For instance, in this one, in your leg, the posterior compartment is a really interesting one. Posterior muscles, if we look at that upper part of our leg and the limb muscles are going to pull things in a posterior direction. When we look at anterior compartment muscles, those are muscles like the quadriceps, we're actually going to look at with anterior muscles, this is a really large group on the anterior side. The posterior getting back to that here are going to include muscles like our hamstrings. Hamstring muscles are the ones that we use when we're moving in that posterior direction when we're flexing our leg or extending our thigh. We'll see that more closely in just a minute. Here's the anterior side. This picture over here is probably a little bit easier to recognize, but this is showing you that large arrangement of muscles on the anterior side of your upper leg. I think most of you are familiar with the quadraceps. That term quadracep, means there are four heads to this muscle. Quadracets are considered prime extensors of your knee. And that's simply because these muscles stretch down and cross the knee joint. And since they cross the knee joint, when you activate them, so when you straighten your leg goat, put your hand on your quadriceps and straighten your leg goat, you're actually pulling on that lower leg and straighten your knee back out. Now, one of them, one of these big muscles that are up there, something called rectus femoris is also a flexer for the hip. So when you lift your knee up toward your body, you're flexing your hip, and by doing that, you're actually pulling across the hip joint. Remember that. In order to move across a joint, a muscle has to cross that joint. Here is that group of quaraceps. Rectus femoris is one of the big ones right here going straight up and down between your hip and your knee. V lateralis, that's the other big part of the quadracep there. Vastus medialis, so the medial part in the middle here, something that we can't see here until we peel the muscle away, something called the vastus intermedius, which would be underneath all of this. And this really interesting little piece too, the sartorius muscle. Now, see if you remember what this is ASIS. When we were looking at the bones of the pelvis, you remember something called the anterior superior iliac spine. This is just showing you that this muscle, even though it's stretching all the way down here, crossing our knee, all the way up through our upper leg, it actually inserts on the pelvic bones. It actually inserts on that anterior superior iliac spine. This is a long thin piece of muscle that technically crosses two joints. I crosses your knee joint and your hip joint. Here's where we see one of the big differences with the legs compared to the arms. It's with these this big group of medial muscles. If you remember on your arm, we had lots of anterior and lots of posterior muscles. But on the thigh, we actually have a fairly large group of medial muscles. But remember what this is going to do for us. If we look at a group of muscles like this one, this medial group of muscles. Notice where it's attaching. We have an anchor point here on our pelvis, and then we have all these muscles stretching out to the femur, individual muscles, and when they contract, that's going to pull my femur toward my midline. That's going to adduct my leg. These medial thigh muscles, they all have a common origin on that pubic bone, but they are adductors of the thigh. We have interesting names for them because they're all doing the same thing. They're all pulling my thigh toward the pelvic bone, and they're all moving it in generally the same direction. But if you look closely, they all attach at slightly different places. We've got an attachment here, we've got attachment here, we've got another one here. We have something referred to as the adductor longus. That's the biggest one, the longest one of them. We have a really short one called the adductor breaths. Then we have this really long one here called the adductor magnus. And again, the big difference, they all originate in the same place right here. But because they insert on that femur in slightly different locations, not only will they pull your femur toward your midline or toward your pelvis, but they can also laterally or medially rotate your leg. Think of it this way. Look at this aductor longus. It attaches way over here in the anterior side of this bone. When I pull this bone toward the pelvis, It's actually going to roll or move that anterior portion of the bone backward a little bit. It's going to rotate your leg internally or immediately. As opposed to something like this adductor brevis, if we look at that more closely, it's actually attaching to the femur on a much more posterior location. When it shortens, it will actually roll your leg to the outside or laterally. But all three of them are going to pull that femur toward the midline. They're all going to adduct your thigh. This should look a little familiar. As it wasn't that long ago, we were talking about something called the corrodi triangle. And at the time, I mentioned that it's a very important landmark in terms of some important vascular and nervous structures associated with the area around the neck and the head, and some of the vascular tissue that's supplying the brain as well as venous tissue coming back from the brain, and nerves passing through there as well. Femoral triangle is similar. Fantastic clinical landmark. When we look at it, first thing that we notice is it's you can actually see this and feel it on your own body. It's kind of to a certain degree, kind of fallowed out or indented area on that anterior thigh. And you can really appreciate and feel some pretty substantial borders. The first one being the actual sartorius muscle. And here's your sartorius muscle. Strip better do afferent color. That strip that's running down here. There's a sartorius muscle. We also have that inguinal ligament that runs along here, like ligaments, it's relatively tough. You can feel that. It's quite a substantial border on that superior aspect. Then finally, we've got the adductor longus muscle here. And just like the name suggests, very important adductor of the thigh. It's anchored on your pelvis, anchor at the midline, and it inserts on that medial aspect of the femur. Of course, when this muscle shortens, it's going to pull that thigh in tooward the midline. It's going to adduct it. But the point here is we're left with this relatively significant area in the borders of that triangle that we refer to as the femoral triangle. Structurally, the big things that pop out there are ephemeral nerve. Let's point out that femeral nerve. The yellow one here is the femeral nerve. We see it's branching already. We have the femeral artery. Massive big artery. Lots of branches coming off. Then finally, we've got the femeral vein. We'll look at vascular tissue in a couple of weeks, but the femeral vein also is actually the result of convergence of other smaller veins, one of which is this great saphanous vein that runs down here. We'll also see that that's clinically quite important as well. But we'll get to that. But just like that corroded triangle, the femeral triangle is one, important for orientation. It can give you an idea where things are. There's a femeral pulse in there. We know that you can locate other structures within the thigh or within that area by starting at your femoral triangle. It's also one of those cool areas of your body that I've mentioned that is relatively sensitive to pain. If you poke around there a little bit, you push a little bit too hard, we do have quite a bit of pain sensation, and that's one of those things that our body does to really protect areas that have vital structures that may be exposed to potential damage. Flipping around to the posterior side. Our posterior hip and thigh are going to do something completely different. Here's where we get into everybody's favorite muscles, the gluteals. Your butt. The gluteal muscles, we have three of them. We have gluteus maximus, being the largest of the group. We have gluteus medius, which is a little bit deeper, but it's also the next smallest muscle. Then finally, we actually have something called the gluteus minimus. You can't see that until you pull the other ones back. It's a very deep muscle of the three of them, but it's also the smallest one. Now, if you look at where these are attached, because these are on the posterior side, and because they have a really big attachment with the pelvic bone and then they stretch out to the femur. The glutous maximus is actually the main hip extensor. Extending your hip, if you're standing straight up and you point your leg behind you, stretch it out, that's extension of your hip. Pulling your knee up toward your body, that's flexion of your hip. This gluteus maximus is a very important one when you're extending It's also therefore, very important when you're lifting your body up. For instance, if you're walking up a hill or if you're walking up a set of stairs. This is why one of the best exercises in the gym to give you a nice toned gluteus maximus is a stair climber. If not, well, just walking up hills or walking up flights of stairs. The gluteus medius and the gluteus minimus, the deep one. These are hip and i abductors. Remember what abduction is, abduction, pulling it away from the midline. Because of their position, they work a little bit like your deltoid muscle in your shoulder. They're attached to your pelvis, but they're going to pull on the lateral side of that femur and they're going to abduct the leg away from the midline. These are really important when you're walking. Think about how you walk. You're not marching. You're not just moving your legs straight up and down, straight forward. Your leg actually swings out to the side a little bit as you're taking each step. When you're recovering, this is called the swing phase of your walk or the swing phase of your gait, and it's the gluteus medius and the gluteous minimus that help you control this. All three of them work together for controlling leg movements when you're walking or climbing, going up stairs, going up hills. Along with the more obvious role as hip extensors and abductors, just like we just looked at. These gluteal muscles do have another pretty significant role that they play. Once again, I want you to just remember that these are just muscles. It is shortened. But when we look at the different places that they're attached, a slight change or a slight difference in where a muscle is attached compared to another muscle can actually give it a considerably different action. So here's what I mean. Here are the gluteal muscles. We've got that gluteus medius muscle. That's originating here along the um. We have that glutous maximum originating here along the Ilium and part of the sacrum almost down to the Cosec. And then a little bit deeper when we remove these things, we also have that gluteus minimus muscle, the one that's a little bit deeper in there here. Here we have the maximus cut off, we have the medius cut off here, and we have the gluteus minimus as well. A deeper one here, but they all originate. They're all anchored on the pelvis, on that um or that sacrum of the cosec. It's the inserted ends, it's those other ends that we want to pay particular attention to here. We know that if we pull in those muscles, we're going to extend the hip. You can see how that would happen. We can also see how it can cause abduction because you're pulling on an angle and it's actually going to pry the leg out this way and abduct it. But that glutous medius inserts specifically on that lateral part of the tcanor. That greater tcanor on the femur. What these all have in common that we're going to see is all of their insertion points are a little bit more anterior than their origins. So those origins along the sacre leucocyx and the Ilium are all in a relatively posterior position. So the muscles are angling anterior. So when they pull, they don't just pull in that extension or that abduction direction, they also rotate the hip. So specifically, that gluteous medius is going to insert on that lateral tcanter, like I said, and it's going to pull that whole structure in a lateral direction. It's going to twist the foot laterally or outward or the whole leg in that direction. Similarly, we've got that gluteus minimus. And so glutous minimus, once again, anchored in kind of the same place as the other muscles more or less. But the insertion point is on the greater tcanter. That big chunk on the head on that proximal head of the femur itself. So again, when we pull on it, we're going to rotate that hip in a lateral direction. And with the gluteus maximus two. Now, they all do it from a slightly different position. Gluteus maximus inserts on that gluteal tuberosity. It's the most posterior of all of them. It's actually more on that posterior side of the femur, but it's still anterior to the anchor point. So regardless, we're pulling this femur from three different spots and we're moving it in a more posterior direction. But as a result of the joint, as a result of that movement at the ball and socket joint, the entire leg or the entire hip rotates in a lateral direction. You can see just for comparison, again, what we're looking at here, the sciatic nerve passing through here. This has come up a couple of times. I'll come up again when we look at the nervous system. But this sciatic nerve tucks into here and it actually passes through this relatively thick, well protected group of muscles. If you remember, there's that wonderful little sciatic notch that it passes through as well in the pelvic bones. There's lots of stuff going on here, lots of structures, things that could potentially be damaged or potentially be impaired if structural damage is done in these areas. This is also a little bit of a jump ahead for you guys. But in the context of clinical significance. The gluteal muscles are actually a relatively common site for injection, as I'm sure many of you know. But unlike what you see in the movies or in TV, you don't see somebody grab this huge needle and wind up and swing their arm around and jam this needle into somebody's but 10 centimeters in. It's nothing like that at all. It's actually a very prescribed type of administration. Now, you'll learn a lot more about things like intramuscular injections and why we choose the muscles that we do to do this. But one of the great things about these gluteal muscles is they're easy to appreciate you to find. They're a relatively significant target in that there's a sheet of muscle there that's relatively thick, you can get a needle into it, and you can achieve that goal of an intramuscular injection. But the reason we don't see the big wind up in the stab, the blind stab into somebody's butt with a needle is, we've already seen there's a lot of structures in there that can be damaged. This is one of the reasons that we look at orientation of structure, why we want to see the blood vessels and the nerves and the bones and the joint components and the muscles and the lymphatics, and everything else. Because when you actually look at it. Now here is a technique that can be used to actually identify the safe injection sites using your hand. Somebody's hand is placed with the thumb is actually at that crest, that bend point between the hip and the leg. You can see that the greater trochanter is right underneath this area around your thumb. A little finger is spread out along the inferior ridge of that iliac crest here, and you've got this area that opens up in between these two fingers. This is, I'll it over on this side, this is the safe area for injection. When you're looking at it, what that means is, some of the underlying structure that we've identified, things like blood vessels, things like nerves. C, vital components of the joint itself or sensitive components of the join itself are not in danger of being hit by this needle once it's inserted into that area. Get away from the dramatic attack with a needle and jamming it in there and catching somebody by surprise. This is something that has to be done very carefully and very specifically. Looking a little bit more closely, we can also throw in a really important groups, a group of muscles. On that I'm sure you guys are also healthy, but I'm sure somebody at some point may have actually injured a hamstring. Normally, this happens when people perform exercise and they haven't warmed up enough or they haven't been exercising for a while. But on your posterior, this group of muscles, they all have a common origin on that isality. Across your hip. But these are the flexors of the knee and the extensors of your hip. So again, play with this. I don't need to remember this, she'll get confused. Put your hand in the back of your thigh in the back of your leg and actually extend your hip. And think about what you'd have to do. In order to pull your hip backwards, you have to have something that's anchored on your pelvis and then attaching to your femur so that when it pulls, it's going to pull your leg backward. Okay. Also remember that these, if they cross the knee joint can act on your knee. And so some of them actually cross the knee joint, and if you pull the posterior part of your lower leg and pull it toward your femur, that's what flexion of the knee actually is. So these hamstrings, very important, not incredibly strong muscles by themselves, but they all have to work together properly. And one of the reasons they get injured so easily is they have to be well balanced. You have to make sure that these muscles are working together. And if one works more than another one or you don't warm these muscles up properly, that's when injuries can occur. If we take a more specific look, here's what we're talking about. There are three muscles in particular. Now, all of the muscles that we're showing here, you recognize a couple of them. We already looked at that gluteus medius, what it does. I'll get back to grcllis in a second. They're all posterior thigh muscles. But these three, semimembranosis, semitendinosis, and biceps. These are the actual muscles that we consider the hamstrings. And you'll notice they look a little different, but what they all have in common is the relative location. We've got bicep fomoris here. It's a relatively wide a strip of muscle. Here is semitendinosis, thinner strip, but still a flattened strip of muscle going this way. And this semimembranosis, looks a little bit like that bicep fmoris, but a little bit smaller. They're all running parallel to each other, and they do all have that common origin. They're all anchored on the isal tuberosity on your pelvis. And what they do. The other thing they have in common is they all cross both joints. All three of these muscles cross your hip joint and they cross the knee joint. Now, just that, that piece of information lets you know that well, that means I can flex or I can move at the hip, in this case, extension at the hip, but it can also cause flexion of that knee joint across the knee joint. Now, when a muscle does that one, it has a double duty like this, the trade off is, it's going to be a little bit less stable. If it is both ends of it, the proximal and the distal end are anchored, of course, and we're going to get movement. But because it stretches across such a large distance and because it crosses two joints. There are going to be forces acting on this muscle and resisting this muscle that are going to make it a little bit more prone to injury. If it's not developed properly, if it's not warmed up for you exercise, if it's not stabilized, if your body's not in the right position. In some cases, incredibly good athletes can pull hamstrings just by generating huge amounts of force in a short period of time and unfortunately, causing a pull or a stretch or in some cases, a tear of this muscle. In some cases in most cases, it's an avoidable type thing, but in some cases, it just can't Now, the other interesting part though is the distal end of these muscles. When we look at where they actually attach, bicep Fomori get an idea here, crosses the knee joint, but it actually attaches on the fibula, the proximal end of the fibula. Whereas semimembranosis and semitendinosis both attach to that proximal end of the tibia. Both crossing the joint, both generating that force, but because they attach to opposite sides, you now have to realize that they're all working together, they're going to give this really nice forceful flexion of the knee. However, individually, they can apply force from a different angle. Semimembranosis and sem tendonosis are pulling more on that medial side, and bicepomors is pulling more on that lateral side. That's going to alter the position of your lower leg. That's going to put force on the knee joint from a slightly different direction. This is what I was getting to when I referred a few minutes ago to having equal or balanced force across joints and things like that as well. If you're not getting balanced force across a joint, you also set it up for potential injury. So once again, hamstrings, incredibly important things. Also ones that we're very sensitive to and we do injure them because they cover such a large area, and there's quite a few pain sensors associated with them as well. Now back to that Gricilis for a second, Gricilis actually does cross both joints as well. Gricils is also anchored on the pelvic bone, but it's closer to that medial portion. And it also crosses the knee joint and anchors on the other side of the knee as well, and we try a different color there so you can see it. It does anchor inferior to the knee. It will also act across the knee joint and hip joint. It's not technically a hamstring, but it's the most superficial of those medial muscles, and it's also a muscle that can potentially be injured fairly easily. It's also using when we look at it, you can see that it would have a very important adduction action as well. It's going to pull that knee or pull that thigh toward the midline to a certain degree and help to close up Let's move down to the lower part of the leg. This is going to look again very similar to your arm with the big exception that remember what happens at your ankle compared to your wrist. Your wrist is normally quite straight. All the bones are parallel and your bones of your hand, thee lower arm all align with each other. Your ankle, however, is normally at about a 90 degree angle. So when we look at the anterior compartment of our leg, we have what are called dorsal flexors of the ankle and extensors of the toe. Let's imagine what we've got here. We have something that's attached to the tips of her toes and a piece of connective tissue stretching across her ankle joint up to these anterior muscles. If I pull on these strings, think what's going to happen. This is dorsal flexion. This is going to pull my toes toward my shin. Now, we also have this wonderful little piece of connective tissue here that prevents these muscle connections or prevents these tendons from popping out. This actually keeps them in place so that we don't get what we call a bowstring effect. Attachments from all of these muscles are associated with the tibia and the fibuls. Both of the bones in your lower leg have attachments for these muscles, and all the insertions are either on the phalanges, like we saw with their hands or on the metatarsal bones that form that arch of your foot. But regardless, if I'm pulling on any part of my foot across my ankle joint and I'm pulling from the anterior side, I'm going to get dore flexion. I'm going to get my toes pointing. Now, if we look a little bit more closely here, let's look at specific muscles that we find in there. In particular, and we're not going to look at all of them again, but this extensor digitorum longus. Remember the names, but only remember them because they're helpful to understand what these muscles do. We know it's an extensor because it's on the anterior side, the anterior compartment. Digitorum means that this is the muscle that is attaching to the digits, the toes, longus, referring to this is a really long attachment. But this is an interesting thing too, and you can play around with this. We have something called the extensor halcus longus. Here's another extensor muscle. But notice where it goes, it doesn't attach to all the toes. It just attaches to our big toe, the hallux. That's what this refers to. If you play with your toes right now, notice you have the ability to move your big toe quite easily all by itself. But try doing that to all your other toes individually. We don't have nearly that much control over them. This is very helpful for things like balance and for having our foot in the right position to support our weight or for walking on uneven ground, it's very helpful to have that big toe functioning properly. If you've ever fractured a toe, if you've ever injured your big toe, you may have noticed how difficult it is to just walk normally. Back to some landmarks and surface anatomy and the dorsalis pedis pulse. I know this doesn't seem like it fits in here since we're not talking about pulses and blood vessels and that thing, but it's about location again. It's about orientation. The idea that this particular pulse, this is one that you may have looked at already. This is a very important pulse when it comes to determining things like efficiency of blood flow distal to the knee. What's going on in your foot. The landmarks that we're looking at we have when you look at this picture of the foot, me are here. When you look at the blood vessels that are actually in here, what we're doing, in this case is feeling for a pulse in this dorsalis pitas artery, and that dorsalis petis artery is going to be located fairly easily because it's right along Next to that piece of tissue that tendon of the extensor halcs longus, one going to your big toe. There's a great landmark for that. Here we have that tibialis anterior. Another great landmark along the edge of your shin or along the edge of that tibia. And so when we look at the location of this pulse, imagine now an injury to that bone to the tibia or injury to any of the muscles associated with that tibia and result in swelling or accumulation of fluid. Any of those things could potentially impair blood flow distal to that point. This dorsalis pedis pulse or this petal pulse, as I said, is a very important one for determining whether or not blood flow is reaching that foot or whether it's efficient. You can tell how strong a pulse is, how regular a pulse is. That's one of those many points in the body where we can gather information that helps us to determine a course of action or helps us to actually get a better view at what's going on. This is going to be related to some of you will have seen this already because there was one of the case studies actually involved something called compartment syndrome. The reason I want to bring this up as well, though is it's related to injury. And I keep telling you that by looking at injuries or by looking at examples of injuries, it helps to reinforce this idea of what structure is supposed to do in the first place, or why it's so essential that structural components be oriented in certain ways, that they have they have certain features on them. If we interrupt those, if we mess around with how things fit together or how something is shaped, it has a big influence on what it can do, and potentially can impact other structures as well. Oh, you guys I don't expect you to be able to read radiographs. I'm not looking for you to identify things. But I do want to point out here that we have a fracture. This is one I've pointed out to you before. We're actually looking at a picture of here's your tibia and your fibula. The ankle joint, and what we're looking at is a malleolar fracture. You can see a little piece has actually of this. Oops. Here we go. You can actually see that a little piece has cleaved off here. Now, the idea the relationship to muscle here is the idea that muscles occur in compartments. When we look at, I showed you those cross sections through the arm, cross sections through the leg, and you can see flexor muscles clump together and extensor muscles clump together, and then we have other muscles, medial ones. Well, when we consider the significance of that, there's some things that make sense. You group muscles together that are going to perform similar functions. It makes sense that all these extensor muscles are going to be located in a group together. But anatomically, they also occur almost with a little vacuum wrap wrapped around. When we look at things like fascia, when we look at the coverings around these groups of muscles, they're sometimes contained in a little package called a compartment. And that also is effective because that helps to keep these muscles oriented to one another. It allows you to have one major blood vessel supplying the area that branches off to different parts. Major nerve can enter that area. It helps keep them oriented with respect to the bones that they're attached to. But one of the drawbacks is, when you have even something like soft tissue, when you have a wrapping or a covering around this group of muscles, you've created an enclosed space. You've created a compartment and there's downsides to that too if you get an injury. Just like we see with something like a skull injury or a bleed in the cranium, there's nowhere for the pressure to go. If you've got damage to a muscle compartment, and blood is filling up in it, or there's swelling, there's fluid filling up, anything like that, this is going to increase the pressure within the compartment. As soon as that starts to happen, things get literally squished. Blood vessels or nerves or lymphatics or the muscle itself. You can cause further damage. You can cause pain, you can prevent efficient blood flow, you can impinge nerve function. In this case, what we ended up with was an injury that had to be treated in a secondary way. So it wasn't a matter of just repairing the fracture. What you're looking at here is The result of somebody who has been treated for compartment syndrome. Now, that fracture that you saw in there resulted in some bleeding, resulted in some swelling. Fluid built up, pressure built up within that compartment of muscles, and the leg began to swell, and there is no relief of the pressure, so blood flow to everything distal to that was impaired. Nervous function was impaired. Tissue would start to be starved of oxygen and nutrients. As you can imagine, that suddenly becomes incredibly serious. Now we're talking about potentially losing a lib or losing a part of a limb. So the picture you're looking at here and this is a little bit of an old one, but it's still essentially treated the same way. What you've seen is a really large deep incision was cut into this muscle compartment. This would have been very deep, it would have cut into the covering around the muscle compartment to the point where it would allow that pressure to be relieved. For those muscles, quite literally, when you cut there, those muscles would push right out of there, that swollen area. Then, well, you can't really close it right back up again because if you do, you're going to have the same problems. In this case, the wound was closed. You can see, I don't know how clear you can see them, but they're actually sutures or staples in there that were closing this up, but this didn't occur right away. Initially, this wound would have been closed with these little pieces of surgical tubing. These are stretchy pieces of surgical tubing. They have been sutured to the surrounding skin, and they have a little bit of elasticity, they have a little bit of distensibility. These would have been put on the wound to put continuous pressure to squeeze it closed without closing it completely. Because of their elastic properties, as the swelling went down, as the wound drained, there may have been a drain in there as well, they will continue to pull that wound together. Once it gets to the point, so it's squeezing this way, squeezing this way. Once it gets to the point where that incision can close back up and come back together, then it can actually be sutured closed again. As odd as that sounds, this would be the only way to make sure that you didn't continue to put undue pressure on the structures within there and allow them to heal properly. Of course, that's going to open you up to infection. It's going to open you up to fluid loss. These are all things that have to be watched very closely and monitored. Well, that's just as an example. Again, this is not a diagnostics course, it's not a pathophysiology course, but I want you to see how things link together. This is an example of something you'll take a closer look at when you do a little bit more with neuromuscular disorders when you talk about neurological deficit. Also with assessments or evaluation of neuromuscular function. But as another example of things that can go wrong or an example of what happens when a structure isn't working properly. Consider what would happen if a group of muscles associated with dorsal flexion. Don't even worry about specific muscle right here. But anything that's responsible for the normal dorsal flexion of your foot. If you try to take a step and these things are not working, you swing your leg forward, your toe is going to drag. We actually refer to this as a steppage gate, but in this particular situation, when you lift your foot up, normally, we reflexively lift our toe. We doors reflex so that we can clear any obstacles as we move our foot forward. This can be a real problem if you can't do this consistently or to a significant degree. And that means that this could be because of a neurological disorder, it could be because of injury, could be because of a problem with the muscle. But regardless, looking at the function of the muscle, the function of these muscles working together and something as coordinated as taking a step. On little missing piece can throw the whole thing off. Now, this is a particularly interesting one. I'll give you an example of one that I'm familiar with. I had a professor in University, a few years ago, and he was actually of the age where as a child, he had poli. We don't hear a whole lot of this anymore. Polio was all better eradicated. There are still some cases of it occasionally, and it surprises people when it pops up. But one of the issues with polio was this interference with normal neuromuscular activity, and my professor actually wore braces on both feet because he had this drop foot. He had the steppage gait. Without his braces when he spoke or me when he walked, he had to lift his knee really high to make sure that his foot would clear the ground and he wouldn't trip over anything. Stairs were a big problem with him. Uneven ground was a big problem. The brace that he wore, essentially, just made sure that his foot was held at a 90 degree angle all the time. That also made it awkward for him to walk, but it prevented anything like his toe dragging or getting caught on something when he did walk. Again, something to consider, something to look at when you're evaluating just how significant, something that seems relatively small, it may be one muscle not working properly. What a big impact that can have on other activities in the body or as it works together as a synergistic muscle with other muscles in the body. Then finally, with the lower leg, we also see a big stress on what we refer to as the lateral compartment. The lateral compartment actually has the muscles that are associated with plantar flexion of the ankle, and also muscles that at your foot. So here's the lateral side of your leg, the lateral side of your foot. And this one makes sense. If we have muscles stretching down from here and latching onto or attaching to the outside edge of my foot, and I shorten that muscle. My foot is going to roll outward. It's going to evert. It's going to move in that lateral direction. Similarly, in terms of the plantar flexors. Remember what plantarflexion is. It's the opposite of dorsal flexion. Plantarflexion means pointing your toe. So it's this group of lateral muscles here that actually have pieces that stretch down attached to the bases of these metatarsals, and when I contract, this whole foot is going to straight node. It's going to pull it from partially the posterior side, but in actuality, they're on that lateral compartment. The peroneus brevis, that's the one that I was just looking at here, actually has a tendon behind the lateral malleolus, goes past that lateral malleolus right here to the base of your little toe. The pronus longus. Now we can't see this from here, but the peroneus longus is similar, except it stretches down, passes over that lateral malleolus, but it goes all the way underneath your foot and then attaches at the base of my first metatarsal. It's actually going to attach underneath my foot over here. But both of them are going to pull my foot toward the outside toward the lateral side. Last but not least, we've got that posterior compartment. Here's where we find the soleus and the gastrocinms. Another great muscle for you two palpate or one that you can appreciate. When we look at the superficial layer of muscle there, we see first of all, this muscle we call the gastrocenus, and the gym, you'll hear people call it the gastroc. But your gastrocnns is one that is actually quite easy to see too when your flexit you can actually see this little shape that appears. When your legs are really well toned, it's a really obvious shape for the muscle. The soleus as well is another one that's blended in with it and considered a superficial muscle. Deep to those, we have something called the tibialis posterior, the flexor digitorumngus, the flexer halcus, those two that we just looked at. But let's focus more on that superficial part because that gastrocenmus muscle, if you notice, the gastrocenms, and the soolus muscle underneath it here, they all blend in to the same connective tissue here, my Achils tendon that attaches to my calcaneus, the heal. You can imagine now when these muscles contract, they are going to pull my heel upward. They're going to straighten my toe out. That's one of the functions that they can perform because of crossing that ankle. Now, let's look a bit more closely. Let's look closely at it here. On the superficial side, on the gastrocinms, we actually have those two heads. Two muscle heads. They attach above the epicondyles of the femur, which means they actually cross the knee joint. They converge into that Achilles tendon or the tendo calcanes we call it. Here's another muscle that really crosses two joints. It crosses the knee joint, and it also crosses the ankle joint. That's a little bit different because not only will it cause movement at the ankle, but it's also important for flexion at the knee. The soleus, however, and here you can see it on this side, when we pull that gastrocnemius away a little bit. The soleus doesn't cross the knee join. The soleus assists that gastrocenmus. It also blends into that tendo calcaneus into that achils tendon and attaches to your heel. Its major function is just movement at the ankle along with that gastrocnemius muscle. Since it doesn't cross the knee joint, it originates on the lower legs. It actually originates on the tibia and the fibula. It even has some little fibers that attach to that inteross membra. Okay. Well, this is a bit of a long one, guys. I know this file is probably a little bit big, but hopefully this will give you something to play with. And when we get a chance to chat hopefully more people can show up next week for our online drop in session. But please let me know if you have any questions, and I will post some more material up for you very shortly. Take care and be safe, everybody. Ed to throw this one last muscle in just because it's interesting and that it functions relatively individually. We can look at it, we consider this individually. The popliteus is actually, it's a funny muscle because it's the only one in that lower posterior compartment of the leg that is associated with only action on the knee and has has nothing to do with the ankle. There are a number of other deep muscles in that posterior compartment, and they act as things like in inverters of the foot, flexion of the toes, depending on where they are. There's a number of different ones in there. But it's only this popliteus that only acts in the knee joint. Essentially, what it does is it crosses, you can see here that it crosses on an angle, and it really is attaching to both the tibia and the femur. When it's activated, it pulls on the f, femur rotates the femur intar the tibia, and it has the action of what we call unlocking the knee joint, and it allows for flexion to occur. It is a synergistic muscle working with the muscles that flex a knee and it's a stabilizing muscle that allows us to activate or inactivate the ability to flex or move that knee. As far as the other muscles, these deeper ones. We focus on a couple of them. But any deeper muscle, smaller muscles that are attaching across the angle joint or across the knee joint. Keep in mind, it doesn't matter how big they're, it doesn't matter what other muscles they're working with. If it shortens, if this muscle contracts, it's going to pull things across the joint. If you're pulling two structures across the joint, you're going to produce some movement at that joint. Without going into a huge amount of detail regarding the intrinsic muscles in your foot. I want you to notice right away that it's a very similar arrangement to what we saw in your hand. As silly as this might sound, as I said before, there are also muscles in there that we become aware of when they've been used a lot. When your feet get sore from standing for a long time, walking on uneven ground, wearing a shoe that's not particularly comfortable. These muscles get a real workout. They're continuously relaxing and flexing, relaxing and flexing, trying to change the position of our foot and the position of the bones in our foot. And just like those small muscles in our hand are necessary for things like improving or adjusting our grip or abducting or adducting the fingers or deviating the position of the metacarpals and the carpals. Well, we get similar things happening in our feet. But with the ad the added component of our feet are supporting our body. They're supporting our weight. We run, we jump, we stand. And so slight changes in our body position, our center of gravity have to be balanced by things like large muscles and our hips and our knees, but ultimately our feet. And when we consider, you'll see in the last slide that I show you right after that. When we consider just how little of our foot is actually ever in contact with the ground. This is pretty incredible. These muscles are continuously fine tuning, contracting, relaxing to try to keep everything positioned in just the right position so that we can do that. Remember the arches of our foot. Remember how important the orientation of the bones were to form those arches and support that weight and absorb that force. Well, it's the muscles that are responsible for holding these things in place. So we see quite a few layers of little tiny pieces of muscle. We also see those tendons, just like we did with the hand, passing both on the anterior and posterior, or in the case of your foot, that inferior and superior aspects of your foot, and all the ones connecting the extrinsic muscles to the toes and to the tarsals and the metatarsals. We also see the short flexor muscles in between. We're going to see things like adductors and abductors. We've got the little pieces in here. We try a different color there. Little pieces in here. We've got those interraci in between. There's going to be muscles and all these layers are piled on top of each other right now, but we're going to have those lumbricals, have muscles that attach to the flexor and extensor tendons to help balance out their function in a system and work synergistically with them. So quite a bit going on in there, which also explains why it's funny with feet because some people really like to have their feet rubbed, especially if there's stress, especially if there's a lot of tension there. But you probably know yourself too. There are some people who just can't stand to have their feet touched. We have a lot of sensory tissue in there. Our body, our brain has to be so aware of the slightest little changes going on in order to maintain our posture in order to maintain our body position, that we get these continuous signals coming back from our feet with respect to muscle stretch and contraction, and joint position, and pain and pressure and all of these There's a lot going on in these pretty serious little structures that we tend to take for granted. This is the last thing I want to show you. I just mentioned that it's interesting how little of our foot is actually ever in contact with the ground. If you look at a typical footprint in like a bare foot in the sand or something like that. You know that the entire outline of your foot, the entire surface area of your foot, even when you're standing up, doesn't come into contact. We have that void or the arches. But when we're walking, it's even more accentuated. We even fast, slow as a matter. We walk in this heel toe fashion. So what you're looking at here, this thermal image is showing when we take a step and if your heel hits first, I mean, you could hit toe first, it doesn't really matter. But a typical step, our heel hits, you can see the relative amount of pressure. There's a combination of thermal and pressure imaging where you can see all that pressure coming down the heel, then slowly as it rolls forward, it's distributed along that lateral part of the foot, and then to where the metatarsals actually actually articulate with the phalanges, and then out to the tips of the toe. So at any given time during a step, there are a very small surface area of our foot that's actually in contact with the ground, supporting our entire body weight along with any force that's there added force from running or jumping or anything like that. So you can imagine how important it is to balance that muscle activity and to make sure that it's coordinated. And why even the slightest little change in that? A slightest impairment of nervous function or muscular function, or pain or anything like that is going to impact our ability to stand or walk.