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Hello, everyone. Um We have Mister Payton here, uh uh he's spinal consultant and he will be presenting to us the back uh anatomy. Uh So, uh Mister Pitman, uh you can start. Thank you very much. Ah, so, uh nice to see you today and I've been asked to uh help you guys with a little bit of a refresher on anatomy of the spine uh in preparation for the MRCS exam. So, what we'll go through today is some of the stuff that you'll find in the textbooks, but perhaps uh sort of highlighting the points that tend to come up as questions uh in the exams and in the ACY and and so on and also pointing out some of the clinically relevant material because that tends to be the focus of any sort of examination and, and questions that we do. So I'm gonna share with you uh some slides now and as I've already alluded to what we're dealing with today as our topic is the anatomy of the spine. So just to initially start with a little bit of um surface anatomy, so hopefully you can see my little marker here. I'm sure you're well aware of the different um areas in terms of where you'd be looking for. Um And, and the spine is, is, is buried within a lot of muscles in the back. So there's only a few areas that you can really highlight in terms of surface anatomy of any relevance. Um But what we talk about the, the most prominent vertebra, the vertebra prominence is usually C seven, although it can be t one. So just at the base of the neck there, where you feel the most prominent vertebra, that's gonna be the C seven vertebra. And then as we come down into the thoracic spine, what we tend to look for is the tip of the scapula. And that levels equates to a a spinal level of about T seven. Then at the base of the rib cage, you've got your short ribs off T 12, you're not really going to be able to palpate that. But as we come down in terms of relevant clinical landmarks for um procedures and things like that, we think about lumbar puncture and what we want to be doing there is looking for the 4th and 5th interspinal space. So we look at the crest here, the iliac crest and as we bring a line across from the iliac crest, usually the, the space we can feel between the two spinus process is the level is usually L4 5. So lumbar 45 and at that point, um So the, the slides are staying on the same. So you should be able to see a little pointer here, um which hopefully you can see my pointer. Um So L4 5 is the um space where you'd uh perhaps consider doing a lumbar puncture or something. And then you've got the dimples of venous back here, which is the posterior superior iliac spine. Uh and that's a prominent landmark there that helps you identify the base of the spine or the top of the pelvis. If you, if you're thinking of it in those terms, so I'm gonna click on to the next slide. Hopefully you'll see the next one presented. Um If there's any issues with that, if you put it in the chat, then my uh my willing helper Ahmed will notify me and we'll do something slightly different. Ok. So now you should see uh a representation of the spinal column. And what we notice here is you've got the cervical spine with in a lateral position, which is the middle image. So you're looking at a cervical lordosis, thoracic kyphosis and a lumbar lordosis. And what we look at here is we've got the seven cervical vertebra, got 12 thoracic vertebra, five lumbar vertebra, and then the sacrum is made up of five fused vertebra along with the coccyx, which is anything between three and five vertebra that are all fused together. Although there's often a little sacrococcygeal joint at the bottom here. So it can be quite mobile. And when we look at the Sagittal balance and we talk about sagittal balance, what we want to see is dropping a plum line down from the external, external auditory meatus. It should drop through C seven and then it should drop through L5 and straight down to the floor. So the spine should be well balanced in terms of its curvature. And then we look at the front or the back, then it should be a fairly straight line down the spine. And we look for that in terms of the normal uh curvature of the spine uh and the the representation of it. So nowadays, we can look at clinical anatomy in in huge detail. And we've got imaging in the form of MRI scans, which are very, very helpful and they can show us a tremendous amount of detail that was never before uh possible. And so in terms of the representation, you might get shown an image in an MRI uh in a um in the exam might be asked to describe various key factors and features in there. What we see here in the lumbar MRI scan, this is a sagittal. So it's taken through the looking sideways on. And what we can see is at two weighted image where the fat is white, the CSF is white um but the other signal is low. So if the CSF is white and the fat is white and that is at two weighted image. And what we can see here is the vertebral bodies. We see the discs and they should be nice and high signal with black signal around. And that's a well hydrated disc. You see the spinal cord coming down here and ending at about the level of L1 and then becoming the cord equina, which is the spinal um nerve roots as they all pass down in the lumbar spine region, the spinal cord ends here, but the epidural sac continues right down into the sacrum. And so this is CSF fluid all the way down here. So in terms of ways to prepare for the exam, um what you can do is you can think about the sorts of questions they come up with and often uh certainly in my day. And I think to a certain extent now they like to show you a model or a picture of a bone. And they'll say, well, what, what bone is this, what part of the body is this from? And sometimes that's quite easy. Sometimes that can be fairly good examples. So in your head, just have a think about which bone you think it is represented here in this um picture. Um some of the clues are in the labels here. And another little trick that you can use when you're doing preparation for exams is to take these images and then just to block out on your screen, perhaps using a um a block of, of, of uh white or black uh text box cover up the words, try and label them yourself and then try and test yourself against that. Because if you're always looking at it with the labels, it's very easy to um actually forget what things are. So um this is actually the C one vertebral body. So the very top of your spine, it's the axis. Um And what we see here is uh an anterior um articulation here, which is the facet for the dens. So this is where your odontoid peg would protrude up into that. Ok. You got your occipital condyle. So the superior facet here of the lateral masses and we call this the lateral mass of C one. So you've got the lateral mass here and then you've got the superior facets which, which articulate with the occipital condyles and then behind where the peg sits, what you end up with is a transverse ligament here. And that's important because at this level of the spine, what we uh tend to use is the rule of thirds. So a third of the space is taken up with the peg, a third of the space is taken up with the spinal cord and a third is taken up with epidural fat and CSF now, if that transverse ligament is disrupted in terms of an injury, then the odontoid peg can translate and slip that the whole of the bone can move forward and the ring can move forward. And if the ring is intact, that can cause compression of the spinal cord and can lead to a spinal cord injury. So, a degree of um stability is conferred by that transverse ligament. And if it's absent or injured, then that can be problematic in terms of allowing translation and then potentially spinal cord injury. We're looking at the lateral masses just in the lateral aspect. Here, we see the Foramen transversarium, that's an important structure. And we see one either side, that's where the vertebral arteries pass through. And they also wrap around the back and then come up together and join the circle of Willis. So at the point of the C one vertebral body, um the arterial supply is quite complex and it can be very close to some of the other structures that are there. So whenever we're operating in this area, we have to be very mindful of that. And there are some great diagrams and, and, and illustrations that will elicit that past. But often what we do in clinical practice. And if you're answering an exam via the question or what have you on this, you'd say, well, we get some uh angiography, Mr angiography or CT angiography to look at the um passage of the vertebral arteries because it can be variable. And when you've got variable anatomy, you need to know what you're dealing with in terms of how you might er operate on that area and proceed. Say it's gonna be a fairly easy guess. Now. So what, what vertebral body is this? Have a little think, see if you can recognize it. It's got some key features there which make it fairly um clear. But we've got the odontoid peg or the dens and it's got a facet where it articulates with the ring of C one. Again, we've got a frame and transversarium. And what you'll find is that they are present in all of the cervical vertebra down to C six. And that's where the vertebral artery runs. And what we see is a little rudimentary transverse process here. So in the upper cervical spine, the transverse processes are only little uh tubercles of bone. The body itself is fairly small and undefined because it extends up into the dens. And then we've got the, the lamina or the arch of the bone here at the back. So, yes, this is C two. Yeah, based on what we've done and following you can always predict what this will be, but what type of vertebra is this? So I'll give you a choice. It's either CVI called lumbar or thoracic. So the key features here that we see, we've got a bifid spinus process. So this is the lamina at the back here. This is the spinus process and it's bifid and that's key. So that makes it a cervical vertebra. You've got the foramen transversarium again. So this is gonna be one of the thoracic cervical vertebra sorry between C three and C six because it's not C one or C two. And it's got a transverse a frame and transversarium with the uh for the vertebral artery. So C seven wouldn't have that vertebral body at the front. This is the canal. So this is where the spinal cord is going and this is the lamina into the spinus process here. So how does this all fit together? And this is what you'd see if you were looking at the cervical spine from the side, what we see is the articulating processes. So, the zygapophyseal or facet joints and they tend to be quite flat in the cervical spine. You've got two at every level, the spinus processes as we've talked about are bifid and they tend to follow a cascade coming right down to the most prominent one which is C seven. You've got this Foramen transversarium down the side where the artery passes and you've got the ring around the peg, which is the Odonto peg. And then you've got disc, joint, disc, uh bone, disc, body, disc body all the way down. And the spinal canal is just in here and that's where the spinal cord is transmitted and passed. So, do you think this is a lumbar or a thoracic vertebra? Then you have to start thinking about why this is where it becomes a little bit more tricky. But there are some certain clues there that will give the game away, I'm sure. And if I were to point out some key features here, so again, we've got a fairly square body at the front. So the body is becoming more well defined and square. What we have here is a transverse uh spinus process, sorry, which is pointing dorsally. So it tends to angle cordially, um or dorsally and cordially. And we've got a transverse process which is becoming more defined so bigger than in the cervical spine. We've got a superior articulating process of the facet. But also what we've got here is the little articulations, both two articulations on each because the rib head sits between each level. So it's gonna articulate with both the level below and the level above. So it's thoracic again, we see the same pattern. We see the lamina into the spinus process. But this time, the transverse process is much more defined and becoming larger and we can see more clearly define the pedicles which are getting slightly longer that take you into the body. And that's what creates the spinal canal. Now, in the thoracic spine, the spinal canal is quite tight. There's not a lot of space for the thoracic uh for the for the thoracic spinal cord in there. Um because it's a fairly rigid area. So it doesn't move around much. So it doesn't need to have the space in the cervical spine. You've got a lot more space available for everything the neck is moving around. So it needs to have more space for the spinal cord. It's not so relevant in the thoracic spine. So it tends to be more rigid and uh and a tighter space. So the only one left to think about now is what makes a lumbar vertebra. Um And when we think about that, what we, what we see here is the spinus process tends to be a bit more um straight, so it points straight rather than heading cord. The uh pedicles tend to be slightly wider apart with a larger body. The transverse process tends to be completely separate with no articulation for the rib or anything else. And then you've got a superior in an inferior articulating process which are orientated like this. So in the cervical spine, they are very much like this as we come down into the thoracic spine and they're front to back, sliding downwards. And then as we come into the lumbar spine, they tend to orientate more in this plane. So they're pointing this way in the lumbar spine, we've got more space for everything and we've changed from being in the spinal cord to being into the, the corda equina in the spinal nerve roots. So there's less, less potential for neurological injury. Now, in terms of injury patterns and the shape of the uh the bones and the articulations of the spine. What we see is that the discs themselves are fairly constant and consistent throughout the spine. But the articulating processes tend to confer translational stability. So, in the cervical spine, because they're very much like this, what you can get is you can get translation with a spinal cord injury, uh with a with a spinal column injury, sorry. Um And, and you're more likely to get uh translation type injuries. What also happens is because it's a relatively mobile area of the spine with a big heavy weight, which is your skull on top and a fixed element, which is the, the rib cage below it, then you're more likely to get injury there. So the cervical spine injury, a spinal spine is an area for potential injury because of that mobility um in the spine, the lumbar spine is also vulnerable, particularly around the thoracolumbar junction. So the junction between the rigid rib cage, which provides a lot of support and the lumbar spine is another area for um potential injury. But because the orientation and the interdigitation of the facet joints in the lumbar spine, what we tend to see there is more bony injuries rather than dislocations. Um and we can see compression of the vertebral body at the front, often with flexion and we can see distraction injuries where the ligaments at the back get torn, but we'll look a little bit more detail at the ligaments a bit later on and just go through that again. So it's worth knowing about the different coverings in the spinal cord and this sometimes comes up in question. So just thinking about the spinal cord itself, what you have is the spinal cord with its meninges around it, you're covered in the pia mater, which is the most inner layer. So the pia mater encloses the spinal cord, then you have an arachnoid layer and then outside that you have the, the dura mater which is much thicker and contains all of the CSF and you do have blood vessels um within those areas. So you just need to be aware of those different potential spaces. The most important being the Jura, so intra Jura or extra Jura. So outside the Jura is outside of all the coverings. Once you get inside that, then you have further layers of the deeper down, but you'll start to get CSF leaking out the moment you go through the uh Jura Mater. So just thinking a little bit about the connection between the different vertical bodies, we've got the discs and one thing that does sometimes come up is, is what are the forces acting through a disc? Why is it the way it is now? Um you have a motion segment to think about and, and we describe a vertical body with a disc and a vertical body adjacent to it as a motion segment within the spine. Um And that's often used for biomechanical testing and things like that. We look at the vertical bodies as having endplates and that is important because that's where you get diffusion across the endplates for um the chemical supply of the disc. And in the side of the disc itself, what you end up with is a soft nucleus, pulposus, a soft jelly in the middle and then you have a more fibrous annulus. Sorry, forgive me a more fibrous annulus around the outside. The anterior bit is thicker and stronger than the posterior part. Unfortunately. And that does present an inherent weakness because obviously, if you get posterior bulging of a disc, then that's going back to the spinal nerves and the spinal cord, if it's coming out the front, it'll be out the front of the vertebral body and not really cause too much trouble. Um But where they tend to go is backwards and they tend to cause neural compression if they do that. So as you load the spine axially, what you do is you create ex uh increased pressure within the nucleus pulposus and that pushes outwards against the annulus fibrosis. And the way that the annulus is created in its layers is designed to contain that pressure and to uh distribute that pressure evenly so that it doesn't rupture or burst. But what you can get is splits in the fibers of the annulus and then disc material can protrude out and that's where we get disc protrusions occurring. So that's just thinking a little bit about the pressures that might be occurring inside. Um the um disc and this is just another representation of a cross section through the spine. Um And this is taken through L4. And what you see is this lamellar structure of the annulus fibrosis. So in the middle, the soft jelly of the nucleus pulposus around the edges, you have the lamella pattern. And actually in reality, that's interdigitate like this. So the different layers are crossed, so that creates some torsional stability as well. And what we see here is how some of this is actually innovated. And so there is a small degree of innovation in the annulus itself and, and uh around the area. But um this, this feeds back in through the main dorsal ganglion into the main spinal nerve. What we can see here is a representation of how the nerves are arranged behind the disc as well. And this is important when we think about when a disc protrusion happens, which nerve is gonna be affected. So if we're at the L4 5 level, what we have here is a L4 5, the L4 root is the exiting root, the L5 root is traversing. And what we talk about is a um a foraminal zone and that's the L4 coming out through the foramen. And so when we've got that, a foraminal disc at that level will cause L4 symptoms at L5. If you have a paracentral disc, herniation, that's in the recess of the spinal canal and that would affect the traversing roots. At L4, 5, you get L5 symptoms. So you can get two different types of nerve pain from a disc protrusion at the same spinal level. And that's why because if it affects it in the recess, it affects the traversing. And if it affects it laterally to that in the foramen or extra foramen or region, and it will catch the um the spinal nerve that's exiting. If it's a an extra foraminal disc out here as well, that's where the dorsal root ganglion is. And that's the swelling of the nerve root as it comes out. That's important because it causes an intense burning type of pain. And so it's relevant to clinical practice because if you get a far lateral disc presses on that dorsal root ganglion, it causes a different type of pain and can be less um more resistant to treatment. So, again, coming back to our faithful friend, the MRI scan, what we can see here is a normal intensity of signal in the disc. The lowest disc there is starting to get a bit darker which we ascribe to uh dehydration because water is high signal on the uh MRI scan, very slight bulging of the discs, but both of the times they're well away from the spinal nerves here. So they're not causing any problems, but that's what can happen. And this little white high signal here is thought to be a splitt in the disc. So you get a split in the disc from hydrostatic pressure increasing and that can cause uh pain and problems from that point of view. So we've talked about this already. This is the motion segment. We can see the nerve root exiting through the foramen here. And what we see is that slight swelling is the dorsal root ganglion um which um is the is the sensory uh axon bodies. So the the bodies from all the sensory fibers gather in there. And that's why it's a swollen area. So at each level of the spine, you have foramen and they can pass out equally what we tend to get is collapsing of that frame. And when you get disc degeneration, so you get a loss of disc eye and then that foramen loses height can become smaller. And that's when you can get pinching of the exiting nerves in particular. So we talked about the different layers and this is just a diagram and illustration to show how you might um use this clinically in terms of the different layers. So just thinking about this, we've got the spinal cord here. We've got representation of the spinal nerves coming out at each level. And what we see here is this yellow outline here is meant to represent the dura mater and the flum terminale comes down here, which is the termination of the Jura and it attaches down into the base of the sacrum there. What you can do is you can put an epidural catheter in which goes in just outside the epidurals, um the dura mater and that's in the epidural space. But if you want to do spinal anesthesia and you want to uh anesthetize the patient, then you pass it through the dura mater outside the Arachnoid. And that's where you're gonna put your spinal. So again, just thinking a little bit about the positioning of the patient when you do a, a um uh lumbar puncture or something like that, what we see here is a representation that shows the needle going through the supraspinous ligament at the back. You've got the transverse processes here and then you've got the interspinous ligament and then you've got the thick ligamentum flavum, which is yellow. Um And then that once you go through those three ligaments. So um Ashot asked a question about what level can spinal anesthesia be given? And the honest answer is you can give it at any level. Normally, if you give a drug um um that it will, if the patient is lying flat, then the level of the block will rise. What you don't want to do is is knock out for respiration. So you block the level that you want to uh operate on or do uh surgery for. Um So if you're doing um inguinal hernia or abdominal surgery or lower limb surgery, then you can block the thoracic um spine or you can do um lumbar spine. Um Obviously, once you start to get higher up in the thoracic spine, you start to affect your intercostal muscles and that can affect respiration. And then once you get up to 345 innervating the diaphragm and you're starting to cause uh diaphragmatic um paralysis and then you need to ventilate the patient. So, um so you can give spinal anesthesia at any level, the higher you give it, the more you are likely to have to anesthetize them for the reasons. I've just uh explained. Um Normally if we're doing it, um we'd be doing it in the lumbar spine because that'll give you a good block of all of the nerves supplying the lower limbs. So, if we're doing lower limb surgery, um a lumbar um block is usually adequate. But when you're taking samples of fluid for spinal analysis, what have you often we go in the four or five space because it's convenient. And what we can see here is exactly why you've got three ligaments, supraspinous intraspinous and then ligamentum flava and 123. And that's the three pops that we talk about going through. Um And you can see those there and then once you've gone through that final pop that's into the um uh into the uh space where the juror is. And then if you go into the jur itself, then you'll get flashback of fluid and CSF now the, the, the illustration above is meant to illustrate the fact that when you have your spine um standing normally, then the spinus process is gonna be like that when you flex the spine forwards, they tend to open up. And so if you're going to inject, you've got more space to get into if you go an extension and all of those spaces and the spinus processes claps down again. And so the distance between them and the space available for you to get your needle in is smaller. So that's why when we ask someone to uh sit for a spinal, we get them to lean forwards uh or we put them on their side and we curl them up in a ball to try and expand those spaces between the spinus processes so that you can um get the needle in. Now the bit that everyone hates from medical school and I II have no idea why. But actually looking at this um picture, it reminds me why there's so many different tracks in the spinal cord. Now, it's lovely fun if you want to sit there with a book. But if you try and hold that information in your head, long term, it always falls out and that's the disappointing thing about it. But um these are all important tracks and they do do important things. But one can summarize that in terms of a simplistic view, which is much more helpful in terms of clinical understanding. And I think this is probably a much more elegant and um useful way of thinking about it. So, what we see here on the right and red is the um pyramidal tracks, which are the motor tracks. So these are the descending tracks and these are um uh crossover in the medulla oblongata come down and they supply um your, your motor function. So that's your, your effectors or your motor fibers coming down in the pyramidal tract. And you've got a direct one at the front and then more laterally, you've got the cross tracks there which um ate in the lower part of the brain and the midbrain and the medullar art, et cetera. Now, in terms of sensory, we've got the ascending tracts which are represented in yellow here. What you have here is several different tracts. You've got a lateral and an anterior spinothalamic tract and they're all named very helpfully. So spino from the spine to the thalamus great spinothalamic tract, you've got a spino cerebellar tract and you've got an anterior and a posterior one of those. So they're all labeled in very helpful ways to tell you what their function is. And then we've got the posterior columns here, dorsal um columns of go and Burdach. I have to say, I never remember that they go and bur but they remem they, they, they're called the dorsal columns. And I think that's the most important thing to remember. Um And what you find is that um the dorsal columns transmit deep sensation and proprioceptive feeling up into the brain and they go up on the same side and then they cross over in the medulla oblongata and supply the opposite side of the brain with the um spinothalamic tract. They tend to go up a couple of levels in the spinal cord and then across. And so pain and temperature tend to be um cross over and then travel up and stay on the same side once they've crossed over. So they cross at the same level. So that's where we get these different representations of um spinal cord injury, partial cord injury and things like that. So each time you do it, you're going to have to refresh it and remind yourself of it. But essentially, there are um key ones to think about is hemisection of the cord, which is incredibly rare. That's Brown Sicard syndrome and that's where you get half of it cut off. And the reason people like to question that anatomically is because of this difference between same sided tracts. So the pain and temperature um are lost on the same side because you've got that. Whereas the opposite side is what you lose um for um the deep sensation and deep um appropriate section. Ok. Uh Central cord syndrome is where you get more of a vascular phenomenon. And that's important to know that in terms of understanding central cord syndrome, what you get there is you get the upper limbs are affected more than the lower limbs. So normally you'd expect a spinal cord injury to be worse from the feet up. And then you get a spinal cord level. What you get with the central cord syndrome is you get the upper limbs are more affected than the lower limbs. And the reason for that is that the way that the um fibers are represented in the spinal cord in the pyramidal tracts is that they are more affected on the uh the upper limbs are more central and more medial. So the lower limbs come off laterally and pass down the cord laterally. So they're representing more media. So a central cord injury will more affect the upper limbs, less affect the lower limbs. And so that's why that, that little bit of knowledge is important in terms of interpreting that clinical sign that you see with central cord syndrome. Other things to mention here, just thinking about this, you've got an anterior spinal artery which supplies most of the blood supply to the spinal cord itself. And that's in this uh fer or the um commissure anteriorly. And you have two posterior spinal arteries that come down the back of the spine. So it's worth knowing a bit about the blood supply there. Just to mention in terms of developmentally, um what we see in the development of the spine is um that the spinal cord starts life in the early fetus with it very low down. Um So you have a flu terminale and you have the dural sac and then the spinal cord and as it migrates to about L3 at birth, I think it is. And then as you get older, up to about L1, by the time you're an adult now, within that there is variation. So some people have a very high spinal cord T 12 level. Some people have it down as low as T three. And if it's very low, then we call that spinal cord tethering or post fixed and that can cause some neurological problems. But normally spinal cord ends at L1 L2. And then what you get after that is the um cord quina. So hopefully what you're seeing is lots of the images that you're used to from LS and other clinical books. So they should be familiar to you and help in terms of uh linking it. I love ne A and I used ne A a lot when I was studying. So um some of those pictures are quite nice, but they can be a bit more um artistic and um therefore have a little bit more artistic license, maybe less accurate and helpful clinically. This is just um another diagrammatic representation, the sort of thing that you might get shown and you just be asked to sort of talk about the different bits or label the different bits. They're important to recognize the vertebral body, the discs with those cross fibers. And what we see here represented is a disc herniation, compressing the exiting nerve root as it comes off here. So that's the exiting spinal nerve. Um and it's highlighted in red here to show us how that's in, in potentially causing inflammation, local pain signals and causing pain. So, one other thing to think about be aware of is reflex arcs and that's an important part of, of spinal anatomy and physiology. Really. So, um we use clinically to look for spinal cord function and certainly in terms of spinal cord injury and uh called a equina syndrome, the importance of the absence or presence of spinal reflexes is important. Um So, in spinal cord injury, once the spinal shock has passed spinal cord reflexes start to return about 24 48 hours after the injury, um that's an important time frame. Um And then in cord equina, we look to see whether the cord equina itself is disrupted in terms of the reflex pathway, such as the Bulbocavernosus reflex, where you can tug on a catheter and then you get contraction of the anal sphincter. So how does the spinal reflex work or you have a uh a sensor in the skin? So you have various different types of receptors within your skin um or your organs um and they can receive a signal that signal goes all the way down the sensory axon. And then what you get is the cell body collected within that dorsal root ganglion, as we mentioned earlier. So you get a collection of cell bodies there all the way down the axon um into the er dorsal horn of the uh white matter. Apologies if I got that wrong, I think it's white matter. Um but it goes into the dorsal horn anyway, where you've got various different interneurons. Now, those interneurons can be at the same level, sometimes they go up or down the level depending on which reflex it is. We're talking about what they will do is they'll connect with an effector um in the uh ventral horn and that ventral horn will send a signal down your motor axon to your effector muscle and cause the reflex response. Ok. So when you, for example, you check your patella tendon reflex, you tap your patella tendon, there's a stretch um effect there, which is picked up by the receptors that's passed back to the spinal cord, sends a reflex out down the muscle to your quadriceps, muscle and your quadriceps muscle contracts and causes the effect. OK. So just w worth remembering that loop. And that's the sort of diagram you might just get asked to sort of label or diagram in terms of sensory receptor effector down to the dorsal ganglion um into the uh dorsal horn into neurons across to the ventral horn and the motor effect and then down to a motor effector. So just thinking a little bit about the complexity of the muscles around the back. It's not something you're gonna have to focus in a major way. But the reason I brought it in here is it is relevant in that there are lots of muscles in the back. And what we see here is several of them. They make up the Ectoine a group. So the erects a muscle is a group of muscles and that includes helio costalis, which is across the back of the helium here and goes up onto the back of the ribs and the costal margin here. Multifidus is the most medial and then you've got longissimus, which is next is between the two. So longissimus runs up and down the spine. M multifidus has lots of different heads and lots of different fibers. And these all go over multiple levels of the spine. Why is this relevant? Well, if you get an injury at one of these levels, and what can happen is you can get muscle spasm and cramp and that's why you get an escalation of back pain and a lot of back pain. It's very common. 80% of people get it is due to a muscular injury which then um cascades in terms of causing further muscle spasms. And that's because they're all linked, they become inflamed once one of them times it can cause spasm in other parts of the muscle body. And all of these muscles work over multiple levels or multiple motion segments. So it's not as simple as one motion segment being deranged can cause uh a simple problem locally, they all work in unison together. Now, fortunately, from a surgical point of view, what we do is we group those together as the um uh uh ecto spinal muscles, we split them down the middle because their innovation comes around from the edges. So they're segmentally innovated, we split them from the middle, pull them apart, do our business and then put them back together again. So from an anatomic or surgical point of view, you don't need to know the detail of the names. But I think in terms of the function, it's helpful to just understand that fact that they run over multiple levels. The multifidus has lots of different heads and attaches to various different parts of the different motion segments. And then you've got the longissimus and the er costalis, which support that. Now, again, thinking more broadly about how we often treat back pain and treat spinal problems. We talk about core muscles. Now, there's several muscles and we see the erect spinal muscles in this diagram are all grouped together now. So these are all grouped together as those ones that I showed you before. You've got the Quadratus Lumborum, which is just next to the T piece here. And you've got the soas which is very closely associated with the spine. But beyond that, what we've also got is all the abdominal wall muscles. So what we see here is the internal external oblique rectus abdominis. Um and, and so on. And as you go round, all those form a barrel and cause a pressure barrel that supports the spine. So when we talk about core muscles, we're talking about the SOAS, we're talking about the ecto spinal muscles of the quadra lumborum. But we're also more broadly speaking about um the abdominal wall muscles and how they can support the spine as well. Say, just thinking about how this translates into the neck. And again, in terms of surgical approach to the neck, this is just really a diagram to represent the fact that by the time you get up here, you get lots of different spinal muscle names and they all get a bit confusing. And but again, what we have is this safe channel down the middle. So we always go midline posterior, we strip the muscle off the lamina and we can come out to the lateral masses here. And then what we can get to is the spinal cord here. We can um yeah, if you want to, you can get to the vertebral arteries here out the sides, but you're going through bone or you can come from the front. But if you're coming from the back rather than going through muscle, which bleeds um and then becomes defunction, what we do is we split it down the middle and then we can stitch back this fascial layer in the middle so that things all knit back together and start to function more normally again, in terms of operating on the neck. And just to be aware of, we do something called a Smith Robinson approach usually and we use, um, planes that are naturally there. So what we tend to do for that is we, we come down through the skin, through the platysma muscle, which is the, the muscle at the front of the neck. Um And then we, we come just next to the sternocleidomastoid. And then these are the striped muscles here and there are several stapedial muscles and we move theroid sheath laterally and we come down onto the front of the spine. And then there's this, this is the um longus coli muscles. Um And as we do that medially, what we do is we take the larynx and the esophagus um and any residual um aid or other muscles that are there, go immediately with that and that gives us an access to the sort of cervical spine and the disc and we can come through there and we can get to the spinal cord through there. So that's our common entry point. It's called the Smith Robinson approach. And it's just using the lateral border of the uh Stenoclada Mastoid as a, as a guide to take us in through um through the sped, taking the vessels laterally. And, and then you go straight down onto the spine. You sometimes have to split the prevertebral fascia here, sometimes it divides very easily depending on how thick it is. So clinically, again, thinking about how spinal function relates to anatomy, it's worth knowing the surface landmarks for sensation and what you need to know is your dermatomes. Because if you're interpreting spinal pathology in terms of how it presents in terms of pain, but also in terms of examining a patient, you need to know what relates to what. So it is worth revising and refreshing your dermatomes. In terms of the key elements that I would highlight to you here. You've got your shoulder, which is C four, C five is the outer aspect of the upper arm. By the time you get down into the hand, those two fingers, there are C six, middle, three fingers, C seven, lateral, three fingers and the lateral border there is C um eight and then T one is on the inside of the arm. T two up into the axilla there. By the time you come down the front you've got across your chest nipples are about T four. The um umbilicus is T 10. And then as we come down into the um lower limbs, what we end up with is the groin area being supplied by L1 L2 is kind of your hands in your pocket, sort of area L3 across the front of the knee, but not really much further than that. And then if you think about the medial aspect of your leg. That's your L4. The lateral aspect of your leg is L5 and that runs down into the top of the big toe and then the lateral border of your foot and underneath the sole and up the back is S one. And if you can remember some of those, you'll be doing well most what we do in terms of clinical practice, the thoracic ones are relevant in terms of spinal cord injury, the upper limb ones and the lower limb ones are relevant in terms of degenerative problems, like um disc prolapses in the cervical spine or the lumbar spine. So it's just uh again, representation of the neck, but that's probably a redundant slide in what we've went through. And this is just a reminder of how you test the motor function as well. So, an Asia chart is a great thing to go back to. They're lying around on the ward they used in spinal cord injury. It's a great um way of um confirming your examination findings because sometimes you get different things written in different books that you're not sure which test to use, which to describe. Um if you go with the AZA charts, then you're probably in, in a good place in terms of uh doing that. But obviously, there is um neural variation and there is an overlap. So not everyone's dermatomes are exactly the same, not everyone's myotomes are exactly the same but um thinking about testing power, what we tend to uh consider not exclusively treated and not exclusively covered by this nerve route because there is some overlap but predominantly. So if you wanna test L5, you test your elbow flexor. OK? If you wanna test out C six, then it's wrist extension, elbow extension is your C seven finger flexors is C eight and then your abduction is gonna be your T one. Ok. And then just thinking about the lower limb when we test it, what we tend to do is think of L2 being hip flexors, L3 being knee extension, primarily L4 is your tib. So your ankle dorsiflexion, but then L5 is exclusively supplies um EHL which is the extensor hallucis longus, which is great toe extension. That's a pretty good 1 L5 also supplies your glute media. So if you're doing a Trendelenburg test, then, um, if you've got L5 weakness, you'd expect them to have a positive trend. Ellenburg as well on that side. Um And then thinking about um S one, then we look at plantar flexion. Ok. And you can test that with the reflex as well. So that's an S one reflex arc looking at plantar flexion. So, um gastroc and soleus uh contraction. So I've come to the end of the slides, I've come to the end of our time, but I'm happy to stay for a couple more minutes. If anyone has any particular questions, I don't know, Ahmed if you want to come back on. Uh Thank you, Mr Bateman for this great presentation. Uh uh uh Any questions, please? Well, I hope that was a useful refresher for all of you. And uh I hope that it was um helpful and encouraging rather than discouraging in terms of uh the MRC S exam. Now, it is tend to be focused on clinical kind of questions and problems. And um as long as you stick to the key texts and as I say, practice covering up the the labels, if you can. So put them on your computer, cover up the labels, try labeling, try talking through things without the labels and then go back to them is a good way of practicing and revising. Um But at the end of the day, anatomy is one of those things that stays consistent. So once you've learnt it, you've learned it and um hopefully, uh that'll be all you need. So you can just build on that knowledge going forward. Ok. Apologies. If I've misspoken anywhere there, don't hold it all to uh um uh to too high AAA regard. Um And if, if I've said anything that sounds wrong, check it out in the books and if it is wrong, I apologize. But hopefully most of what I've said was uh was helpful and straightforward. Thank you. Thank you, Mister Pitman. We appreciate it. It was uh very, very useful. Um Thank you so much. You're welcome. Thank you very much, Mister Bateman for speaking today. You're welcome. Take care everyone. Bye-bye. Take care. Bye bye bye.