Computer generated transcript

Warning!
The following transcript was generated automatically from the content and has not been checked or corrected manually.

Into seven different sections. I pretty much cover every single learning outcomes in this presentations here. So you see how um and first section is talk about the anatomy. I think that's the bit that, you know, um I will tell you which section will at least have one question. So, you know, I think there's about 15 to 16 question on SBA as an SBA on it. And then the later sections are talking about the disease state like uh the clinical reasoning bit six and seven, those are very heavy on the S ap So uh I'm gonna tell you also as well which ones are relevant to help you guide your study. So the first bit on the uh anatomy bit of it. So I broke down the companies of the orbits into different slides. So, and also give you acronym as well. And a lot of these slides, it took so long because I came up with a lot of omics uh to help you um study for them. Um For the roof of the orbit, there are two bones that are made to it. That was, are the circle. 11 is the lesser ring. Of sphenoid, you can't quite see it unless you have the arrow and then you got the frontal bone. So the monomma is front, less the lateral wall on the side, you got gray Z. So you got greater ring of sphenoid. So the green part here and then you also have the Zygomatic bone, which is the purple part here. The medial wall is the one that get tested the most in uh S VA. Um There are two reasons for it. One is that um it has a lot of bones and a lot of the bones are quite obscure, are not things you will easily remember or think of. Uh So it's easy to trap students. And then the second thing is media wall has a very unique property. So to start off Maxillary Bone, you see as a Newcastle medical student, you have an advantage of remembering what's in the media wall because the acronym is ML ESM Les. And the acronym also goes very well with the order in which the bones are arranged from anterior all the way into the posterior bit. So M stands for Maxillary Bone. That's the one that they never test you on because it's obvious. Um then, then comes lacrimal bone which is a small bone that you see there. Um And then the third one is Ethmoid bone. The green one, the reason why medial wall significant is because the Ethmoid bone is very, very um thin uh and it's uh it got a la even a Latin term for it. Um Piperis uh to kind of uh let you know is how thin it was. Um That's actually got tested quite often in the, in the, when you're meeting up with consultant during your electives. Um And then you have your um last one is the sphenoid bone. That's the body part of the sphenoid bone. So M les the f the fourth one is the floor. Now, the floor is also very significant, not so much because the bones are obscure. There is one that obscure, I will tell you which one. But the important applications of it is because whenever you hit the eye socket, let's say if you got punched right in the eyes, a lot of times you would think that the part that breaks is the paper thin part the ethmoid bone. But that is not the case. What happened is when you have got hit and punched in the face, you actually broke your f floor of the orbit far more often than anything else. And it shows on X ray, it's a very easy test to see. So you got three bones. There. One is maxillary bone again, you got the Zygomatic bone which is obvious. The third one that always goes up in the exam is a palatine bone. See because it's so small. Nobody even remember that's there. So a person got punched in the eyes after an argument in the P which bones likely to be fractured. Give it a go. OK. Got some answers. So C is the answer because C is the only bone out of the bunch that is part of the floor of the orbit. Now, interestingly enough, um The frontal bone, frontal bone is actually quite strong. It, it's the roof of the orbit so it usually doesn't get damaged. Um And you can see it on the X on the one of the CT scan here. Look at that. E so putting them all together, this is a summary slide of what I've just talked about. Again, a hint, hint is something to help you study. Um Sometimes they may ask you about optic canal um or superior orbital fissure, inferior orbital fissures, what forms it and what of the borders are? So these are might be something that, you know, you might want to take a look um out of this whole slide. At least there's gonna be one question uh from the exams. And often the questions might be um just a simple diagram question. So, do you know these uh little color bits? Well, the f the second one is uh this is gonna be also one, at least one questions in it in every single case. And that one question is usually center around this diagram. Um I like this diagram because it's so simple and clear. Uh what you know in the know is the Annulus ring of zine. Um the tendinous ring, why tendinous ring is so significant because all four rectus muscles wrapped around this ring to form this ring. And a lot of important structures are inside. So, the optic canal is actually within the ring itself and the optic canal has only two things, optic nerve and ophthalmic artery. So, um good thing to know, but usually it doesn't pop up in exam, what's pop up in the exams? A lot are the other bits within the tendinous R that is outside of the um optic canal. And those are the four things. There's a little nice little acronym, there is called several orbital nerves in one annulus. What that means is several orbital. So you got the S and the o because you got the superior branch of ocular motor nerve and then the second nerve is the nasociliary nerve. So that's the second bit just right beneath. And then the third one is the inferior branch of oculomotor nerve. The I and N the in and one abduction is the A uh uh annulus part. So you got four nerves in that one little area and then outside of the tendinous range in the superior orbital fissure, that's also very commonly examinable. What you have is LFT S. So it's kind of like the, the, the, the lab test you do for liver function test. Um So you got lacrimal nerve, you got frontal nerve, you got truck near nerve uh and you got the superior branch of oculomotor nerve. Sorry, sorry, not the superior ocular motor nerve. It's the superior branch of uh ophthalmic vein. Sorry about the typo. There. Uh There is a typo, it's ophthalmic vein, not ocular motor nerve. Um Sorry about that. Um I will have to change it when I type in, put those slides up. Um And then the inferior orbital fissure is a less lower yield. Usually doesn't get tested as often. So I won't spend your time too much on it. So the conjunctiva um just wanted to let you know the conjunctiva is the cov outer covering of the eye. Uh The on juncta does not cover the cornea though the cornea is a very clear bit on its own that is like forming the front wall of the eye. Uh So that's the h there. So that is completely crystal clear, it's bare naked. Um But G is the bulbar conjunctiva, the F is the forex and then the E is the palpebral conjunctiva. That's the eyelid uh conjunct uh part of the conjunctiva. What I want you to know very important is the tarsal plate, why the tarsal plate is so important? Because later on, as you see um in the before, if you, if you have infection in your eyelid or the eye area and it is still outside or superficial to the tarsal plate, then you get what we call prestep cellulitis. Those are not serious it does not affect patients. It does not cause pain when you move your eye and it's fine. But if it breaches the tarsal plate, which is a tough fiber cover layer, um then if you got what you call orbital cellulitis, now that is serious and that will affect your vision. So it will cause vision loss, it will cause red eye, it will cause pain on eye movement and will cause you to have fever um and even possibly shock uh septic shock. So that usually happens just for the kids in the pediatric populations. So, torso plate is out of this diagram is a key landmark. You got eyelid muscles, you got the vata palio L PS. It's for the, if the muscle is not working, you got full ptosis, it's controlled by a parasympathetic nerve, oculomotor nerve. And then you got molar muscle, which is the s see that that's the superior orbital. So that's a neva palp superior oris. That's the big muscles that lift up the whole eyelid. That's the parasympathetic part. The molar muscle is the smaller part is only cause partial ptosis. And that's the symp innervated by the sympathetic nerve. So those ones open up the eyes, elevated the eyelets, open up the eyes. This one closes the eye and that's the orbicularis oculi, it's innervated by the facial nerve. What's important to know is sometimes called corneal reflex where you got the loop, the afferent part, the message feeding part is the part where somebody tells you your, somebody's touching your cornea. That's the uh ophthalmic nerve, uh cranial nerve 5.1. And then when you closes the muscles, that's the EHR part, uh the effector part, that's the facial nerve. The, the CCN seven lacrimation is one of the learning outcome. What I want you to know is the lacrimal glands is actually on the later side of your body. So it's on the outside of your um so on the on the side of the, on the eyes, it's not actually close to the nose, it's actually on the other side. When it pumps out all these tears, it goes down the duct. So it kind of goes through all the holes that I showed you. But the thing I think it's very key for exam purpose is that it drains into the nose eventually. So inferior meatus is where it drains the final destination for your tears. Now, thing to know is that tears is controlled by the parasympathetic system and that parasympathetic nerve comes from the pterygopalatine ganglion and is related to the cranial nerve seven. Now this is the bit about refraction, the bending of the light. The key thing is the bending of the light. Most of the bending actually is not done by the lens. The lens is not a key refractor. The key refractor. On the other hand is actually the cornea. So the tough outer bit, the clear bit that allows you to see. That's the stuff that are um the bit that is uh doing most of the bending of the light to allow you to see. But why do we still have the lens? Because the lens is the only part in the whole system that is flexible. So it allows you to adapt, changes, it can change shape when it's thin, it has less reflective power. So you see the distant objects only. Now, if you have a thicker lens, you got more refractive power, it's more powerful and you can see the near object easily. Now everybody hate glasses um including myself, but you wear out of necessity. But at the end of the day, everyone has to wear glasses. And if you notice anything, usually it's after the age of 40 why does that happen? It's because after age 40 what we develop called presbyopia and that means your lens has lost flexibility, it cannot adapt to what you want to see, it cannot change shape anymore. And that's why you need the reading glasses that your parents wear. Now, the bit about the lenses is that it's controlled by the ciliary muscle, the ciliary muscles, it's a interesting bit because when it's innervated by the parent sympathetic system by the ocular motor nerve. And what happened is if you want to see um close object, close up, you need more refractive power. So your lens need to be thicker. So what happened is your sill muscle actually contract. And when it contracts the things that holding up the lens zone to the fibers actually become loose, it relaxes. Um and that gives you a ability to see closer object. Now, when you don't need to do that anymore, then your ciliary muscles relax. But oddly enough, when your ciliary muscles relax, the fibers holding it up, the zonular fibers become typed. Now, the big thing is the main thing I want you to get out of is when you want to see close up, your ciliary muscles need to contract and your lens need to become thicker. And that explain why when you're looking at a book or at a computer screen for too long because you're looking at a very close up objects, your eyes become tired, you got what we call eye strength and that's got you what these guys you blame for. And then the one of the key learning outcome is to talk about accommodation reflex, which is a triad of things when your eyes are trying to adapt to see near objects. And that is guaranteed to be one of the big S ap um uh questions or SBA uh uh question as well. I think I remember I wrote these three things down for my S ap because they literally asked you to remember these free things. Word for word. So I'm gonna print it out here for you, pupillary constrictions, you need to constrict your pupils. So that you can see the light, you can focus the light easier. Otherwise, if your people are open to wide, it's going to scatter things. Second things is you get to have lens accommodation, which is a fancy word of you need to fatten up the lens. Ok. So you need to gain more refractive power from fattening up the lens. The third one is called convergence. The convergence means your eyes need to move inward together. You need to a DD uh to move the eyes closer together, to see the near object. OK. And conveniently enough, all three actions are done by one nerve is the c and free, the ocular motor nerve. OK. Um I on the chat in uh when I started doing the recruitment for this session, a lot of people ask me about blood supply, they really worry about it. And the anatomy sessions have loads and loads of blood vessels they talk about, but most of the blood vessels actually are not that important for you to remember. The key flu blood vessels you need to know for the retina is that it's the retina and the retina can only see in the central part, the the clearest and that's the macular and the blood vessels obviously supply, the macular will be the most important because that's a prime real estate in your eye and which are the two blood vessels that supply the area. I want you to kind of give it a try just type something on the chat. Yes, Bianco, there will be feedback form and there will be slides date available. Sorry, it might be a little fast because I got loads of content to go through. Ok. So I guess most people get a That's correct. So central retinal artery and the short posterior ciliary arteries, those are the two main blood vessels that you really need to know for the eyes and they are very key. Um And then also you've got the blood retinal barrier, which is similar to the blood brain barrier. But this one, you got two layers, you got the res part which is the retinal pigmented epithelium. I'm gonna show you in the next diagram where that is and then the inner B RB, which is the endothelium of the capillaries that's feeding off these arteries. So this is the 10 layers of retina. Um There's a nice little um a memo, little, little something to memory a to help you. It's called the new generation. It, it is only ophthalmologists examining patients retina and that stands for the 10 things that are listed there. And definitely there is one multiple choice questions that asks for you to identify things. What I want you to know is not to get scared by it because there's only a couple of things that are really worthy of asking. One is the bottom layer, that's the retinal pigmented epithelium. That's the outermost part of the eye. So imagine this is the inside the eye. That's all the jelly, the white clear jelly, the vitreous. This is the part that's closer to the sclera, the the heart outer covering of the eyes. So this is the part that's what I just said before. It's the blood retinal arch uh barrier that has a lot of tight junctions to keep this area safe. So that will be uh questioned. Second one is the photoreceptors which for obvious reason, that's where all the visions happens, right? Mm OK. And then the rest of it, you know, maybe they might ask you the nerve fiber layer, um they may ask you the ganglion cell layers, why are these two important? Because that forms the op all these together will eventually form the optic nerve. So these are the they asked about structural correlations. So I'm just gonna show you something about the bleeding. I'm not sure if they show you that. Um So there's a couple different types of rebleeding that's pre retinal. So before the retina, if that happens, you can see that it's both shape. It has a fluid level, it's a flat fluid level, it happens between the vitreous and the retina. And so because it's in front of the retina, it covers everything beneath that. So you can't see through it and it's both shape. There's also intraretinal, intraretinal, it's basically happens on the superficial layers of retina. So where that is is um if I go back, that's where these guys are, the blood, they bleed. As you can see, it's very loosely packed area. So they got a lot of space to expand. So it kind of turn because it's got so much space to expand, it just fans out like a flame. So that's what they call flame hemorrhage. And that happens with central retinal vein occlusion. So the retinal vein occlusion that that happens, it happens pretty much like this intraretinal um but deeper layer of hemorrhage. Now, these guys, what we talk about here with the deeper one is how deep are they? Let's see. Oh sorry, they are way around here. So you can see it's got packed with a lot more cells and stuff. And because of that, the space is limited and these bleeding tends to be more well demarcated. They more like a dot And these are called dot and blot hemorrhage. Now these guys happens in diabetic retinopathy. So, diabetes, very important signs. The other f the last the f fourth one, the last one is subretinal uh bleeding. So that's beneath the retina. So beneath the R pe the retinal pigmented epithelium. So what that is is actually here, that's the subretinal bleeding now because it's behind everything else. So you can see what's in front of it. So you can still see some blood vessels in front of which is kinda odd and it looks like it's stain the other part they want you to ask is ischemia. So loss of blood supply. So you got this cherry red finding, which is very much like something that you need to imprint in your mind because that's definitely one of the exam questions that's central retinal arterial occlusion, cr AO. And it has a very distinctive picture. It's called cherry red macular. And that goes back to the dual blood supply of the retina again because it's so pale because the central retinal artery is occluded as in the name says, but the outer layer still supply the macular because the macular is so precious. That's where all a high resolution vision happens. The body has to protect with two different blood supply. So if the central retinal arteries is occluded, you get the short posterior ci arteries spc that's still working. And that's why you get that cherry rip color blindness. I'm not gonna bore you too much with it. The one thing I do want you to know is red and green is the most common type of problem that affects people. So they cannot tell from red and green. And um one thing to help you memorize it is because uh in football, uh it's, you know, used to be seen a lot by men only. So the, you know, and men are very affected by color blinders. So they tried when they designed the jerseys for football, footballers, they try to always avoid having a green jersey wearing team. Uh playing against a red jersey playing team so that the people with colorblindness can still see which players belong to which team. At least that's how I was told to help me memorize this. So 5% of men are actually colorblind. That's because the gene defect is actually on X chromosome. Now, blue, on the other hand, is very rare and is not in any X chromosome. It's on just a regular chromosome seven phototransduction. Um The the teaching unit goes through very much de a lot of details to teach you this. Uh they did a very good job, but it's very complicated as an undergraduate student to understand. Now, what I do want you to impress upon you is that the photoreceptors is the one that's always firing something. So they mostly are continuously depolarizing in the dark. So they're always the one that's pumping up like this firing. And when they depolarize, then the neurons is activated, they release neurotransmitters and that neurotransmitter is called glutamate. So without light, that's what they do by default. Now, um with that kind of in mind, you will realize that that's a lot of metabolic activity that's going on. You need a lot of energy to keep firing neurotransmission, right. So that is why retina is actually the most metabolic active part of the body. So they actually did a study to measure amount of oxygen being consumed um from the arteries to the vein. And they found the biggest difference is actually in the retina, not the heart, not the kidneys, but the retina. So um in Newcastle, it takes on the significance because we are such a center of excellence for mitochondrial studies. So you need mitochondria to generate ener energy. And if you have mitochondrial genetic disorders, a lot of times these kind of energy got affected and the retina will be affected first. So a lot of mitochondrial defect will result in blindness. Now, once you have light, what happened is it has a cascade of a fan that happens. What matters at the end is what you call hyperpolarization. So your body just stuck here when the light hits the photoreceptor, the row stops and and, and why? That is the case? That's because the CGMP is cleaved and the sodium channels are closed off. So the sodium channels can no longer rush into the photoreceptors to depolarize it. And when you can't get sodium, then all you have left is potassium. Keep leaving because the potassium is always leaving. Um you get hyperpolarization, you got negative negative potentials in the, in the neuron itself. So you cannot fire neurotransmitters and that stopped the rot cells from secreting glutamate to bipolar cells to do whatever that bipolar cells does. Um They talk about on and off. Uh II just don't think that you really need to know that for S ap for sure and probably not even for S PA but you do need to know the depolarizations, the hyperpolarization part of it. OK. There, there's a learning outcome talking about the driving standard. Uh I'm not gonna board you with detail. The only thing I want you to know is the part that is highlighted in red. The acuity is 612. Um And um you need to read a number plate at 20 m from 20 m away. And then these are the lists of occupations that cannot, you know, that's uh you know, that's have really stringent um uh very strange and uh visual requirement. OK. So that brought us to section two. Anybody need a break or happy with what they have crack on Lauren, any feedback from you guys. OK. All right. So Frere say good, good, good, good one. So um in terms of extraocular muscles, that's definitely at least two or 32 or three questions in your ba it's very high yield and an S ap there's a lot of clinical reasoning, at least one big case on it. Well, I want you to know this. A lot of people bring in tables for you to memorize yada yada ya. But the next two slides of the memory aid that I use because I always get lost with extraocular muscles. Those tables does no good to me. These memory a helps you to remember the basic principles to allow you to work your way out when you're lost memorizing all these muscles and movements and stuff the first one is highlighted in red. It's kind of like a chemical formula. You probably see that before L six. So four R three, because only lateral rectus is done by cranial nerve six and superior oblique is cranial nerve four. Everything else is cranial nerve three, oculomotor nerve. The next two, the next three is to help you memorize all those very terrible things about abduction and auction or inor and extortion. Um So what I would say is any both oblique muscles means the opposite. So when they say superior oblique, that actually means the superior oblique is to bring things down, not up, the inferior oblique. On the other hand is to bring things up rather than down. So all means oppo opposite the thinners and international exchange is a silly thing for me to memorize. What happened is every single superior muscles in that group of six. If they say they are superior, whether they're oblique or rectus, they always in to. So they move their eyes to the nose, they spin it toward the nose. Now, the inferior extraocular muscles is exchange is, is extort, sorry. And whether they're oblique or rectus, they always spin the eyes away from the nose. And you will see why later on in this presentation oblique muscles, they're always of a B duct. So what that means is they always move away from the nose away from the center. So one way I memorize it is called overactive bladder, oa b, oblique, active uh sorry, oblique. It's for uh A B duction, the rectus muscles. On the other hand, whether they are superior or inferior, um they always ad duct. Um So what happened? Well, except for the, except for medial and uh and uh lateral rectus, those are exceptions. But um but in general, the rectus muscles, ad ducts, so bring toward the center. So they are rent. So this is a horizontal direction is uh easy one to go through. It's very straightforward and somebody gave up uh acronym called you when you a duct, some something you're taking them away. So ad duct is ad duct is away from you away from the nose, ad duct on the other end, you're adding things together, you're bringing them towards you to together toward the nose. Now, the horizontal directions straightforward because there are only two muscles really involved. And that's the lateral rectus and the medial rectus. And that brings us to the first question. Sorry. Um That's if you guys later on, if I go through this too much and if it's something that's already covered in the anatomy sessions, please let me know, I will skip a bunch of the slides if you already got it. But uh the later part of the, after this, the presentation seems to be something that confuses me for quite a bit. So I will spend a little bit more time talking for them. OK. This is an easy one. Seems like there's a good stream of answers. So you guys are right. It is uh d because if you can see this is on the left when the guy is trying to look toward the left, um the eye is just not moving at all. It's still looking straight now, six nerve palsies when you cannot look to the affected side. So the nerve that is affected is on the left side as well. And you know, six nerve is actually the one that always gets squeezed. And when your nerve is getting squeezed, it can defectively become paralysis or palsy. Um One of the reason is look at this carver sinus, I think they still have that old Tom cat acronyms in the anatomy sessions. See that cranial nerve is, you know, it's so close to the carotid artery. So if there's any trauma or anything like that, it squeezes it. In fact, um other than papilledema, the other sign of intracranial pressure increase is six nerve palsy. So it's not very helpful to help you localize where the injury is. But it's a sign to tell you your brain is a little bit too much pressure building up the vertical direction is the one that I spend a little bit more time. If the anatomy sessions guys did a really good job this year, then let me know. Otherwise, uh uh I would just keep continuing. So what happened is with the vertical direction everything's wrong because of the angle. Um So I will show you why. So your eyes, when they look straight, it should go through axis of eyeballs here. It's, uh, it should be there, you know, but the superior rectus muscle, which is supposed to pull it up, it's on a different axis. It's slanted, see that it's slanted. It's not exactly in parallel. Now, the other muscles that are supposed to depress it, that's the trochlear, the, the trochlear muscle, sorry, the, the, the the secure oblique muscles, see this guy is also slanted, he's on a different axis to what your eyes are looking at. So you've got these really weird situations where you got two muscles doing the same thing, but neither of them in parallel to the actual way the eyeball is looking. And so that's why you got these really weird, you know, to, you know, um you know, things going on with uh the diagram. So to help you understand this diagram that's always shown in any textbook because you see if it's straightforward, you will just have the oblique mus, the inferior oblique muscle and the sefer rectus in here, right in the middle. And then the other one will be tear down the middle, but there's nothing in the middle. Um It, it's split. What happened is when your eyes are A B ducting. So looking to the nose, see the the, the eyeball, the axis of the eyeball actually become parallel to the trochlea, the, the, the superior, the, in the, the oblique muscles, either the inferior or superior, they, they align that way. And when you align in parallel, you get maximum action. So that's when you, if you try, if your eyes are ad ducting, it's go going toward your nose, your eyes can, you know your oblique muscle is actually working well. It's actually, um in the case of inferior oblique muscles, it's raising it up. And in the case of the severe oblique muscle, it is depressing it down. Now, in that situation, the superior rectus and the inferior rectus muscle is actually perpendicular to what the eyeball is looking at. So it's at right angle. Now, in that case, you're actually not exerting the force very usefully like if you try to do something when you are perpendicular to it, well, it, it just doesn't act very well. So it that they at the positions in the ad duction positions, the rectus muscles are not moving. So diagram doesn't show that it's not working very well. Now, when your eyes are A B ducting is moving outward, not when A B duct, the axis actually in parallel to the, the eyeball axis is actually in parallel to the rectus muscles. So that is the location when the eyes are moving outward. You can actually the superior rectus muscle can do its job, it can raise the eyeball up and the inferior rectus muscle can pull the muscles that eyeball down, you know, it depress the eyeball. So you've got that situations where you at that in that position as well, the oblique muscles are at right angle perpendicular to it. So it's not really acting very well, it's not the force is not being applied very well efficiently to bring the eyeballs up or down. So that's why you got this diagram here. And then, you know, as a summary, everything just kind of wash out, you know, the, the your brain and all is that the oblique muscles, both of them inferior and superior. When the eyeball is ad ducting is moving toward the nose, it works. But when it's moving away from the eye, the nose a be ducting, then the rec the superior in the inferior rectus muscles are the ones calling the shots. The other thing about oblique muscles is is they change, they, they spin the eyeballs, they're the one that rotates the eyeball. Now, the spinning needs to have a reference frame. Otherwise you'd be confused looking at some of the diagrams and the internet. What I want you to know is inor means when they talk about retort inor, they're referring to the upper part of the eyeball that is going to the nose. Now, extortion, on the other hand, it's talking, it's still talking about the upper part of the eyeball, but the upper part of the eyeball, it's spinning away from the nose. So in summary, that's what they do. So the media rectus muscle and the lateral rectus muscles are moving horizontally. So that's the primary functions. They don't have anything else. Now, the inferior rectus muscles and the superior rectus muscles, the vertical ones are a little bit more complicated. But what it really comes down to is that you have the moving up and down, that's the primary action. Now, they could do some movement like spinning, extortion and ints, OK. Um But the oblique muscles, the main job is to spin. So the primary is extortion and inor they, the going up and down is only secondary and the tertiary is, you know, the things that they do really as after thought. Well, that's the a ab duction and a ad ductions are really, they, they're, they're after after thoughts. And that's because it's already done by the other two horizontal muscles mainly. All right. So this is a question to test your understanding, which combination of right sided muscles are required for this person to look down that way, any answers from the audience that be being in the chat, more people. OK. We got some answers. So a is the answer. So you got the media rectus muscles that's moving toward the nose and then the secure oblique, which is uh on that directions, it super depressed and the, you know, and the oblique muscles is works well when you're ad ducting. Now, the all concepts you take for granted that's the slightest of both definitions. I'm not gonna go over every one of them, but something that, you know, might be helpful because it actually does show on my SBA. When I did my paper is that synergist is in the same eye, you got two muscles that are working in the same directions, antagonist is means same eye, but your two muscles that are working in the opposite direction. Now, the yolk muscles on the other hand is one muscle from each eye and they bring the eye toward the same place. So in this example, you see the left inferior oblique muscles is going up that way. Well, the other eye, the right eye has this superior rectus muscle that's going in that way too. So it moves the eye toward the same position for gaze and that's yolk muscle and yolk muscles as you can tell is something they will test you on quite a bit. So it's something to kind of mentally know will be. Well, the last two is not very well tested the Sherington law just to tell you that if the mu muscle moving, let's say toward the nose and the the muscles toward the nose will be activated. But at the same time, the nose opposing the actions. So the ones that are going against the nose will be inhibited to the same degree so that it does not impede the movement of the eye. Herring's law just saying that yolk muscles both muscles are equal in their movement in their, you know, nerve signals. Otherwise you got one eye that moving all the way up here and then the other eye will be maybe down here. One is strong, the other one is weak. Then you're really gonna end up with diplopia, you're gonna have end up with double visions. You don't want that. Now, this is the one about which nerve is damaged. This is the, the a harder one to spot. Give it a try. Mhm Freddy's good. Any other tried anybody else from the audience brave enough to volunteer. Yeah, I guess uh I guess we could crack on. It's just very difficult. So the answer is actually e right? For nerve palsy. Now, this one, if you don't get it, don't feel bad. And I don't think that the the examiner is actually gonna put this one on the exam because it's so difficult. Uh It's subtle. Now, if I take this guy's diagram away and just tells you that he has a tilt toward the left, then it'll be a lot easier because, you know, out of the three different nerve palsy for fourth or sixth, the only one that cause you to tilt your head is fourth palsy. Now, if you can see on this guy's eye, the rise is fourth nerve palsy because you see this fourth nerve innervate, there's super oblique muscles that causes the eye to go down, right? So if the nerve is palsy. The secure oblique muscle won't work and when it won't work, the eyes will appear elevated in the primary position. So winning just go looking straight ahead now and then when it's trying to get, look toward the opposite side, it can't, it can't, you know, control the elevations well enough. So it goes up see that because the, the, the superior muscle is supposed to pull the i towards this way. But when it, sorry, when it's paralyzed, uh uh can anybody see my arrow there when it's paralyzed, the eyes will move the opposite way. And it's most obvious when you're looking away from the, the side and the defect, that's fourth nerve palsy for you on the diagram, fourth nerve palsy, um you know, there's a really nice easy memory aid to help you to kind of realize what happened. So it's called wich. So it's worse on the ipsilateral side. So if the person tilt the head to the side where the, the problem was, you know, the, the, the, the, the, the, the double vision will be first, they will say, you know, I can't see as well. It actually sucks. But then if it tilts to the opposite side. So in this case, um if the person's tilt toward, you know, the opposite side to the left, to the left of the black arrow, the eyes can inor better. So uh on the, on the uh on the other to work can sorry can extort better, can extort better. And then the double image won't be as bad. See if it tilts to the left, the right side can extort and it won't be as bad and they can see better. So and then also the eyes will look like the hypertrophia. So one eye will look higher. So this right eye, when you look straight ahead, if you're not tilting, your head will be like, that guy will actually look higher than the other than the unaffected eye. So that's why they need to tilt their head all the time because they always have double visions unless they tilt their head. So they will also say, oh my nerve hurt for some reasons. Uh This is the other one, that one actually did show up on my exam. This is the easier one to recognize. Give it a try. All right. Um I'm just gonna tell you the answer. So it is a y well, if you look at the primary position, so when it's looking straight ahead in the center, it gives you a clue. Already. Look at that, look at the eyelid, so low down, it just toss the whole time, you know. And then the second thing is if you actually look at the eyes, it's down, it's down and out. So third nerve palsy, if you need to know anything about it from this presentation, it is when it first nerve palsy, it's always down and out while you see the first nerve controls uh uh loads of things around the eye. So I'm gonna break it down into components to help you memorize that in your exams and also understand the concepts better. One is to further innervate the le peloris. Uh L psi never can pronounce that properly. So it the, the L PS elevate the eyelid. So if you have a defect, it causes ptosis like the last guy just showing the picture. And then also it control two parasympathetic functions. One parasympathetic function is the sphincter pupil. So it causes the these, these parasympathetic functions cause the eye constriction, the pupil, right. So a defect will cause the pupil to dilate some mydriasis. And then also it causes problem with the fattening of the lens. So the accommodations of the lens. So it may cause people to have blurry visions. So they don't see very well, especially the near objects. Now, the other ocular muscles, the four ocular muscles, the effect. Ok. Well, out of those form ocular muscle, two of them are making the eyes to go up. So the superior rectus muscle and the inferior oblique muscles, they all make eyes follow up. So any defect in that area in the cranial nerve free in ocular motor nerve free will cause the eye to go down. OK. And then also the cr uh ocular motor nerve control the medial rectus muscle that ad duct to bring the eyeballs back toward the nose. So any defect will causes the eye to go out. That's why you got down and out now. Well, um, the last one I live out is inferior rectus. But you know, like I said, the effect is not as prominent because the ocular muscle mus, most ocular motor muscles control two elevations and versus just one depressor muscle. So obviously, two beat out against one. Um, other things that, you know, like the bottom bit, they didn't explain very well is the that the ocular motor nerve is arranged in such a fashion that the paras fibers are on the outside and the symp parasympathetic muscles that are on the outside the most is the one that's controlling the pupil. So if you have somebody something that's compressing the pupils, then you get pupillary dilations and in the traditional sense, which is now wrong mostly. But you know, whenever you think there's a compression, then, you know, you need a surgical way to fix it to, to remove the compression. So when you see people with vert nerve palsy that has a blown up pupil, they call it surgical for nerve palsy in some textbooks, but not all cranial nerve problem. Palsies are caused by compressions. Let's say if they're caused by vasculopathy, which is a fancy way of saying blood vessels problem, things like diabetes or high blood pressures and stuff that causes the cranial nerve free to get damaged, then because it's go from the inside out, sometimes may not go completely toward the outside. So sometimes if it doesn't affect the outer fibers of the ocular motor nerve, then the people will be spared. And because diabetics and hypertensions are usually managed medically, people call it medical foot, nerve palsy, putting it all together just a summary slide that helps you facilitate. Looking at the big picture. We got nerve, fourth nerve and sixth nerve palsy.