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Session 5: Head & Neck Anatomy

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Summary

In this on-demand teaching session, Mr. So, an experienced E and D surgeon, will guide medical professionals through the comprehensive anatomy of the head and neck. This crucial session will address a variety of topics including fascial planes, the LAL framework, muscle structures, and the details of particular glands. Mr. So will also explore the connections between E and T and other specialties. Aimed at core trainees, the session uses illustrations and personal analogies to clarify ideas, making it relevant for both medical students and practicing professionals.
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Description

This session was taught by: Mr Bindy Sahota who is a consultant ENT surgeon in East Midlands

Learning objectives

1. Understand the structural anatomy of the head and neck: by the end of this session, attendees should be able to identify and acknowledge the important structures of the head and neck region, including the function and orientation of individual muscles, vessels, bones, and glands. 2. Comprehend the functional anatomy of the head and neck: attendees should be able to outline the basic functions of structures within the head and neck, including interactions between different components and the physiological roles they play. 3. Identify anatomical landmarks in the head and neck: attendees should have a firm grasp of significant landmarks such as the sternum, the mastoid process, and the clavicles, and standard muscular structures such as the sternocleidomastoid and trapezius muscles. 4. Grasp the divisions and subdivisions of the neck: the session should provide participants with a clear understanding of anterior and posterior triangles of the neck and their corresponding components. 5. Recognize the clinical implications of head and neck anatomy: attendees should develop a keen sense of the implications and relationships between anatomy and clinical diseases, disorders, and treatments within the head and neck region.
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Computer generated transcript

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

Uh OK. Are you all good? Cool. Just waiting for us to go live. Just tell me uh we are now live. So, hi, everyone. Thank you all for joining and thank you for those who've been following our MRC series. So today we're delighted, we'll be joined by Mr. So who is a E and D surgeon, um Minie Midland. And we're gonna be teaching us the best part of anatomy, which is uh head and neck, uh which I hope you'd find really useful. Um As always if you've got any questions uh do ask her and I there'll also be a bit of time at the end. Um And I hope you enjoy so over to you. Thanks very much for having me. I'm going to run through wide classes, regions and compartments of the head and neck, primarily aimed at the MRC S. There isn't huge amounts to know and pretty much this session should cover most things, you know, this is what I give to medical students. And then there's a higher level I give for a foundation year and a higher level I give to core trainees and even a higher level I give it to RS. So this is the one which is set up for core trainees specifically. So we'll talk very briefly about triangles of the neck fascial planes, the hyoid muscles. I'll give you a quick overview of the LAL framework, but that's the end. We'll talk about the major arteries, major veins, the muscles of facial expression, the muscles of mastication, the protid gland and the S MG. I've got a couple of other powerpoints that I'll kind of flip in between and so on. So from a head and neck point of view, it's kind of all encompassing and it's like somebody looked at all the bits that the other specialities weren't really interested in with ear, nose and throat and kind of all through it in one is kind of this weird amalgamation, but it's because there's an interlinking between what ent does. So realistically ent ends up as ears, nose, throat and head and neck primarily. And there's lots of crossover in regards to obviously the nasal side of things, the neurology side of things from that point of view, the otological side of things with balance, then the major head and neck with airway larynx, swallowing and voice dysfunction. And then obviously, there's the eye point where you just separate and then we ent surgeons do two thirds of thyroid surgery and parathyroid surgery within the UK as a whole. And there's also the slide free glance. So a lot of these images are from more. And dli these are my old illustrated flash cards from medical school which are over 20 years old and this wonderful grays Atlas of Anatomy, which is really good to show you on a cross section on through the anatomy. Would you be able to press the hide button of the? This is showing your screen. Wonderful. I apologize for being a tech hobo with some things like that. Cool. So let's make it really simple and start in the most basic places. So we're gonna pretend your head and neck is split into really, really simple bits. So we're gonna pretend you've got the mandible. And so you think of that as a rim of bone which then comes up and articulates with your, basically your skull and joins part of your cranium. So if you take your mandible and you take two clavicles on either side, each of them are slightly shaped, they shape from the medial aspects laterally and raise upwards and we'll put the sternum in place. So there's your basic bony structure of the head and neck. And if you think about that, that's everything from the angle of your jaw down to your chest. Everything lower down is your thorax, thoracic cavity. So we're gonna put some bony landmarks and you can easily feel these. If you follow your jaw around to the back, go behind your ears and follow up words, you'll feel a big prominent of hard bit rock bone which is your mastoid process. Now, the mastoid process is a really important landmark from head and neck surgery point of view. We come to in a second, so we're gonna stick in a couple of muscles. So we'll put the ST cla of Mastoid in first. So, um, you might not understand this, um, analogy but, um, it was a famous advert in the eighties, which is called R Seal wood stain and, um, r Seal Woods saying the um kind of sign off for it was R Seal Woods does exactly what it says on the tin. And the sterno cleidomastoid is exactly that. It does exactly what it says on its tin. Its name gives away where it attaches from to. So it's a sterno cleo mastoid. So it's a triple attachment muscle. So it has a sternal attachment down at the bottom that you can see here which attaches to the medial part of the manubrium. Then it has a clavicular part which attaches to the er medial one third of the clavicle. Then you have a bit that attaches upwards to the mastoid process. And so the SE M splits um up those bits and connects them together by direct attachment. There is technically a little triangle of a gap in between the two heads which you can see surgically in, in the theater. Now, the reason I've put the stone called a mastoid straight in is if you look at this, this big triangular area here in the middle between both sides of the cm. That's the entire, both sides of the anterior compartment of your neck. And there's this concept of anterior and posterior compartment, which I'm gonna drill into you. And I wanna make it really quite simple. So these are the important landmarks to define your anterior triangles that I'll talk about in a second. So this is your cm on a lateral view and you can see where it attaches. And here you can see the clavicular head here, you can see the sternal head, there's a little triangle of the dry area that I've mentioned as they attach upwards, they attach up to the an mastoid process and this therefore, splits the anterior and this is the posterior that we'll talk about in a second, we'll stick our second muscle in, in a second, which is. So this is the muscle at the back and this is a long broad fan shaped muscle which starts with the superior nuchal line on the back of your calvarium. It comes down and it goes down all your vertebrae in the long bit of the spinus process and goes down to t 12. It then spans out, then sits over your scapula and it almost makes this rhomboid or diamond shape over both sides. So the trapezius, when you're looking at it from the front, this is what it looks like. And this is kind of the overall arch that you get. Now, this is where you're gonna get these definitions coming through of the anterior triangle here and your posterior triangle here. And we'll talk about that in just a second. So this is the description that I said about the super nuchal line coming down all your spinus process right in the middle, spreading out on both sides and it's almost like a diamond shape and you get the same on the other side. So this rhomboid kind of flapped muscle, which is attached to your shoulder GD across. When you look at this with relation to the actual clavicle, I said to you just a minute ago, this attaches up to about one third of your medial clavicle with the cm, your trapezius attaches on your lateral one third of your clavicle. So when you're looking at the clavicle and the muscle attachments on the top, majorly, you've one third, you've got your SCM, you've got a gap with no muscles on the superior aspect and you've got your trapezius on the lateral aspect. It's a really nice way of kind of thinking that as a sandwich to separate the posterior triangle out versus the anterior triangle. This is a picture from grays as a whole. And here you can see your S CMS, you can see like a much better image of a much broader take of that taking over one third of the clavicle there. You can see this bear area that I spoke about here and you can see here is the lateral aspect where the trapezius attaches and then that will go up around the back and it will join up down here and it will splint over across from the clavicle going over the um actual main body of the scapula itself. So everybody keeps on banging on about anterior and posterior triangles. But this is the basic crux of anterior and posterior triangles. And I'll talk about them just a, a bit more in a second. So clinically, when you look at them, the anterior triangle splits like this. The posterior triangle comes here, most of the gubbins in the neck, most of the money is in the anterior triangle, there is very little in the posterior triangle overall. So my advice for questions, especially for the kind of part one exams is when they're asking about anterior triangles almost always will the answer be anterior triangle because that's where most things are. And if you look at this kind of macroscopic image, here's your right anterior triangle. And here would be your left anterior triangle. But you can see here, you've got where the submandibular gland would live. The tail of the protid. The carotid lives here. The jugular vein lives here. The thyroid lives here centrally. The larynx is here and then the trachea is sitting here and behind that is the esophagus. There are a few nerves with the hypoglossal, the marginal mandibular and the upper part of the accessory nerve before it goes on into the posterior triangle. Now, in the posterior triangle, there isn't huge amounts. Like I said, the accessory nerve comes across down here into the upper one third of the SE M goes through the SCM down like this and makes like a zig zag and comes out of the lower one third of the SE M and traverses across um the posterior triangle. So when you actually look at the posterior triangle, what's really in there is the skin, the muscles, the fascia. And then after that, you've got the accessory nerve which descends down, you've got a few other nerves, you've got some lymph nodes and you've got the trunks of the brachial plexus sat right down at the base and they're sat between the anterior and the middle scaling muscles. Um So sorry, they're between the middle and the posterior scaling muscles, apologies. Um sat down there at the back and that is the base. And so when you're looking at this and you're splitting these two things up, I'll come to the next page to describe this a bit more. This is your anatomical break up. So your landmarks, your anterior triangle are split with your mandible at the top. So your superior surface is your mandible, your posterior surface. So the back of the anterior triangle is the anterior border of it's still quite a mastoid. Yeah, the invisible line in the midline running from the men, the middle of the mandible straight down to your sternum is your midline where both your left and right anterior triangles kiss and touch together. The floor of it is basically the spinal vertebrae and the musculature associated with that. And then everything lives within the anterior triangle. The posterior triangle. So if you remember, I said to you here in the anterior triangle, the anterior border is, is associated with this anterior border of this. When you go to the posterior border, the anterior border is the posterior aspect of this no mastoid. So on this side, the back border, yeah is the anterior border of the SCM. On this side, the anterior border is the posterior aspect of the SE M. So the way you remember it is for the anterior, the posterior is the border and vice versa. So they, they kind of mismatch when you look at them. So when you're splitting up your posterior border, um here sorry, your posterior triangle, your posterior aspect of the SE M makes your anterior border. The posterior border is boundaries via the anterior aspect of the trapezius muscle. The medial, one third of the clavicle with no muscle on top is the kind of um inferior aspect. The floor is made up by um the base of the neck over the scaling muscles and musculature and then there's the apex of the lung at the bottom. Now, like I said, here, there really isn't huge amounts apart from the accessory nerve, a few lymph nodes, a couple of other sensory nerves, the base of the lung and the trunks of the rial plexus. Because the rest of the basal plexus then goes deep to the neck to then coming out to your arm as a whole, the anterior triangle gets split up into different triangles that we'll talk about. But you can see while all the gubbins and all the important things are in the anterior, not the posterior triangle. So these are just the surface landmarks. So when you're clinically examining the patient and you're running through this and we can go through this. So if we need to, this is your land marks for your anterior triangle and they follow exactly what I've said. Your mandible, your se M and chasing it down in the midline across your posture triangle is attached to the back and it's that gap between your SCM and your TRBE. So we've already spoken about what the contents of the posterior triangle are. And here's kind of just a little sharing here. You can see you have a muscle which crosses which crosses from the posterior triangle and the anterior triangle and we'll talk about that later. Um And because it's the least important muscle when um from a swelling point of view, but it's very good anatomically from a surgery point of view. Um And that's the M hyo and here you can see the trunks of the recal plexus, the branch of the external jugular vein runs in here here. You can see the accessory nerve, here's a great uric nerve and there's a few other minor sensory nerves there as a whole. This is the actual kind of cheat sheet and this comes out of um instant anatomy um which is by Whittaker et al. And the website is really good to give you kind of these um good aid memoirs and especially for remembering important areas for the MRC S such as the axilla. Um thinking about um the brachial um sorry, the antecubital fossa, think about the femoral triangle. He's got really nice images that he's made of where things lie and where things are in relation. And then we've already spoken about a lot of these kind of landmarks in the posterior triangle. Like I say, most important things do not live in the posterior triangle. Most of it lives in the anterior triangle, the anterior triangle split up into four other subang. Let me just check if I've got an image of them. Um And these kind of subdivide them into, don't worry too much about the sub triangles. Um But they're fairly easy. You've got the hired bone, which is the equivalent of the human wish bone free floating in the neck. And this has different muscle attachments which attach in different areas and then it forms a few little subang that I'm going to talk about in a second. Now, the anti triangle, like I said, contains everything. Um this uh the anterior um neck basically with your S cm partially removed. So you can see things underneath all the larynx overall. Now, I said to you that to make it a little bit more complicated, the anterior triangle split into these other um kind of central compartment um triangles. So you've got the hyoid bone, the high bone has the digastric, which goes from the men down to the high bone back ups that mastoid process that we spoke about. And that triangle there is your submandibular triangle. And so that's really important in regards to submandibular surgery. Now, the omohyoid muscle that I mentioned a minute ago, that's the only muscle that crosses across the neck across the brain of everything else. And this has a double head just like the digastric. This comes from your scapula comes up to the SCM. And under that takes a sharp turn upwards and you can see it here where it turns upwards this here where the MRI it is splits upwards, this area between the posterior belly of the digastric and the SCM. Um There is your carotid triangle where your, basically your jug and your I JV are easy to get to in regards to the omohyoid piercing the posterior triangle across this splits this into the superior bit of the posterior triangle and the inferior bit of the, the triangle as a whole. When you come around to the front, you can have what's the central compartment or the muscular triangle, which basically is everything else, which goes to the midline, which is where all the gubbins are. For instance, regards to the thyroid, the larynx itself and they associate musculature with it and other bits including the esophagus. So just very briefly from a definitions point of view, connective tissue is defined as the tissue that supports binds and separates more specialized tissues, organs. It acts as kind of packing tissue or binding tissue. And it's kind of the bits between the important bits to kind of help and support what you're up to. So when you look at connective tissue, you can split it into different ways and you define this as either loose or dense and then with the dense ones, this can be either dense, regular or dense, irregular. So the way to kind of think about it is loose tissue is stuff that doesn't follow normal boundaries. So this is kind of superficial fascia and all the white stuff you see when you're operating on people, the adverse tissue often can be, you know, not following any boundaries. And this varies from person to person, from body habitus point of view, when you look at the actual connective tissue itself, it's split into the dense and the regular and the irregular. All the regular things are things that have a specific function primarily. And these are split into muscles. And remember the definition of a muscle is a piece of tissue which connects over a two bits of bone, which allows for movement around that point point of a bone or between two areas of soft tissue to allow for movement to happen between those two things. This also includes tendons and aponeurosis, which is basically a continuation of muscles. Then the dense irregular is where they don't really follow a normal boundary. And this is your dermis, your subdermis, uh your sub particular dermis and your deep rash primarily. So why are we gonna talk about planes? So fascial planes. So this is the compartmental aspect of cross sectional asom of the neck. Now, if you think about what the actual neck does, when we look at the neck, you have some very physical, easy movement things and that's things like flexion extension, lateral movement and rotation in either side. So you've in effect got six movement modalities which can all happen at the same time or independently. So, as a consequence, there's a lot of physical movement. And if you compare that to your elbow, you've literally got a flection extension and you've got some super and pronation and that's it. So therefore, it gives you quite a few large degrees of motion. But when this also happens, there are important things to think about other things related to movements such as swallowing. So when you swallow the entire larynx moves upwards and the epo down to stop food and liquid to go down into your lungs which is a really important thing. So these f planes all live there basically forming a natural plane. And as a consequence of this, this is what determines the spread of where infection goes. And if you primarily think about what the, what runs in your neck, you basically have big blood vessels that go up and down. Whether they're arterial or venous, you have nerves that normally come down from the central um part of your nervous system down to the peripheral, but you do have some variations of vice versa, then you have your breathing passages, whether that's your oral cavity, your larynx, your pharynx, so to speak, or your trachea. Then from a swelling point of view, you've got your swelling passages, whether that's your pharynx, hypopharynx or your esophagus, which all live in the same place. So there's quite a few different things that you can do. So you also need to think about what can be damaged in regards to the neck. And a lot of questions are written over these types of things of thinking of either the normal planes or what you can damage and what? So, um and don't forget, kind of the special things like salivary glands and the thyroid gland itself. So let's do the Pringles, bit of the stalk. So um this is this is often called the pringle to when we talk about it. So I'm going to try and get you to figure out and understand a 3d uh approach to the actual neck. So you have some sort of organizational structure that if somebody put a CT scan or MRI scan with you, that you wouldn't be completely lost or floundered. So we're gonna take a normal, so I called vertebrae. And I've drawn one here with a circle, a triangle and a central circle primarily to demonstrate that now, if we start from the outside and work our way in what we're going to start with is the layers of the neck and I'm gonna peel them away or put them on, so to speak as we go through this. So if we start from the outside, you've got your skin and then underneath that, you've got your subcutaneous fat and the superficial fascia. So you can see these two white lines, the peripheral one to make the skin the next one for the fascia. And if you're operating on the neck, this is what will make you talk about from operative surgery point of view, what do you go through to get to somewhere? So, for thyroid surgery, this is one of the examples and we can talk about the layers that you get through to get there. So l layers of the neck, we've got the skin that obtains fat that we've already put down. Next, we're gonna put a very small muscle, which is the PTIs muscle. So your PTIs muscle acts like a band. It sits here from the Mandible. It goes down to your clavicle and it kind of swings down as like a little fan in the middle. You've got this triangular gap space, which is where there's no cover with the pleth. Now, the PSA in humans is actually fairly thin. It tends to be a little bit thicker in men than women. This is because quite a few men shave. Um, overall, it's often the grimacing muscle which allows you to do this in creatures like horses, pigs. Um, it's a lot bigger and a lot stronger primarily because of things like snout use and things like that, which we, most of us don't tend to use as human beings primarily. So this is your platysma muscle. Now, one of the things that people often get wrong is if you're coming really low down here and you're doing a, a tracheostomy, then you won't run into the platysma. Yeah. But if you're opening the neck over here, you'll open up your platysma often with the thyroid gland, you'll run into the platysma, uh, partially because you normally descend over it laterally as a whole. So here's your platysma. I've not drawn a gap, so I've drawn it as a single orange line all the way across. And so you can see this kind of fan like muscle as where it would sit in the neck. Now, what we're gonna do is gonna stick on the deep Cervial fascia. Now, the way I think about the deep Cervial fascia is, it's a very dense piece of connective tissue which is irregular primarily. And um it sits overall in the neck. It lacks like an Elizabethan collar and wraps around the entire neck primarily. So let's now um add in the survive called fascia in a second and uh we'll put that in. So first things first, we spoke at length initially about the sternocleidomastoid where it attached to the mastoid and it comes down. The reason I spent so long talking about that at the beginning is this bit. So this here represents your stern cleidomastoid in your right. This here represents it on the left. So we're going to say this is a section roughly about where I'm pointing subhyoid. So an infrahyoid but high up in the neck so that we're not low down where the thyroid gland is next. What we're going to do at this point in time is going to put the trapezius which sits right at the back here from the vertebrae and then the swing over to this area. And if we went lower down, we know the clavi cords sit here. Now, what I'm going to do is I'm going to do get my Tony hat on and I'm gonna do some free hand drawing. Now, everybody knows what Elizabethan collar, those white collars which we use in Elizabethan Times that wrap around the neck, which are often bubbly. Now, the deep cervical fascia or sometimes the investing fascia of the neck. It's the same thing. They are interchangeable terms, acts as a connective tissue that packs and wants to keep your neck contents inside your neck. So they don't spread out elsewhere. Now, if I draw it and you think of it like a collar, you wanna come round and draw it and I apologize for my absolutely rubbish drawing coming around here over the posterior aspect of the trapezius, it coming forward and going over this. Yeah, then it's a wrap around like I said to the other side. Now, if you imagine at this point in time, it does this. So that is a wrap around around your entire neck and this is the hard collar that keeps stuff inside it. The problem is by keeping some things inside it, it has got a positive benefit because it stops things coming out of the neck. However, if you've got infection in the neck, it's also a nuisance because it keeps your infective stuff inside the neck. Now, the thing is this isn't quite a single fascial band like this. It's deep and it's investing. So what's actually investing? Will it invests your neck? But the other thing is it double invests both these muscles. So it invests over the trapezius over the back of it, but it also invests over the front of it and it does that on both sides. And so here I'm gonna draw the front bit of this. Here is your cla of mastoid and again, it does the same thing around this, it double invests. And if you've ever opened the neck and you've looked at the sternocleidomastoid, you see that kind of white band around it, that's the deep cervical investing fascia. And that's what this is that you can see as it wraps around. And I always think this looks like Pringles whenever I draw it. Hence why I call it the pringle lecture. Um But that's what it looks like. And here is some free drawing from what when I did it before. Now that gives you a cross section of skin, subcutaneous fat, the other fascia around it, the deep investing fascia, a couple of muscles and the platysma all in the mix. Let's um reintroduce all these back in. Now, let's put in what I'd class as the gubbins and central workings from the neck point of view. So we're gonna look if you go through the neck and you're gonna go to do a tracheostomy and you can look at this. Unfortunately, this should have a gap here and I, I've always forget to reupdate that. So if you're doing a tracheostomy were low in the neck, you would go through the skin scop fat, you would go through the gap in the P plasma, you'd open a deep investing fascia and the next layer that you'd hit would be the pretracheal fascia. So the pretracheal fascia wraps around the trea. Yeah, but it doesn't just incorporate the trache. Yeah. So the pretracheal fascia holds these three predominant structures inside. So it holds the trache itself. It holds the esophagus as well, which is directly behind the trachea. But it also encompasses the thyroid gland which sits around it as a whole. There are a few blood vessels and a few nerves which are associated with it, but we're not going to go into those primarily. So when you look at this zone, that's what this contras. So this is your pretracheal fascia and this is what it looks like on kind of cross sectional imaging and effect. And we'll have a look at that in a minute. So here's your pretracheal fascia. Now, as I said to you before, you've got to think about what actually runs in the neck. We spoke about airways, we talk about big blood vessels, we talk about your pretracheal fascia with your um with your thyroid gland, your esophagus primarily. Now, let's put your big blood vessels in. So your big blood vessels are associated with your carotid sheath. So inside the carotid sheath, you have a big artery, a big vein and you have a very big nerve and you have some lymphatics, these also inside with the carotid sheath itself. Now, the carotid sheath is basically a fascial band which like the deep vesting fascia and more importantly, like the pretracheal fascia wraps around the important thing. So this one here wrapped around your, basically your esophagus your trachea and your thyroid. This here wraps around your um internal uh sorry, your carotid artery, your internal jugular vein and your vagus nerve primarily. Now as it wraps around, it comes down and joins around and it does the same on the other side. What's interesting though here is this fascia here, sits next to this fascia and they often fuse and they often have this really tight area here. So when you're doing surgery, and let's say you're a vascular surgeon and you're coming to do a carotid and arterectomy. And you approach something this way, a lot of um vascular surgeons do a um slightly angulated but almost vertical following the ac and they often make an incision through here. So the approach for a vascular surgeon to do a chrono arterectomy before they do, the surgery would be a vaso linear incision, incision through the skin, soft tissue, identify the stern cladosin cut through the investing, so called deep fascia associated with the sternal Clamato, identify the carotid sheath, open up the fascia, access the carotid above below, open and then basically start doing your endarterectomy. And so this is the general approach that you need to think about and that's why this is really useful. So if you do get asked questions about this, you can just think about these Pringles pictures as a whole. Now, like I said to you, there's primarily what lives in area is a big artery, a big vein a big nerve and some lymphatics, which are the deep cervical lymph nodes, which are associated with as a whole. Now, you've got the common carotid artery and that always sits on the anterior medial aspect of this. You've got your I JV, which is your anterior lateral and at the back, you've got your vagus nerve ak the wandering nerve which starts basically in your brain and then goes off to finish way down in your abdomen as a whole. And the way if you ever struggle to think about these things is if somebody was stabbing you in the neck and you were going design and defense mechanism, you definitely don't want a hole in the artery. The hole in the vein is probably not so bad, but actually damaging your vagus can give you lots of weird problems including problems with your voice breathing and just general kind of overall bad body habits issues primarily here. You can see that lateral aspect that I've spoken about. So here's your carotid as it comes up and remember your carotid bifurcates, the level of C 41 of my old bosses used to tell me all important bifurcations happen at four C four in the neck for the internal vessels, external carotid T four in the chest, for the arch of the aorta L4, the splitting of the descending aorta into your um IAC vessels primarily. And then that's the main things that you could talk about from a cross she point of view, here's grow sheath back in. Let's talk about the prevert fascia. So the prevertebral fascia is the fascia that wraps around the bony and musculature associated with the spinal column and canal. Um And I don't know all the muscle names, you know, most orthopedic spinal surgeons do not know muscle names. So you don't need to know um about spinous capitis or anything like that. But just being aware that these muscles are all packed together and like your um pretracheal fascia here, what you have is you have your vertebrae, your spinal body and canal and you also have this muscle that's wrapped around here. Um And you really do not need to know the m shy of this in any way, should perform. Honestly, just ignore it for the NRC S and even for your Fr CS to a certain extent. So, um like I've said, it contains the muscles that surround the vertebrae. Now, what's really important about the prevertebral fascia that you need to know is that it starts at the base of your skull and then it drops down like a column and it goes through your cervical vertebrae and it goes down to around about your t two t three vertebrae where it fuses with the lateral aspect of the vertebrae. But further on down than that, it doesn't really continue in any way, shape or form, which is really important for the tracking of infections that we're going to talk about in a second. So here's your previous whole fascia er in, you can see you're investing fascia and you can see all these fascial layers and compartments. Now starting to take up in the neck, obviously, this isn't proportional and you go about to see some proportionality. So this is a cross section of the neck and this is in the infrahyoid neck. So hyoid bones up here, we're below the hyoid bone and we've gone at a level basically through the thyroid gland to show you this primarily. Now, when we split this, you can see up here, you can see the skin, the subcutaneous fascia and the soft tissue. Here's your plasma which is split. Like I said, low down here, there's a gap in the middle. Whereas higher up which where my image was, there's no gap here are the infrahyoid muscles, which we'll talk about in the next few sections which people get really worried about. But actually, I'll try and make it fairly simple for you. Overall. Then here is your pretracheal fascia marked out in purple and like we've already said, airway esophagus, thyroid things that live in. Here. Here is your continuation of your carotid fascia with a big artery, a big vein, a big nerve in. Here's the continuation on the other side and you can see this thickening of this band and you can see where it sticks together with all of this. Here's your prevertebral fascia wrapping around those vertebrae. And I promise you, you don't need too much. How much this green is your investing deep pressure in the neck. And you can see how it wraps around your entire neck. And you can see how it double envelopes around your cm. Here and here it double envelopes around your trapezius primarily. That is the crux of cross anatomy for the um head and neck primarily. So here's a picture from grays which basically shows you the same thing just laid out. And you can see from this image that everything's bared out fairly similar. People always don't understand the proportion of the spinal bit, actually takes up quite a large bit of your neck, all the kind of work and intricate stuff that happens at the front. But the back's all taken up by the musculoskeletal component of this as a whole. Here, we can talk about the buccopharyngeal fascia. This is the fascia, which is a continuation to become your esophagus. Later on here, you can see your prevertebra fascia, eye, the fascia right in front of your vertebrae. So here's a cross sectional anatomy with the imaging and these are all marked out actually green area is your pretracheal fascia. Your red area is your um carotid sheath and the blue area is reversible fascia and musculature associated with it. Now, when you think about where these kind of things happen and where they go to each bit, kind of goes to different places. So if you get, let's say a mosquito bite and you get a superficial um, um skin infection and you get cellulitis, the cellulitis will stay out of your neck primarily. And what I mean by that is it'll go into the soft tissue in the skin, but it often does not breach through the cell deep pressure. And this is because it acts as a boundary that the infection often can't transcend through unless you've got something like necrotizing fasciitis. But this is a really nice way of knowing that actually you'll get local eye swelling, but it won't go into the deeper structures and things like movement will be painful, but they're normally not restricted. These types of things. If you're getting an abscess, they point outwards. Now, when you look at your retropharyngeal space, and you've got to think that the pharynx is the upper bit before the esophagus. Yeah. So this is the bit that lives behind the actual pharynx itself but lives in front of the vertebrae. Now, this runs all the way down to your diaphragm. Yeah. And as it runs down to your diaphragm, this is where it's important to know this anatomy because having a retropharyngeal abscess with pus behind your pharynx, this can track down to your diaphragm, um your parapharyngeal space, which is the space which is basically lateral to your swelling pipe, sits between your pretracheal fascia here and it sits wedged against your um carotid sheath structures. This goes down to your mediastinum. Yeah. So we spoke about the brang fascia to T two. We've spoken about this one going down to your Mediastinum. And we've spoken about the pre um vertebral fascia which goes down to your um um diaphragm. So therefore, infections in different zones can go down, but certain ones can be a lot further and more problematic as a consequence. The further down they can go, the more problems they can cause because actually the morbidity and mortality associated with the infections that go to your mediastinum and down to your thorax increases as you go past multiple body cavities. Now, I'm going to just very briefly speak about the higher bone. So the high bones, the free floating bone, it's intimately linked with the larynx and has this fascial layer which drops down to the thyroid cartilage. And when you swallow everything lives up, you've got four muscles above it and three muscles below it, the muscles below it drag it the higher bone upwards, the muscles blow it, drag the high bone downwards. Um And it's very closely and intimately linked to swallowing. Now, the hyd muscles II always find people find this bit what gets slightly dry and it gets. So cos actually, everybody gets the 3d anatomy the way I normally go through it and then they look at this and go oh my God. Um This looks horrendous, realistically, you don't need to think of it like this, you need to split it up into a really simple way. You've got your hired muscles. Yeah, you've got four above which basically lift your higher up. You've got four below which basically bring your higher, higher down. And both those obviously move the larynx at the same time. Now, the ones above all go from different places, you've got three muscles that have a singular belly, but you have one muscle above that has a double belly and inferiorly you have one muscle that has a double belly. And so these are the muscles that split up your triangles, both the anterior triangle and the Hyde also splits up your posterior triangle. And actually, if you remember back to what I said, way back in, I think it was slide 10 or so, the digastric is the muscle that splits up to give you things like this ail triangle. And it's a really, really, really important landmark. I've had neck surgery and the hyoid splits across. And it's the only muscle that goes across the grain when you look at the um throat itself and the posterior triangle of the neck. The way I think about the super high muscles is the other three are named from where they go. So one is the myeloid sling which sits inside the mandible and slings. The hired one is the Stylo Hyde which goes from the stylo process down to the Hyde which is associated with swallowing and moving your plate structures. And then the other one is a geno Hyde which goes to the tip of the inside of your jaw. So, basically, these ones are associated with either the jaw or the stylo um or the styloid process, your infra hired muscles, which are the ones which depress the larynx. These ones again are a bit of Rums wood stain. They do exactly what they say on the tin. They sit in two bands as a whole. You basically have one which goes from the sternum to the hyoid bone, which is a singular band. And then these two basically make up these in two splits. So you've got one which goes to the sternum to the thyroid cartilage and one from the thyroid cartilage to the thyroid. These basically sit over your thyroid gland themselves and the thyroid cartilage and they just sit as a double layer and they really aren't very important apart from in um thyroid surgery in regards to. So these are the howard muscles split up when you break them down here, you can see the higher brain itself sitting just right there here. You can see the digastric, which is a really important muscle. Above here, you can see it going from the inside of the Menon coming down, attaching to the lateral aspect of the Hired bone and integrally linked to the horns of the Hired bone and then coming backwards and attaching the mastoid process. So this is the one that splits up the different ones. So you've got the submental triangle here. You've got the submandibular triangle here. You've got the carotid triangle here. And then you've got often what's called the visceral triangle here and there are your four triangles when you split up the anterior compartment of the neck primarily. Um That's what I'd say about the hired muscles, the straps at the bottom, which are the three layers which are lace muscles, which are steno hyo steno thyroid and the thyrohyoid. Always difficult to remember which one you've said versus not when you're saying them quickly, they're not really that important. Overall. Here, you can see your Hyde marked out and you can see where it crosses the posterior triangle of the neck and the anterior triangle of the neck. And it's always got this fascial fusion just over the I JV and the crossing. So here is another image again from instant anatomy by Whittaker of that split. And you can see how the muscles are related to the Hired Bone itself and how they pull in. You can see the different triangles. So the submandibular, the carotid, the submental and the muscular triangles and where they all sit is kind of a posterior separation of the hid muscles super highly. You don't need to know huge amounts of them as a whole, but it's worth knowing about the digastric and they r hi specifically OK. And this is just the layout of the Hyde and again, the digastric because these bits are the important bits of the muscles in the. Hi. Um, this just tells you a little bit about what each of the muscles does and it tells you about the, um, sensation and, um, nerve innervation, primarily. I'm not gonna go into that, um, overall fairly easy to read about. So we've gone through your triangles and now I'm pretty happy that if we went through and we said we were going to make an incision for a carotid or a thyroid or a neck dissection or we're going to do a spinal approach to the vertebrae that I'd be happy for you to be able to talk through roughly which layers you're going to get there. And that's really important for things like the exam. So this is just a very quick bit about the anterior bit of the, of the actual neck. So when you've got the neck and you've got low down, you've got three sets of jugulars, you've got the internal jugular vein, which is the big one. Yeah. So when people go, you go for the jugular, that's the one you're talking about. That's the one closely associated with the actual carotid artery itself. You have a small anterior jugular vein which sits often in the midline overall. And then you have an external jugular vein that sits in the posterior triangle. So your internal jugular is always the most important and the deepest to get to primarily here, you can see your um strap muscles underneath as we were talking about before. So I'm going to just push this into something more clinically relevant. Um Especially if you're going to examine somebody's neck, they often talk about levels of the neck and it gets really confusing and, you know, people really, really, really overcomplicate this whereas we keep this fairly simple. So when we look at levels of the neck, this was created primarily to think about if you have a cancer somewhere where do cancers spread. And that's why it originally came down. And this is split up in different ways. Now, level one of the neck is the area basically here under the omentum that goes up around to the back of your hyoid bone and goes up to the angle of the mastoid. Level two is your upper part of your cm. The upper one third, level three is your middle, one, third. Level four, is your lower bit. Level five is your posterior triangle and that'll split into A and B. And on the way, I think of that is five above the um accessory nerve and five below. Um There are different ways of defining this, whether it's radiologically versus clinically. So that sometimes um radiologically they'll use the cricoid cartilage and the hi bone as the markers to differentiate between this level six is the central component of your neck that we spoke about where all the Gibbons are, and level seven is the extension of this into your mediastinum sitting behind the manubrium itself. And when you examine, I tend to go from 123456. And I tend to examine in that fashion. And here you can see that kind of layout primarily going up. And like I said, I kind of do it like Az and then I come to the central bit. So when you're examining, that's what you want to do. And when you're feeling for neck nodes, use the palp of your fingers and you rotate and you press gently as you go just very quickly about the anatomy and larynx, I'm not gonna say huge amounts to this because this is more for the dons rather than the MRC S. Um as it's getting a bit niche. Now, the anatomy and the larynx, I often think is um kind of a little bit of a split. Um It's made up of multiple paired bits of, of cartilage. It's got singular cartilages. The windpipe starts at the bottom. And the first cartilage before that is the cricoid above that is the double shield of cartilage, which is your thyroid cartilage. The big one which makes up your Adams apple, then you've got a membrane that sits between them, which is soft and then goes up to the thyroid brain. And then you have the epiglottis attached to the internal aspect of the thyroid cartilage which then flaps backwards and forwards to protect your airway. These are the normal opening and closings of the larynx. Um We can talk about it with the cricothyroid muscle and the rest of the muscles of the larynx. All the muscles of the larynx are supplied by the recurrent laryngeal nerve. Apart from the cricothyroid muscle, which is supplied by the um by the superior laryngeal nerve primarily. So, questions that are often liked in regards to head and neck is about branches of the um external carotid. There is an acronym that I'm not gonna say um which starts out as, as she lays flat. Um but I won't finish off the rest of the ACR acronym, but I'm sure you can google it. Um These are the branches of the actual external crossed. So, one of the most common questions that gets asked in regards to arteries and this happens at multiple levels, both at undergraduate and postgraduate is people often ask you, what is the, what are the branches of the internal carotid in the neck? There are no branches of the internal crosses in the neck. The internal carotid artery starts at the level of C four as we spoke, it then is the internal carotid artery. So it internally needs to go supply your brain and the other structures. So actually the first branch of the carotid internal aspect of the carotid artery is your ophthalmic artery. And if you remember back to a FS and having that curtain veil in certain types of tia A s that'll remind you about the internal carotid, all branches of the carotid artery come off the external carotid artery. So you have both branches coming up as in the common carotid artery. See four, it splits into an internal component that goes to your brain and the external component that comes out twice your neck. And so if we're doing robotic surgery, then one of the things that we do is ligate the branches of the external carotid artery. And what I do in theaters particularly for this, identify the cross I come up to see for, I chase both and I see which one starts having branches. The one which has the branch is the external crossing. The other one is the internal. So that makes it happy when I need to ligate and cut off these branches. So the branches growing up start with the ascending pharyngeal, the superior thyroid, the lingual, the facial and sometimes that's a common lingual facial tongue, the occipital that goes to the back, posterior auricular, the maxillary which has 18 other subbranches and the superficial temporal, which is the last one primarily. And this is just another layout of the same type of images. So all of these branches here are from your external, this would be your internal going up to your brain. And the first branch it gives off is to the eye with your ophthalmic primarily. And here you can see the internal coming off and the external coming off and externally supplying your face overall. So your muscles are facial expression, all of them are supplied by cranial nerve seven. And you're well aware of all of these because you remember them from medical school. So when you're actually looking at this, primarily, you want to look at all of kind of the subgroups and you want to think about your testing for cranial seven and I'll talk about cranial N seven in just a second. So when you're testing for this, you want people to raise their eyebrows to scrunch your eyes up, smile at you, puff out your cheeks and they're all the kind of subcomponent that you actually test for primarily. Now, cranial nerve seven branches are often used by the acronym to Zanzibar by Motor Car or other acronyms that are available. The cranial F seven has a, a long course, but the head and neck course as it comes out of the style of a frame and comes forwards, goes into the prot gland, into the protid gland, it goes into a central core opens up to what's called the pessaries or the goose's foot where it splits into two branches, one that goes upper and one that goes lower, they then subdivide across there primarily. Um I'm not going to go too much into detail of that. It sits through the pro gland. 80% of the proto gland is superficial to this 20% of this is deep primarily. Um and this is how it all kind of subbranches and separates off. And each one of these has kind of different features, but that's well over the breadth of the MRC S. But it is more in discussion for the Fr CS. Here's just some general bits about the actual protid gland. So we've already spoken about well lives there. So in the deep aspect, you have the branches of the external carotid, you've got the retromandibular vein primarily and you've got some lymph nodes and there's the auricular temporal branches of the nerve which go there. This is a really nice exam question as well because they often like talking about the branches of the facial nerve. And here you can see the facial nerve where it comes out of the stylomastoid frame and goes forwards for about a centimeter to splits into the superior inferior branch and then gives off those other sub branches as a whole. So this is just um the actual full in depth workings of cranial nerve seven where it basically sits. The medulla comes forward to the geniculate ganglion splits off to give you the nerve that goes to us to be in the inside the ear, in the ear, gives us what's called a tympani which goes off to basically give you a taste fibers um at the front of your tongue. And then the other bits that I was talking about are further down here where they go through the actual prostaglandin itself. This is called a tympani inside the ear. Um And like I say, this is the cranial nerve seven branch, which comes off cranial nerve seven as it comes from the back and then comes off, scoots through your ear and then dips off and joins up with your anterior two thirds of your tongue. So remembering it joins the lingual to give you your special sense of taste, for your anterior two thirds of your tongue. So the muscles of mastication. So with chewing, you've only got four muscles of mastication. So one, you have the master, basically sitting here two, you have your temporalis, which is a very large broad muscle which sits over your infra temporal fossa. Next, you have your buccinatus which sit on the inside and then you have your medial and your lateral pterygoid primarily that allow for you to move your jaw from left to right. In effect sore five, the things to think about this are the three branches primarily and this is sensory to your face and primarily this splits into the upper, the middle and lower parts which are the V one and V two. So the ophthalmic maxillary and mandibular branches of your facial nerve and allows for you to have sensation over it. Well, very briefly talk about the submandibular gland. So the submandibular gland is important to know about because this is one of those things. They often like asking questions for primary because they can ask you about the approach to it. They can talk about the nerves that are in close context. Submandibular gland gland basically sits in your submandibular ti between the two bellies of the digastric, between the anterior and posterior. It's ac shaped gland and it sits round and curves around the back of the mylar muscle. In regards to this, there are three nerves that you need to be aware of which have close proximity. The submandibular gland gives off a duct that goes to the floor of your mouth. Now, there are several nerves. One is the marginal mandibular nerve which supplies the corner of your mouth and that can be injured when you do some mandibular gland surgery. This is why you classically use two fungal breaths underneath and you make your incision low. So you come up on it so you don't damage through it. The next nerve is on the deep side and this is closely related to your duct and this is called nerve and it wraps around your subicular duct um on its side. And then the deepest nerve to that is the hypoglossal which moves your tongue. So all three nerves are potentially at risk in submandibular surgery. So we've spoken about cranial N five, we've spoken about the muscles of mastication and I'm going to finish up there if you want to further reading a copy of Ellis or either the anatomy coloring book which is fantastic. Everybody thinks it's a babyish book, but usually it's a really good way of picking up anatomy. I often use Alan's Anatomy DVD s which are good more. And Dali, which is my textbook that I probably go to and I've done for over 20 years. And finally, a lot of these images that I used to say for the cross sectional anatomy came from Gray's Atlas of anatomy. This is what we've run through primarily and last, but not least I am ready for some questions if people would like to run through some cross sectional head and neck anatomy questions. Thank you so much. That was a really great, really great overview. Um If anyone has any questions at all, uh please do take the opportunity. You don't get many opportunities to ask a consultant surgeon questions. So please do. Um And for those of you who've just seen in the chat, I'm delighted to announce that all of our teaching sessions are now CPD approved. Er, so our certificates will reflect that as well and if you ever attended any previous sessions, um I'll make sure that is updated as well, so you can claim CPD hours. Um So please do um, ask any questions or if there's anything that you'd like him to repeat or go over. Um, now is your opportunity? Otherwise we'll draw to a close. So I'll give you a few more moments in the meantime, er, just so you've given us some really good, um, resources that you've used. Um, where do you, where should people start if they're going from the very beginning? Uh It's hard, it really is. Um, head and neck anatomy makes you feel like you're drowning. Um, which is primarily why I made these talks originally. So these are my talks that I have given since 2000 and 12, maybe earlier to medical students from the University of Leicester. And so like I say, I've raped them up as a whole and kind of ramped them up. So I often find the weirdly enough, either a combination of using AINS and A DVD s are really good or just starting really simple with the coloring book. The issue with the coloring book is when you're learning, you kind of look at it and you convince yourself while you're coloring, you're learning whereas and you're thinking, oh, I'm sitting here coloring for ages and this information is coming in. So one of the things just to be aware of with the coloring in book is that sometimes a coloring doesn't actually improve what you're understanding or learning at that time. Once you've got a basic understanding, you want to then multilayer and put more information on top. And your multilayering comes with a little bit more of an in depth anatomy book. When you get to something like more and Delhi, they're quite hard to digest. But once you've got two or three layers of information in your head. It's really easy to then read them because you have a lot of prelearn that you can then stack on top of it and, you know, you continue to learn as you, as you go. I hope that makes sense. Yeah. No, that's really great. We've got a question in terms of the part. B so I know that's what he's called on. That's called just MRC ent. Um, any just advice and common questions or things I get asked during R to head and neck. Yeah. Well, it's pretty much this session. I've tried to cram as much as I can. So the things that I would concentrate that I didn't go into much is the submandibular triangle. I've not mentioned about the blood supply of the thyroid gland. That's a really common thing. Um, and then there's cross sectional bits. So from a head and neck point of view, really good. If you're specifically looking for ent stuff, then it's worth the middle of anatomy. But generally they're, they're fairly sensible and they're not too brutal with what they do in most of MRC S Ent. Wonderful. Thank you. Well, I don't think there's any more questions. So, thank you again for joining us and thank you for, er, those who have joined us tonight as well. Um Oh, we've got a more question. Uh We've got, um, what is the safe reason to make an incision in relation to the dias muscle Ok. Um, so, um, I'm gonna, so the digastric muscle is, um, you can damage it if you want. Yeah. So there's no, no issues about that at all because it's a muscular thing that goes from one side to the other. Now, it depends on what you're doing. So, if you're doing parotid surgery, your incision would come like this. Yeah. If you're doing a neck dissection, there are lots of different incisions but I tend to use an inverse hockey stick incision. But you would follow exactly what I'm doing there that you would go through the skin, subcutaneous fat. You'd identify your SCM. For instance, with the neck dissection, you then split, split it up and you'd raise your flaps north and south because you've then incised into your se kind of mastoid fascia. You remember, I said those two points and I specifically dropped to the point earlier that the SCM attaches directly onto your mastoid process. Well, you've got your like this on the deep outside the digastric attaches to the mastoid process, but you've got to go past the SE M to get to the digastric. So the answer to your question is you can't really, and with an incision, unless you start stabbing in the neck quite deep, you can't really damage the digastric muscle. But as an axis approach, what you use is you use your SCM normally is the way to find it. And that's because you chase the fracture. Go on the other side and deep to that is where your dias is. Mm Thank you. Um Any other questions I give you a few moments and please do um make sure you provide feedback as well. Um No. Ok. So I'll draw it. So thank you very much, everyone. Um All sessions are recorded and will be uploaded as catch up content afterwards. Um And you get a stick attendance for your portfolio. So I hope you've enjoyed it tonight and um enjoy your weekend everybody. Thank you and thank you so much. No worries at all. Take care. Bye.