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Summary

Master the complexities of human anatomy with the Master's Anatomy Series. In our upcoming teaching session led by clinical research fellow Matt, dive deep into the intriguing world of thorax, the region between the neck and abdomen. Gain a firm grasp on its component parts such as the heart, lungs, trachea, esophagus, pleura, and mediastinum, as well as the bones, including the ribs, costal cartilages, and sternum. Understand the intricate facets of the thoracic vertebrae and the significance of the neurovascular bundle. Matt's engaging session also covers the thoracic articulations, the anatomy of the sternum, various thoracic muscles like intercostal muscles, diaphragm, and serratus anterior, among others, rounding off with an informative discussion on clinically relevant areas of the thorax. Get ahead with your learning and join us in this comprehensive study of the thorax in our latest session.
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🌟 Dive into the wonders of Thorax anatomy! 🫁

✨ Join us on March 28th at 19:00 GMT for an insightful lecture presented by Mr. Matthew Arnaouti as part of our Anatomy Lecture Series.

Don't miss this chance to enrich your understanding of thoracic anatomy!

Stay tuned for more updates and future events. Elevate your anatomy knowledge with us!

Learning objectives

1. By the end of this session, learners will be able to accurately describe the anatomy of the thorax, including its boundaries and internal contents. 2. Participants will understand the structure of the thoracic cage, including the sternum, the ribs, and their associated cartilages, as well as the characteristics of typical and atypical ribs. 3. Learners will be able to discuss the relevance of thoracic anatomy in clinical settings, with a specific emphasis on conditions such as thoracic outlet syndrome. 4. Participants will become familiar with the intercostal muscles and their arrangement, and be able to identify and describe other key muscles of the thorax. 5. By the end of the session, learners will be able to identify key neurovascular structures in the thoracic region and discuss their practical implications, such as where chest drains are typically inserted.
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The following transcript was generated automatically from the content and has not been checked or corrected manually.

Ok, good evening, everyone. Welcome back to another series of the Master's anatomy series. Today, we're gonna have uh Matthew uh teaching us on thorax. We just before he, we do hand over the stage to him. Uh We've got another lecture tomorrow that's on head and neck. So do join us on that. And if I hand off to Matt, brilliant, thanks very much so. Yeah. Hi. My name's Matt. I'm a um clinical research fellow currently working at the Royal National orthopedic Hospital. Um I'm interested in orthopedics and unfortunately, Jerome's asked me to give a lecture on the thorax, which is maybe not my strong point, but I'm hoping that we're gonna cover lots of useful information today. Um So yeah, we'll move on to the next slide. So the thorax is um that runs from the superior part of the trunk and it's between the neck and the ab abdomen. The border superiorly are the first rib, the mediastinum and the T one vertebrae and inferiorly, it's bounded by the costal cartilage, the t the T 12 vertebrae and ribs, 10 to 12. It's got two apertures one superiorly and one inferiorly and the superior aperture is also known as the thoracic inlet or outlet, which is slightly confusing, but that's the top end even if it's called the outlet. Next slide, please. So, oh, dear, that's gone a bit wonky, hasn't it? Um So the contents of the thorax. So heart lungs, trachea, esophagus, pleura and the mediastinum. So there's quite a lot of things in the, in the thorax and some associated structures which we're not going to cover today are going to be the breasts and the upper limbs which would also articulate with the thorax itself. But I think they're topics in and of themselves. So we'll try to keep focused on the thorax today, moving on to the next slide. So we've got the bones of the thorax which consist of the ribs, the costal cartilages and the sternum. And then posteriorly, you've got the thoracic vertebrae. So that's t one to T 12. And if we have a bit of a closer look at the ribs and move on to the next slide, so typical ribs three through nine, which have got a, a fairly similar growth structure as you can see from this diagram here. So there's a head um at the posterior aspect which then articulates with the neck, moves round into the angle and there is a cubicle which articulates with the transverse process of the adjacent vertebrae. And then you've got the main part of the rib which is the shaft and then the costal groove which articulates with the costal cartilage. Um And does anyone know anyone in the chat able to put what runs in the costal groove at all? I don't know. I let me see if I can see the chart there if anyone wants to pop VVA N Absolutely. Yeah. The neurovascular bundle. And you've, you've covered one of my later questions. So that's very good. And we'll move on to the next slide now if that's OK. And so all can people see that? Shall I share my screen? Jerome cos this is looking really dodgy. Yeah, please if you don't mind. Right. Let me see if I can make this work. Sorry guys been let down by technology. Do you want me to share it or you doing it? No, I've got it like this should work now if I just go from here. Um Right. So yeah, we can everyone see that. Is that alright for you guys to see? Om, is it visible for people? Yeah, it's visible. Brilliant. All right. So yeah, we've got the neurovascular bundle. That's exactly right. So this runs inferior to each rib and it's got art um divisions in arterially. So you've got an anterior and posterior branch anteriorly. You've got nine and ribs, 1 to 6. It comes from the internal thoracic artery or the internal mammary artery and seven through nine, the branches come from the musculophrenic posteriorly. You've got 12 and the first two come from the costocervical trunk and then the remaining ones come directly from the thoracic aorta. And we've already had an answer in the chat. I saw earlier talking about the arrangement of the neurovascular bundle and it's V AM. So as you can see from this diagram here, you've got the vein at the top, then it's the artery and then the most inferior structure is the nerve, so typical ribs. Um We've got Demi facets at the head which articulate superiorly with the vertebrae at the corresponding vertebrae and then inver articulate with the vertebrae below. Um And then we've got a cubicle which is another articulating facet and that articulates with the transverse process of the um adjacent vertebrae. And here's another diagram just highlighting that's the um articulating process with the transverse process. And again here. So we can see that's where it are with the vertebrae. So atypical ribs, there are a few. So the first rib, it's shorter and flatter. It's only got a single facet and it's got a few cubicles for the scaling muscle, muscle, sorry, on the inner border. In particular, the second rib is a bit thinner and longer. It's got a ubic for the posterior scaling as and a tuberosity for the serratus anterior. And then you've got your 10th to 12th ribs which only have single facets and on the 11th and 12th rib, they, they have no neck either. So they're slightly different to the remaining ribs and the first rib. Um I can't see the chat. So this was meant to be a question. The subclavian vein and artery are separated by the anterior scaling muscle, which you can see on this diagram here. So as we mentioned, it's got attachment to the anterior and middle scaling as well as the serratus anterior muscles and between the anterior and middle scalene, you've got the subclavian artery and then the root of the brachial plexus. So we can see that we can see that here on the diagram, the nerves and the arterial structure. So why is this clinically relevant? So we, we spoke about thoracic thoracic outlet or inlet earlier. So the top part of your thorax, you can get something called thoracic outlet syndrome, which is a pathological compression of the neurovascular bundle and it can affect the artery and vein and also the brachial plexus. So, as a result, you can get ischemic symptoms or neurological symptoms and this can be caused by trauma or you can see it sometimes in um high functioning athletes who do um lots of overhead movement. So, um Javelin, for example, or people who do things like shot put um and other certain occupations that require a high level of um manual dexterity. And you can also be born with a uh an additional cervical rib and this can result in thoracic outlet syndrome as well. So you can look on the diagram here and you can see that you can get compression of these vascular structures or the neurological structures and that obviously leads to um symptoms for the patient. So, costal articulations. So ribs one through seven, again, this was meant to have a few questions. I'm sorry about this. Um rib, ribs one through seven are your true ribs and they articulate individually with a costal cartilage which articulates in turn with the sternum. Ribs, eight through 10 are um sh they share a costal cartilage. Um And then this joins onto the bottom of the seventh costal cartilage, as you can see on this diagram here and then ribs are, are floating ribs. So that's kind of the general structure of um the rib cage. And it's something that does seem to come up in, in exams as I remember quite frequently. So it's a good thing to just have an idea of. So the sternum, it's split into, split into three parts. We've got an Norio sternum at the top, the sternal body in the middle, which is the pink bit. And then at the bottom, we've got the zippy sternum um or the Zippo process. And these are, these are joined to um by symphysis type joints. So that's the same type joint which is a secondary cartilaginous joint that, that you see in your pubic symphysis. And these can ossify as you get older in life. So it can just be become one solid bit of bone. But actually, when you're a bit younger and before everything's fused together, um it is three separate um bones that are joined by those secondary cartilaginous or synthesis type joints. And as you can see, they've got these facets again on the side, which articulate with the costal cartilages. So, having a look at the muscles of the thorax. So we've got the intercostal muscles and the diaphragm, which make up our respiratory muscles predominantly. And then we've also got our intrinsic muscles of the Thora um thoracic wall, which are our anterior and posterior serratus, as well as our transversus, thoracis, our subcostal muscles and our um levatores costarum. Just to clarify. You don't need to know these inside out. The ones that are probably best to focus on are your intercostal muscles and your diaphragm and also your serratus anterior muscles. They're ones that do um get, get asked a few questions about I II was planning to ask you what the in the supply was for some of these um with serratus anterior. So it's the long thoracic nerve and that's something that you test for when you ask patients to lean on the wall and look for winging of the scapula. So, if they've had injury to that nerve, then the scapula wings out because the serratus anterior muscles are not holding it down anymore. Your intercostal muscles are supplied by your um intercostal nerves and your diaphragm is supplied by your phrenic nerve. And the way to remember that er the nerve roots of that are c 345, keep the diaphragm alive, which is quite a nice easy rhyme muscles of the thorax, looking further at the intercostals into three layers. So you've got your external intercostal muscles and these run in parallel to your external oblique muscles. So they go anterior inferiorly. So it's like hands in pockets again, which is the same for your external obliques. And then you've got your internal intercostal muscles and they go anterior posteriorly. So they run in a diff in the er in a perpendicular orientation. And then you've got your innermost intercostals which again mirror the um orientation of the internal intercostals, but they can be slightly more vertical, which is what you see in this dia diagram here. And these are the other muscles of the thorax, they break about earlier. So you're subcostal and your the vs costarum here. But these are not ones that you need to know inside out. But these are some nice diagrams that I thought might be useful to share the relevance of this. I'm gonna see if I can sort of look at the chat cos I really do want to ask the question, what, what is the, the, the area that you place a chest as anybody know, I'll give you, I'll give you a few seconds. And if Jerome's got his eye on the chat, then he can let me know if anyone's popped in an answer and read out a couple of them uh mediastinal. That was one of the answers. Oh, don't do that one. You don't want to pop it in the mediastinum. You get a very angry cardiothoracic surgeon on the phone to you. Can you repeat the question? So where do you place? Oh, I've just taken my camera off. Accident. Um Where do you place? Oh, for God's sake. Just a minute. Hold it there. Give me a minute. Let me share my screen. It'll be his name. Yeah. Can you hear me at all? Yes. Sorry. I thought my camera had died. Don't worry, my I can still share my screen. It'll be fine. Sorry about that. I don't know why it crashed out. So the question was, where do you place, where do you place a chest drain? What's the answer to your location? I think there's a few right answers. Is there right? Well, we'll move on. So the, you wanna place it at the fifth intercostal space within the safe triangle just anterior to the mid axillary line. That's your go to answer if you get asked that in a, in an Aus or something or on the wards and the safe triangle boundaries are superiorly, the axilla anteriorly, the pec major muscle, posteriorly thes dorsi and then is the sixth rib and here's quite a nice um of it here. And this is the area where you, where you, it's safe to place a chest drain. And the steps of placing a chest straight. So I think this is quite good just to whiz through quickly. So you wanna mark out your site and get your equipment ready, prep and rate the patient to make sure you maintain an aseptic non touch te technique. Put local anesthetic in. If they're, if they're conscious, particularly if it's a trauma patient, you might not need to do this. If they're unconscious and you make a horizontal incision directly onto the rib, use your artery forceps going over the rib. Because if you go underneath, that's where our neurovascular bundle is, we might damage something. So you want to go over the rib and then you perform a finger, finger, thoracostomy, insert your tube which has already been loaded onto some forceps. You point it up for air and you point it down for blood and then you wanna connect it to an underwater seal and look for swinging and bubbling. If there's a leak, it will bubble. If it's uh if it's just blood that's coming out, then it will just fill up. But there will also be swinging of the drain, then you wanna secure it in place and don't forget your chest X ray. No. Can we just go back uh slides to me in the chat one to see the sliding. Which one do they want me to look at this one? Yeah, I assume so. So this is just showing our underwater seal. So that's the chest drain. Connected to the underwater seal there. And then this is our boundaries of the safe triangle. I'm happy to have the slide sent round to everybody afterwards if they, if they do want to have a look at the pictures again and I'll move us on. So the pleura, we've got, we've got two layers of pleura, the visceral and the parietal. So the visceral covers the lungs and the parietal um covers the chest cavity and it's got the cervical costal mediastinal and diaphragmatic aspect. And we've then got two pleural cavities, one either side. And this, this are potential spaces. They can fill up with fluid or air, but it just to facilitate the movement of our lungs within the chest um within the thorax during respiration. Um So, in terms of where the pleura run from, they start above the lele, which seems like it's outside of the thorax, but it is still contained within it. They run from a line um from the supraocular junction to a junction of the medial and middle third of the clavicle and they then move anteriorly and inferiorly meeting at the second costal cartilage behind the um er subclavian joint. And then they on the right side, go down to the sixth costal cartilage before um diverging and on the left side, they diverge a bit earlier on the fourth costal cartilage to accommodate the heart. And then bilaterally, they cross the midclavicular line, mid axillary line and the posterior chest at the eighth, 10th and 12th ribs respectively. And if you wanna know where the lungs are, you just take two off. So the level of the lungs at these same places is at 6th, 8th and 10th rib I've written tib there by. So this is quite a nice diagram explaining that. So the red outline is the lungs of the, the pleura and then our blue outline is the is the borders will be. So again, this is quite a nice picture to have a look at to try and get an understanding. So, clinical significance, I was gonna ask what's what, what's on these diagrams? So let's, I'll let people have a couple of seconds to pop in the chat. What they think might be going on in both of these. I'll give you a clear, there's a pathology on the right side in each of them. Have we got a few answers? If people put a guess in, we got Victoria that said pleural effusion. Brilliant. That's on, it's on the right hand side. Yeah. Oh sorry. That's on the left hand side. And then the other side, we've got a pneumothorax, a pretty big one. So yeah, that's very, that's very good. Um So the mediastinum, this is quite a complex topic and I'm gonna try and cover it as best as I can. I'm just gonna keep an eye on the time. Um So the mediastinum is a region between the pulmonary cavities it's covered by me. The mediastinal part of that parietal pleura that we spoke about doesn't have the lungs in it and it extends from the inlet down to the diaphragm. And the super is divided into two parts, inferior mediastinum and the inferior mediastinum um which has then got a third of three subdivisions and these two, so the superior and inferior are separated um from one another by an imaginary line drawn at the level of T four. So as you can see coming across here from the level of T four, which is at the junction of the manubrial and manubrial sternum and the sternal body, which is the angle of Lewy that we can all feel on the front here. And that mark marks our second interco. So that corresponds with T four below, that is where we've got our inferior mediastinum. And above that is where we've got our superior mediastinum in the superior mediastinum. So I'll let you guys have a look at the borders here and the contents is not something that you need to know inside out until you're revising for your MRC S examinations. But it's good to have an idea of what's what's going on in there. So the superior mediastinum has got some quite important organs in it. So the trachea, the esophagus, and then the thymus gland, the vessels including the superior vena cava, the brachiocephalic veins, the aortic arch, and the thoracic duct and then it's got the vagus nerves bilaterally and on the left side, it's got the recurrent laryngeal nerve which wraps around the arch of the aorta. And then it's got the phrenic nerves on both sides as well. And if you have a look at the posterior border here, we can see it says T one to T four. So remember I said that's where the division is. So that's why, you know, your angle of lo is at the level of T four, which is where a few things happen, which will cover later as well. So the inferior mediastinum, the anterior portion is not too much here. So it's mostly the remnants of the thymus gland, some lymph lymph nodes, some fat and some loose connective tissue. The middle mediastinum again is another quite important one. So we've got the pericardium, the heart, the bifurcation of the trachea and the main bronchi as well as the aortic root and the ascending aorta, the pulmonary trunk and the superior vena cava. And then some also some important nerves, the cardiac plexus as well as the phrenic nerves on the right and left hand side. And then looking at the posterior media sty, the only one that's got a really nice mnemonic for um which is dates. So it's got the descending thoracic aorta, the azygous vein, the thoracic duct, the esophagus. Although it's spelled with an O, we let, we let the Americans off cos it is quite a useful mnemonic and then the sympathetic trunk and it also does have the vagus nerves in. That's just another, another thing to make sure you've got in your mind. And this diagram is a bit complex, but it's to take a picture of cos it does show you all of the different aspects of the media stum and the various contents. So the cardiac anatomy, we're gonna really try and whizz through and looking at cardiac anatomy as electro in and of itself again. So there's three layers to the pericardium. You've got your fibrous pericardium, which is the outermost layer and then your serous pericardium, which is again, again, divided into your visceral. So your visceral layer is the layer that's the deepest on the endo on the myocardium. And then your um parietal is um attached almost to your fibrous pericardium. And again, we get this potential space between the two that allows the heart to move during um, the cardiac cycle. We've got four valves, they're all tricuspid except from anyone know in the chat. I'll let, let people have a have wants to put that in. Does anyone know which one it is? Have you got any answers in the chat room? Yes. Well, Victoria said mitral. Brilliant, good. Yes, absolutely. All of them are tricuspid except for the mitral which is bicuspid and all heart sounds one and two are caused by. So when we get closure of the mitral and tricuspid valves, that's our heart sounds number one. And then we, when we get closure of our aortic and pulmonary valves, that's heart sound number two. So that's part of the cardiac cycle, cardiac anatomy. This is quite complex and I'll go through it quite quickly cos it's not something that we need to know in too much depth again until you're coming to your MRC S examinations. So, the origin of the coronary arteries, this is something that is quite important. So, on the left side, it comes from the left posterior coronary sinus, and the right coronary artery comes from the right anterior coronary sinus. There is a right posterior coronary sinus and this doesn't have anything arising from it. Um We've then got branches. So the left side, this is probably the most important bit to have an idea of. These are the major branches that you need to know about. So the left one, the left coronary artery has the left anterior descending, the left marginal and left circumflex vessels and then the right side, you've got your right marginal and your right posterior descending. They're, they're quite useful to know about. There are more branches, but these are the ones that you are expected to have a, have an understanding of the supply of the right coronary artery. So the two big things that it supplies are your sinoatrial node and your atrioventricular node in the large proportion of the population. Um And the left coronary artery supplies most of the anterior part of the heart, um, the left atrium, left ventricle, as well as part of the right ventricle and the large amount of the, um, interventricular septum. So these are the ones that if they get colds, people have really bad heart attacks. So it's quite important in terms of supply of the muscle of the heart, in terms of the venous drainage. So it all drains into the coronary sinus, which is on the posterior aspect of the heart. And this drains into the right ve the IVC and the Tricuspid valve. It's got three major tributaries, which is a great cardiac vein, the middle cardiac vein and the small cardiac vein. So the great cardiac vein is basically follows that left, the left anterior descending. Um So that's, that's mirrors that left coronary artery. The middle cardiac vein is on the posterior aspect with our um following the um posterior interventricular branch of the right coronary artery. And then our small cardiac vein is just a small bra that wraps around the right atrium. And again, these are just some nice diagrams. You don't need to know these inside out. But I found these quite useful when I was revising cardiac anatomy. So I let people take any screenshots if they want them and then we can move on. So, cardiac anatomy conduction is something that is useful to have an idea of. So it starts at the sino atrial node, you get a bit of a delay at the ATRIO ventricular node, it then you get further conduction through the bundle of his, which is your left and right bundle branches and then you go, it goes down through the purkinje fibers and you get retrograde ventricular conduction. So it comes from the bottom up. And that's why your heart contracts from the bottom up and squeezes the blood out into the aorta or the um pulmonary arteries. The innovation comes predominantly from the cardiac plexus, which has got superficial and deep branches. And then you've got autonomic fibers coming from your vagus and sympathetic trunks. The thoracic aorta, you can divide into four components consisting of the root, the ascending part to the arch of the aorta and then your descending thoracic aorta. And this is quite a nice diagram here. So you can, the root is, is the very bottom part which is um next to the valves of the er aortic root. So that's right at the start and then it evolves into your ascending aorta, your arch and then the descending aorta and there are three major branches. Does anyone know what they are on the aortic arch? I'll give you a clue. It's A B and C. Have you got anything in the chat room? Let me know if anyone pops anything in. Yes, we got brachiocephalic trunk, common carotid and left subclavian. Yeah. Brilliant. Yeah, that's exactly what it does. So the, you get your brachiocephalic trunk, then your common carotid and then your left subclavian artery. Um and then from the descending aorta, there are some unpaired impaired branches. It's good to have an idea of these. But again, you don't, probably don't need to know them inside out. But here's quite a nice diagram to have a look at those. So the subclavian artery is divided into three parts and this is in relation to that anterior scaly muscle that we were talking about earlier. So the first part is medial to it. The second part is posterior to it and the third part is lateral. And then we've got quite a nice mnemonic for the branch of the subclavian artery. It's vit C and D. So vit are the branches of your first part. So it's your vertebral, your internal mammary and your thyrocervical trunk. C is your second part, as you can see on the diagram, costocervical trunk. And then you've got your dorsal scapular artery for third part. Yeah, having a quick look at the lungs. So you've got on the left side, two lobes, three lobes, on the right hand side. And on the fissures, you've got bilaterally oblique fissures and the right also has a horizontal fissure and then segments, you've got nine or 10 on the left and 10 to 11 on the right, the hilar anatomy. So the, the, the hilum of the lung is the root of the lung. And superiorly, we've got the contents that are the pulmonary arteries which are usually at the top and anterior inferiorly, you've got the veins, the superior and inferior pulmonary veins. And then posteriorly, you've got the bronchi, the bronchial arteries and some lymph nodes and then relations to like the hilum. So the phrenic nerve goes in front and the vagus nerve goes behind. So just remember phrenic front, the trichia. So it's again, very important begins at the C six. the lower border of the cricoid cartilage and the cricoid cartilage is the only complete ring in the trachea. So it's a complete um cartilaginous ring. Whereas the remaining tracheal rings are U shaped. So they accommodate the esophagus posteriorly. So there's not a complete um constriction at the back, it ends at the level of T four. So again, remember the manubriosternal junction, the level of T four, that's where your trachea divides and it ends up dividing into your right and left, main bronchus, um which goes to the right and left lung. You've then got divisions that are secondary um going to the lobes of the lung and then you've got tertiary divisions which goes to the individual individual segments. Now touching quickly on the esophagus, it's 25 centimeters in length. It consists of stratified squamous epithelium. That's the important bit there and it's divided into thirds. So the upper middle and lower third and the, this, I'm not gonna go through this. I've made this table. So you guys can take a picture of it and have a look at. It is quite complex, the esophagus and it's something that you do need to do a bit of revision on in your own time. And this table covers all of the important aspects in terms of the supply from um blood vessels and the lymphatic drainage and then also the um composition in terms of the um mus mus muscle layers. So you've got striated muscle at the top, it transitions and then becomes smooth muscles. So it's not under voluntary control in the bottom bit. Whereas the top bit, you do have voluntary control, which is what initiates your swallowing constrictions of their esophagus. Does anyone know what these might be? ABCD? I'll give 20 seconds or so to see if people wanna pop anything in the chat. Let me know when some answers start coming in. Drew. I will indeed have a think about those th the things that we've been talking about so far, I'll give people a few more seconds and I'll pop them up. So you've got your aortic arch, you've got your bronchus, particularly the left main bronchus, you've got the cricoid cartilage and then you've got one that we haven't spoken about yet. The diaphragm. Um Again, this is quite a nice dia diagram that just shows the cricopharyngeus muscle, which is at the level of the cricoid cartilage causing a constriction. And then you've got the broncho aortic constrictions a bit further down. And then you've got the esophagogastric junction um at the level of the diaphragm. And just above that is where you get a constriction from your diaphragm. Again, another good um image, if people wanna take a quick picture, this covers all of the constrictions, the arterial and venous drainage um and also the er mo the neurological supply and again, some more quite nice pictures. If people wanna take any screenshots that show the lymphatic and venous drainage on the right hand side, in terms of the venous drainage, it's just where your um azygous vein is. And then on the left side, you've got your hemizygous and your accessory hemiazygous vein, that's kind of the pre predominant um drainage in terms of the venous side of things. And again, his art arterial supply as a name for anyone who wants to do some further revision, some clinical um information regarding this. So, Barrett's esophagus, I'm sure everyone's heard about this. They do love to tell us about this in medical school and it is something that is very common. So it's useful to know about. So it's metaplastic change where you get transition of this squamous epithelium, which we spoke about to columna and it's stimulated by exposure to its stomach acid and you've got an association with dysplasia and then adenocarcinoma as well. So, metaplasia is pre malignant and reversible and it's when one differentiated cell type becomes an alternative type of cell. So we've got here, squamous becoming columnar dysplasia is pre malignant and again reversible and it's disordered differentiation and growth. So the cells start to become a bit strange. And then another one that's quite, that comes up from time to time is, is heterotopia and this is where you get differentiated cells. So for example, a squamous cell that is located as a non physiological site. So it sh it's, it's turned up somewhere that it shouldn't be. Um which is, I think Meckel's diverticulum is an example of this. It usually contains heterotopic cells within it. The diaphragm, very important muscle to talk about, it's attached peripherally. So at the lumbar vertebrae and at the arcuate ligament, L1 to 3 on the right side and L1 to 2 on the left, it's attached to the ribs, the costal cartilages of seven through 10 and directly to our floating ribs, 11 and 12. And then also centrally at the zip sternum here. Um And it, sorry, it's in terms of the midline of the um thorax at the zip sternum and then centrally it's attached to the fibrous pericardium. It's got openings. Does anyone know at what level? These are? These are quite a common question come up. I've given a bit of a clue. Some of the words are in bold and if you count the letters, it does give it away, I'll let people pop those in the chat. So the caval hiatus, the esophageal hiatus and the aortic hiatus, what levels are those lo located at, let me know if we've got anything in the chat room, if not, I can t eight T 10 T 12. Excellent, good. Yeah, II gave it away. It is just counting the letters but it's useful to know that cos I still, now, when I think about these count the number of letters in, in each of the individual aspects cos it's just a fail safe way of knowing where they are. It's innovated as we said, the phrenic nerve and that c 345 which keeps it diaphragm alive. Um And then some other things just to know. So the cable um the Vena cava, the C opening transmits the Vena cava and the right phrenic nerve, the left phrenic nerve just passes directly into the diaphragm itself. The esophageal hiatus transmits the esophagus and the vagus nerves. And then the aortic hiatus has got a few things in it. So the aorta, the azygous vein, the thoracic duct and the sympathetic trunk. And that one, I try helps me to remember um what goes through it because I think the aorta is the most important of three. So it's got more stuff going along with it. Um But yeah, that's just the way I try and change my memory. So here's some good images. You can see the attachment of the diaphragm here and the central tendon as well as well as the individual hiatus. Um for the vena cava esophagus and also the aorta and then you can see these sort of vertebral attachments. That's remember I said it was L1 to L3. So you can see that it actually passes down the vertebrae a bit, it's not stuck to one. Oh, and we're onto the last slide, I've run a bit quicker than I thought I was going to. Um So this is quite a useful thing to talk about in terms of um relevance of the thorax. I'm very interested in trauma. Um, and thoracic trauma is one of the most important um, areas you need to um, have an understanding of as that's, these are the things that we look for on our primary survey when we're doing a, um, a trauma call in their A&E department. And a really good mnemonic is atom FC. And since we've got a bit of time, we'll let people try and work out what these are. So what are life threatening things that could occur following an injury to the thorax? Cos that's what our primary surveys all about. It's about identifying and treating life threatening injuries. So, what do we think a might be jerome? You're gonna have to let me know when stuff starts coming into the chat because again, I can't, I can't see right. So after this question, we will go back to um the neurovascular bundle slides because Nicola asked. But after this question, so the first one, Mozilla er, has said airway obstruction. Absolutely brilliant. That's, that's the first one that you need to look for cos that will kill people immediately. Although in trauma, you should have AC abc approach. So, c being catastrophic hemorrhage and then you move on to your A cos they all the biggest killer in trauma is, is bleeding. So we need to make sure we deal with that. But yes, A is airway obstruction. What do people think t could be new one? Good. Have we got an O it's related to the t, not yet. Open wounds. Yes, open, but it's related to the T, so it's an open pneumothorax. And then we've got m, again, it's, it's, it's in, it's on a similar vein. We looked at, uh, we looked at an X ray earlier that might have shown one of these, the pleural effusion could also have been, what if they'd had some trauma? What could fill up in the chest? Nothing yet. Nothing yet. Oh, this one's, this one's a bit more tough. So a massive hemothorax. So that's where you've got more than 1.5 L of blood in the chest. So that's a really, really nasty situation to be in f this is quite, we're getting into the tougher ones. Now. We haven't spoken about this specifically. Um, but does anyone know what it's called? If you've got your ribs, you've got sequential rib fractures and it's, it's disassociated from the rest of the chest wall it's got a particular name chest as we know. Brilliant, very well done. And the last one we spoke about the heart quite quickly. But remember there's two types of pericardium, one of them's fibrous. What could happen underneath that if something starts to collect, you might end up with a cardiac tamponade. That's, oh, I did actually separate these out. That's really silly of me. Sorry. The last one, cardiac tamponade. Um So, yeah, that's important to just be aware of when you're doing your primary survey. Atom FC are the things you want to identify and treat immediately. Otherwise your patient's gonna be at at risk of coming to a coming to a un you know, unpleasant outcome, right? Should I, what slide do you want to go back to neurovascular bundle slide? OK. Um You go downstairs. I can't find it. Sorry. Give me two seconds. I'm just trying to OK with them where that one is. Uh Here we go. So did people have any particular questions about this or did they just want to have a bit more of a look at the uh different things that so far it was just about the slide itself. Can we revisit the slide? Absolutely. So I can go over it again. So, the neurovascular bundle which is your vein, your artery and your nerve intercostal nerve artery and vein runs underneath the, underneath each rib in the costal groove. Um and you've got the artery in terms of the, the supply is anterior and posterior. You've got nine anterior um branches and 12 posterior branches, ribs, 136 are supplied by the internal thoracic, which is a branch of the subclavian artery, which from the first part, which is what we spoke about earlier. The vi T so the eye part of that and then the musculophrenic um is a branch again from the subclavian but not directly. So it's an indirect branch. I can't remember where I think it might be the costocervical trunk, but I'm not sure. Um And then you've got posteriorly 12 branches, ribs, 1 to 2 come from the costal cervical trunk directly and then ribs 33 to 12, you get your um branches straight from your thoracic aorta and then that's your arrangement. So vein at top artery in the middle nerve at the bottom. And the question was, I think she said I'm confused by the anterior and posterior division. So you've got anterior branches that come from. So your internal thoracic artery comes from your subclavian and it runs down the front of the inside of the thorax and it gives off branches anteriorly and then these anastomose with the posterior branches that then all you know, meet along the inferior edge of the rib. So you've got a continuous um artery then basically, that's what I meant by that. Sorry if I didn't explain that properly. Does that make a bit more sense? I'm waiting on Nicola to answer yes or no. But it makes sense. Um We do have another question which is uh has asked them if we could go back to the esophagus slide with, with the parasympathetic drawing. Absolutely. Let me see if I can find it. The, this one. So I think it's just, it's just highlighting that your parasympathetic supply is from your vagus nerve at the top. You've got skeletal muscle, which is involuntary control and then smooth muscle further down which you don't have voluntary control over. And then you've got your um sympathetic um which comes from your sympathetic trunk and there's preganglionic cells from T four to T six. And that's where you get referred pain from. I wouldn't worry about learning this in tons of detail, but it's good to have an idea of, of what's going on. And I thought this was quite a handy diagram that I used during my revision. And yeah, so Nicola was asking and Nicola was the girl that asked about the um uh the anterior and the posterior division of uh the intercostal, the bundle. Uh She was asking. So, is this separate to the uh VA N that runs in the intercostal and innermost? No, it's not, it's, it's continuous. So the arteries are continuous. Um Let me see if I can find a quick grounds show what I mean. They're all I didn't include one cos they're really difficult to kind of explain. So, oh, I'm getting a bit of feedback there. Um No, I can't really sorry. I can't find any diagrams that explain it very well. It they're, they're part of that. So the neurovascular bundle consists of a vein, an artery and a nerve. The arteries are divided into anterior and posterior divisions. The anterior ones come from the midline and go back around the chest this way. And then your posterior ones, for example, come from your thoracic aorta, which is in the midline at the back and then run around the ribs to meet in the middle here. So you've got a continuous arterial um ring. Basically, that's all I meant by that saying co OK. So thank you very much Matthew for hosting at the Thax and most of the anatomy series. It was an informative. It helped me.