hello everybody and welcome back to another Anatomy tutorial today we're going to be looking at the anatomy of the larynx now I know this is a topic that many people find difficult to conceptualize the 3D relationship between the various different components that make up the larynx and hopefully by the end of this talk we'll have a much better understanding of how the various structures fit within one another we'll start by looking at this diagram that I've made and then move on to look at these structures within the CT now today's focus is going to be mainly on the major components of the larynx and the components that we need in order to Stage laryngeal cancers there are lots of smaller components that I will look at in another video especially the intrinsic and extrinsic muscles of the larynx so let's start by having a look at this cartilaginous and bony structure that make up the exterior shell of the larynx and provide the larynx with its anatomical structure and it's these various components that we're going to be trying to look for on our CT in order to figure out where the different components are in relationship to one another so on the left hand side here I've drawn a lateral view of the larynx and at the superior aspect of this diagram we can see a hyoid bone wrapping around this red structure so this green structure here is the hyoid bone coming around this red structure which is known as the epiglottis now the epiglottis runs from inferior to Superior as well as running from anterior to posterior so you can see the left hand side of this side of the image is the anterior portion of the patient here is our posterior portion and our epiglottis Slants posteriorly like that wrapping around the epiglottis in the semicircle or C shape this incomplete ring of cartilage around the epiglottis is what's known as our thyroid cartilage we've got these large left and right lamina of the thyroid that come and form this laryngeal Notch at the front of our thyroid posteriorly we've got these Superior horns both the left and a right Superior horn and inverity we've got these inferior horns that articulate with this cartilage below here which is known as the cricoid cartilage now the cricoid cartilage is a complete ring and it gets much thicker posteriorly and as we head out anteriorly that band or that anterior arch of the cricoid cartilage becomes much thinner and people describe this as a Signet ring shaped structure here and it's one of the only rings of cartilage within this upper respiratory tract that make a complete ring all the way around not shown here is our thyrohyoid membrane that I've got on this other image which connects the hyoid bone to our thyroid cartilage you can think of that hyoid bone as holding up all these structures there's membranes connecting each and every one of these components so the top of our larynx is that hyoid bone and the bottom of our larynx is this cricoid bone from which everything stacks on top of it between our cricoid and our thyroid cartridges we've got this cricothyroid membrane and that's if we were to make an emergency Airway that's the membrane that we would need to cut through now if we rotate this image round and we look posteriorly we look in that angle to this image this is what we will see here now you can see I've cut off the highway bar in here and cut off this section of thyroid cartilage in order to be able to see into the main area of our larynx again our hyoid bone wraps around and we can see the spiral hyoid membrane between the thyroid Cottage and the thyroid bone our epiglottis has this leap shape and the stalk of the epiglottis heads down towards our thyroid cartagen attaches here the epiglottis will fold backwards as we swallow it will go in this direction and cover these structures that we see here we can see our cricoid cartilage is making a complete ring all the way around thicker at the back than it is at the front and on top of those cricoid cartilages which we couldn't see on this image are our arytenoid cartilages and these are really important structures when we're looking at the vocal cords the arytenoids are paired cartilaginous structures and there's a cricoaryotenoid joint here it's actually articulation between that cricoid cartilage and later retinoid cartilage we can see coming from the erotenoids as a vocal process of the erotenoids and then this vocal ligament that heads from the erytenoid cartilage all the way to the anterior surface here of our thyroid cartilage and these ligaments are the structures that run within our true vocal cords we're going to look a lot more closely at these vocal cords especially on the Imaging and lastly to note on these diagrams are our tracheal cartilaginous Rings we've got our tracheal rings that head down the trachea below our cricoid cartilage is the beginning of our trachea and you can see that they don't make complete Rings all the way around the track yet and this is actually where the esophagus runs posteriorly to the trachea and this incomplete ring allows for a food bolus to travel down here unobstructed by those quadrilateral strings so let's move on this is the image that we have seen now that we've examined and there's some soft tissue that drapes between these arytenoid cartridges and the epiglottis itself so I've cut away this section of diagram here and I've overlaid this soft tissue or this mucosal membrane that wraps from the arytenoids heading up all the way to the epiglottis so this fold of soft tissue that creeps between the superior process of the aristenoid and the epiglottis is known as our area epiglottic fold our area epiglottic fold then sends down this mucosal membrane that heads all the way down to our vocal cords and within this fold of mucosal soft tissue is our quadrangular membrane that also heads down towards those local chords now what's important to appreciate here and quite difficult to illustrate but we're going to see much better on our CT scans is that this fold of mucosal tissue that heads down towards our vocal cords holds inwards before reaching these true vocal cords here it folds inwards on itself makes a space that we can't see in this image and then heads out again to make these vocal chords so this first fold of tissue coming around like this is what's known as our false vocal chords that Boulder tissue comes right the way around makes a space between this false vocal cord and the true vocal cord known as our laryngeal ventricle I laryngeal ventricle then Falls round and comes and makes our true vocal cords which has our vocal ligament running within that form of tissue that might be quite difficult to see on this diagram but I want you to realize that that false vocal chord comes in makes a laryngeal ventricle and then comes out to make our true vocal chords is actually a space between these two pieces of tissue when we look especially at our coronal images we're going to see that laryngeal ventricle is a really important Landmark when staging laryngeal cancers now lastly I want to look down the larynx like this we're going to be looking in theory at the vocal cord so let's move to that view we're now looking down like that and this is what we'll see when we pass an endoscope into the patient where we're trying to place an endotracheal tube which is going to have to come between these vocal cords anteriorly here is the base of our tongue that is where you slide the blade of the endoscope down and lift forward and lifting that tongue forward will lift this epic lattice here anteriorly as well because the base of the tongue and the epiglottis has a fold that connects them this is our median glosso epiglottic fold and we're going to see that really nicely on our images on either side of that median glossary epiglottic fold we have these spaces here known as molecular so the blade of our endoscope is going to come in here that Medium gloss epiglottic fold as we apply pressure anteriorly we'll lift this epiglottis away from the vocal cords we can see posterity here our cricoid cartilage with our retinoid cartilages lying on top of the glycoid cartilage and we can see our true vocal cords coming towards this anterior commissure here the angle of the anterior part of our vocal cord now those arytenoids can rotate internally to close the vocal cords or rotate externally to open the vocal cords open vocal chords are going to allow us to breathe slightly closed vocal cords will allow us to phonate or to speak the vibration of those vocal chords is going to create sound and then closing of those vocal chords will prevent fluid from coming into the trachea and actually head down into the esophagus rather we can see this tissue here which is our false vocal cords and in between this dark false vocal chords and this light true vocal cords will be our laryngeal ventricles what I haven't drawn here is the connection between the superior process of our retinoids and our epiglottis like this which is our area epiglottic fold coming across like that posterior to this we've got large sinuses known as our piriform sinuses which form part of the hypopharynx if you can imagine this epiglottis folding downwards like this the primary function of that epiglottis is to divert food and fluid away from this larynx and into our esophagus now the epiglottis doesn't actually provide a watertight seal it's our vocal cords coming together that provide a water Tight Seal but our epiglottis is curved and it allows for deflection of the food and liquid away from this laryngeal complex now all of these structures constrict together to form a closing of that larynx and we're going to look at that first on a barium swallow identify these various structures and then move on to our CT scan so let's start by looking at this lateral radiograph we are now going through a basic sequence of a barium swallow to get our orientation here we can see the mandible here we can see the patient has a mouth full of contrast a hard palate coming across a soft palate coming down separating our nasopharynx from our oropharynx and then we can see our hyoid bone here below the mandible posterior to that hyoid bone is our epiglottis coming up like this and that space in front of the epiglottis between the epiglottis and the base of the tongue are alvecular here we can see our piriform sinuses behind our larynx that will eventually head towards our esophagus then we can see our trachea anterior to that esophagus we can actually see the true vocal cords our laryngeal ventricle here and our false vocal cords lying below this epiglottis now as the patient swallows I want to show you what those laryngeal structures do when we swallow and you can actually do this on yourself by holding your tracheal cartilage and swallowing you'll feel all those structures rise and then fall and that's what's going to happen on this patient let's start by looking at the hyoid bone as the patient swallows you see that hyoid bone lifting up now that thyrohyoid membrane means that that thyroid cartridge is going to lift up and as that thyroid cartilage lifts up our epiglottis lowers down so let's look at our epiglottis here as we swallow that epiglottis goes from being upright to going more shallow and then completely sharp like that you can see how our epiglottis has gone on top of those vocal cords and this fluid now is having to track posteriorly into our esophagus none of that fluid is coming into the larynx similarly you can see our vocal cords here lifting up up and shutting to be completely shut that trachea off from our digestive tract you can also see how the soft palate rests against that posterior pharynx which prevents fluid from coming up through our nose as well and then we can follow that liquid all the way down now as we shut all these structures once we've swallowed the liquid and we open those structures up again those structures will be lined Now by some of this barium contrast and that helps us to identify those structures more easily on the radiograph so we follow them swelling all the way and we can finish with this picture here you can see the contrast on top of the tongue running down to the base of the tongue and pooling within the velecular here you can see our hyoid bone running across and our epiglottis coming up like this we can actually see that array epiglottic fold here extending from the epiglottis all the way down towards the alertinoids and again here we can see our piriform sinuses which have been layered by some of that contrast and then our esophagus heading off down posteriorly there's no contrast on the vocal cords because our epiglottis have covered those vocal cords when we did the swallow so now let's move on to our CT scan and identify some of the anatomy there we'll start by having a look at the Electoral CT scan which will mimic that lateral x-ray that we've just taken so here we are we can see our hard palate our soft palate our nasopharynx above our oral pharynx heading down towards our larynx here you can see the clivasts and our seller toastica and our sphenoid sinuses all structures that we've covered in previous talks and then we can look more closely at the larynx itself let's start by looking at the hyoid bone which is anterior to our epiglottis here we can follow that hyoid bone all the way around you see how it wraps around that epiglottis all the way around on both sides as we go back to the midline now we can see our epiglottis with our molecular those spaces anteriorly to the epiglottis and the base of our tongue here and we can just see that median glossoplottic fold attaching the base of the tongue to the epiglottis here the epiglottis has a free Edge and it extends all the way down to its root where it attaches to the thyroid cartilage here now anterior to that epiglottis we can see a really useful Landmark which is known as our pre-epiglottic fat you can see that the density here is fat density if we were to look at our subcutaneous fat here it's the same density as this that we're seeing here this is our pre-epiglottic fat the epiglotto says then heads down to our thyroid cartilage and I've actually chosen this image because the cartilages in this patients have become a little bit ossified and makes it more easy to identify them on a CT so we can see our thyroid cartilage wrapping around here all the way down with our Superior and our inferior horns coming down to the anterior portion with our laryngeal Notch of the thyroid the atoms Apple that you can feel on the on the male below that thyroid is our large posterior portion of our cricoid and our anterior portion of our cricoid there's our cricothyroid membrane between the two you can see above the cricoid we should be able to find our arytenoids if I go slightly laterally we can see our retinoids there with our cricoarytenoid joined there our retinoids will give off our true vocal cord across the larynx as well as superiorly giving off this Airy epiglottic fall that we see heading down here if we head then to the midline we can see our true vocal cord as well as our false vocal cord that fold of tissue down separated from the true vocal cord by this laryngeal ventricle so let's have a look at what that looks like on an axial CT we can start off in the nasopharynx head our way down we see the UV lay here coming down and keep scrolling down until we see the tip of the epiglottis so there's the tip of the epiglottis coming into view we can see our median glosso epiglottic fold here joining the epiglottis to the base of the tongue laterally to this fold or our left and our right follicular that's where the blade of our endoscope will go down and lift that epiglottis away posteriorly we can see these piriform sinuses that don't form parts of the larynx they actually head down into the hypopharynx so as we head back up let's look at this epiglottis coming down we should see our are epiglottic folds now come into view we're scrolling inferiorly on the patient this is that tissue that heads from the arytenoids to our epiglottis are are epiglottic Falls our area epiglottic folds then should come down towards the peritonoids here are our retinoids let's hit slightly superiorly and try and find those false vocal chords you can see anteriorly that fat density in our pre-epiglottic space our area epiglottic folds here and as we come down we can see that fat density coming out laterally here and this is a sign that our folds here are our false vocal cords if we were to scroll down slightly inferiorly we should then come into those laryngeal ventricles below those false vocal cords let me scroll down slowly one slice here here are our false vocal chords starting to see the openings of our laryngeal ventricles let's go one down here we are now in the space of our laryngeal ventricles this widening of that Gap we can see our cricoarytenoid joined here which is an indicator that we're heading to the level of the true vocal cords let's go one further down and we should see our true vocal cords coming into frame here with a sharper anterior commissure here this is not the hyoid bone this is in fact the thyroid cartilage it's just been ossified in this patient we can see our cricoid bone posteriorly and then these true vocal cords with the vocal ligament within them now we know that this is a true vocal chords because we passed that crico retinoid joint as well as we've lost that fat density around these chords so we're at the level now of the true vocal chords as we scroll down further we should see that complete cricoid ring forming like that and now we are in the track here you can see posteriorly to the trachea is our esophagus and our tracheal Rings don't make a full complete ring allowing for a fruit bonus to pass unobstructed by those tracheal rings lastly we can look at our coronal some people find this quite difficult to understand and we're really lucky here because our cartilages are so ossified we can see our hyoid bone that's wrapping around our epiglottis here's the tip of our epiglottis and epiglot is heading now down towards our thyroid and cricoid cartridges and this is our Airy epiglottic fold that piece of tissue that's coming down of piriform sinuses can be seen laterally here and this area epiglottic fold is going to come down and this fold of tissue here is going to form our false vocal cords you can see that fat density surrounding those false vocal cords then we have our laryngeal ventricles coming out like that before getting to our true vocal cords here no fat signal on either side of those true vocal cords we can see our cricoid cartilage there articulating with those inferior horns of our thyroid cartilage and this is the kind of goblet-shaped cup that you'll see here from the bottom of our cricoid that now becomes trachea that is no longer larynx now in order to Stage laryngeal cancers we may need to know the boundaries of our larynx so we separate the larynx into three separate sections our supraglottic section our glottic section and our subclotting section and it's really easy to do our supraglottic section runs from the tip of the epiglottis here all the way down to the superior surface of our true vocal cords so from this region of the epiglottis all the way down we find our true vocal chords anything above that Superior surface is known as Supra epiglottic I'll learn your ventricles our false vocal cords our area epiglottic folds our epiglottis the thyroid cartilage all of that is in our supraglottic region our glotic region is made up solely of our true vocal cords anything from the superior border to the inferior border of our true chords is known as the colotic region our subglottic region is from that inferior border of our true vocal cords all the way down to the inferior border of our cricoid cartridge here so this is where our larynx ends and our trachea begins so you can see that in order to understand the structure or the anatomy of the larynx they actually aren't that many big components that we need to know but if we can identify the hyoid bone the epiglottis the thyroid cartilage our retinoid cartilages and our cricoid cartilage as well as those array epiglottic folds and our false and true vocal cords we've come a long way in identifying the various structures within the larynx now if we were to see a mass within the larynx that's extending throughout the lungs we can then subdivide the larynx into those three separate sections of supraglottic alkalytic and our subclotting section in order to describe the origin and the extent of that mass or cancer or laryngeocell that is growing within the larynx so I hope that's helped you understand the various structures within the larynx we haven't covered the blood supply the nerve Supply and the different muscles that surround the larynx I'm going to leave that for another video because this then starts becoming extremely complicated I want you to understand the broad brush Strokes approach to the land so if you like this style of video where we go through some medical diagrams and then we actually go through clinical images identifying the various different pieces of anatomy please consider subscribing to the channel liking the video and signing up to my newsletter I send out a newsletter once a month sharing some of the resources that I've been enjoying I share with you various cases I share with you the odd meme or two as well as sharing with you some of the tips that I have for writing your part one anatomy and physics courses the link to that monthly video will be down below otherwise I'll see you all in the next video goodbye everybody