Swallowing anatomy (pharynx)

[Music] hello I've been fat buying again all day marking exam please I've has enough for that so let's do something more interesting let's talk about an interesting Anatomy I was talking about swallowing this week I've normally left the anatomy of swallowing or maybe the physiology of swallowing to expert and I realized you can actually summarize the important stuff quite nicely so we're going to talk about how swallowing occurs we're going to talk about three longitudinal pharyngeal muscles three constricting pharyngeal muscles we talk about how the larynx moves and we'll talk about how you don't inhale food hopefully but the real I think there's that mechanism of how it works and the other real take home idea is the cranial nerves involved and what happens if those cranial nerves are not working properly if you see what I mean you will see what I mean because we're going to talk about it now all right [Music] first things first then probably the tongue you probably heard of the tongue it's a muscular structure muscular organ inside the old cavity hey we did the cranial nerves of the tongue a little while ago didn't we right so food goes in your mouth you chew it the tongue moves the food random mouth gets mixed with saliva first part of digestion right now when you read about like stages of swallowing and phases of swallowing they might all seem different don't worry about that we don't know talk about that stuff but to start with the tongue moves the bolus of food to the posterior part of your old cavity now this is the hard palate here the bone which is maxilla and this is the soft palate here which is made up of a number of muscles this is the oral cavity this is the nasal cavity this is the larynx down here so all of this posterior space here is the pharynx and down here we have the esophagus so the aim is to get that bolus of food from here to here and avoid putting it in here so the pharynx then we've got nasopharynx or ro pharynx and there enjoy pharynx so the what happens as that is the tone no you'll be doing a lot of swallowing when we're doing this video hopefully do a swallow notice what your tongue doe so the tongue presses against the roof of your mouth so presses against the hard palate and pushes the if I'm going any major saliva but it pushes the bolus of food towards the soft palate and the soft palate raises and it raises separating off the nasopharynx from the oropharynx when it separates off the nasal cavity from the oral cavity which seems like a good idea because that's then going to push the bolus of food down towards the esophagus this is my kids when they're laughing and drinking milk spurt milk out their nose right because the soft palate stops working properly because they start laughing and it drops and air pushes out from the lungs and the milk goes up that away now at the nose and that's all things phalaris so the soft palate raises and pushes against the posterior wall of the pharynx almost all of the muscles of the soft palate are renovated by the cranial nerve the vagus nerve cranial nerve 10 and see that's a theme this is mostly going to be about cranial nerve nine the glossopharyngeal nerve and cranial nerve 10 the vagus nerve the muscles of the tongue incidentally controlled by the hypoglossal nerve cranial nerve 12 is another video about that right alright so the food is pushed into the oropharynx now there are three longitudinal muscles of the pharynx running longitudinally in that direction let's say the first one is stylopharyngeus they're all caught pharyngitis because it all go into the pharynx now stylopharyngeus is coming from the styloid process here right the styloid process is sticky bony bits so from the styloid process down into the soft tissues of the pharynx stylopharyngeus and then we have sour Pingel pharyngitis Sal pings what's the Sal pings well we're talking about the opening of the auditory tube so this is the opening of the pharyngeal team panic tube or eustachian tube or the auditory tube which is the easiest one to spell here which runs towards runs into the middle ear now asal pings was it Greek I think was an ancient Greek trumpet right long flared trumpets we've got a tube that's flared at the end hence Sal pings like the trumpet right so there's a muscle running from the edge of the opening here down into the soft tissues of the pharynx kind of outside the midline Sal Pingo pharyngitis and you know about this one right you know about this because you do it all the time right so when you're in a plane and the cabin pressure changes when you take off or when you're driving and you're going up and down hills you get some discomfort in your ear don't you say years pop and what's happening there is that you've got your external air pressure here and then you've got the tympanic member and then on the other side of the tympanic membrane you've got your middle ear and then that continues as a tube that opens here that auditory tube or foundation Panna tube or eustachian tube or whatever now this opening here isn't very open you've got you know a mucous membrane here you've got nasal mucosa and stuffing there's even more blocked when you have a cold sometimes so this means that when the air pressure changes the tympanic membrane gets deflected so you get a little sensation of pressure and maybe it gets really deflected you go a bit death in that air cuz of course that's impairment paneling memory is not going to vibrate in the same way and detect those sound vibrations is it so what you do is you swallow these you know on a plane might swallow a boiled sweet if you're eating the car driving down hills you do a swallow and the air pressure equalizes because during swallowing the longitudinal pharyngeal muscles are involved and sour Pingo pharyngitis being one of those longitudinal muscles pulls on the opening of the auditory tube and opens it properly and air goes in and goes into the middle ear space and the air pressure is then equalizing your tympanic membranes happy again that's why that works so cell Pingo phone and jeaious do the same thing with you if you're diving into the water and going really really deep you got a lot of air a lot of water pressure on the outside and you increase should've done that even that little bit did it you increase the pressure by you know closing your nose and then blowing air into your nasal cavity and increase the pressure inside the middle anyway that's enough about the year we're talking about swallowing it's not 1 2 3 the third muscle is palate oh Ferran Jaya so the third muscle is running from the soft palate down into the pharynx now if you look inside someone who's made readable light you'll see pillars on either side and there's two pillars on either side when we looked at the muscles of the tongue we said there was palate oh glosses running from the soft palate to the glosses the tongue and posterior to that then the second set of arches those are the pallet o pharyngitis muscles running from the palace they're going just to give you an idea they're running a reign the oral cavity you know it's like the news box that's palliative laryngitis those are the three longitudinal muscles the three pharyngeal longitudinal muscles why are they there and what do they do during swallowing then well when you swallow what happens to your larynx your laryngeal prominence Bob's up and down your Adam's apple Bob's up and down and what we're talking about there is we're talking about the talk about the the thyroid cartilage I mean that's the like that's the laryngeal prominence there and the thyroid cartilage is part of the the larynx and this is all this is all stuck together families when you swallow the larynx moves up and down and this is this is pretty clever actually because we've got a bit of we call it design floor is there a better way of doing I guess dolphins and porpoises and whales do it differently right they have a separate air hole and a separate food intake hole but we have one okay knowing as the nose as well but essentially one intake hole that we pass food and air into and it's incredibly important that we don't get food bacteria and stuff into the airway because that leads to pneumonia or we call it aspirated aspiration pneumonia which is pretty dangerous right so there's a lot of mechanisms to make sure that doesn't happen now you know about one of them what's that flap eCollege they're called the epiglottis and you there's a common misconception in the epiglottis does all the work there's more to it than that it's not terribly complicated there's more to it than that anyway so these three longitudinal muscles of the pharynx contract now if you know your embryology in the pharyngeal arches you'll remember stylopharyngeus is innervated by cranial nerve nine the glossopharyngeal it's a Pingo found jeaious and parts of fine jazz renovated by the vagus nerve cranial nerve 10 nice we're still praying with over 9 and 10 a year now what they do is they lift up the larynx but they're also lifting they're making the pharynx this bit here shorter and wider so by getting shorter and wider it more easily receives the bolus of food from the back of the oral cavity and also then we're bringing the esophagus up to the bolus of food and now this here this is the epiglottis in mid sagittal section and if we look at the laryngeal cartilages here's the hyoid bones the hyoid bone gets lifted up as well we've got digastric the digastric muscle and stylohyoid muscles they also lift up the hold which is attached to all these things this is one of the purposes of the hyoid bone anyway there's the epiglottis cartilage the epiglottis there's the thyroid cartilage cricoid cartilage and can you see that these then these are the vocal cords here and the original cartilages there's another video on that surprisingly enough now there is there is a muscle that attaches the epiglottis cartilage to the written oyd colleges may be called a hairy epiglottis something daft like that aryepiglottic yes that sounds like a gladiator doesn't it but it's I don't think it's not a terribly important muscle but you see here you see how the epiglottis is actually embedded really in the tissues around it so when the when the larynx is elevated by those longitudinal Ferengi or muscles the epiglottis you see so as all this raises the epiglottis kind of stays in place and by staying in place it then covers the the airway it covers the vocal folds and the rest of the larynx so the epiglottis doesn't completely seal off the airway when you swallow it's more like an umbrella defect the deflecting food around it as the larynx is elevated and directing the food into the esophagus so it's not perfect and you know it's not perfect because you coughed and spluttered after having a drink and it going down the wrong way or eating something in the hood and that coughing and spluttering is really important so what really closes off the airway will come to in a minute so the other thing and the other muscles in the pharynx are that are involved in swallowing anyway the other muscles in the bearings are these muscles here now these are the pharyngeal constrictor muscles they're typically described as three cups sat in one of them wouldn't it be sensible if I have actually had three cups somewhere and look at that three cups so the pharyngeal constrictor muscles are going around the face they're described like three cups inside one another and we have the superior middle and inferior pharyngeal constrictor muscles that's that's all there is to it and those guys then those where as the food jug in here is the food then passes into the pharynx is is being shortened and widened those fancy or constrictor muscles then constrict and start off that wave of peristalsis sending the bolus of food down towards the esophagus now this is another interesting idea here is that all the stuff up of this and these are all voluntary muscles under voluntary control their skeletal muscle based right and the muscles of the the pharyngeal constrictors are innervated by the pharyngeal plexus which receives nerves from again the glossopharyngeal nerve root of 9 and the vagus nerve cranial nerve 10 I think that pharyngeal constrictor muscles are typically described as being innovative by cranial nerve 10 the vagus nerve but then as we go down the esophagus the upper part of the esophagus also has skeletal muscle and as we descend that skeletal muscle changes to smooth muscles we go from voluntary skeletal muscle in the upper part of the esophagus to involuntary smooth muscle in the lower part of the esophagus and then of course it's been all like that all the way through the GI tract until the end and we have that wave of peristalsis pushing things along all right so there's that there's that blend there and of course it's the vagus nerve that innervates the rest of the GIH and that's where the parasympathetic innervation comes from right which is cool the way starts here 4z all the way down does that make some more like structural engineering sense now like what are we talking about oh yes coughing and spluttering after food going down the wrong way right so what's happening there is the food or water more commonly in whatever you're drinking gets around the epiglottis because it's not a perfect seal and it gets into then the upper part of the larynx inside the larynx here it's very irritating got a lot of sensory nerves they're allowing she's not very happy about this because it doesn't want physical things going to your lungs it just wants air going in na'vi lungs the thing that really stops aspiration really stops food and water getting into your lungs and get into your airway are the vocal cords also known as the true vocal folds right they close when you swallow so there's another funky thing that happens is that during swallowing the Centers of respiration is a reflex that goes to the Centers of respiration nearby in the medulla telling them to stop respiration so respiration actually stops for a moment while you're swallowing and I think there's an idea that when you when you swallow you tend to swallow when your lungs are full on an aged breath then you stop breathing which makes sense because if you do need to cough or splutter you've got air in your lungs you can cough and splutter it up right it's really difficult to test because now you think about it if you try it when you're eating and drinking because you've already thought about it you've already knackered the experiment only but that's an idea anyway it seems like a sensible idea so it's these intrinsic muscles of the larynx the review on that which closed the true vocal folds and make a proper tight seal preventing that water that might have got past the epiglottis with the food from going any further into your airway stops it and then you can cough and splutter it back up again that's the idea if it all works properly what nerve innervates the intrinsic muscles of the larynx it's the vagus nerve again cranial nerve 10 and of course it's branch which you might have said the recurrent laryngeal nerves the recurrent laryngeal nerve comes off the vagus in the thorax on the left side it loops around the aorta on the right side it loops around the right subclavian artery but good Ambria logical reasons and then ascends back up and innovates all these intrinsic muscles of the balance all of this means that for safe swallowing to occur these cranial nerves need to be working properly cranial nerves 9 and 10 The Closer pharyngeal and vagus nerves need to be functioning properly so if somebody's got a problem that means that they've got a brain injury brain trauma and they've had a stroke they've got you know whatever neurodegenerative disease might be affecting cranial nerves 9 and 10 you then have to worry about their ability to safely eat and drink food because you know there's a risk of choking and that sort of thing but a bigger risk is aspiration pneumonia and that's that's a really big thing all right so do you see how the emphasis is on those cranial nerves so now hopefully you'll think about those cranial nerves and swallowing is a process gag reflex we should do the gag reflex while we're here shouldn't we so the gag reflex which you may well be familiar with because it's probably happened to you describes what happens when an object you know when you're not swallowing when a knob touches the posterior often the posterior parts of your cavity and the oropharynx that sort of space there and then you are kind of rich and try and push that object up the purpose of the gag reflex is to prevent choking is preventer a physical body blocking the airway isn't it now the posterior part of the tongue you may remember if you watched that video the cranial nerve carrying sensory information when the posterior part of the tongue is the glossopharyngeal nerve cranial nerve nines I see the glosso pharyngeal the glosso is the posterior tongue bit the pharyngeal is the pharyngeal bit and the soft palate and this sort of region around here so it's generally described but the glossopharyngeal nerve is the sensory limb of the reflex which sense is the object and then the vagus nerve cranial nerve 10 is the motor limb of the reflex that then causes contraction of these muscles to stop the object from going any further or any closer to the airway and then of course you've got a whole gagging thing where you try to expel the object so cranial nerve nine is the sensory bit cranial nerve 10 is the motor bit interesting thing about the gag reflex is that it can be unlearned and it can be relearned and they may come and go over the years for no apparent reason some people might have a really sensitive gag reflex for a period of time like your toothbrush touching the back of your tongue might trigger it and then they're my go away so when assessing a patient if if there is no gag reflex there might be entirely normal and there may be no pathological reason for it you when you when you are something say you don't test the gag reflex normally that's not a very nice thing to do but when you ask somebody to say you look at the soft palate you expect both sides to raise that's testing cranial nerve 10 because as we said the vagus nerve innervates almost all of the muscles of the soft palate anyway there's lots of fun and that's me in the head and a butt that'll do for the minute so how's that do you now have a better understanding of the anatomy of the swallow knots much the physiology of the swallow we've talked about the tongue and its purpose in pushing the food to the posterior of the oral cavity we've talked about the hard palate and the soft palate we've talked about those three younger tune or pharyngeal muscles and the three constrictor pharyngeal muscles and how thee the palate gets short so that the pharynx gets shorter the larynx is elevated had the epiglottis acts as kind of a shield kind of an umbrella over the airway but it's the true vocal cords that actually block off the airway and prevent food and water from going down there and that's it in a nutshell and our cranial nerves of today are cranial nerves 9 and 10 and the glossopharyngeal nerve and the vagus nerve all right [Music]

Channel: Sam Webster

Views: 136,573

Keywords: anatomy, human, swallowing, gag reflex, pharynx, larynx, stylopharyngeus, salpingopharyngeus, palatopharyngeus, constrictor, hyoid, vocal cord, thyroid cartilage, oesophagus, esophagus, vagus, glossopharyngeus, CN X, CN IX, Sam Webster, Swansea, dontbeasalmon

Id: 0HklsPDqkmg

Length: 21min 42sec (1302 seconds)

Published: Mon Dec 24 2018