hi ninja nerds in this video today we're going to talk about the medulla oblongata or as bobby boucher from the water boy would say because my mama said it's alligators so orange because they got odd empty no toothbrush all right guys so what we're going to do is we're going to talk about the medulla we're going to have three cross sections right we're going to go over all the internal structures of the medulla just like we did with the mid brain and the pons what i want to do though is we're going to have three sections i want to explain at what cross section we're looking at okay so first thing let's go ahead and take and just do a frontal section so basically i'm gonna take and slice right here okay and we're gonna look at this at three levels right so here we have midbrain here's pons here's your medulla and then continuation to the spinal cord right first you know complicit you know complete in the sake we have the cerebellum now what we're going to do is here's from this point here to this point here is our medulla okay the first one that we're going to look at the first level i'm going to slice it here with this red is we're going to look at this level here this transverse section or cross section is going to be at the pons medulla junction this is going to be this section here section one is the most superior aspect or section of the medulla or another word that might come up is the most rostral portion of the medulla then what we'll do is we'll come at another level here kind of within the middle this middle portion is where we're going to call the sensory decussation this is where you have that nucleus cunatus nucleus gracilis the receiving the sensory information from the fasciculus gracilis fasciculus cunatus and they cross and go up as the medial meniscus that's going to be the second part then we're going to come down here at the last part the most inferior or caudal portion of the medulla and this is going to be at the pyramidal decussation so that's when you have those corticospinal fibers that are coming down and they're going to cross at that level the lateral ones cross 85 cross into the lateral column and 15 stay straight in the ventral column right so three sections first one is going to be here at the top the middle one is going to be here on the bottom and the third one is going to be here at this right okay so let's go ahead and start focusing on the most rostral portion all right engineer so let's go ahead and start with the rostral portion okay this part here is the most superior most rostral component of that medulla cross section right and again just to give you guys some orientation this portion here is the ventral portion of the medulla this portion back here is the dorsal portion of the medulla right what we're going to do is to help you guys out is we're going to start here at this structure here and we're going to kind of work our way in a circle and the nice thing is that this video is going to be very repetitious because a lot of the things that you see at this level you're going to see it pretty much all the other levels so it's going to be very very consistent repetitious by the end of this video you guys will know this completely well okay so let's go ahead and start here with this first structure that's paired on both sides if you guys look at this guy this is called your hypoglossal nucleus hypoglossal nucleus is what cranial nerve it's cranial nerve 12. so again what is this guy we're going to have a key it's pretty long key but it's the best thing that we could do here so we don't have arrows coming all over the place making this diagram is not very nice so again first one here orange nucleus that is going to be the hypo glossy nucleus okay this is for what cranial nerve cranial nerve 12. okay next one we got this structure we're going to move a little bit we're going to keep moving laterally and then forward okay so now we go here outside just a little bit lateral to the hypoglossal nucleus what is this guy this is the dorsal nucleus of vagus again what is he dorsal nucleus of vegas and again what cranial nerve is the vagus nerve this is cranial nerve 10. so hypoglossal nucleus and the dorsal nucleus of vagus move out a little bit more laterally and a little bit more anterior what do we have here we got this guy the nucleus of tractus solitarius right so what is he called the nucleus of tractus solitarius right this guy is so cool and again we'll discuss more of their functions in a second i just want to go ahead and start off by knowing the structures then we'll get more into their function okay so hypoglossal nucleus dorsal nucleus of vagus what's a little bit more lateral in anterior the nucleus of tractor solitarius okay go out a little bit more a little bit more laterally you have this two structures that are part of a whole nuclear complex this is actually the vestibular complex right the vestibular nuclear complex but if you guys remember in the ponds video we had four components of it the superior the lateral the medial and the inferior vestibular nuclear complex if you guys remember in the pons video you can really only see the superior the lateral and parts of the medial vestibular nucleus you can't see the inferior at the pons right the lowest section of the pons now in the medulla you can see parts of the medial vestibular nucleus and primarily the inferior vestibular nucleus so again what are these two structures here these are your medial and inferior so medial and inferior vestibular nucleus okay sweet next guy these green guys we're going to move a little bit more louder the hypoglossal nucleus dorsal nucleus of vegas nucleus attractive solitaries medial inferior vestibular nucleus more laterally you got your dorsal cochlear nuclei and your ventral cochlear nuclei again dorsal more in the dorsal component of the medulla ventral more in the ventral portion of the medulla pretty self-explanatory right guys so again we've got dorsal and ventral and ventral cochlear nuclei sweet deal okay go a little bit more laterally over here you got this big white matter tract okay this is the white matter connection between primarily the medulla and the cerebellum i know you guys know this this is the inferior cerebellar peduncles so again what are these the inferior cerebellar peduncles sweet deal again what is this is that white matter connection between primarily the medulla and the cerebellum okay what do we got here again hypoglossal nucleus dorsal nucleus of vegas nucleus attractive solutaries medial inferior vestibular nucleus dorsal cochlear nuclear ventricular cochlear nuclei inferior cerebellar peduncles move out a little bit more laterally what do you got here this is the ponto bulbar body okay what is this little green here called this is that ponto bull bar body okay and again we'll talk about its relationship with this kind of blue fiber in a second okay okay move a little bit more anterior now what do we got we got this pink tract here what is this guy called this is your ventral spino cerebellar tract okay so what is he called your ventral spino cerebellar tract sweet deal okay move a little bit more anterior here what do we got we got our inferior olivary nuclear complex again what is this guy here this little weird-looking u-shaped thing that son of a gun right there is the inferior olivary nucleus okay and we'll talk a lot about this sky a little bit later when we get to his function okay all right move a little bit more again kind of medially and anteriorly here we hit this blue structure what is this guy called this guy is the arcuate nucleus so again what is he called here we have him as the arcuate nucleus okay i want to take some time to explain what the heck all these like blue structures are moving all around the place the arcuate nucleus is really cool because what it does is let's say again this is our left medulla right the hemp part of it the left section of it and this is the um right section of the medulla right so if i were to kind of slight this and slice this in half this is the left is the right this left arcuate nucleus gives fibers that moves to the contralateral side as you see here and it also gives ipsilateral fibers moving that you see here okay now these fibers when they cross they form these contralateral connections that move along these kind of like little divots on the anterior portion of the medulla and work their way towards this ponto bulbar body what are these fibers here called these are called your anterior external arcuate fibers again what are they called interior external arcuate fibers and again they're connecting between what the arcuate nuclei and the pantobobar body okay but again they have contralateral connection okay arcuate nuclei are actually interesting because they're believed to be the inferior kind of portion of the pontine nuclei remember those we had the ponte nuclei and that pons these are just believed to be an inferior extension of those ponte nuclei and they're believed to play some type of role and maybe sleep okay so again you have these actually sleep and more of the breathing processes as well but again what i want you to know here arcuate nucleus has the connections going to the pontool bulbar bodies as the anterior external arcuate fibers now these arcuate nuclei also give fibers that move on the same side so far so this is ipsilateral so from the left arcuate nucleus this is the left from the right arc nucleus is that right fiber they're coming and working their way posteriorly through the midline of the medulla as they work their way posteriorly through the midline of the medulla they cross so they come out the back and eventually they cross and when they cross they form another special structure but look where they're moving towards they're moving towards this ponto bull bar body okay so again arcuate nucleus gives its fibers that work posteriorly and cross to the contralateral sides of that contralateral bulbar body so again right arcuate nucleus will give its fibers and this will cross over here what is this blue structure here in the back of the medulla this is an important one and we already talked about this in the pons this is called the straya medullaris this is called the straya medullaris the striatum medullaris is really important because do you remember what we said about that structure remember we said that the fourth ventricle and the posterior part of the brain stem at the pons and medulla area you have the fourth ventricle forming the anterior wall of that fourth ventricle right was the pons and the medulla above the stria medullaris that fourth ventricle anterior wall was formed by the pons below the stria medullaris right the anterior wall that fourth ventricle is formed by the medulla and again that is that stria medullaris all right so we hit this arcuate nucleus let's move a little bit more dorsally right so we've kind of gone from here working our way around okay this kind of red dicey-like structure here is called the corticospinal tracts right so this is going to be the corticospinal tract you guys remember those coming from the cortex moving down to the spinal cord those are motor pathways so again what is those called those is called the corticospine tract all right sweet let's move a little bit more dorsally so we're kind of just working our way around here now we're coming to this guy this maroon son of a gun what is this guy this is our medial lemoniscus medial limb meniscus who comes up with these names you know so medial liminiscus you guys remember this guy you guys better remember him we've talked about him so much again this guy carries that proprioceptive information that fine discriminative touch that vibration sensations through that dorsal column again we'll recap it a little bit later okay we hit this one let's go here now so again working our way around here to this purple structure what is this guy this purple where's my purple marker oh i got here this guy right here is called the spinal lemniscus what is he called the spinal lema niscus okay so good we hit that one so we got went through here we hit the medial meniscus we hit the spinal meniscus now we're gonna do is we're gonna kind of work over here and then we'll come back here to the middle okay so we're going to go here and work our way here so now let's cover this structure this guy right here is called we've seen him so many times this is one of the trigeminal nuclei remember at the medulla at the midbrain it's the mesencephalic nucleus at the pawn it's this the principal pontine or central pontine nuclei and in the medulla it is the spinal nucleus of the trigeminal nerve and associated with it is the trigeminal tract now i'm going to write these down but i want to explain something a little bit better than i did in the pons video with this one so that we completely understand this one okay so again this is the spinal nucleus and this is the tract and this is for what of cranial nerve five the trigeminal nerve i want to take some time just really quickly to explain what this means okay so here i'm going to draw acro a sagittal section here so okay cerebrum midbrain pons medulla spinal cord cerebellum right since we have this in that kind of navy blue color i'm going to have here spinal nucleus of the trigeminal nerve that central or principle ponte nuclei and the mesencephalic nucleus all of these are for the trigeminal nerve right if you guys remember from the trigeminal nerve video we had that trigeminal ganglion right they gave off the v1 v2 v3 divisions right all those different things we talked about in that video we're not going to go over that but remember they're picking up sensory information from in the entire face on the ipsy lateral side when they send this information in and they go to these individual nuclei this right here is the trigeminal tract okay or that spinal tract okay so again this part here since we're talking about the spinal nucleus this right here is that tract that's the spinal tract of the trigeminal nerve then what we said is coming off of these nuclei they give their fibers that move upwards towards the thalamus what is that structure called that is the trigeminal lemoniscus or the trigeminophthalmic tract so again i want to make sure we understand that this is the trigeminal leniscus or the trigeminophthalmic tract coming from these nuclei and this right here is the trigeminal tract particularly at this portion here this is the spinal tract okay all right let's go ahead and move on to the next structure here all right so the next one we got here we went this way medial meniscus spinal meniscus spinal nucleus and tract let's kind of come back over here to the middle okay so now we got this guy this kind of blue tract here what is this son of a gun this guy is the tacto spinal tract there's so many things in the medulla it's insane right so tectospinal tract again this is that that track we talked about already so many times it's involved with what the reflexive movements of the head and the eyes in response to supercaliculus is visual stimulus inferior colliculus is auditory stimulus done next one let's move out just a little bit back here so a little bit more posterior then a little bit laterally here what do we got we got this rubro spinal tract we've talked about this one about a thousand times what does this guy do he carries descending motor pathways rubber spinal tract carries descending motor pathways from the red nucleus in the midbrain down to the spinal cord that can play a role with flexor movement okay done go a little bit backwards a little bit more dorsally so we hit media lemoniscus spinal meniscus again we hit the spinal rubric spinal we're at this green guy this is one another one that we've hit like a thousand times this is the medial longitudinal fasciculus what is he called the medial longitudinal fasciculus again what does this guy do he connects the media vestibular nucleus right he sends the information to the six nerve nucleus that six nerve nucleus sends contralateral fibers up that connects the third fourth and sixth cranial nerve nuclei so again it's the connection between the three four six rhino nerve nuclei helps with conjugate movement of the eyes boom done go a little bit more backwards here so a little bit more posteriorly we hit this black tract nucleus ambiguous all right weird name all right nucleus ambiguous but it's actually a really cool structure here responsible for the special visceral efferent fibers which is going to be supplying muscles of your pharyngeal arches and we'll talk about those later all right sweet move a little bit more laterally here what do we got here this brown one here is the inferior salivatory nucleus alright so this is the inferior salivatory nucleus again so what is he he's the inferior salvatory nucleus this is actually specifically related to the glossopharyngeal nerve right so it connects the glossopharyngeal nerve has that general visceral efferent fibers and that basically connects to what's called the odec ganglion has fibers that go from this nucleus out to the other ganglion and then has parasympathetic fibers that go from that to the parotid gland right so it plays a role in salivation all right sweet so we hit the nucleus ambiguous we have the inferior salvator nucleus we got one more guy here and this one here as you move a little bit laterally here what is this one this one right here is actually super interesting this is actually your descending sympathetic tract okay coming from the hypothalamus we'll explain that later okay so again what is this one we have a little bit down here this one here this blue one here with the dots this is that sympathetic tract and again it's a descending tract all right sweet we hit a bunch of structures here within this most rostral portion this cross section of the medulla at the pons medulla junction now we're going to go do is we're going to move caudally right so we're going to go a little bit we're going to take another slice kind of a little bit lower in the medulla a little bit more cuddly inferiorly all right so now again we have a cross section at what level the sensory decussation again that's what i want you to remember when we did that there was ponzo modular junction this section that's more caudal is at the sensory decussation we'll explain what that means in a second again let's start from the posterior aspect work our way around here a lot of this stuff is going to be things that we already covered we'll pick up a couple structures along the way though so it's going to be good repetition okay so now work here what is this structure here in the most dorsal again dorsal back here ventral here this is going to be what is this this is the fasciculus gracilis so again what is this guy here this blue tract here this is attract so it's called the fasciculus fasciculus gracilis the fasciculus gracilis is taking that sensory information right from the dorsal column carrying proprioception fine discriminative touch vibrations but where is those these this fasciculus this track coming from i want you to remember that this is coming from the lower extremities okay so lower extremity proprioception uh fine discriminative touch and vibrations this thing this fasciculus gracilis is eventually going to terminate on this nucleus a little bit more ventral what is this guy well this is the fasciculus chrysalis it terminates on the nucleus gracilis so what is this guy here nucleus gracillus all right sweet now move a little bit more laterally okay as we move a little bit more ladders so again you get your nucleus you get your fisticulous gracilis and your nucleus gracilis move a little bit more laterally you have your fasciculus cunatus and your nucleus cunatus so again what is this son of a gun here this is the fasciculus cunaitus and this is the nucleus cuneiatus all right again fasciculus cunatus it's carrying proprioceptive sensation fine and discriminative touch vibrations from the upper extremities okay and even a little bit from the trunk okay so again it's picking up sensations from the upper extremities gracilis is lower extremities simple as that okay cool we hit the sympathetic track already so if we were to move laterally we know that what we would have here is the sympathetic tract and again we already covered this structure what is this structure here called this is the inferior cerebellar peduncle so again we've hit fasciculus gracilis fasciculus cuniatus nucleus gracilis nucleus cunatus inferior cerebellar peduncle and the sympathetic tract all right cool you guys already know this one what's this thing we already covered it above this is the spinal nucleus and the spinal tract of what cranial nerve cranial nerve 5 the trigeminal nerve okay move a little bit more anteriorly this is a new one we didn't cover this one before this is the orange structure here this is another tract okay this one if you guys remember what was the pink one this was the ventral spino cerebellar tract this one's just a little bit more dorsal what do you think it's called the dorsal spinal cerebellar tract right so this is the dorsal spino cerebellar tract sweet deal so again we hit our sympathetic track we had the spinal nucleus contract we had our dorsal spinal cerebellar tract we already know what this one is guys this is your ventral spinal cerebellar tract move a little bit more anteriorly here what do we got here this kind of bluish guy here actually is going to be attract it's a it's going to actually be a a descending track this is your olivo spinal track so again what is this guy here this is the olivo tract again we'll discuss this track a little bit more in detail but again it's going from the inferior olivary nuclear complex down to your spinal cord to this lower motor neurons okay which will go out to your muscles and again we'll explain that later move a little bit more medially here what do we got we had olivo spinal what do we got here this is actually spinal olivery tract okay so this one is the spino olivery tract so again i want to make sure we understand here let's go over it again right what is this one this is the olivo spinal tract from inferior olives to the spinal cord this is the spinal olivery tract coming from the spinal cord from sensations proprioceptive sensations okay bringing it up through this to the inferior aliber nuclear complex okay so we understand that okay cool so we covered the spinal uh sorry the olivo spinal tract and the spinal olivery track let's move a little bit more medially here we already covered this one what is he this is your inferior olivery nucleus move a little bit more immediately we already covered this one what is this guy your corticospinal tracts move posteriorly a little bit you're starting to see some of the formation of what was that structure above the medial meniscus we'll explain what i'm talking about in just a second okay but again you're starting to see the beginnings of the medial meniscus work here what do we have what was right behind the medial meniscus the tectospinal tract what was just behind the tectospinal tract the medial longitudinal fasciculus let's come out here for a second want to cover these last because we already know these let's cover this let's move over here what do we got here what is this green structure here this green structure if you guys remember before it was one big clump called the spinal meniscus right do you guys remember what were the components of the spinal luminescence so again just more rash really that the section above this thing right here was the spinal meniscus spinal and meniscus i want you to remember three primary there's a lot of things but three primary components of it this one right here is the lateral spinal thalamic tract so the green one is the lateral spinal thalamic tract okay so lateral spinal thalamic tract what does this carry this carries that pain and temperature sensations from the contralateral side what is this one here this purple one here this guy is your spinal tactile tract this is your spinotectal tract so this is picking up sensations from the body and taking it to the tectum okay which again is that superior colliculus and inferior colliculus move a little bit more anteriorly here what do we got here this blue one this is your ventral spinal thalamic tract okay or your anterior spinal thalamic tract we're just going to do ventral spinothalamic tract okay and again the ventral spinal thalamic tract you guys know what this carries this bad boy is carrying that crew touch and pressure sensations from the contralateral aspect of the body these three components will eventually as they start moving and ascending rostralia more superiorly they'll fuse together and become the spinal meniscus okay but they haven't formed yet so that's what i want you to remember that's the only kind of big thing that's really different at this point we also have another structure do you guys remember we had the vestibular nuclei the medial and the inferior vestibular nuclei well what happens is the medial and primarily the lateral vestibular nuclei give off fibers that descend downwards as a particular tract what is that called the vestibulospinal tract this is the vestibulo spinal tract so again what is this black structure here this is the vestibulo vestibulo spinal tract what does this guy do he's carrying descending motor pathways for your extensor muscles anti-gravity muscles okay boom last portion here okay in this dorsal gray matter component of the medulla you have some nuclei we already know these what was the orange nuclei and then it was dorsal aspect that was the hypoglossal nucleus that was cranial nerve 12 nuclei more laterally the purple ones was the dorsal nucleus of vagus dorsal nucleus of vegas again that is going to be for cranial nerve 10. and then more laterally to that was the nucleus of tractus solitarius right and again we'll talk about its significance in just a second but that is kind of the big structures that we talked about the only other thing i want to make sure we understand here and explain is this sensory decussation so if you guys remember very simple kind of concept here here we are going to have two diagrams that i want to explain here so we'll have two diagrams so remember coming into the spinal cord you had that sensory information right this is coming basically from your proprioceptors right proprioceptors from muscle tendons joints all that stuff let's say that this is coming from the legs what they do is they move into the spinal cord more medially and then ascend upwards and then if you had again some more proprioceptive sensations coming from the arms this will ascend inwards this will move in and then ascend upwards a little bit more laterally so again if we had the midline through the brain stem and the spinal cord the most medial portion here is going to be through that dorsal column is going to be picking up sensations from the lower extremities the more lateral is going to be picking up sensations from the arms this bundle this kind of arrow going up is the fasciculus gracilis this one coming up here from the arms of the fasciculus cunadus eventually they terminate at nuclei in the medulla the nuclei that's more medial is the nucleus gracilis the nuclei that's more lateral is the nucleus cunaitus so again here's our nucleus lateral ones nucleus cunatus synapses on the nucleus cuneitus fasciculus gracilis is going to be the more medial ones they are going to synapse on the nucleus gracilis okay and then what happens is the fibers of the nucleus again lateral one is cuniatus medium one is the gracilis they are going to cross and move to the contralateral side so they're going to cross this way if it were coming from this side they would also cross and move to the contralateral side that crossing right here is the sensory decision and that's what we see at this point here so the fibers that are coming from the nucleus gracilis and the nucleus cunatus are crossing and going into this component here what the heck is this son of a gun that's our medial meniscus we talked about it here so what is this fibers after they cross and go up what is this medial liminiscus on the left side what is this one medial laminiscus on the right side so again they cross and then ascend upwards as the medial meniscus beautiful so that explains the rostral and the middle section of the medulla let's finish up hit it home with the most cauter portion all right so now we're at the last section of the medulla we hit the first top section okay ponto medullary junction we hit the middle section at the level of the sensory decision now we're at the most caudal inferior lowest portion of the medulla and this is at the pyramidal decoration okay a lot of this stuff is going to already be very familiar so we're just going to abbreviate it the only one that we'll kind of write out is the only thing that's really different here all right so let's start here dorsally and just kind of do what we've been doing kind of working our way back around so again at the most dorsal aspect you guys better know this what is this guy this is your fasciculus graceless again they're paired right and then associated with it where it will terminate is the nucleus gracilis more laterally is the fasciculus cuniatus again they're paired they'll terminate eventually on the nucleus cuneitus this one's a little bit different you saw this at an other area but this is your spinal tract for that trigeminal nerve and this is the spinal nucleus of the trigeminal nerve so again they're paired spinal tract of the trigeminal nerve and spinal nucleus of the trigeminal nerve this we already know this with this was your sympathetic tract that descending sympathetic tract and again you don't see that hypoglossal nucleus you don't see the dorsal nucleus of vegas you don't see the nucleus subtractive solitarius here what do we see we see this guy this was our dorsal spino cerebellar tract this is our ventral spinal cerebellar tract again they're pear dorsal spinal cerebellar ventral spinal cerebellar tract then we had this guy this was the olivo spinal tract going from the inferior olives down to the spinal cord this is your spinal olivery tract coming from the spinal cord going up to the inferior olives then we already covered this but this is going to be what this is your corticospinal tracts and again right here corticospinal tracts we'll explain this in a little bit more detail in a second then what do we have here we already hit this one this was your vestibulospinal tract so this is your vestibulo spinal tract this was carrying that descending motor pathways for the extensor muscles this was the three components that eventually become the spinal meniscus this is your lateral spinal thalamic tract this is your spinal tactile tract this is your what is this this is your ventral spinal thalamic tract okay so again they're paired lateral spinothalamic tract spinal tectal tract and then ventral spinal thalamic tract the other thing we actually should add in here is again you what do we have what else do we have coming down this was our tectospinal tract right and again that was coming from the tectum we should have had that one in there and again you're also going to have your we'll put it right here this is your rubra spinal tract right and that's going to be coming from the red nucleus coming down so again what do you have here your tactospinal tract paired and then up here you're going to have your rubra spinal tracts and again this is going to be going to the distal muscles for the upper extremities for flexion and again you'll notice here that we don't have the medial longitudinal fasciculus we don't have the medial limb meniscus because it hasn't been formed yet at this part okay all right the only thing that i really want to kind of end here is this pyramidal decussation i want to explain this so again you guys remember we had like a little mini diagram here here's our midbrain pons medulla going down into the spinal cord right so again here we'll kind of do this here here's our medulla midbrain here pawns there and again spinal cord down at the bottom here you guys remember the corticospinal fibers right coming from the cortex it'll come from an upper motor neuron come down through the midbrain come down through the pons scatter through the ponte nuclei come to the level of the pyramids and when it gets to the bottom part of the pyramids it crosses over and then descends downwards right then same thing if it was coming from the right side comes down through the midbrain through the cresceribri through the pawns so that scatters around the ponte nuclei moves through the pyramids at the most lower part it crosses over and comes down as the corticospinal tracts right the ones that cross these are going to be crossing and forming the lateral corticospinal tracts again we'll explain this in just a little bit in a second but again this portion here you see how this is going to be the corticospinal fibers that are coming through the pyramids some of these fibers that cross and descend downwards cross and descend downwards 85 percent of these corticospinal fibers do it and they will form the lateral corticospinal tract okay so again what is this guy here some from these corticospinal fibers descending down through the pyramid some will cross 85 percent of them and will descend downwards and this is going to be your lateral corticospinal tract okay some of the fibers 15 of them will not cross so they won't cross and they'll just descend downwards and eventually come down to the spinal cord and at the level that they're going to be stimulating those motor neurons they'll cross and that's your ventral corticospinal tract that's accounts for about 15 percent okay but this portion here where the corticospinal fibers cross and move downwards as the lateral corticospinal tract what is this called this is called the pyramidal decussation okay so the pyramidal decision all right so we've covered that now that we have covered the most caudal portion the most inferior the bottom portion of the medulla what i want to do is just really quickly cover some of the cranial nerves to recap what we've covered and to cover a little bit of the external anatomy of the medulla then what we'll do is we'll start talking about a lot of the functions of a lot of these structures here okay all right so last thing i want to do here kind of covering the anatomy so we kind of hit home this medulla neuroanatomy thing is covering a little bit of this external anatomy so a lot of us will see you know whenever we're looking at the brain stem in this kind of coronal view here right this is the anterior kind of portion of the brain stem mid brain pons medulla spinal cord cerebellum right some of the big things that we should understand is is when you look here at the medulla right so again medulla is going to be you see how this kind of have like this little jaggedy line here from this portion here that's all medulla you have this line coming right down the middle that's your anterior median fissure okay then you have these lines over here and these are called your anterior lateral sulcus there's a reason why i'm explaining this just give it a second and then the most outer ones here is your posterior lateral sulcus and again this kind of wavy line just above it is the pons so this is that pons medulla junction so again real quick recap anti-median fissure anterior lateral sulcus posterior lateral sulcus this is that pons medulla junction right okay what i want us to know is all the cranial nerves that are coming off of the pons medulla junction the anterior lateral sulcus and the posterior lateral sulcus and then what are the names of this and this and then some of these other structures that we'll cover just as an aside all right first thing let's cover some of the nerves that are here on this ponto medullary junction easiest thing to do is to kind of make a line to go right down the middle because this is all paired alright first one let's cover the blue ones here okay right at this ponto medullary junction here what are these two cranial nerves i want you to remember that this is cranial nerve six or the abducens nerve okay go a little bit more laterally on this pond's medulla junction here what is this guy here this is your facial nerve or cranial nerve seven all right cool let's go a little bit more laterally on this pons medulla junction what is this called the green component is for the cochlear nuclei the ventral dorsal cochlear nuclei right so that's the cochlear branch the red one is going to the superior medial medial inferior and lateral vestibular nuclei that's the vestibular branch this is the vestibulocochlear nerve or cranial nerve eight okay and it's paired here okay sweet let's move down so we got eight we're going to come here on this poster lateral sulcus so anterior median fissure anterior lateral sulcus posterior lateral sulcus on the most top portion of this this guy here is going to be cranial nerve nine or the glossopharyngeal nerve so again this is the glossopharyngeal nerve a little bit more caudal or inferiorly we have this guy this is cranial nerve 10 or the vagus nerve sweet and at the most inferior portion a tiny little portion of this outer uh posterior lateral sulcus around the inferior portion of the medulla you have this kind of bluish one this is the accessory nerve and it's the cranial part of the accessory nerve okay because there's two parts of the accessory nerve one part of the accessory nerve is coming off of the medulla and another part is coming from the cervical segments of the spinal cord like c1 all the way down to like c4 okay so again this is the spinal component which is coming from c1 to c4 and then this is the cranial component all right sweet now come more medially onto this anterior lateral sulcus on the anterior lateral sulcus we have these guys what are these this is cranial nerve 12. and cranial nerve 12 is the hypoglossal nerve okay okay we covered that next thing we give a specific name to these little fat bulges coming out the anterior portion of the medulla what is this guy this is your pyramids and they're paired okay then you got two other fat bulges okay on the lateral sides of the pyramids this is your olives okay so the anterior median fissure separates the two pyramids and the anterior lateral sulcus separates the olives sweet from all those from the pyramids okay then we got these little tubes that are connecting the three parts of the brainstem to the cerebellum in order at this level is the inferior cerebellar peduncle so what is this guy here this is your inferior cerebellar peduncle this one here is your medial cerebellum middle cerebellar peduncle and at the most superior portion between the midbrain and the cerebellum is the superior cerebellar peduncle so again superior cerebellar peduncle middle cerebellar peduncle inferior cerebellar peduncle okay now while we're here might as well hit some other structures what is this cranial nerve nuclei it's always good to do repetition it's the best way to learn right what is this cranial nerve nuclei here this is cranial nerve five the trigeminal nerve that's kind of at the pons right so we hit that section in the pawns video then you come over here and we got two cranial nerves coming out of the midbrain one's coming through that interpeduncular fossa what is this son of a gun this is cranial nerve three oculomotor nerve and then this last one that kind of comes around the back crosses and comes around the sides of the midbrain this is cranial nerve four or the trochlear nerve okay so this covers that nice little external anatomy questions that kind of come up that you might see on certain exams for the medulla all right now let's hit it home with the general functions of a lot of these structures the structure is complementing the function so it's it's not just important for us to know what is the name of this structure okay what is the name of this fiber what's the name of this nucleus we need to know kind of an idea of what these things do so we're going to kind of have a general overview on some of these things because we have more detailed videos that cover these topics exclusively okay this will be a three-hour video if we go through everything okay so so we're going to cover it generally first thing we're going to cover is these corticospinal tracts these descending motor pathways we've already talked about this so many times you guys know this you know like the back of your hand so again we have these upper motor neurons right coming from the primary motor cortex the pre-motor cortex the primary somatosensory area all sending these corticospinal fibers down they move their way down they go through the you know you guys remember the internal capsule they'll move through the crust cerebri they'll move through the ponds and kind of scatter you know they scatter around some of those pontine nuclei but then some of them reform and eventually they come to the medulla and they move through that pyramid that big fat chunky thing here in the anterior portion and when they do that they move down through this portion of the pyramids and what happens is these corticospinal fibers remember i told you as we get to the lowest portion of the pyramids some of the fibers will cross and then move a little bit posteriorly and then descend downwards do you guys remember what those fibers were whenever they cross they move a little bit posteriorly and then descend downwards and they descend downwards into the lateral white column okay what was that that decussation called that was called the here we'll abbreviate it pyramidal decussation right and the fibers that move laterally and descend downwards this is your lateral corticospinal tract now this was 85 of the fibers that are crossing we said that some of the fibers will not cross and we'll just descend downwards into the ventral column okay some of the fibers will not cross and will descend down into the ventral column and eventually at the level will cross okay stimulating those lower motor neurons here we'll represent this to really differentiate the color we'll do blue so here we'll have some blue motor neurons here that are coming out right so ventral across at that level dorsal crosses at the and the lateral crosses at the pyramids and they'll synapse on these lower motor neurons so again lateral corticospinal tracts are 85 of the fibers that decastate at the level of the pyramids the ones here that are ventral that don't cross at the level of the pyramids is the ventral corticospinal tract they account for about 15 lateral corticospinal tract accounts for about 85 percent okay and again this will stimulate the lower motor neurons that will go out to your skeletal muscles to allow for contraction of those skeletal muscles simple concept there okay so again that's covering the corticospinal fibers with the pyramidal decussation covering the ventral corticospinal and the lateral corticospinal tract let's move over okay now we're going to cover these sensory pathways that i i think we've hit like a million times but it's again it's worth going over and hitting at home one more time so you guys remember we had the medial liminiscus and the spinal limit is because we already talked about the trigeminal luminiscus so we can kind of knock that one out for right now but you guys remember dorsal column right picks up medial limboniscus this is picking up sensations proprioception vibration fine discriminative touch taking this in to the posterior gray horn right you guys know it moves into the posterior gray horn and then as it moves into the posterior gray horn it moves into the dorsal white column when it moves into that dorsal white column it then ascends upwards if it's picking the sensory information from the legs it's going to be coming up as the fasciculus gracilis if it's coming from the upper extremities which is more laterally that's the fasciculus cunatus we know this okay let's repeat it though again coming here is the fasciculus gracilis coming here is the fasciculus cunatus they'll eventually come up and those synapse on the medial is the nucleus gracilis lateralis is the nucleus cunnitus and these fibers will cross and whenever these fibers cross what is that cross called that's called the sensory decussation but then whenever they're kind of moving towards that decussation before the decussation that's called the internal arcuate fibers so just before they cross over is the internal arcuate fibers but the decussation is called the sensory decision then they ascend upwards as the medial lemoniscus we've we've knocked that cold right we know that now okay hit another one let's say here we have pain temperature crude touch pressure all of those sensations are coming in dorsal root ganglion coming into the dorsal gray horn synapsing on the neurons in the dorsal gray horn and then crossing over if it's the pain and temperature it's going laterally and then ascending upwards if it's crude touch and pressure it's going ventral and ascending laterally again there's also the spinotectol pathway that will eventually fuse but again the one that's going ventrally that's your ventral spinothalamic tract the one going laterally for pain and temperature is the lateral spinal thalamic tract and again another track that will come in here i'll just add him in blue here is your spinotectal tract what happens when the lateral spinal thalamic tract ventral spinal thalamic tract and the spinal tactile tract come together and fuse they make the spinal lemeniscus so what is this called spinal meniscus and some of these will go to the thalamus some of it will give collaterals off to the reticular formation a lot of different components of that pathway okay we already covered the trigeminal lumeniscus so again we know the medial meniscus we know the spinal and meniscus that's good and again we know the trigeminal lumeniscus so we can move on thing that i got to talk about that's a little bit different is the inferior olives now you guys remember the inferior olives are very important we've talked about this in a couple different videos some in the descending track video some in the cerebellar video so this kind of might be a recap but again it's important for us to just kind of quickly go over this give a general concept remember i told you that there was two tracks that we talked about in the medulla okay we had the spinal olivery tracks and the olivo spinal tracts and this is important it's pretty simple though right spinal olivary is sensations coming from the spine going to the olives olivo spinal is going from the olives down to the spinal cord not to the muscles so let's kind of talk about that okay olivo spinal pathway it's relatively simple you have again dorsal root ganglion here sensations and again what kind of sensations is this this is proprioceptive sensations okay this is a little bit of a pressure and touch that is going to be sending information to these inferior olives okay so again these are going to be coming from proprioceptors from muscles spindles uh joint capsules ligaments tendons all that stuff sending that information into the dorsal gray horn and then what happens is it crosses over into this kind of like ventral portion of the white column and then ascends upwards here to the inferior olives okay so again here's an inferior olive here's an inferior olive now when these fibers cross over to this ventral white column ascend upwards go to the inferior alloys the inferior olives will then take the sensory information and they do something really cool here they cross it over to the contralateral cerebellum right so in the same way here if it was coming from this side right so here you're going to have proprioceptors you know from an and vibration all of that stuff uh coming in here synapsing on the dorsal root ganglion crossing over into the ventral white column coming up where it's synapsing on the inferior olives the inferior olives will then do what and then cross that information over into the contralateral cerebellum there's an important reason to mention this one of the reasons why is that these fibers that are going into the cerebellum here right going into the cerebellum is very important coming from the inferior olives these are called climbing fibers i want you guys to burn this into your memories these are called climbing fibers so the climbing fibers are going to be the fibers coming from the inferior olivery nucleus going into the cerebellum via the inferior cerebellar peduncles all the other sensory fibers going into the cerebellum are called mossy fibers okay good so we covered here which one was this one spinal cord two olives that's spinal olivery tract what about that olivo spinal tract there's a lot of controversy some of the books i read um in an article i said that there's a little bit of controversy and doubt on whether this track actually exists i'm going to just briefly cover it okay because there is some newer things that they're saying the inferior olives are believed to receive information from the red nucleus right so you know the cerebellum has a bunch of different cerebellar nuclei right the dentate the emboliform the globose all of those things they believe that some of the information will go into the contralateral red nucleus from these deep cerebellar nuclei right and that these red nuclei can then send some of this information down to these inferior olives okay so what does that mean remember the cerebellum is aware of all of your proprioceptive sensations it knows where your muscles your tendons your ligaments your joint capsules are in space it sends it to the red nucleus red nucleus sends this to the infrared ellipse it receives that sensation the cortex also has the ability let's do this in a different color here let's do pink the cortex also has the ability to send down the motor plan to the inferior olives letting them know what the motor plane is so the cerebellum tells them tells the inferior olives all the position of your muscles your tendons your joint capsules all that stuff cortex tells them the motor plan then here's the interesting newer information that i read about you know where you have the putamen and the globus politis externus and intern it's all of that comportion of like the striatum they are believed to send information down to the inferior olives this is the newest thing and this is what they believe it might be involved in so they believe that there might be some type of connection or association between the basal ganglia and the inferior olives but here's the final concept what they think is that the inferior olives will send down descending motor fibers they'll send down descending motor fibers and these descending motor fibers will go to muscles that are believed to control reflexive movements okay that's all that we really know is again it's kind of unknown about this track but again i wanted to make sure that you guys understand there is some belief that the inferior olives receive information from the cerebellum rubra olivery fibers and they also receive information from the cortex and they receive information from the striatum the newest information is that they believe there's an association between the striatum the basal gang part of the basal ganglia and the inferior olives and they believe that it's involved with reflexive movements okay that covers these inferior olives now let's move on okay we've already covered this one like a million times too but the vestibular system you guys remember the vestibular nuclei superior middle medial inferior lateral they're all receiving information from what they're receiving information from two things one is from the inner ear right from the uh cristae ampullaris right and then the macula right you guys remember these structures chris ampullaris is for the rotational acceleration maculo is going to be for more of the linear acceleration they send information to these vestibular nuclei then you have the vestigial nucleus and he sends information to the vestibular nuclea about all the different proprioceptive sensations in the body now this vestibular nuclei then has a choice it decides i'm going to send descending information down to motor fibers to cause contraction of specific muscles extensor muscles anti-gravity muscles what is this tract this is going down to the spinal cord from the vestibular nucleus this is your vestibulospinal tract we talked about that one then it also can connect from the vestibular nucleus it can connect to the vestigial nucleus right we know that there's a connection between those via the inferior cerebellar peduncles via the juxtaform body so it can go into the cerebellum it can go down to the spinal cord or it can send information up to the thalamus and it can do one more thing it can send information to your abducens nerve and then the abducens nerve will do what it'll send information to the contralateral third and fourth nerve nucleus what is that blue tract the medial longitudinal fasciculus right so the medial longitudinal fasciculus technically can extend from the medulla all the way up to the midbrain okay so we know now vestibular spinal tract we know the connection to the vestigial nucleus via the inferior cerebellar peduncles we know the connection between the vestibular nucleus and the medial longitudinal fasciculus that covers it boom we move on all right so let's cover this next point we already talked about the tectospinal tract in the rubric spinal tract like a thousand times it's worth repeating though right so tectospinal superior colliculus inferior colliculus we already know that's a part of the tectum posterior portion of that midbrain right sends information downwards that can go to two points one to the spinal cord what is that called the tactospinal tract right but it can also give off fibers to go to the cranial nerve nuclei that go and supply different muscles of the eye what is the importance of this tectospinal tract it's to supply muscles of the head and neck via the spinal cord and muscles of the eye for move reflexive movements if someone calls your name that stimulates the inferior colliculus move your head in your eyes that way if you're watching somebody move that's the supercaliculus and it's going to be causing you to move your head in your eyes in that direction if you step on something when you step on something it sends information upwards to your tectum lets your tech to know that you're receiving this sensory information what is that called let's do this in a different color just to recap this you receive sensory information you step on something that comes here into your uh your actual spinal cord ascends upwards stimulates the tectum what is that track called you better tell me the spinotectol tract the one going down is the tectospinal tract okay last one here red nucleus we know this one right we know that this guy is going to it forms that ventral tegmental decussation and then descends downwards goes to lower motor neurons that go to the flexor muscles primarily of the upper extremity done okay let's move on all right so the next one we've got to cover is that sympathetic tract you guys remember the sympathetic tract right sympathetic track remember you have the hypothalamus right the hypothalamus has two portions one portion that's a parasympathetic portion here we'll draw the parasympathetic portion we'll do it in here like a red and then there's a portion of the hypothalamus that has a sympathetic portion that's going to be in this baby bluish teal color right this hypothalamus will have fibers that will then come backwards you know posteriorly and then descend downwards through the midbrain through the pons through the medulla and go into the spinal cord where it'll synapse on preganglionic motor neurons within the thoracolumbar portion of the spinal cord and then from this do you guys remember what we said here from that t1 all the way to like l2 that thoracolumbar outflow that's all going to be for sympathetic outflow so i just wanted to make sure we understand what the heck the sympathetic tract is the sympathetic tract is that descending sympathetic pathway coming from the hypothalamus that'll then synapse on some of these the preganglionic motor neurons located within the intermedial lateral portion of the spinal cord at t1 to l2 that'll control the thoracolumbar outflow boom let's move on all right so the next thing we got to cover that we talked about in those medulla structures was um the spinal cerebellar tracts and again we're not going to go into total detail on this if you guys want we have another video on this but to give you an idea of what they're doing remember you have that uh the dorsal spinosaur bella track you guys remember we talked about it really quickly in in that video if you have here uh midline portion of the spinal cord right and let's say that we go here at the top we have c1 then we'll go about right here we'll say that's about c8 then we'll go about right here let's say let's say like l2 l3 then we'll go down a little bit more and let's say that this is going to be like coccygeal one okay if you guys remember from c8 well actually let's do this in order from c1 to c8 this was picked up by that cuneo cerebellar tract i'm just going to put ct okay and then from c8 to l2 l3 this was picked up by that dorsal spino cerebellar tract we'll put dct and then from l2 l3 down to the coccygeal one was picked up by the ventral spinocerebellar tract we'll put vct okay this is basically picking up proprioceptive sensations you know some pressure and even a little bit of touch and taking it to the cerebellum which has a kind of an unconscious basically awareness of all of these proprioceptive and touch sensations okay and they're carrying it to the cerebellum again really quickly to cover this cunio cerebellar that's taking it kind of like mainly from c1 to c8 okay so you're getting more of like the neck a little bit a teensy bit of like the upper extremities okay so you're going to have that cuneio cerebellar tract picking up proprioceptive sensations moving into the dorsal gray horn moving into that little funiculus ascending upwards and going to that remember this guy the accessory cunyate nucleus so here let's remind this what color do we have okay here was the nucleus cuneitis nucleus cunatus what did we have medially guys you guys better tell me nucleus gracilis nucleus gracilis so there's another nucleus just lateral to that called the accessory cuneian nucleus it's receiving information from the cuneo cerebellar tract will go to this nucleus and then send it in via the inferior cerebellar peduncle into the cerebellum okay boom done dorsal spinal cerebellar tract receive proprioceptive sensations from the structures from c8 to l2 l3 takes that into the dorsal gray horn when it synapses in the dorsal gray horn it moves ipsilateral into the lateral white column right and then does what it ascends and then as it ascends what does it do eventually it will go into the inferior cerebellar peduncles and it'll synapse there right again this is your dorsal spinal cerebellar tract the light blue one here is your cunio cerebellar tract and let's hit the last one which i think we had in pink and over there so where that was going to be the ventral spinal cerebellar tract so this is picking up proprioceptive sensations touch sensations from l2 l3 down to coccygo1 comes into that dorsal gray horn synapses and then what does it do it crosses over and it moves into the lateral white column but more eventually to the dorsal spinal cybel attract and then does what ascends upwards ascends upwards and then it goes all the way up to the midbrain at the superior cellular peduncles and then what does it do it does that really weird thing where it moves into the cerebellum via the superior cell battle peduncles and then runs behind the midbrain into the contralateral cerebellum okay because everything from these proprioceptives to the cerebellum these pathways all have to be ipsilateral so again that covers those tracks giving you an idea of what they're doing putting a function to the name sweet and again do you guys remember what these nuclei are called from c1 as we go down here remember that that was called clark's column so again those are those first order neurons that are within the dorsal gray horn that they're synapsing on and then either crossing over or moving into the same lateral white column all right sweet deal all right let's move on to the last thing here and then we'll cover the cranial nerves a little bit but this was that cochlear pathway you guys remember what the cochlear nerve pathway does i think we've done this like three times but this is it's always worth repeating i guess right so let's hit this one again you got the inner ear coming from what portion of the inner ear the cochlea what part of the cochlea the spiral organ of cordy which is taking auditory sensations remember vestibular cochlear nerve it has the two portions cochlear branch vestibular branch this is going to be the vestibular branch i'm sorry the cochlear branch and that synapses on what two structures in that pons medulla junction the cochlear nuclei the ventral cochlear nuclei and the dorsal cochlear nuclei then what did we say some of the dorsal cochlear nuclei will cross over and ascend up some of these ventral cochlear nuclei what do they do they'll cross over and they'll send up but some of them will synapse on what structure remember some of them will synapse on a structure called the superior olives right some of them will synapse on the superior olives and then those will ascend upwards but do you guys remember what this is called whenever there's this crossing of the cochlear nuclei that's called the trapezoid body we talked about that before in the pons but you got the cochlear nucleus they receive information via the vestibulocochlear nerve synapse on these cochlear nuclei some of the cochlear nuclei will cross some of them will synapse on the superior olives and then ascend upwards when they ascend upwards they go to a portion of the midbrain that you guys know called the inferior colliculus what is this structure though called that's ascending upwards you guys remember this was called the lateral lumeniscus and eventually it'll synapse on the inferior colliculus in the midbrain and the inferior colliculus will have a connection called the brachium of the inferior colliculus and that brachium of the inferior colliculus will connect to the thalamide and the thalamus will then relay that information to the temporal lobe okay so again what i want you to remember is that the cochlear nuclei that are in that area are responsible for sensory information primarily hearing okay covered that let's finish up briefly talking about these cranial nerves that we've seen within the medulla again we have videos that discuss these cranial nerves in way more detail on their anatomy we're just going to cover the general functions of them here all right so now what i want to do is just really kind of just basic overview i just want you guys to be able to know what the functions of these things are because whenever there's lesions because we're going to have to cover medullary lesions what can happen if there's damage to the hypoglossal nerve you just have to know the general functions okay so hypoglossal nerve is responsible for movement of the tongue right so it's primarily a motor nerve and the types of motor fibers that it has is those general somatic efferent fibers but i want you to know is that it controls the muscles of the tongue okay and again what kind of fibers are they just to kind of write it down here this is g s e fibers general somatic efferent fibers i want you guys to tell me though just so we know because one of them is very important the muscles of the tongue what are the muscles the styloglossus the hyoglossus the what else do we got we got the genioglossus this is the really important one that i want us to really know and then the last one is your intrinsic intrinsic muscles of the tongue you guys really want to know style of glosses really quickly elevates the back of the tongue kind of retracts it hyloglossus depresses retracts genial gloss is primarily protrusion of the tongue if you guys remember it does play a little bit with retraction but primarily protrusion of the tongue and the intrinsic muscles of the tongue they help you to change the shape of the tongue right you know doing something like that so it's really important that you guys understand the the function of the hypoglossal nerve but the real big one that i want you guys to know is it's going to come up when we talk about lesions is the genioglossus again primarily for that protrusion of the tongue okay glossopharyngeal nerve this is a mammoth you know not as compared to the vegas but it's a pretty beast you know kind of guy we're going to cover some of the nuclei that we talked about okay what was one of the nuclei that we had we went kind of as we went immediately we had hypoglossal nucleus dorsal nucleus of vegas what was that next one the nucleus of tractus solitarius right if you guys remember the nucleus attractive solitarius is important because it picks up sensory information from what kind of structures so let me draw here a tiny diagram here for you so again here we're going to have the kind of a sagittal section here and then what we'll do is we'll draw kind of a little small section here for this guy's face okay okay so what i want you guys to know here is the tongue right the tongue you have different taste that comes from the tongue and these taste fibers right that's going to be serving what portion of the tongue the post here one third of the tongue the taste sensations from the posterior one third of the tongue is going to be taking this into the medulla and going to what nucleus the nucleus of tractor solitarius so what is one of the functions of the glossopharyngeal nerve because it connects with that nucleus subtractive solitarius it plays a role within taste of what portion of the posterior one third of the tongue okay cool what was another structure that we talked about there another one is that it's also associated with that nucleus ambiguous do you guys remember the nucleus ambiguous when we talked about that the nucleus ambiguous controls a lot of different muscles but one of the muscles that it goes to is called the stylopharyngeus do you guys remember that guy the stylopharyngeal kind of elevate the soft palate that was another one but what was the nucleus that was associated with it the nucleus ambiguous that was one of the nuclei that we talked about over there so it also plays a role within the deglutition process right so so it also plays a role within the d glutation process okay because the stylopharynges does help to play a role with kind of elevating that soft palate going back here taste what kind of fibers is it that's actually carrying there that is your you guys remember sva fibers sensory visceral afferent fibers the fibers for digoutian these are motor fibers this is your sve fibers that's your special visceral efferefibers you guys remember special visceral efferent is for pharyngeal arches which pharyngeal arch does the glossopharyngeal nerve serve the third french arch first is trigeminal second is facial third is glossopharyngeal okay cool we had another nucleus the other nucleus that we had there was the inferior salivatory nucleus and the inferior salvatory nucleus we said would go to the otic ganglion and then go to a gland what was that gland called the parotid gland what does the product land do plays a role with salivation you guys are so awesome i know you guys knew that right so it also plays a role with salivation and again via what nucleus the inferior salivatory nucleus what kind of fibers is that general visceral efferent fibers i know you guys knew that right so general visceral efferent fibers cool okay the other thing it does is it picks up uh sensory information from the soft palate from the pharynx from the posterior one-third of the tongue okay we already said the soft palate uvula so again what does it also pick up it picks up sensory sensations okay so visceral sensations coming from the posterior one-third of the tongue coming from the soft palate coming from the uvula coming from the pharynx and carries it back and they believe that most of these fibers synapses on the nucleus of tractor solitarius what are these fibers the sensory fibers that are picking up sensations from the soft palate the uvula the posterior one through the tongue the pharynx these are gva fibers if you guys want to be rock stars which i know you guys are it also picks up some sensations from the areas called the carotid bodies and the carotid sinus right you guys know g of aortic arch and then you have your sinus there and again the sinus is going to be having the barrel receptors the bare receptors are going to be picking up they're going to there's gva fibers that will also be carried on the glossopharyngeal nerve and then you're also going to have the carotid bodies which are going to be carrying the chemoreceptor information that's also going to be carried on the glossopharyngeal nerve but again all of these fibers sensations from the soft palate from the posterior one third of the tongue all that stuff and then from these chemoreceptors and bare receptors is all carried on gva fibers so it plays a role with sensations and we're just going to put of oral cavity okay of the oral cavity and again those sensations that we're picking up from the chemoreceptors and the barrel receptors the last one that's really kind of an easy one thank goodness is that it's also picking up sensations pain sensations from the external ear pain temperature touch sensations from the external ear tympanic membrane middle ear fringe or tympanic tube so it's also picking up kind of ear sensations okay and those types of sensations go to your spinal nucleus of the trigeminal nerve okay so again that's all the kind of the functions of the glossopharyngeal nerve let's move on to this beast the vagus nerve again this one's it will never cover everything here you know so again it's just general vagus nerve what i want you to remember here the dorsal nucleus of vegas the dorsal nucleus of vegas carries primarily general visceral affair fibers which are all the sensations of your larynx of parts of the soft palate of all your thorax and abdominal parts of your abdominal viscera all of that information secretion contraction and sensations are all kind of carried to and out of the dorsal nucleus of vagus that we talked about over there so again if we were to cover some for the gva fibers it picks up sensations okay okay and we can say here from what structures from the larynx the trachea i mean we we're gonna go on forever here we'll put thorax abdomen all of that stuff right and then also plays a role within secretion and motor function so peristalsis and things like that right so secretion from glands and peristaltic activity so it plays a role within secretion and motor functions all for the same thing for structures of the larynx for the trachea for the thorax for the abdomen all of these different things and again if you guys want more detail on that go watch that video the other thing so again what kind of the sensations are carried on what things gva the c cradle motor fibers are gve and these are primarily coming from the dorsal nucleus of vagus the nucleus attractive solitarius also is going to be receiving information from the vagus nerve that's picking up taste from primarily the oropharynx the posterior wall right of the pharynx the oral pharynx and even it also will pick up some sensations from like the veleculae on the epiglottis so taste sensations so those are special visceral affair fibers so it plays a tiny role within taste okay and again the two portions that it picks it up on is the oropharynx and there's also some a tiny bit of taste receptors on the epiglottis okay the molecular of the epiglottis and what kind of fibers are those sva fibers what are they going to the nucleus of tractor solitarius okay it also plays a role and has connections to the nucleus ambiguous the nucleus ambiguous is going to have what kind of fibers sve fibers that we talked about for the glossopharyngeal nerve it's also going to have sve fibers for the vagus nerve that's going to be going to muscles of the pharynx the pharyngeal constrictors muscles of the larynx okay and that's really really important for the deglutition process and for phonation right so the the laryngeal muscles right so if you're cricopharyngeus you have your crycothyroid you have all those cricoarytenoid muscles all of those things that are important for phonation for speech and then the superior middle inferior fragile constrictors for that kind of deglution process so again those are going to be coming from the nucleus ambiguous via the sve sve fibers that's going to be uh basically supplying the pharyngeal arches the vagus nerve supplies what two pharyngeal arches four and six one is trigeminal two is facial three is glossopharyngeal four and six is vagus good so it's gonna supply muscles of larynx for speech and the muscles of the pharynx primarily those constrictors for degolitium and thankfully the last thing is it also picks up the pain temperature touch sensations from the external ear the tympanic membrane and even a little bit of the middle ear cavity so again it picks up sensations from the ear and again what kind of fibers are those going to be those are going to be your gsa fibers what kind of structure is it going to go to the spinal nucleus of the trigeminal nerve boom okay finally oh thank goodness the last one the accessory nerve cranial nerve 11. so we hit cranial nerve 12. we hit cranial nerve nine we have cranial nerve 10 we hit cranial nerve 11 now accessory nerve this guy thank goodness it's really important to know that this guy is primarily supplying two muscles okay so primarily has general somatic efferent fibers that supply two muscles one is the sterno clydo mastoid muscle okay so the sternocleidomastoid muscle which has a lot of different functions that we've talked about in other videos the other one is it supplies the trapezius okay this is going to be really important to know these okay but here's the other thing this is primarily supplied by the spinal component that c1234 that moves up through the lateral funiculus and combines with that cranial portion of the accessory nerve we talked about on the external anatomy they supply primarily the sternocleidomastoid and trapezius some of the kind of parts coming off of the brain stem a little bit of that goes into this internal uh kind of parts that supply the pharyngeal plexus okay so there's three parts of the pharyngeal plexus okay what are the three parts of the pharyngeal plexus one part of the pharyngeal plexus is the vagus nerve second part is the glossopharyngeal nerve and the third part is the accessory nerve okay these three structures here make up your pharyngeal plexus all of these three components are receipt are their pharyngeal plexus is formed by the fibers coming off of the nucleus ambiguous so again accessory nerve a thing that you have to remember is that it is a part of the pharyngeal plexus so it's a component of the pharyngeal plexus which is going to be carrying fibers sve fibers from the nucleus ambiguous and it's a one of the three components of the pharyngeal plexus which is made up of the vagus nerve the glossopharyngeal nerve and the accessory nerve all of the fibers of the nucleus ambiguous that are coming from vagus glossopharyngeal and even a little bit from the accessory nerve okay that covers all of the functions of all of these things within the medulla all right ninja nerds this was a monster of a video and we covered so much it was so so in-depth and i really hope that a lot of this stuff made sense i hope that you guys did enjoy it and at the end of this video i hope that you can literally name every single thing within the medulla and what they do if you guys did learn a lot from this video if you love this video please hit that like button comment down in the comment section and please subscribe also if you guys get a chance down in the description box we'll have links to everything that you guys need to communicate with us facebook instagram uh even our patreon all of those things if you guys want to go there check that out we appreciate it nigerians we love you we thank you for everything that you do all the support and kind comments that you give we do look at them and we do appreciate them all right nurse as always until next time [Music] you