Gray Matter of the Spinal Cord

all right ninja nerds in this video today we are going to talk about the gray matter of the spinal cord so let's go and get started all right ninja so when we talk about the gray matter of the spinal cord we obviously have to have an understanding of what in the heck gray matter is so let's take here we have a neuron here on the neuron we obviously have these little extensions coming off of the neuron what are these things called these are called our dendrites right little kind of extensions coming off the receptors on them that respond to neurotransmitters then here we have the cell body sometimes referred to as the soma right then coming off of that cell body going down here to your axon terminals we have our axon and then again lastly we have this last portion here called our axon terminal or terminal bulb whichever one you prefer what i want us to know is that there's these little fatty lipid sheaths that are surrounding insulating covering this axon what are these lipid sheaths here called these are your myelin sheaths and your myelin sheaths are a lipid kind of protein structure that allows for action potentials to be carried very quickly along that axon we're not going to go into detail of it now but you guys remember what these little nodes are called between these myelin sheets they're called the nodes of ranvier right and action potentials skip along these which allows for quick conduction which is called saltatory conduction we know that we'll talk about that later but what i want you to understand is wherever you see myelin i want you to remember that's going to be what is causing the neuron to appear whitish okay so wherever there is myelin it is white wherever there is not myelin that is gray matter so here let's take a look here at this structure here you see how we have the cell body and the dendrites that's going to be pretty much making up a lot of our gray matter another thing to add on though is if there is axons let's say that we had another neuron here's another neuron and this neuron here had no myelin sheaths covering that axon if there is no myelin covering that axon guess what that axon is it doesn't have the myelin it's not going to appear white so therefore it is gray matter so remember a lot of the time we say gray matter is unmyelinated cell bodies and dendrites for the most part it is but there's a couple areas in the body where the axons are not myelinated and therefore that is also gray matter okay so we know what gray matter is it's basically the structures of the neuron that are not myelinated next thing we have to talk about which i'll use a lot throughout the course of this video is what in the heck is the term for a nucleus and what in the heck is the term for a ganglia so let's imagine here we have a group of cell bodies i'm just going to have a bunch of cell bodies here okay and this is the cell bodies of our neuron here's a bunch of cell bodies of a neuron okay i have a bunch of neurons these clumps this whole clump or group of cell bodies of in the actual central nervous system so this kind of group of cell bodies in the central nervous system is referred to as a nucleus the group of cell bodies which are clustered together and the peripheral nervous system are referred to as a ganglia okay so we know what gray matter is it's the part of the neuron that's not myelinated we know the nucleus is a group of cell bodies in the cns group of cell bodies in the pns is a ganglia now next thing we have to talk about is the anatomical portions of the gray matter they're special names right we already know a lot of these this is going to be a quick reminder we have here this portion here what is this portion here this gray matter here these kind of like shaded in portions here what is this this is called our posterior gray horn we already know this and then if we have this other region here let's kind of shade this one here we have this one which i'm going to box here this is called our anterior gray horn this is called our anterior gray horn now there's a last one that i want to talk about briefly here and we're going to kind of call this one here and this one here you see how this is kind of what we're going to call the intermediate zone we're going to call this for right now the intermediate zone but what i want you to remember is that in this intermediate zone we have lateral gray horns which come off of a specific part in the spinal cord so if we have this intermediate zone okay at what level do these horns kind of pop off that intermediate zone you have lateral gray horns we're going to write this on this side it's a part of the intermediate zone lateral gray horns they're the parts that are coming off of this intermediate zone only at t1 to l2 and we'll talk about their functions a little bit later last thing that i want you guys to know is let's say that here i kind of make a line coming here and a line here so this horn this anterior intermediate zone anterior gray horn this posterior horn intermediate zone and anti-gray horn are connected through a sliver of tissue here and that sliver of tissue connecting the two sides of the horn is called our gray commissure beautiful so we know the post trigger horn right when our intermediate zone at the t1l2 region coming off of it is the lateral gray horn and anterior gray horn and we know the central or great commissure here connecting the two sides of that horn all right so the next thing that i want to talk about is the basic function of these horns so we're going to have one side right and what i want us to do here is we're going to kind of circle this portion here the posterior gray horn we know it's responsible for what type of function remember the posterior gray horn is i just wanted you to remember the lat on that last video we talked about the gross anatomy of the spinal cord and spinal nerves it's primarily sensory function okay now we're going to talk about this kind of this intermediate zone and this anterior anti-gray horn this is going to be primarily for motor functions let's break it down even a little bit more okay when we look at the posterior gray horn right what i want you to remember is that it's picking up sensations it's sensory neurons which are located in this area but it's going to be sensory neurons here in green i want you to remember that they're picking up somatic sensations what does that mean somatic sensations means it's picking up sensations from the skin from your skeletal muscles all right from your joints from your tendons from your ligaments and things like that whereas other parts of your posterior horn are going to pick up what's called visceral sensations what are visceral sensations it's sensations which are coming from your internal organs your heart your lungs your gi tract things of that nature then we have that motor function right well the motor function you're going to have here in that intermediate zone that's going to be able to be responsible for visceral motor functions so in other words this is going to be going to your smooth muscle to your cardiac muscle to the glands right a part of your sympathetic parasympathetic motor nervous system then here anterior most ventral this is going to be motor neurons for these somatic nervous system so this is somatic motor going to your skeletal muscles okay so that is what i want you to know when we talk about basic anatomy and basic function now let's dig in a little bit deeper into this gray matter all right so we know the basic concept of the gray matter of the spinal cord but we're ninja nerds we gotta dive in we gotta dive in deep so what we're gonna do is we're gonna talk about another concept here called rex lamina or lamina of rex and their associated nuclei within the gray matter so rex lamina basically was a way of that we can categorize or separate the different areas of the gray matter on our spinal cord here and it's a really simple system thank goodness that if we just numbered this as we go from posterior to anterior you're going to be going here the first lamina lamina 1 2 3 4 5 6. now from 1 to 6 this is pretty much the rex lamina that make up most of your posterior gray horn right then you get into that intermediate zone we talked about that's primarily occupied by lamina seven then we get into the anterior gray horn and the anterior gray horn is primarily occupied by lamina nine we're going gonna have the laminate nine here and lamina eight and there's one more so we kind of worked away all a one to six for posterior horn the seven primarily for intermediate horn eight and nine for anterior horn well guess what what that little structure was that we had connecting the two horns that was called our gray commissure that's called our central lamina right that's the central zone that's going to be laminate 10. okay so that's one way that we could define this so this way that we can categorize the different parts of the gray matter of the spinal cord is called the rex lamina the other way that we can categorize it is that there are specific nuclei that are present in specific lamina and have specific functions what are those those nuclear structures so you see here we have this one shaped like a p there's a reason why it is called our posterior marginal nucleus what is it called the posterior marginal nucleus sweet that's that one the next one here this one's shaped like an s oh real quick though posterior marginal nucleus we said that these occupy certain lamina right which lamina does the posterior marginal nucleus occupy primarily lamina one then you have the substantia gelatinosa of rolando that's the s that's what that one's for so this is called the substantia substantia gelatinosa of rolando one heck of a name right that's going to be primarily occupying laminar two then we have this next one here in green this is called the nucleus proprious this is called the nucleus proprious and the nucleus propria primarily occupies laminas three and four beautiful okay that pretty much takes care of what we said lamina one two three four now five and six they do have little nuclei in them but i don't really want to focus on those we'll talk about their function separately okay now the next one is we get into this intermediate zone that was around lamina seven there's three specific nuclei situated here let's go from medial all the way out to lateral so let's get this pink marker in here c what does c stand for that's clark's column our clark's nucleus so this is clark's column or clark's nucleus that is what this one is here right so we have clark's column or clark's nucleus which is most medial that's occupied within lamina seven again these three are going to be in lamina seven then we have this m this one's a weird one but they love to do this stuff this is called your interomedial medial medial nucleus group right so the enteromedial medial nucleus there's an m there that's the reason why we have that one there right so we got our interomedial medial nucleus and again this is going to be occupied within lamina seven last one here that's occupying laminar seven this is that brownish color here that's this one l that's enteromedial lateral nucleus this is our antero medial lateral nucleus these are sons of a guns aren't they and this is going to be occupying laminar seven beautiful okay now we're going to talk about laminate eight okay a little bit later lamina 8 there is no specific type of nuclei associated there but we'll talk about what the functions of those nuclei are for a little bit later in the video lamina 10 no specific nucleus associated here this is really just the simplest thing to know about laminate 10 is that this is where the axons cross over from one side to the other that's really all it is and it's called the gray commissure and if the axons are crossing and it's gray what does that mean about those axons they're not myelinated that goes to show you what the gray matter is okay let's come here to this last part lamina 9. lamina 9 we're actually going to zoom in a little bit more in here for but this is going to be a part of our nuclear group right and it's really simple this is our lateral nuclear group this is our central nuclear group and this is our medial nuclear group but what i want us first to do is take this nuclear groups here with the event the ventral gray horn and zoom in on it talk about some of the anatomy the somatotopic arrangement and function so let's go ahead and do that now all right so now we're going to do is we're going to talk about a little bit more about the structures within lamina's nine and we'll talk again we'll briefly recap ten so we're taking this cross-sectional spinal cardio right and what we're doing is is we're gonna zoom in on these nuclear groups remember these we had already talked about those up there our medial central and lateral nuclear groups we're going to cut this off and then zoom in on it right so this is going to be right here on this part of that black line this is that medial side and this is that lateral side okay so this is over here this is over here simple kind of like a basic outline of the anatomy now nuclear groups we already gave these guys name names lateral nuclear group this is our central nuclear group and this is our medial nuclear group we already know that what i also want you to know is is something really interesting the lateral nuclear group you know it's actually only present let's see if you guys remember this at c5 to t1 and a l2 to s3 do you guys remember where that was in the spinal cord in that gross anatomy video if we only find these at two sections we only find these at c5 2 t1 and we only find this at l2 to s3 what were those areas in the spinal cord segments that was our cervical enlargement and our lumbar enlargement why is that significant do you guys remember what we said happens in those areas in those areas if i draw a cross section here or i draw a sagittal section here right remember i said there was a little bulbous portion here and a little bulbous portion here remember we said that these were bulbous in these areas because that's where there was more gray matter in that anterior gray horn particularly in the lateral region and that these were going to the muscles of the upper limbs so the cervical enlargement so upper extremity and lower extremity for the lumbar enlargement that's why that's important okay beautiful next thing we have our central nuclear group now the central nuclear group here actually has a couple nuclei kind of spursed within it so there's a couple nuclei that are spursed within this that i want to talk about and you can kind of see them here we're going to kind of zoom in on them over here the reason why is they have specific areas that they serve so in that central nuclear group there's three particular nuclei that i want you to remember one is a p for the phrenic nucleus a for accessory spinal nucleus and o for onefs nucleus okay why do i want you to know this you guys know the phrenic nerve which supplies the diaphragm from what areas of the spinal cord are those nerves coming from c32 c5 where do you only find the phrynic nucleus in that central nuclear group at c3 to c5 accessory spinal nerve the accessory spinal component right that is going to be coming from c1 to about c 5 and that is going to be supplying the sternocleidomastoid and the trapezius so what does this one supply sternocleidomastoid and the trapezius muscles whereas the phrenic nerve will supply the diaphragm beautiful onuf's nucleus this is only present from s2 to s4 in that central nuclear group and this is going to be going to your sphincters the external sphincter so the external anal sphincter and external urethral sphincter and it also goes to the muscles involved in the erection and ejaculation process okay so that is another thing i want you guys to remember so again central nucleus within that central nuclear group there's specific nuclei that are scattered in there that are only present at these segments of the spinal cord beautiful next one we already talked about the medial nuclear group right now actually we didn't let's talk about the medial nuclear group now so now we have our medial nuclear group there's something that i need to kind of address here because this is kind of going to give you that somatotopic arrangement so we have a line here right this line that's going this way this is separating these nuclei into a posterior portion and an anterior portion right what i want you to remember first with this somatotopic arrangement here is that the nuclei that are going to be on this posterior portion are primarily supplying the flexors so they're supplying your flexors on this side of that line so these kind of nuclei that will be situated here on the anterior aspect of this imaginary line this is going to be supplying our extensors okay so when you look at these nuclei the nuclei that are situated more posteriorly in the in this anterior gray horn supply the flexors the nuclear that are more situated anteriorly in the anterior gray horn supply your extensors beautiful next thing we have another imaginary line here you see these purple lines here they're separating again these nuclei right so the lateral nuclear group guess what i want you to remember that they supply they supply your distal limbs so imagine that is kind of like your forearms your hands right the muscles of that area the central nuclear group guess what they supply the proximal aspects of your limbs maybe your shoulder joint maybe your biceps so that's going to be your proximal limbs and then this medial nuclear group guess what it supplies your axial musculature so your trunk and your neck right so this is going to supply your axial musculature all right beautiful that explains our somatotopic arrangement that describes the nuclei that describes their basic function now one more thing here these are cell bodies that are going to your somatic motor neurons right so these are cell bodies of the somatic neurons going to skeletal muscles of the distal proximal and axial limbs or axial structures both flexors extensors but guess what else you guys remember that we have these things called upper motor neurons coming from our cortex coming down here into the spinal cord right and then synapsing on the cell bodies here in that spinal cord going out so this was our upper motor neuron and this was our lower motor neuron right what were these structures called that going from the cortex to your spinal cord your corticospinal tracts the corticospinal tracts synapse on these neurons so these are cell bodies right in this area of the anterior horn they're a relay station for the upper motor neurons that'll synapse onto them stimulate them and then go to the skeletal muscles of flexors extensors of distal limbs proximal limbs and the axial skeleton beautiful that's all i want you to know for right now okay we already talked briefly about lamina 10 just to remind you all it is is imagine here we have a sensation coming in dorsal gray horn right so the dorsal root ganglia coming into the dorsal gray horn synapsing here and then it crosses over here and then goes up you see how these axons are crossing over to the other side through that gray commissure that's all it is and since it's gray what does that mean that means the axons are not myelinated boom let's move on all right so now what i want to do is we already talked about the kind of the function of laminas nine and ten let's now talk about some functions of some of the other lamina or their associated nuclei like which ones remember in laminar one there was the posterior marginal nucleus right and this was situated within lamina one now basic thing that i want you guys to know about this one simple straightforward to the point this is receiving this these nuclei associated right here i'm gonna put one nuclei there these are picking up pain and temperature sensations pain and temperature sensations and if you really want to add on to that a little bit more guess what kind of pain and temperature sensations from what types of pain fibers this is primarily fast pain so this is carried on your a delta fibers okay your a delta fibers that's all i want you to know so if you guys kind of remember here is going to be the receptor picking up the pain stimulus carrying that on this sensory neuron through the peripheral branches of this pseudo-unipolar neuron then its central branch sends into that dorsal gray horn synapse on the cell bodies of the posterior marginal nucleus and then what will happen is it'll cross over and enter into your anterior uh or lateral spinal thalamic tract so this becomes a part of it leads into your anterior lateral spinothalamic tract that's all i want you to know about this one okay next one we have is the s substantia gelatinosa so substantial gelatinosa of rolando right this was occupying lamina two now a couple things that i want you guys to know about this one this guy he also picks up pain and temperature sensations but the type of pain and temperature is slow pain do you guys remember what the fibers were that carried slow pain that was your c fibers okay that was your c fibers the other thing i want you to know is that it actually becomes a part of that anterior lateral spino thalamic tract the last thing i want you to know just as a fun factoid here is that the substantia gelatinous overlando as you ascend up the spinal cord it becomes a specific nucleus in the medulla and that is called the spinal trigeminal nucleus this is for cranial nerve five and that is again present within the medulla so it becomes the spinal trigeminal nucleus within the medulla and again i'll give you guys a basic concept here's that cell body is there picking up a pain stimulus carrying it down this sensory neuron into the dorsal gray horn synapsing and then crossing over and then ascending upwards one last thing i want you to remember here do you guys remember in that video we talked about pain modulation you had the gait control theory remember that we had in the central nervous system like that locus cyrillius and the dorsal medium raphe and all those periaqueductal periventricular gray matter all those structures they were sending axons down to inhibit the pain pathway okay it is also involved in pain modulation so i also want you to remember another function of the substantia gelatinoservillando is that it also is responsible for that descending pain pathway or pain modulation boom let's move on so next one we have the nucleus proprious the nucleus proprious you guys remember this one we already talked about the hockey pies laminas three and four big thing i want you to know about this one it takes pain and temperature sensations pain and temperature sensations it takes touch it takes vibration sense it takes proprioception this son of a gun takes a bunch of different information right so pain and temperature it's going to be both c fibers and a delta fibers right touch vibration proprioception that's primarily carried by a beta fibers and one a fibers the big thing i want you to know about this one is the same concept here you have a stimulus whether that be a touch whether that be vibration whether that be position sense with your proprioceptors whether that be pain and temperature these guys can send information onto the cell bodies in laminas 3 4 to the nucleus proprious and what will he do cross this over and go up as a part of what the spinal thalamic tract or he can give off cell bodies that move up via the dorsal column medial meniscus pathway we know these things right so we know that it can actually give way to the dorsal column medial lemoniscus pathway or the spinal thalamic tract boom roasted laminate five and six again we didn't have any specific nuclei so we're just going to talk about the function of lamina five and the function of lamina six all right just for the simplicity sake lamina five okay let's talk about that one first right so what i want you to remember we're going to talk about laminate five primarily over here on this part of the diagram so lamina five i don't wanna spend a lot of time on this one because it's not a super important one what i want you to know really all i want you to know for lamina 5 is that this is carrying pain and temperature sensations from the viscera that's all i want you to know so if you have visceral sensations coming from different areas right here's your stimulus carried on this sensory neuron it's going to come in to the cell bodies in laminate five and then it's going to cross and go up right as a part of your anterior lateral system right and again synapse here and cross over and then ascend upwards but it's primarily going to be kind of that pain and temperature sensations from your visceral organs okay that's all i want you to know for lamina 5. lamina 6 on the other hand this one's actually really cool all right laminate 6. i want you to remember two functions for laminar six one is it involved with what's called your ventral spino cerebellar tract which is from l two to about coccygeal one so it's picking up sensations primarily from the lower extremities and so if you guys remember that's picking up proprioceptive sensations so it's picking up proprioception okay and that proprioception that's stimulating these sensory neurons will send come into your dorsal gray horn synapse on the cell bodies here cross over and then ascend upwards as your ventral spinal cerebellar tract and then eventually that ventral spinal cerebellar tract will then move into your cerebellum via the superior cerebellar peduncles and then cross behind and come to the other cerebellum on the same side of the stimulus so that's one thing i want you to remember the second thing i want you to remember is that lamina 6 is also involved in limb reflexes so you know like if you have some type of painful stimulus let's say you poked your hand or you stepped on a nail whenever you do that it's gonna there's gonna be a stimulus right to a particular receptor that's going to come into your dorsal gray horn it's going to synapse on cell bodies in lamina 6 and then the cell bodies in lamina 6 are going to send some specific pathways to stimulate the motor neurons your anterior motor neurons that are going to your skeletal muscles to come out and stimulate a skeletal muscle and cause that skeletal muscle to contract so for example if i stepped on a nail what's my my response going to be pick up my foot so the stimulus to the pain receptors in the foot sends it to my spinal cord activates the motor nerves that are going to go to my flexors and pull my foot off okay so it's involved in limb reflexes boom roasted let's move on to the next part next part is lamina seven now we said that there was three structures and lamina seven and we're gonna blast through this part because it's pretty straightforward okay first one we said was that intermedial lateral nuclear group and we said that was only present at t1 to l2 the intermedial lateral nuclear group are present right here in that lateral gray horn at t1 to l2 and what do these do i only want you to know one thing these are the cell bodies of the sympathetic nervous system but primarily the preganglionic in other words this is the first motor neuron it has to go to your second motor neuron which is your post ganglionic so these are your pre-ganglionic motor neurons so cell bodies of the sympathetic nervous system we're just going to add on here pre-ganglionic that's all i want you to know okay and again these are the motor neurons that we'll go to glands smooth muscle and cardiac muscle that's what i was talking about with that visceral motor neurons beautiful boom roasted move on we have the interomedial medial nucleus enteromedial medial nucleus we said that that is only present at s2 2 s4 there's no lateral gray horn at s2s4 that's why we call it that intermediate zone but there's nuclei here and these nuclei are going to go to again cell bodies of the postganglionic motor neurons that will go to smooth muscle that will go to glands what are these structures these are the cell bodies the parasympathetic nervous system which type your preganglionic so what are these again these are your pre-ganglionic boom roasted move on alright the next one is called clark's column or clark's nucleus and we said that clark's nucleus is actually only found at level c8 to about l2 l3 of the spinal cord now the only thing i really want you to know for clark's nucleus is that this is where the cell bodies that'll act as a relay for making the dorsal spino cerebellar tract and again what kind of sensations does that carry proprioception and it's only carrying proprioceptive sensations from what levels again c8 to l2 l3 so that is important whereas ventral spinal cerebellar was carrying it from l2 l3 to the coccygeal one area boom let's move on here we have proprioceptors they're getting stimulated from different positions of our muscle tendons our muscle spindles our joints our ligaments things of that nature coming in dorsal gray horn comes into the dorsal gray horn of the spinal cord synapses on the cell bodies of clark's column from here it moves into our ipsilateral white column here lateral white column and then ascends upwards and then we go through the inferior cerebellar peduncle and synapse and the cerebellum that is the purpose of that structure move on to the last one boom roasted all right lamina eight laminate eight is really cool i want you to know one thing and one thing only about this this is going to be a relay station so this contains cell bodies again we had them right here just to put that there right there was our lamina because we had nine all situated right here i want you to know that this is going to be the cell bodies that are going to be picking up information so they're cell bodies that are relayed that are relay stations for the sub cortical tracks i know you guys know what the heck those are we already talked about a video on them what were they hit me that was our rubr spinal pathway that was our vestibulo spinal pathway that was our uh reticulospinal both pontine and spinal pathways and the last one is our tacto spinal pathway all of those guys were coming from different areas right red nucleus vestibular nucleus pontine and medullary reticular nuclei and the superior colliculus all of these sons of guns were coming down here and synapsing on these structures here on the cell bodies in lamina eight guess what the cell bodies in laminate eight are for they're going to go to the skeletal muscles responsible for what what does the rubric spinal play role in distal flexion what is the vestibulospinal player rolling extension primarily of the trunk and limbs reticulospinal depending upon which one if it was the medullo it was going to be for flexion if it was the pantoreticular spinal that was for extension and tectospinal is for head and neck that's it boom roasted hi ninjaness so in this video we talked about the gray matter of the spinal cord i hope it made sense hope you guys liked it hope you enjoyed if you guys did smash that like button comment down in the comment section and please subscribe also if you guys get a chance down in uh the description box web links to all the things like facebook instagram patreon all that stuff you guys want to go check that out we truly appreciate it all right ninja nurse as always until next time [Music] you

all right ninja nerds in this video today we are going to talk about the gray matter of the spinal cord so let&#39;s go and get started all right ninja so when we talk about the gray matter of the spinal cord we obviously have to have an understanding of what in the heck gray matter is so let&#39;s take here we have a neuron here on the neuron we obviously have these little extensions coming off of the neuron what are these things called these are called our dendrites right little kind of extensions coming off the receptors on them that respond to neurotransmitters then here we have the cell body sometimes referred to as the soma right then coming off of that cell body going down here to your axon terminals we have our axon and then again lastly we have this last portion here called our axon terminal or terminal bulb whichever one you prefer what i want us to know is that there&#39;s these little fatty lipid sheaths that are surrounding insulating covering this axon what are these lipid sheaths here called these are your myelin sheaths and your myelin sheaths are a lipid kind of protein structure that allows for action potentials to be carried very quickly along that axon we&#39;re not going to go into detail of it now but you guys remember what these little nodes are called between these myelin sheets they&#39;re called the nodes of ranvier right and action potentials skip along these which allows for quick conduction which is called saltatory conduction we know that we&#39;ll talk about that later but what i want you to understand is wherever you see myelin i want you to remember that&#39;s going to be what is causing the neuron to appear whitish okay so wherever there is myelin it is white wherever there is not myelin that is gray matter so here let&#39;s take a look here at this structure here you see how we have the cell body and the dendrites that&#39;s going to be pretty much making up a lot of our gray matter another thing to add on though is if there is axons let&#39;s say that we had another neuron here&#39;s another neuron and this neuron here had no myelin sheaths covering that axon if there is no myelin covering that axon guess what that axon is it doesn&#39;t have the myelin it&#39;s not going to appear white so therefore it is gray matter so remember a lot of the time we say gray matter is unmyelinated cell bodies and dendrites for the most part it is but there&#39;s a couple areas in the body where the axons are not myelinated and therefore that is also gray matter okay so we know what gray matter is it&#39;s basically the structures of the neuron that are not myelinated next thing we have to talk about which i&#39;ll use a lot throughout the course of this video is what in the heck is the term for a nucleus and what in the heck is the term for a ganglia so let&#39;s imagine here we have a group of cell bodies i&#39;m just going to have a bunch of cell bodies here okay and this is the cell bodies of our neuron here&#39;s a bunch of cell bodies of a neuron okay i have a bunch of neurons these clumps this whole clump or group of cell bodies of in the actual central nervous system so this kind of group of cell bodies in the central nervous system is referred to as a nucleus the group of cell bodies which are clustered together and the peripheral nervous system are referred to as a ganglia okay so we know what gray matter is it&#39;s the part of the neuron that&#39;s not myelinated we know the nucleus is a group of cell bodies in the cns group of cell bodies in the pns is a ganglia now next thing we have to talk about is the anatomical portions of the gray matter they&#39;re special names right we already know a lot of these this is going to be a quick reminder we have here this portion here what is this portion here this gray matter here these kind of like shaded in portions here what is this this is called our posterior gray horn we already know this and then if we have this other region here let&#39;s kind of shade this one here we have this one which i&#39;m going to box here this is called our anterior gray horn this is called our anterior gray horn now there&#39;s a last one that i want to talk about briefly here and we&#39;re going to kind of call this one here and this one here you see how this is kind of what we&#39;re going to call the intermediate zone we&#39;re going to call this for right now the intermediate zone but what i want you to remember is that in this intermediate zone we have lateral gray horns which come off of a specific part in the spinal cord so if we have this intermediate zone okay at what level do these horns kind of pop off that intermediate zone you have lateral gray horns we&#39;re going to write this on this side it&#39;s a part of the intermediate zone lateral gray horns they&#39;re the parts that are coming off of this intermediate zone only at t1 to l2 and we&#39;ll talk about their functions a little bit later last thing that i want you guys to know is let&#39;s say that here i kind of make a line coming here and a line here so this horn this anterior intermediate zone anterior gray horn this posterior horn intermediate zone and anti-gray horn are connected through a sliver of tissue here and that sliver of tissue connecting the two sides of the horn is called our gray commissure beautiful so we know the post trigger horn right when our intermediate zone at the t1l2 region coming off of it is the lateral gray horn and anterior gray horn and we know the central or great commissure here connecting the two sides of that horn all right so the next thing that i want to talk about is the basic function of these horns so we&#39;re going to have one side right and what i want us to do here is we&#39;re going to kind of circle this portion here the posterior gray horn we know it&#39;s responsible for what type of function remember the posterior gray horn is i just wanted you to remember the lat on that last video we talked about the gross anatomy of the spinal cord and spinal nerves it&#39;s primarily sensory function okay now we&#39;re going to talk about this kind of this intermediate zone and this anterior anti-gray horn this is going to be primarily for motor functions let&#39;s break it down even a little bit more okay when we look at the posterior gray horn right what i want you to remember is that it&#39;s picking up sensations it&#39;s sensory neurons which are located in this area but it&#39;s going to be sensory neurons here in green i want you to remember that they&#39;re picking up somatic sensations what does that mean somatic sensations means it&#39;s picking up sensations from the skin from your skeletal muscles all right from your joints from your tendons from your ligaments and things like that whereas other parts of your posterior horn are going to pick up what&#39;s called visceral sensations what are visceral sensations it&#39;s sensations which are coming from your internal organs your heart your lungs your gi tract things of that nature then we have that motor function right well the motor function you&#39;re going to have here in that intermediate zone that&#39;s going to be able to be responsible for visceral motor functions so in other words this is going to be going to your smooth muscle to your cardiac muscle to the glands right a part of your sympathetic parasympathetic motor nervous system then here anterior most ventral this is going to be motor neurons for these somatic nervous system so this is somatic motor going to your skeletal muscles okay so that is what i want you to know when we talk about basic anatomy and basic function now let&#39;s dig in a little bit deeper into this gray matter all right so we know the basic concept of the gray matter of the spinal cord but we&#39;re ninja nerds we gotta dive in we gotta dive in deep so what we&#39;re gonna do is we&#39;re gonna talk about another concept here called rex lamina or lamina of rex and their associated nuclei within the gray matter so rex lamina basically was a way of that we can categorize or separate the different areas of the gray matter on our spinal cord here and it&#39;s a really simple system thank goodness that if we just numbered this as we go from posterior to anterior you&#39;re going to be going here the first lamina lamina 1 2 3 4 5 6. now from 1 to 6 this is pretty much the rex lamina that make up most of your posterior gray horn right then you get into that intermediate zone we talked about that&#39;s primarily occupied by lamina seven then we get into the anterior gray horn and the anterior gray horn is primarily occupied by lamina nine we&#39;re going gonna have the laminate nine here and lamina eight and there&#39;s one more so we kind of worked away all a one to six for posterior horn the seven primarily for intermediate horn eight and nine for anterior horn well guess what what that little structure was that we had connecting the two horns that was called our gray commissure that&#39;s called our central lamina right that&#39;s the central zone that&#39;s going to be laminate 10. okay so that&#39;s one way that we could define this so this way that we can categorize the different parts of the gray matter of the spinal cord is called the rex lamina the other way that we can categorize it is that there are specific nuclei that are present in specific lamina and have specific functions what are those those nuclear structures so you see here we have this one shaped like a p there&#39;s a reason why it is called our posterior marginal nucleus what is it called the posterior marginal nucleus sweet that&#39;s that one the next one here this one&#39;s shaped like an s oh real quick though posterior marginal nucleus we said that these occupy certain lamina right which lamina does the posterior marginal nucleus occupy primarily lamina one then you have the substantia gelatinosa of rolando that&#39;s the s that&#39;s what that one&#39;s for so this is called the substantia substantia gelatinosa of rolando one heck of a name right that&#39;s going to be primarily occupying laminar two then we have this next one here in green this is called the nucleus proprious this is called the nucleus proprious and the nucleus propria primarily occupies laminas three and four beautiful okay that pretty much takes care of what we said lamina one two three four now five and six they do have little nuclei in them but i don&#39;t really want to focus on those we&#39;ll talk about their function separately okay now the next one is we get into this intermediate zone that was around lamina seven there&#39;s three specific nuclei situated here let&#39;s go from medial all the way out to lateral so let&#39;s get this pink marker in here c what does c stand for that&#39;s clark&#39;s column our clark&#39;s nucleus so this is clark&#39;s column or clark&#39;s nucleus that is what this one is here right so we have clark&#39;s column or clark&#39;s nucleus which is most medial that&#39;s occupied within lamina seven again these three are going to be in lamina seven then we have this m this one&#39;s a weird one but they love to do this stuff this is called your interomedial medial medial nucleus group right so the enteromedial medial nucleus there&#39;s an m there that&#39;s the reason why we have that one there right so we got our interomedial medial nucleus and again this is going to be occupied within lamina seven last one here that&#39;s occupying laminar seven this is that brownish color here that&#39;s this one l that&#39;s enteromedial lateral nucleus this is our antero medial lateral nucleus these are sons of a guns aren&#39;t they and this is going to be occupying laminar seven beautiful okay now we&#39;re going to talk about laminate eight okay a little bit later lamina 8 there is no specific type of nuclei associated there but we&#39;ll talk about what the functions of those nuclei are for a little bit later in the video lamina 10 no specific nucleus associated here this is really just the simplest thing to know about laminate 10 is that this is where the axons cross over from one side to the other that&#39;s really all it is and it&#39;s called the gray commissure and if the axons are crossing and it&#39;s gray what does that mean about those axons they&#39;re not myelinated that goes to show you what the gray matter is okay let&#39;s come here to this last part lamina 9. lamina 9 we&#39;re actually going to zoom in a little bit more in here for but this is going to be a part of our nuclear group right and it&#39;s really simple this is our lateral nuclear group this is our central nuclear group and this is our medial nuclear group but what i want us first to do is take this nuclear groups here with the event the ventral gray horn and zoom in on it talk about some of the anatomy the somatotopic arrangement and function so let&#39;s go ahead and do that now all right so now we&#39;re going to do is we&#39;re going to talk about a little bit more about the structures within lamina&#39;s nine and we&#39;ll talk again we&#39;ll briefly recap ten so we&#39;re taking this cross-sectional spinal cardio right and what we&#39;re doing is is we&#39;re gonna zoom in on these nuclear groups remember these we had already talked about those up there our medial central and lateral nuclear groups we&#39;re going to cut this off and then zoom in on it right so this is going to be right here on this part of that black line this is that medial side and this is that lateral side okay so this is over here this is over here simple kind of like a basic outline of the anatomy now nuclear groups we already gave these guys name names lateral nuclear group this is our central nuclear group and this is our medial nuclear group we already know that what i also want you to know is is something really interesting the lateral nuclear group you know it&#39;s actually only present let&#39;s see if you guys remember this at c5 to t1 and a l2 to s3 do you guys remember where that was in the spinal cord in that gross anatomy video if we only find these at two sections we only find these at c5 2 t1 and we only find this at l2 to s3 what were those areas in the spinal cord segments that was our cervical enlargement and our lumbar enlargement why is that significant do you guys remember what we said happens in those areas in those areas if i draw a cross section here or i draw a sagittal section here right remember i said there was a little bulbous portion here and a little bulbous portion here remember we said that these were bulbous in these areas because that&#39;s where there was more gray matter in that anterior gray horn particularly in the lateral region and that these were going to the muscles of the upper limbs so the cervical enlargement so upper extremity and lower extremity for the lumbar enlargement that&#39;s why that&#39;s important okay beautiful next thing we have our central nuclear group now the central nuclear group here actually has a couple nuclei kind of spursed within it so there&#39;s a couple nuclei that are spursed within this that i want to talk about and you can kind of see them here we&#39;re going to kind of zoom in on them over here the reason why is they have specific areas that they serve so in that central nuclear group there&#39;s three particular nuclei that i want you to remember one is a p for the phrenic nucleus a for accessory spinal nucleus and o for onefs nucleus okay why do i want you to know this you guys know the phrenic nerve which supplies the diaphragm from what areas of the spinal cord are those nerves coming from c32 c5 where do you only find the phrynic nucleus in that central nuclear group at c3 to c5 accessory spinal nerve the accessory spinal component right that is going to be coming from c1 to about c 5 and that is going to be supplying the sternocleidomastoid and the trapezius so what does this one supply sternocleidomastoid and the trapezius muscles whereas the phrenic nerve will supply the diaphragm beautiful onuf&#39;s nucleus this is only present from s2 to s4 in that central nuclear group and this is going to be going to your sphincters the external sphincter so the external anal sphincter and external urethral sphincter and it also goes to the muscles involved in the erection and ejaculation process okay so that is another thing i want you guys to remember so again central nucleus within that central nuclear group there&#39;s specific nuclei that are scattered in there that are only present at these segments of the spinal cord beautiful next one we already talked about the medial nuclear group right now actually we didn&#39;t let&#39;s talk about the medial nuclear group now so now we have our medial nuclear group there&#39;s something that i need to kind of address here because this is kind of going to give you that somatotopic arrangement so we have a line here right this line that&#39;s going this way this is separating these nuclei into a posterior portion and an anterior portion right what i want you to remember first with this somatotopic arrangement here is that the nuclei that are going to be on this posterior portion are primarily supplying the flexors so they&#39;re supplying your flexors on this side of that line so these kind of nuclei that will be situated here on the anterior aspect of this imaginary line this is going to be supplying our extensors okay so when you look at these nuclei the nuclei that are situated more posteriorly in the in this anterior gray horn supply the flexors the nuclear that are more situated anteriorly in the anterior gray horn supply your extensors beautiful next thing we have another imaginary line here you see these purple lines here they&#39;re separating again these nuclei right so the lateral nuclear group guess what i want you to remember that they supply they supply your distal limbs so imagine that is kind of like your forearms your hands right the muscles of that area the central nuclear group guess what they supply the proximal aspects of your limbs maybe your shoulder joint maybe your biceps so that&#39;s going to be your proximal limbs and then this medial nuclear group guess what it supplies your axial musculature so your trunk and your neck right so this is going to supply your axial musculature all right beautiful that explains our somatotopic arrangement that describes the nuclei that describes their basic function now one more thing here these are cell bodies that are going to your somatic motor neurons right so these are cell bodies of the somatic neurons going to skeletal muscles of the distal proximal and axial limbs or axial structures both flexors extensors but guess what else you guys remember that we have these things called upper motor neurons coming from our cortex coming down here into the spinal cord right and then synapsing on the cell bodies here in that spinal cord going out so this was our upper motor neuron and this was our lower motor neuron right what were these structures called that going from the cortex to your spinal cord your corticospinal tracts the corticospinal tracts synapse on these neurons so these are cell bodies right in this area of the anterior horn they&#39;re a relay station for the upper motor neurons that&#39;ll synapse onto them stimulate them and then go to the skeletal muscles of flexors extensors of distal limbs proximal limbs and the axial skeleton beautiful that&#39;s all i want you to know for right now okay we already talked briefly about lamina 10 just to remind you all it is is imagine here we have a sensation coming in dorsal gray horn right so the dorsal root ganglia coming into the dorsal gray horn synapsing here and then it crosses over here and then goes up you see how these axons are crossing over to the other side through that gray commissure that&#39;s all it is and since it&#39;s gray what does that mean that means the axons are not myelinated boom let&#39;s move on all right so now what i want to do is we already talked about the kind of the function of laminas nine and ten let&#39;s now talk about some functions of some of the other lamina or their associated nuclei like which ones remember in laminar one there was the posterior marginal nucleus right and this was situated within lamina one now basic thing that i want you guys to know about this one simple straightforward to the point this is receiving this these nuclei associated right here i&#39;m gonna put one nuclei there these are picking up pain and temperature sensations pain and temperature sensations and if you really want to add on to that a little bit more guess what kind of pain and temperature sensations from what types of pain fibers this is primarily fast pain so this is carried on your a delta fibers okay your a delta fibers that&#39;s all i want you to know so if you guys kind of remember here is going to be the receptor picking up the pain stimulus carrying that on this sensory neuron through the peripheral branches of this pseudo-unipolar neuron then its central branch sends into that dorsal gray horn synapse on the cell bodies of the posterior marginal nucleus and then what will happen is it&#39;ll cross over and enter into your anterior uh or lateral spinal thalamic tract so this becomes a part of it leads into your anterior lateral spinothalamic tract that&#39;s all i want you to know about this one okay next one we have is the s substantia gelatinosa so substantial gelatinosa of rolando right this was occupying lamina two now a couple things that i want you guys to know about this one this guy he also picks up pain and temperature sensations but the type of pain and temperature is slow pain do you guys remember what the fibers were that carried slow pain that was your c fibers okay that was your c fibers the other thing i want you to know is that it actually becomes a part of that anterior lateral spino thalamic tract the last thing i want you to know just as a fun factoid here is that the substantia gelatinous overlando as you ascend up the spinal cord it becomes a specific nucleus in the medulla and that is called the spinal trigeminal nucleus this is for cranial nerve five and that is again present within the medulla so it becomes the spinal trigeminal nucleus within the medulla and again i&#39;ll give you guys a basic concept here&#39;s that cell body is there picking up a pain stimulus carrying it down this sensory neuron into the dorsal gray horn synapsing and then crossing over and then ascending upwards one last thing i want you to remember here do you guys remember in that video we talked about pain modulation you had the gait control theory remember that we had in the central nervous system like that locus cyrillius and the dorsal medium raphe and all those periaqueductal periventricular gray matter all those structures they were sending axons down to inhibit the pain pathway okay it is also involved in pain modulation so i also want you to remember another function of the substantia gelatinoservillando is that it also is responsible for that descending pain pathway or pain modulation boom let&#39;s move on so next one we have the nucleus proprious the nucleus proprious you guys remember this one we already talked about the hockey pies laminas three and four big thing i want you to know about this one it takes pain and temperature sensations pain and temperature sensations it takes touch it takes vibration sense it takes proprioception this son of a gun takes a bunch of different information right so pain and temperature it&#39;s going to be both c fibers and a delta fibers right touch vibration proprioception that&#39;s primarily carried by a beta fibers and one a fibers the big thing i want you to know about this one is the same concept here you have a stimulus whether that be a touch whether that be vibration whether that be position sense with your proprioceptors whether that be pain and temperature these guys can send information onto the cell bodies in laminas 3 4 to the nucleus proprious and what will he do cross this over and go up as a part of what the spinal thalamic tract or he can give off cell bodies that move up via the dorsal column medial meniscus pathway we know these things right so we know that it can actually give way to the dorsal column medial lemoniscus pathway or the spinal thalamic tract boom roasted laminate five and six again we didn&#39;t have any specific nuclei so we&#39;re just going to talk about the function of lamina five and the function of lamina six all right just for the simplicity sake lamina five okay let&#39;s talk about that one first right so what i want you to remember we&#39;re going to talk about laminate five primarily over here on this part of the diagram so lamina five i don&#39;t wanna spend a lot of time on this one because it&#39;s not a super important one what i want you to know really all i want you to know for lamina 5 is that this is carrying pain and temperature sensations from the viscera that&#39;s all i want you to know so if you have visceral sensations coming from different areas right here&#39;s your stimulus carried on this sensory neuron it&#39;s going to come in to the cell bodies in laminate five and then it&#39;s going to cross and go up right as a part of your anterior lateral system right and again synapse here and cross over and then ascend upwards but it&#39;s primarily going to be kind of that pain and temperature sensations from your visceral organs okay that&#39;s all i want you to know for lamina 5. lamina 6 on the other hand this one&#39;s actually really cool all right laminate 6. i want you to remember two functions for laminar six one is it involved with what&#39;s called your ventral spino cerebellar tract which is from l two to about coccygeal one so it&#39;s picking up sensations primarily from the lower extremities and so if you guys remember that&#39;s picking up proprioceptive sensations so it&#39;s picking up proprioception okay and that proprioception that&#39;s stimulating these sensory neurons will send come into your dorsal gray horn synapse on the cell bodies here cross over and then ascend upwards as your ventral spinal cerebellar tract and then eventually that ventral spinal cerebellar tract will then move into your cerebellum via the superior cerebellar peduncles and then cross behind and come to the other cerebellum on the same side of the stimulus so that&#39;s one thing i want you to remember the second thing i want you to remember is that lamina 6 is also involved in limb reflexes so you know like if you have some type of painful stimulus let&#39;s say you poked your hand or you stepped on a nail whenever you do that it&#39;s gonna there&#39;s gonna be a stimulus right to a particular receptor that&#39;s going to come into your dorsal gray horn it&#39;s going to synapse on cell bodies in lamina 6 and then the cell bodies in lamina 6 are going to send some specific pathways to stimulate the motor neurons your anterior motor neurons that are going to your skeletal muscles to come out and stimulate a skeletal muscle and cause that skeletal muscle to contract so for example if i stepped on a nail what&#39;s my my response going to be pick up my foot so the stimulus to the pain receptors in the foot sends it to my spinal cord activates the motor nerves that are going to go to my flexors and pull my foot off okay so it&#39;s involved in limb reflexes boom roasted let&#39;s move on to the next part next part is lamina seven now we said that there was three structures and lamina seven and we&#39;re gonna blast through this part because it&#39;s pretty straightforward okay first one we said was that intermedial lateral nuclear group and we said that was only present at t1 to l2 the intermedial lateral nuclear group are present right here in that lateral gray horn at t1 to l2 and what do these do i only want you to know one thing these are the cell bodies of the sympathetic nervous system but primarily the preganglionic in other words this is the first motor neuron it has to go to your second motor neuron which is your post ganglionic so these are your pre-ganglionic motor neurons so cell bodies of the sympathetic nervous system we&#39;re just going to add on here pre-ganglionic that&#39;s all i want you to know okay and again these are the motor neurons that we&#39;ll go to glands smooth muscle and cardiac muscle that&#39;s what i was talking about with that visceral motor neurons beautiful boom roasted move on we have the interomedial medial nucleus enteromedial medial nucleus we said that that is only present at s2 2 s4 there&#39;s no lateral gray horn at s2s4 that&#39;s why we call it that intermediate zone but there&#39;s nuclei here and these nuclei are going to go to again cell bodies of the postganglionic motor neurons that will go to smooth muscle that will go to glands what are these structures these are the cell bodies the parasympathetic nervous system which type your preganglionic so what are these again these are your pre-ganglionic boom roasted move on alright the next one is called clark&#39;s column or clark&#39;s nucleus and we said that clark&#39;s nucleus is actually only found at level c8 to about l2 l3 of the spinal cord now the only thing i really want you to know for clark&#39;s nucleus is that this is where the cell bodies that&#39;ll act as a relay for making the dorsal spino cerebellar tract and again what kind of sensations does that carry proprioception and it&#39;s only carrying proprioceptive sensations from what levels again c8 to l2 l3 so that is important whereas ventral spinal cerebellar was carrying it from l2 l3 to the coccygeal one area boom let&#39;s move on here we have proprioceptors they&#39;re getting stimulated from different positions of our muscle tendons our muscle spindles our joints our ligaments things of that nature coming in dorsal gray horn comes into the dorsal gray horn of the spinal cord synapses on the cell bodies of clark&#39;s column from here it moves into our ipsilateral white column here lateral white column and then ascends upwards and then we go through the inferior cerebellar peduncle and synapse and the cerebellum that is the purpose of that structure move on to the last one boom roasted all right lamina eight laminate eight is really cool i want you to know one thing and one thing only about this this is going to be a relay station so this contains cell bodies again we had them right here just to put that there right there was our lamina because we had nine all situated right here i want you to know that this is going to be the cell bodies that are going to be picking up information so they&#39;re cell bodies that are relayed that are relay stations for the sub cortical tracks i know you guys know what the heck those are we already talked about a video on them what were they hit me that was our rubr spinal pathway that was our vestibulo spinal pathway that was our uh reticulospinal both pontine and spinal pathways and the last one is our tacto spinal pathway all of those guys were coming from different areas right red nucleus vestibular nucleus pontine and medullary reticular nuclei and the superior colliculus all of these sons of guns were coming down here and synapsing on these structures here on the cell bodies in lamina eight guess what the cell bodies in laminate eight are for they&#39;re going to go to the skeletal muscles responsible for what what does the rubric spinal play role in distal flexion what is the vestibulospinal player rolling extension primarily of the trunk and limbs reticulospinal depending upon which one if it was the medullo it was going to be for flexion if it was the pantoreticular spinal that was for extension and tectospinal is for head and neck that&#39;s it boom roasted hi ninjaness so in this video we talked about the gray matter of the spinal cord i hope it made sense hope you guys liked it hope you enjoyed if you guys did smash that like button comment down in the comment section and please subscribe also if you guys get a chance down in uh the description box web links to all the things like facebook instagram patreon all that stuff you guys want to go check that out we truly appreciate it all right ninja nurse as always until next time [Music] you

Transcript for:Gray Matter of the Spinal Cord

Transcript for:
Gray Matter of the Spinal Cord