hey everyone welcome to professor long's lectures in anatomy and physiology i'm professor bob long you're not going to see my face today but that's okay i have a face for radio um you are going to hear my voice i'm going to be covering the spinal cord model and we're going to be following along on our list of things to know are the laboratory assignments the lab guide and we're going to be covering i think it's on page 35 and 36 where the spinal cord structures are if you're in my class use that list of things to know for the laboratory guide and follow along if you're not in my class well then hopefully these words sound familiar because your instructor has covered some of this as well different instructors go into different levels of detail have different models cover things differently so if you're not in my class please learn it the way your instructor wants to learn it but hopefully this is helpful if you find my videos helpful please hit like so now this is the spinal cord itself sitting inside what we would call the spinal foramen of the spinal column or the vertebral column this is a vertebra out here we can see the body the superior articular facets and the spinous process so this is a cervical vertebra i can tell because of this little v-shaped structure and i have these arteries and veins running through the transverse foramen that's what we call your vertebral arteries and veins only cervical vertebra have that now in addition to covering the spinal cord and knit structures we're going to be covering one part of your spinal nerves and we're also going to be covering the meninges of the spinal cord we went over the meninges of the brain the dura mater arachnoid monitor and pia mater and they're called cranial meninges they are continuous with and really the same layers as the spinal meninges now what the outermost layer that we covered of the meninges is this one up here called the dura mater dura because it's very tough if you try to poke it it's very very tough and hard so that's called the dura mater now all of this yellow area out here where the blood vessels are is called the epidural space and the yellow is some adipose tissue turns out that we have two layers of dura mater we didn't cover that when we did the cranial meninges but it's there so this is the dura mater it's actually called the periosteal layer of the dura mater because it's up against the bone you don't need to know that but that's dura mater and if i poke down on top this very thin layer right here on the edge is also dura mater all the way around back up the space between the outer and the inner layer of the dura mater is called the epidural space it is filled with adipose tissue and lots of blood vessels this is where they stick an epidural injection they've tried to find a gap between the vertebrae usually in the lumbar region and they stick a needle in when they hit the dura mater they can feel its toughness and they poke through and they know they're in that epidural space they inject some medicine to numb your legs that medicine filters around here and numbs these nerves coming out so that you don't feel anything at that level of the spinal cord or lower so dura mater epidural space and dura mater now the subdural space is not very pronounced on this model you see that very thin gap right there i can barely fit a fingernail in it or the pointer here it goes all the way around that little dark line or gap is called the subdural space and it's almost like if i took my two fingers and stuck them together if one of them is the dura mater this would be the subdural space this would be the arachnoid motor that's this membrane on the other side of that little gap so i have dura mater subdural space arachnoid mater and the arachnoid mater also goes all the way around right next to the subdural space deep to the arachnoid motor on the spinal cord is a much larger gap here that is called the subarachnoid space and in this subarachnoid space there's a lot of cerebral spinal fluid flowing around and that's where they stick a needle in to do what's called a spinal tap they pull some cerebral spinal fluid off and look for bacteria and viruses and infectious agents so dura mater epidural space or same thing here dura mater epidural space dura mater subdural space is that little gap and then the next membrane would be the arachnoid mater all the way around the larger gap i can almost fit my pinky in it would be the subarachnoid space and then right up against the spinal cord this little white edging all the way around would be your pia mater that little white edge okay so those are the meninges of the spinal cord now the spinal cord itself is pretty easily laid out this is posterior with the spinous processes this is anterior our spinal cord starts off kind of large and then folds up on itself to fit in a smaller space and it creates this little groove or line on the back side and on the front side on the front that gap is a little bit larger a larger gap is called a fissure so this little groove or space right here is called the anterior median fissure median because it's in the midline the groove on the back half is called the posterior median sulcus a sulcus is a very tight gap a fissure is an open one so that's the anterior median fissure the posterior median sulcus the little hole in the middle is called the central canal and it was connected to the fourth ventricle once you find that everything else starts to fall in place once you know anterior and posterior at least for the spinal cord proper because everything else is labeled either a gray horn or a white column and their anterior lateral and posterior white columns anterior lateral and posterior gray horns now on our brain the gray matter was on the outside the white matter was underneath spinal cord is reversed on the spinal cord the white matter is on the outside the gray matter is in the middle and the gray matter forms this funky looking h or butterfly in the middle and it's a darker tissue it has three parts this area that sticks out down here this area that sticks out here and then this one here and to someone else i guess they look like horns so they're called the gray horns this would be the anterior gray horn this would be the lateral gray horn this is called the posterior gray horn and i have it on both sides anterior grey horn lateral gray horn posterior gray horn okay now those all of this is running up and down vertically in a column of your spinal cord if we slice the spinal cord at any level we will see these structures they may take on different amounts of gray and white matter and change their shape a little bit but they're there and our spinal cord has what's called bilateral symmetry because both sides are symmetrical or look alike if i can name it on one side i can name it on the other now the gray matter here has to communicate to each other sometimes and there's axons that will come across here and either go right in front or right behind the central canal so these are called the gray commissures there's one in front of the central canal called the anterior gray commissioner there'd be one right there where that number 35 is which would be called the posterior gray commissure a commissure means a coming together or a crossing so quick review dura mater epidural space dura mater sub-iraq subdural space arachnoid monitor subarachnoid space and then pia mater and by the way we have three little connections that hold the arachnoid motor up off of the pia monitor creating that subarachnoid space because they look like little teeth but they're connective tissue they're called denticulate ligaments this is a little denticulate ligament here there's one over here and then there's one on top right there those little connectors are called denticulate ligaments they stabilize the spinal cord so then we have the anterior median fissure central sulcus i'm sorry central canal posterior median sulcus anterior median fissure central canal posterior median sulcus enter your gray horn lateral greenhorn posterior gray horn anterior gray commissure posterior gray commissioner now the white matter is arranged to what we call white columns and the reason is there's all these neurons running up and down the brain like these sticks if i took a couple of these and these sticks were running through here running through the model and down your spinal cord vertically they would look like little columns running up and down kind of like little columns that you would have outside of a building so these white areas are referred to as the white columns this area here is the anterior white column this is the lateral white column this is the posterior white column and we have it over here anterior lateral and posterior white column now the white matter has myelinated axons in it and they have to cross over and there's a little crossing right here and right here they're next to impossible to see but they're called the anterior white commissure and the posterior white commissure i can't ask them because i can't point to them very well now our spinal cord is going to carry information from down from the brain through what we call descending tracts through the white columns and then into the gray matter and then out to some organ sending motor commands causing some smooth muscle or cardiac muscle or skeletal muscle to contract but when we touch something the sensations are going to come into the spinal cord and go up to the brain so our spinal cord really is a bunch of wires running up and down our spine where those wires exit they're going to form what we call some roots of the nerves and then the nerve will form itself sort of the actual nerve and then it will split off into some branches called ramai remus means branching and so ramay would be branches so coming out of this posterior gray horn there's this little yellow structure here that comes all the way down over here and there's one that comes here from the anterior side those are called the roots and we don't tend to use the term anterior and posterior for this we tend to use the term ventral and dorsal this is called the ventral root and it comes all the way over here this is called the dorsal root and it comes all the way over until this big swelling you can see the ventral root continues the dorsal root comes up to this big swelling called a dorsal root ganglion i see it over here as well but they're covered with the meninges ventral root dorsal root ganglion where the two roots come together it forms the actual spinal nerve here and here that's where the spinal nerve is and then immediately as it exits the intervertebral foramen the spinal nerve will branch one branch goes more posterior or dorsal the other branch comes anteriorly and i have the same two over here this is called the ventral ramus and this is called the dorsal ramus okay so ventral root spinal nerve ventral ramus dorsal root dorsal root ganglion spinal nerve dorsal ramus now the dorsal ramus will go to the back of our body the ventral ramus will cover the front sides and limbs at least those areas of the spinal cord that have limbs these two pieces right here here and here they cut one of them but it would come up and connect and it ends up being two branches that communicate to each other those are called the ramai communicantes remy camino contes and then this would be called the autonomic ganglion and it would go down and then go out to some organs so on this model you should be able to see these things the anterior median fissure central canal posterior median sulcus anterior lateral and posterior white column anterior lateral and posterior gray horn i have the anterior gray connoisseur the posterior gray commissure i have the dorsal root the dorsal root ganglion and the ventral root and they come together to form a spinal nerve over here would be dorsal root dorsal root ganglion ventral root and the spinal nerve from the spinal nerve it will branch into a ventral ramus and a dorsal ramus and then there's two branches coming off the ventral ramus called the rami camino contes i hope that anatomy made sense to you and we're going to draw this out in lecture we're going to talk about it in lecture we're going to talk about the physiology of the spinal cord which will be really cool tells us a lot of information but it's all based upon the anatomy anyway i hope that you enjoyed this as much as i did i hope you had as much fun as i did and i hope that you will sit here and go over your pictures of the models until you can't stand it do it till you understand it then do it five more times until you can make an a on your lab test if you have any questions email me blng delmar.edu and i'll see you in the next video thanks for watching