so today we are going to talk about cerebrospinal fluid what is cerebrospinal fluid it's a very special type of fluid which is present within the central nervous system and around the central nervous system that this is a fluid which is present within the central nervous system the special cavities within the central nervous system which are full of cerebrospinal fluid and this fluid is also present around the central nervous system in subarachnoid space in this lecture now onward cerebrospinal fluid will be called C SF whose the right we'll be calling it CSF right let's make a very simple diagram to show you how CSF is formed within the central nervous system then how it circulates within the central of a system and around the centre of a system and then I will teach you where the CSF goes eventually right we have to see from where it comes how it circulates and where it goes fine so let's draw a simple diagram here let's suppose these are your cerebral hemispheres right here is your brain stem these are sample hemispheres brain stem and what is here pons medulla and a spinal cord out of proportion right spinal cord so very simple diagram of course spinal cord should have strained downward now within the central of a system there are special cavities right in which CSF is produced let me show you those cavities but before I make those cavities you must know there are two very special structures and the top of the midbrain this is the midbrain so at the top of the midbrain there are two very very special structures right what are these structures helymus talam I is right and these structures are present just above the midbrain but within the deepest part of central nervous system or deepest part of cerebral hemispheres now first of all I will draw the cavities of the hemisphere cerebral hemispheres right so now this is this cavity then one cerebral Hemisphere this isn't other cerebral hemispheres these cavity is fluid-filled cavities which are present within the cerebral hemispheres these are called lateral ventricles what are they called in that from ventricles of course there will be one right lateral ventricle another will be the left lateral ventricle so over cerebral hemispheres have fluid filled cavities which are called lateral ventricle I will teach these ventricle in detail later right and these lateral ventricles are connected with other another space and this space with which they are connected through very special foramina right connected with another space and this space is present yeah in between the Salama now I'm talking about this space the right this one this fluid filled spaces present mainly in between the two thalam eye and this space is called third ventricle it is called third ventricle this is the right and lateral ventricle are connected with the third ventricle natural ventricles are communicating with the third ventricle through these foramina through these foramina this is one foramen and this is another foramen a hole communicating window between the lateral ventricle and the third ventricle this special window between the lateral ventricles and the third ventricle is called yes please what is the name of this window I'm about to be impressed by one anyone of you what is this window called foramen of Monro we call it foramen of Monro so we can say the lateral ventricle of cerebral hemispheres right are connected with the third ventricle through the foramen of Monro is that right actually cerebral hemispheres are T lung Cephalon and structures around the thalamus are called diencephalon so we can say the lateral ventricles are the cavities of telencephalon and third ventricle is the cavity of diencephalon so we can say now third ventricle form its floor right it is connected with a tube and this happened I am aligned tube her cavity is the cavity of midbrain as lateral ventricle are the cavities of telencephalon third ventricle is the cavity of diencephalon then this particular fluid filled space are a narrow tube which is present in the midbrain that is the cavity of mesencephalon that is the cavity of mesencephalon then what really happens that at the lower end of the midbrain this CSF filled cavity start expanding right the CSF filled cavity starts expanding let me get again see a separate cavity starts expanding here and expands like this you know it become wide right and from in the spinal cord there is also a CSF filled cavity and that cavity is called central NR the central canal continues up to the mid of the middle ah here is pawns and here is madala central canal continues up to the mid of madala right around the middle submit the lock central canal also expands outward this is it right so this is spending cavity from the top and down the meat together and they make a cavity now this whole cavity this cavity is called fourth ventricle right this is the cavity of the on the posterior aspect of pons and a pyramidal LA and this is interior to cerebellum this is interior to cerebellum right now this cavity is called fourth ventricle right so this is fourth ventricle here we have which Pentagon third ventricle and of course right and the left one should be one first and other should be the second but they don't label as which is the first one which is a second they say that there are two lateral ventricles one third ventricle right and there is one fourth ventricle now this is the cavity system within the central nervous system is that right now this tube which is present in the midbrain what is it called will tell me yeah cerebral cerebral aqueduct cerebral aqueduct was that right this is the cavity of the midbrain and fourth ventricle is the cavity of pons medulla and cerebellum or we can say simply the cavity of rhombencephalon hind brain cavity of the Romans have long is that right and central canal is the cavity of spinal cord is that right now these are the CSF filled cavities within the central nervous system this is right now I will show where and how the CSF is formed and how it's circulated within the central nervous system and how CSF comes out and then moves around the central nervous system actually CSF is formed within lateral ventricles for third ventricle and fourth ventricle be very very specialized structures which are called core ID plaque CSF is found by very special structures which are called caride flexes right for example I draw one choroid plexus here of course they should do one choroid plexus here right and there are our core ID flexors in the roof of what is this third ventricle and also there are two right places and the roof of fourth ventricle right these choroid plexus are special places where there is formation of CSF where there is formation of CSF now let me show in detail what is the exactly choroid plexus this is the right I will show this choroid plexus with enlargement is the right how the choroid plexus are formed let's suppose that this is brain substance it's very very simple diagram that this is brain substance all of you must be knowing that brain substance is covered with which meningeal layer Pia mater this is the PIA mater right just outside the central of a system covering that intimately this is the PIA mater is the right and let's suppose this is the cavity in the brain right and cavity in the brain is covered by just plays what is this happened I'm all cells all the cavities within the central of a system right which may be lateral ventricle the third ventricle or cerebral aqueduct enforcement trickle or central canal all of them are lined with in by special type of cells and these cells are called happened daemul cells whose the right now how the choroid plexus is formed let's suppose this is your brain substance right now what really happens these are core idol arteries right these core idol arteries are going to the through the central of a system they are going to the cavity and when this core Idol arteries are going in inside they will make what is this specialized capillary loops and then what will be coming out kreidel wanes and these are your choroidal arteries this is carotid arteries these are kreidel veins now carotid artery is going n making collagen coming back as wing this arterial and venous bender which is entering to the going to versa ventricular cavity it is covered by what is the structure please Pia mater so it takes a fold of Pia mater along with it and this PR matter is throughout covering this vascular Taft so this vascular bundle which is going n is covered by artery tipple rays Wayne right they are taking a fold off what is this fold off Pia mater now this structure the vascular tuft or bundle within a fold off Pia mater this structure is called tillich or ID what is the structure called Tila alrigh d this vascular structure inside Tila core ID this is the right now when this structure reaches the deepest to the ventricular area right it is covered by what are the same yeah ependymal cells and when this structure Dilek right is covered by ependymal cells then the structure is called core ID classes that here ependymal layer is covering it so when Dilek or ID is covered by a lining of a pond i'ma this whole special Secretary's unit because it's a critter there's a critter CSF this whole specialized creature unit is called Co right classes this tonight so all these co-ed flexes these are in the lateral ventricles here in the roof of third ventricle and the they're in the roof of force ventricle all these core at lectures are made by the Dean locker ID which is a double folded layer of paya matter with blood vessels right Dilek already having additional layer of happen dyma I'm a clear now so next time you know what is the exactly t locker ID and what is overhead flexors and you know the basic function of correct licenses to produce CSF next point which we have to see is how choroid plexus functionally produce seals CSF let me tell you how it is doing now Allah will make a more simple diagram actually the cells here all these cells which are covering the choroid plexus these cells are special I will just show you one cell to cell and three cells right now what really happens these cells are having a very specialized pump for sodium so these cells actively secrete sodium there are active sodium transporters present in the epithelium of chloride plexus now I'll call it epithelium of korad lectures the epithelial cells of the choroid plexus are having lot of sodium transporters so they actively transport the sodium from the cells to the ventricular CSF idea right and sodium is with the expenditure of energy it is constantly pumped from the cradle epithelium to the CSF area when sodium is constantly pumped you know sodium is positively charged it will attract which thing yes please caller ID of course so what really happens the corridor epithelium will actively throwing the sodium and what is the follow following the sodium is for the right so in this way rhodium and caller-id are actively pushed especially sodium actively and caller-id passively they are going from the choroidal plexus to the CSF of course when sodium and chloride come over here a smarting pressure in this area will increase when a smartie pressure in this area increased instantaneously it pulls the water with it it pulls the water with it and then water also follows so what are the steps step number one is that there's active secretion of sodium that is passively followed by color ID and sodium chloride or somatically pol water so this is how CSF is being formed with that these epithelial cell have glucose transporters which can transport the glucose from the blood but these transporters are not very efficient due to that what is then the Guru course which is transported from the blood right it's concentration is in the CSF is less than the concentration of glucose in the blood for example if in the blood glucose concentration is hundred milligram per dr then in the CSF concentration will be two third of that may be 66 milligram per dr a mcclure so sodium is efficiently transported caller-id efficiently follows sodium and chloride both pull the water right there special transport mechanism for glucose but usually the CSF level of glucose is less than the glucose level in the blood and Julie CSF level in the of the glucose about 2/3 of the level of the blood glucose right next is there's a few tens which are transported in reverse direction from the CSF to DES where to the blood one of the edges potassium so naturally potassium level in the CSF will be less than the production level in the blood this is the right any question up to this No so this is how skiers have found the most important thing in the formation of CSF you have to remember active transport of sodium that's for passively followed by chloride sodium chloride both of them pull the water automatically and this way CSF is formed glucose is transported but in efficiently and the few substances they are transported form the CSF back to the blood am i clear so this is how choroid plexus formed any question up to this now we can see that CSF is formed in the lateral ventricles is that right and from the lateral ventricle CSF will go to the third ventricle through foramen of Monro this is the CSF coming in the third ventricle and this CSF is coming from where from the second ventricle in the same way the CSF is also coming from the second ventricle so the choroid plexus present in the lateral ventricle right they are forming the CSF within the lateral ventricle from their CSF through the foramen mondo is transported to the third ventricle and in the roof of the third ventricle there are also Co red blood cells so some CSF is further added right to the ventricular system by the choroid plexus of third ventricle then the CSF will start moving from the third ventricle this is moving in the third ventricle eventually right will go downward and now it has entered into yes please cerebral aqueduct no CSF has entered into cerebral aqueduct from there cerebral aqueduct inferiorly open into fourth ventricle so in this way CSF will come to the fourth ventricle while it is from cerebral liquid of CSF is coming to the fourth ventricle colloid fluxes of the fourth ventricle also adds further CSF am i clear now this CSF also fills what is this your central in all is the right and sometimes lower end of the central canal is little bit dilated and then if it is little dilated they call it terminal ventricle then they call it terminal ventricles but this is a dead end fluid cannot move further from here this is the right now we know exactly how CSF is formed in where CSF is formed within the ventricular system within the brain substance emmaclaire now once it is produced there now CSF has to come out of ventricular system outside the brain now let me show that how it comes out okay let me make here what is this special covering around the brain substance PR matters right so we can show that all of the brain substance is covered by Pia mater and around that Pia mater there is another meningeal covering and what is that that is a recognized matter right now so this is the outer covering and this covering is what is this yes please no it is a recognized matter devera has to be still outer because out after the paya what is there there should be a recognized outside the paya there should be Rek night right now you know the space which is between the paya PR and the recognized this space is called subarachnoid space this is called sub sub recognized space right so this is your sub arachnoid space does it right now what really happens that fourth ventricle you see fourth ventricle as it moves down from the sarah.billick we ducked and it moves up from the central canal it expands laterally it expands laterally and eventually fourth ventricle open on the surface of the brain right through a foramen naturally these two four immense these are called from enough leshka these are called from enough leshka so what really happens that CSF will move laterally here and through this foramen of leshka CSF will exit from the cavities within the central nervous system it will exit from the cavities within the central of a system outside into subarachnoid space so this is a fourth ventricle it gives a chance to the CSF that it can move from cavities within the central nervous system outward into subarachnoid space this is the right here subarachnoid space is little bit dilated it is expanded so it is called bone tine system is that right separated spaces here excessive fluid and that is why this dilated subretinal space which is full of CSF wear formal Lashkar open right what is this this is foramen lashka from in the sky opens literally from the lateral recesses of fourth ventricle right into Ponton cisterns or more accurately we call them cerebellopontine cisterns and from there of course CSF is now going into which area subarachnoid space is that right then there is very important point there is one more for a men right there is one more for a men on the posterior aspect of on the posterior aspect of fourth ventricle this is a million from end these two are lateral for men this is the median for men right it also releases this foramen also releases CSF from the fourth ventricle from the roof of the fourth ventricle through the foramen of Magendie right CSF is it into another sub ragnar space and that CSF filled space is also dilated so that is called which system that is called cerebellar medullary these were opening into cerebellopontine sister and cerebellum and Ponton junction here is cerebellum and middle our junction so this as cerebellopontine sis trans and this for a man million foramen opens into cerebellar middlee right cistern and this median foramen is called foramen of Magendie this median foramen is called foramen of Magendie is the right this is called foramen of Magendie right so how many Foreman's you know through with the CSF passes foramen of Monro which helped the CSF to move from lateral ventricle into third ventricle is the right then foramen in the fourth ventricle there are three foramen to lateral faraman faraman lashka right and one posterior median foramen which is called foreman Magendie these two from Alaska and foramen of Magendie they allow the CSF to move from cavities within the central nervous system outward into subarachnoid space the very special thing is that these three from n are the exit point for the CSF from the central of a system to the outside of the central nervous system into subarachnoid space and specially in the system's dilated areas right now I will make this diagram a little more clear from the lateral aspect now that will make you the what is this ventricular cavity the same thing I'm showing now from the Sun but from the side this is third ventricle this is the right what is that this is third ventricle first I will make the easy things I'll make the relationship of third ventricle and rest of them this is the third ventricle of course third ventricle should have interior wall host a wall a floor roof and lateral walls this is the right ventricular system I will teach into detail later but actually what happens in the floor of the third ventricle here is a hole puncture point and from this point what is going down what is this cerebral aqueduct and this cerebral aqueduct right it is moving midbrain and as soon as goes to the point I'm the cerebral aqueduct start dilating right now it is approaching into what now what is this central canal and what is this now found now look at it this structure is your cerebral aqueduct this structure is cerebral aqueduct and this is your displays central canal right and what is this fourth ventricle right this is the interior part of fourth ventricle anteriorly fourth ventricle has spawns right interior leaf force pentacle has pawns and upper part of madala and upper part of madala posteriorly it is making a tent shape area right which is going to yes please which is a very special structure here yeah this is cerebellum right what is this this is of course this is brain substance now what really happens that here are the lateral foramina one foramen here and other on other side and this is the posterior foramen which was this magenta does the right if I make it more clear I'll bring it out for span trickle it's like this above it is crafted with cerebral if we down below it is connected with right here are the foramen Logica and this is the roof and here should be foramen Magendie and CSF cat can exert from these points it can come out from certain levels from these points and also from there the point which you have to understand the head let's pose here you are what is this you are standing in fourth ventricle on one leg you are standing on the fourth ventricle with one leg you put your foot into back what is this Magendie and you put one hand here and other hand there and to which foramen ah leshka here is nescau opening on this side and there is a scar which is opening on that side and here is it so we can imagine like this look here I'm standing on the fourth ventricle who's the right I'm standing in the fourth ventricle here I have palms here I have better Allah and very dangerous cerebellum on my back i contrast cerebellum that is on the back right pons medulla and cerebellum above is the midbrain blows the spinal cord if I'm in the fourth ventricle some shower is coming from there top what is that from cerebral aqueduct and my one foot is in a pipe going down stuck there what is that pipe which is going down to spinal cord yeah central canal and my this fourth right one it is going backward trying to plug what foramen of Magendie so I'm trying to be clever I plug the foramen Magendie from the foot backward median with one hand I block what from a lock on right side in the other hand I will block on the left side and I stuck my head into inferior part of cerebral aqueduct now you have to remember it when you are in the fourth ventricle you had it stuck into inferior part of syllable if we ducked this is the right my hands are into foramen las casas which were opening the into molten cisterns are cerebellopontine cistern and my foot on the back is in the forum an agenda which was opening into cerebellum meter lewis's Tran and my foot which is downward struck on the top of opening half Sancho cannot you understand all relationship of these things very Claro okay now once the fluid come out from from the posterior central or foramen Magendie and from the lusca now where the CSF goes we have to see okay I did not make the lateral material you want to see lateral ventricle in relation to that okay lateral there is one opening here and there is one opening here what are these foramen of Monro what are these formal Monro I will make a lateral ventricle with different color lateral ventricle has one extension into what is this frontal lobe right this is called frontal Horn of the lateral ventricle then lateral ventricle has this is the body of lateral ventricle this is the body of lateral ventricle this is frontal Horn of lateral ventricle this is lateral ventricle right then from here it has strained the HAR what is this posterior horn and this is in occipital lobe so lateral ventricle has frontal extension from its body it is occipital extension and from here it has one more extension what is this temporal lobe is the right in the same way there are two hemispheres so there will be one what is this on right lateral ventricle and this is a body on the right side and right occipital and right now let me make it more clear one I will make it separately first of all you must recognize now listen I will orient your mind towards the lateral ventricle right we already know what is here third adventure third ventricle has an opening here and through this opening you can jump to the this opening of course one on this side right foramen Monroe and that is left from an mundo it means if I'm standing on the third if I'm standing in the third ventricle right there's one telling us here and one column is here under my feet what is their midbrain this is the right I'm standing in the third ventricle and again I tell you there's an interior wall of third ventricle there is push your wall a third ventricle on the side their lateral walls this floor and there is roof if I move my hands like this this hand will go through one window and another window these windows which are near the roof in the lateral wall interiorly these windows are foramen Monro and the top there showers go red flashes off third ventricle I am trying to stop the water should not come from one row to flood me but showers from the top are also working is that clear so this is now what really happens this foramen opens into body of lateral ventricles it has one frontal extension this is the body and it has one occipital extension right and it has one temporal extension so how many part of the lateral ventricle frontal extension of frontal horn which is the cavity of the frontal lobe body of the lateral ventricle which is the cavity of the parietal lobe posterior extension which is the cavity of occipital lobe occipital extension or ha this is inferior horn or temporal horn or we call it simply we call it simply Garrity of the temporal lobe it means that lateral ventricle has to provide you with frontal extensions for the frontal lobes body for the parietal lobe posterior extensions for occipital lobe and inferior extensions for temporal lobe I'm at left and in the lateral ventricle they are connected with the third ventricle through for a man wonder any question after this No now the CSF has come out from Foreman the scan Magendie into subarachnoid space in the subarachnoid space you can go down and it will be filling the subarachnoid space around the spinal cord this is CSF filled subarachnoid space around the spinal cord in adult spinal cord terminate at l2 number 2 level but this subarachnoid space goes up to s2 sacral 2 and in between them we can puncture and get the sample of CSF we call it lumbar puncture right that is really puncture point we make between l4 and l5 that I will discuss later in the lecture right now what is how you do the lumbar puncture what are the layers which are pasted right we'll do it later right now we see the spheres have come out some of it goes down but again down there the dead end and of course most of it is going upward is that right and as it is moving upward you have to tell me that this is the dura mater what is this dura mater right what is this thing can you tell me these are dual fold in between them midbrain is going up and under these fold there is cerebellum and the brain stem poorer than middle ah this is tentorium cerebelli you know tanto diem cerebellar okay someone who doesn't know I will tell you maybe from the side view you can see it better that if this is the central nervous system this is the midbrain pons and medulla here it is cerebellum right now there's a special fold of dura mater which is from here up to here and then going back this fold is called tentorium cerebelli because it make a tent above the cerebellum so you call it tentorium cerebelli is the right so but from the side yeah tentorium dorium cerebellar this is the right anyway now what we really see that for CSF which has come out from foramen of Magendie and from Nazca into sistrums and then into subarachnoid space it moves down and fill up all the area plus it moves upward as it is moving upward now it is going around central nervous system this is right outside the PR but within de a recognised layer right first one which is it it is around the pons medulla and cerebellum then it goes up right then it is under surface of the cerebral Hemisphere then it goes on the convexity of the cerebral Hemisphere and eventually CSF reaches to the top of cerebral fierce does that right now the Doudna matter at the table has you know it has two layers one layer of the dura mater is called inner layer of dura mater is called meningeal layer of zero matter and outer layer of the dura mater side this is outer layer this is the inner layer outer layer is called periosteal thereof dura mater and this is a miniature layer of deer metal at the top both layers become separate this is your outer layer and here is your inner layer outer and inner layer right at the top this separate and then defuse right now they refuse over here these two layers there are also fuse over here and when they are then at the top they separated so dick tree 8 are triangular space here they create a triangular space are you understanding am i clear look here it is like this that this is one layer of dura mater this is a other layer and it separates like this here and then it is doing like this now this is a triangular space this space is lined by endothelial cells like veins this is a special venous drainage system of the central nervous system right within the doodle we also call them dural venous sinuses what we call them dural venous sinuses now so we can say this dural venous sinus is lined by Watson EPI everything ever endothelium it is lined by and Davi do you know this is like a brain it has to be lined by endothelium is that right and of course what is there there's venous blood into this and this face is called superior sagittal sinus look why because it is superior ly present and it is in the sagittal position superior sagittal sinus are you with me are you understanding or not sure good now this is a space which is concerned with venous blood drainage is the right speedier sachet of sinus which is here a very special type of euro sinus a look here this dura mater here has holes and through this whole do you know metal is connected to the subarachnoid space and from here what about was this what is this recognized matter now through these spaces I reckon I'd matter goes into that and make finger-like processes are you understanding what is happening if you really want I can make a bigger diagram here let's suppose this is the cerebral Hemisphere this is cerebral Hemisphere now please tell me the layers or make it a little bit more open this is cerebral hemisphere right now it is covered by a yes please generator no problem of do this around it there is what a recognized matter who's the right and what is this space subarachnoid space which is full of CSF am i clear here is your dura mater which make a triangular this is dura mater right and this is Bureau matters outer layer now in between the inner layer of the dura mater this is the inner layer of bureau and this is outer layer of the dura mater a space is formed there is a space formed this space what is the space called yes please spiritual finest now what really happens Bureau mater has a hole here and it is a puncture point here through this hole you see what is going there I recognize matter into sinus and it is making finger light process recognize matter here and going making finger like processes is that right finger like processes now within this dural sinus there's once was puncture point here one puncture point here and this was your recognized with multiple finger life processes right now you know what is present here what is moving here yes please CSF am i clear to everyone CSF this is CSF filled cavity CSF from these points right will drain into venous sinuses it means CFCs have coming from here and coming from here through this point it will enter here right again it will come into this now these finger-like processes are microscopic processes these are called what are they called I recognize villi what are these fingers called finger like projections of recognize the membrane is salt I recognise villi right so out of this this is the recognized vilnius this is another rectangle s this is an arachnid vilnius this is an arachnid Villas now these are at night relate together as a group they make a projection like this macroscopic projection which can be seen with naked eye villi are very small but many will lie together they make a projection that is called a recognized granulation what is that called I recognized granulation again listen here these are the fingers you know through that doodle hole these fingers are projecting what are these finger called villi and this finger come together as a fist and this is called a recognized granulation so you know there are exactly a recognized villi and arachnoid granulations now what really happens there through these wines look here through these points CSF is being drained from subarachnoid space into dural venous sinuses here in this example this is draining into which area superior sagittal sinus is there Claire so this is a diagram which we can focus and we can see there from the subarachnoid space right there are CSF moving through the arachnoid villi and granulations and now CSF drains into venous blood is there clear now there is one important point here to be explained that these are recognized will lie they have special endothelial caps on them there are a lot of endothelial cells on them let me make one electrolyte villas this is one I recognize Valles right it has lot of endothelial cells and endothelial cells which are present on them with electron microscope they discovered there these endothelial cells have radicular channels what are they having vesicular channels and through this channel actually CSF very easily move to dural sinuses and not only these vesicular channels within these endothelial cells allow the movement of CSF fluid even they may allow some larger particles to move like protein particles may move even sometimes RBC's may also move from CSF through these channels but if there are too much cells here inflammatory cells or RBC's or tumor cells they may clog the or block the drainage system am i clear now so in this diagram let's come to the major diagram that here are sbrick not matter doing it here and making recognize villi and together we'll I made what they made granulations am i clear and in this way CSF which was from coming from down through this process drains into dural sinuses is their player any question up to this one thing you have to remember that these recognize we learned dren relations they act as a one-way system they allow the movement of fluid from subarachnoid space to the venous space but they do not allow the reverse direction because if pressure here become too high these will be compressed when they are compressed the channels collapse and close so the dude Lauda reverse direction so these recognized villi and recognized granulation allow the movement of fluid only from subarachnoid space to the bureau sinuses but they do not allow the reverse direction of venous blood and dural sinuses to go to subarachnoid space am i really clear about the same another thing the pressure in pressure of CSF and subarachnoid space depends mainly on the drainage system quality not on the production because the most of the condition production of CSF is very stable production of the CSF is very stable normally whenever pressure of CSF is about 1.5 millimeter above the dural venous pressure you know there can be pressure of fluid in CSF subarachnoid space and pressure of fluid in Durrell Venus actually for movement of the fluid from subarachnoid space to do live in the space the pressure in the dude in the subarachnoid space should be more and pressure in the dural venous space should be less whenever this pressure is you can say subarachnoid space CSF pressure is just 1.5 millimeter or above more more than the dural sense will I start working and letting the fluid to move from subject matter space into dural sinuses if CSF pressure become really high these keep on the channels become more open and they allow the fluid to move more efficiently this is a clear now what we really know up to now in the slag first of all you must know what is CS f let's recap a little bit CSF is a special fluid which is clear colorless odorless fluid right which is present within the central nervous system and special cavities and also around the central of a system in subarachnoid space and cisterns well where CSF is produced CF CSF is produced by specialized security units which are called core ID plexus and these covert Lexa's are present within the ventricular system is that right there are two choroid plexus present in the lateral ventricles then the roof of the third ventricle there are two Corot plexus then remove the fourth ventricle alpha has to go right practice all of them are constantly producing CSF every minute at least half ml of the CSF is produced and in 24 hour about 500 ml ofte CF CSF is produced every day you are producing how much CSF about half later is the right total amount of CSF within the brain and around the brain is about 130 mm it means their daily production of CSF is 3 to 4 times then that total amounts of CSF which is present at a given time within the within and around the CNS so it means it is constantly being produced and it is constantly being drained now to understand the secretion of CSF and circulation within and around the brain we have discussed this diagram