hello everybody welcome back i hope you're all doing well today we're going to have a look at the ventricular system in the brain as well as identifying some of these subarachnoid cistones and let's start by having a look at this diagram here showing the four ventricles of the brain we have our lateral ventricles out laterally the largest of the four ventricles coming here then connecting to this middle ventricle our third ventricle which then comes down and connects to our fourth ventricle here so our lateral ventricles are the largest and we can if we look laterally like this onto the ventricles we can see our anterior horn the body of the lateral ventricles coming down into our atrium or our trigone backwards into the occipital horn and then coming down all the way into the temporal lobe are temporal horns of our lateral ventricles now this diagram has quite a large gap between them but it's normally very close just a thin sheet of tissue separating them the septum polluted them we'll have our corpus callosum coming across the top here and laterally as you've seen from previous videos we'll have our chordate nucleus coming right the way laterally to these lateral ventricles those lateral ventricles then feed down into our third ventricle via our interventricular foramen both on the left and right hand side coming into this narrow third ventricle that lies between the two thalami and the hypothalamide we can see there's a hole here this is only seen in some patients that's where the thalami touch and that's what's known as an interthalamic adhesion posteriorly to that third ventricle we'll have our pineal gland we have our cerebral aqueduct coming down to our fourth ventricle the floor of this third ventricle is our midbrain coming up with our mammillary bodies here and then anterior to that will be our pituitary this is our infundibular recess here and anterior to the pituitary is our optic chiasm so this is our optic recess here and there's a thin sheet of tissue coming on the anterior portion of the third ventricle that's what's known as the laminar terminalis so our third ventricle feeds down through the midbrain into our fourth ventricle our fourth ventricle is bordered anteriorly by the pons and posteriorly by the cerebellum making this classic triangle or diamond shape here and then we have these lateral apertures here as well as this median aperture and then we have a connection with our central canal of our spinal column so i just wanted to show you this diagram here so we can understand now when we go into our scans what we're looking for when we're cutting through those axial and sagittal slices so we'll start by having a look at this axial t1 weighted scan and we can see we're at the level of our basal ganglia here we've got our lateral ventricles and part of our third ventricle so let's scan all the way up to the top of our lateral ventricles until they disappear out of you and then we're going to scan down slowly so we can see our lateral ventricles separated by this thin membrane here the septum pellucidum and we'll follow the anterior horns coming forward here our chordate nucleus to the side this is our gnu of our corpus callosum and our splenium of our corpus callosum here and you can see our lateral ventricles are quite small and this is a young patient with a nice full non-atrophied brain we can see that those anterior horns come out there and then connect with this interventricular foramen into our third ventricle let's scan back up again forget about the third ventricle for now we're going to follow this lateral ventricle down we'll see it give off our occipital horns here small occipital horns in this patient coming off backwards and then we can follow them further down let's look on the left hand side of the patient we'll see that this comes all the way down into our temporal lobe here these are our temporal horns of the lateral ventricle now why is knowing about the ventricle so important well for me the ventricles provide major clues to other things that are going on within the brain they act as good red flags or smoke signals where we can see if there's a mass in the brain we may have compression of one of those lateral ventricles if there's increased intracranial pressure or herniation we might get obliteration of some of those ventricles or if there's a mass blocking csf flow and causing some hydrocephalus we can then see expansion of those ventricles it also shows us in older patients when the brain atrophies we get that x vacuole dilatation of the ventricles where the ventricles get larger and we need to just be comfortable with looking at many many scans seeing that the ventricles vary quite a lot between patients but if we can see something that's abnormal we can often look for a primary cause that's causing these secondary abnormalities in the ventricles it also helps us to localize lesions if there's lesions in specific regions they're more likely to be certain diagnoses when they're related to the ventricles or not and then if we had interventricular blood we can see often in these occipital horns or gravity dependent regions remember these patients are lying flat in an mri scanner that block and then settle on those gravity dependent regions and we can look for interventricular blood so we've looked at our lateral ventricles let's go have a look at our third ventricle so we can see our interventricular foramen coming down into our third ventricle the ventricle is flanked by those two thalami let's head further down in the scan now so we can see we're at the level of our third ventricle here here is our third ventricle our thalami on the side this is a cistern that we'll talk about later let's follow this third ventricle down we can see it narrows right down into the cerebral aqueduct we're now getting into the level of the midbrain that cerebral aqueduct will head down we follow it down follow it down we can see posteriorly we have our cerebellum we have our inferior portion of our midbrain here we're going to just now transition to pons and we can see our fourth ventricle here between the pawns and the cerebellum coming down down down we see our lateral apertures lateral apertures otherwise known as framing of lushka lateral lushga and then as we head further down we'll see our medial aperture coming down that's also known as the foramen of magenti median magenti and then also we're continuous with our central canal of our spinal cord so let's have a look at a sagittal t1 image and try and follow those ventricles again i'm going to go ahead all the way out to the peripheries our most lateral ventricle that we will find is the temporal horn of our lateral ventricles so let's start there we have our temporal horn coming here head giving off our occipital horn we can head up into the trigone or the atrium hit all the way to the body of those lateral ventricles and the anterior horn of the lateral ventricle we can see our chordate nucleus running lateral to that lateral ventricle as we head further we can follow that lateral ventricle down and hopefully we can see there our interventricular foramen coming down into our third ventricle so here we have our third ventricle you can see the fornix coming down that will head down towards these mammillary bodies that thin sheet of tissue at the front our laminar terminalis coming towards our optic chiasm then we have our second our infundibular recess coming down towards our pituitary here we can see sitting in the cellar here's our sphenoid sinus we've got this floor here caused by the the superior aspect here of our midbrain i decided that our cerebral peduncle's coming down our pineal gland at the back and then we can see we've cut right down the midline we can see our cerebral aqueduct coming down now into our fourth ventricle and our fourth ventricle we can see our median aperture here and just very carefully we can see our central canal of the spinal cord so that's where our csf is within our ventricles now where is the csf produced well it's produced in the choroid plexus and we mentioned earlier in the previous talk that our our seventh division of our internal carotid artery gives of our anterior core that's heading to the lateral ventricles there's also posterior choroid artery as well as a choroid artery coming off the posterior inferior cerebellar artery so where do we find that cory plexus well let's go into our temporal horns the choroid extends from the temporal horns it runs along the roof of the of the temporal horn of the lateral ventricle all the way up along the floor of our lateral ventricle and then heads into the third ventricle and runs along the roof of the third ventricle so if you can imagine that corrie plexus coming along the roof of those temporal horns through the trigone along the body of the lateral ventricles heading down into the third ventricle and running along the roof of the third ventricle there's no coriod plexus within our occipital horns or our anterior horns it runs continuously like that and in some patients it's really big some patients it's difficult to see and then we also get choroid plexus along this floor here of our fourth ventricle we get along that vellum there now that we're in the sagittal plane and we are at our midline it's a good time to talk about the subarachnoid systems and some people find this quite confusing and the best place to learn it is on the sagittal t1 section here we can see our fluid is dark and these are areas where our pmrta is against the brain surface but our arachnoid is allowing for some space away from those brain surfaces so it's generally in the folds of our brain where that arachnoid is away from our peer that we get these cisterns and these systems are generally the flow of csf is continuous through all of them and we've kind of drawn arbitrary lines and they're more for us to know where in the brain we're describing that's why we've named them so we can if we say something is in the interpedicular system another radiologist will know where we're talking about the best place to start is at the top so we'll start with the cistern here so this is our laminar terminalis coming here that thin sheet of tissue on the anterior portion of our third ventricle and this is what's known as the cistern of the laminar terminalis very easy to remember it's anterior to that lamina terminalis as we come down we can see where our optic chiasm comes and we can see our infundibular store coming to our pituitary gland this has got two names we can either call it the supracellular system so the cistone above the cellar above the teleceletosica or it can be called our chiasmatic system where our optic chiasm is that's anterior now to this cistern here which has at the roof of it our mammillary bodies and this is what's known as our interpeduncular cistern and we'll see when we look at axial slices it's between the cerebral peduncles our interpeduncular system here it's anterior to the midbrain wrapping around the midbrain then are our ambient cysteines which connect our interpeduncular cistern come our ambient systems all the way around to our quadrigeminal cisterns at the back here we've got our superior inferior colliculi sitting here we can see them there one bump two bump there's two of them paired so a total of four colliculi in our tectum of our midbrain and that behind that is our quadrigeminal system so i'll take momentum of the midbrain here cerebral aqueduct tectum quadrigeminal cysteine and then posterior to that this is what's known as the superior cerebellus stone which is above the cerebellum below the tent that's separating the cerebellum from the cerebrum as we head our way further down we have our pre-pontine cistern a really easy system to remember it's before the ponds pre-pontine then wrapping around we have our cerebellum pontine system between the cerebellum and the pons and that's where our lateral apertures will have csf communicating with our ventricular system out into those cistones then we have our pre medullary cysteine again before the medulla oblongata and our cerebellum medullary system coming around easy to remember and then our largest cistern at the base of the brain here coming through our foramen magnum is what's known as our cisterna magna if we have increased pressures and the patient is coining for whatever reason or we've got low hanging cerebellar tonsils we can have obliteration of this cisterna magna so we've seen that in cross section let's have a look at our axial t1 and go and identify those cistones i'm going to head all the way up now we can see our lateral ventricles let's find our third ventricle and let's find that thin sheet of tissue at the front of our third ventricle we can see it forming here our laminar terminalis now anterior to that will be our cistern of our laminar terminalis and that should be slightly superior to our supracellular system so let's go down and see if we can identify our supracellular system you can see our mammillary bodies here we're going to have to head further down our optic chiasm we see it forming there we can see the stalk of our pituitary so we know we just above the cellar so this is what will be our supracellular system here if we head down we should be able to see that here's a supracellular system and here's a pituitary stalk we had further down we should be able to then see that pituitary you can see how carotid is coming up so this is our supracellular archismatic system let's come back up to the level of the midbrain we go down we can see our cerebral peduncles here so this is our interpeduncular system our ambient sister and the system that surrounds the midbrain like ambient temperature surrounding temperature ambient cysteine coming across to our quadrigeminal cysteine where we can see our superior colliculi here and our inferior colliculi below it here posterior to that is our superior cerebellar system and then let's head down into the pons we can see our pre-pontine cystone our cerebellum pontine system you can see our trigeminal nerve coming out there we know where that goes superior orbital fissure raymond rotundum frame and a vile if you don't know where those go have a look at our uh skull base foramina video we're gonna head down into the medulla oblongata we got our prima dallari uh cistone our cerebellum medalari cistern and then heading down into the cisterna magna at the bottom and our spinal cord heading further down so i hope that's helped i hope you can see where the ventricles lie within the brain as well as where those subarachnos are and how the csf flows in between them now the csf will eventually end up in that subarachnoid space after it's come out the choroid plexus in our lateral ventricles third ventricle fourth ventricle out of the lateral and median aperture into those subarachnoid space and then it's resolved into the blood in our superior sagittal sinus and our transfer sinuses through our arachnoid granulations and that process is repeated multiple times a day we replace our csf many times throughout the day so i hope that's helped let me know what anatomy you want me to cover next i'll see you all in the next video goodbye everybody