all right today we're going to dissect the Sheep rain with hypothesis hypothesis is another word for pituitary gland so we're going to open up the bag and we'll take out that brain and we'll throw out the bag clean up some of this liquid here for the paper towel and again I have set up my tools to dissect with over here and I have a knife I have a probe I have a pickup and two pairs of scissors which I'm likely not going to use it's up for taking the Marine out of the bag if I actually have two brains here all right and because we're going to dissect them both in different ways and how you dissect it will depend upon how your instructor tells you to do it but again like all Anatomy we have to orient ourselves so this is the inferior surface of the brain here this is the superior surface and I have them faced so that the anterior is on this side sometimes with the brain we use the word rostral which means towards the nose and down here is a posterior portion so I'm going to start with this one right here because we're looking at the superior surface this is what you would see directly underneath the top of your skull and you can see that there is this glistening surface to it so the duramada has been removed that's the outer covering of the meningese but you'll see there's sort of a glistening surface if I stick my probe inside one of these I might be able to pull it up a little bit so you can see it Maybe all right but that glistening surface sits there is called the arachnoid it's like Saran Wrap and you'll see inside that you'll see these little vessels so all these little brown things in here are blood vessels most likely most of them are going to be arteries all right and those blood vessels are sitting in narrow parts of that arachnoid so the outer layer is arachnoid it's called the arachnoid it might remind you of something else if it reminds you a spider that's why it's called the arachnoid because if you pull this up sometimes you can see the little spider-like projections that go from that arachnoid down to the layer which is the surface of the brain called the Pia the Pia Mater so if I do our meninges again which are the coverings of the brain the outer is the Durham author Dura for durable right Durham means tough Mater means mother we don't have that it's been removed already the glistening layer here is the arachno layer and it will have some spider-like projections that go down into the layer on the surface of the brain right here we can see it with not so glistening the Pia mate Pia means soft if you play piano you might have realized that all right so if we look at the brain it has Hills which are called gyri the singular is gyrus and they have valleys which are called sulci the singular sulcus and again here we can see the blood vessels in the in the sulci right there all right so most of the brain right here is the cerebrum back here the high and brain part of the hindbrain is the cerebellum and here we have a little bit of the spinal cord so this is the superior surface we have a fissure right here Fisher for a big crap this is called the medial longitudinal fissure we also have another fissure that we sometimes can see down here which is a lateral fissure or I call it just Sylvian sulcus we're gonna believe that one right there we're going to come to this one all right we're going to flip it upside down and this is the inferior surface all right and then a fury surface we might be able to see the pituitary gland here it looks like he's sitting right here so here's the pituitary gland let's flip this one over too and see if we can find it on this one looks like he might be a little bit right here sometimes the pituitary gland gets pulled out with the dura but we also can see this again is anterior that we'll start seeing some cranial nerves so this is the olfactory tract oh factory cranial nerves actually are in the crude form plate but this is part of the olfactory track going back this right here is a little bit of the optic nerves all right but you're going into the optic track and where they cross is optic chiasum cranial nerve three well this might be a little bit of cranial nerve three right here this little wisp all right cranial number four actually comes around from behind Five I don't know if I can see the rest five is usually pretty big and sits about right here this is probably seven and eight and then 9 10 11 12 are going to sit down here in the brainstem oh actually we do have a little bit of the dura oh this helps us look what I found okay so this is a little bit of the residual Dura and again the pituitary gland was right here at the base and if I pull this up I'm going to pull the pituitary because he actually sits in between the two portions of the dura so there's the dura mater and if you can look he's very very very very very tough so that was the outer meninges outer meninges is a duramata the clear glistening is a arachnoid and the surface of the brain is the Pia mutter all right so there goes the pituitary gland oh there's cranial nerve too this is probably number five because it's big all right I'm gonna pull them out there all right pituitary gland sitting right there so here again we're on the posterior excuse me we're on the inferior surface this would be your temporal lobes here front so if we turn this laterally on this one here's your temporal lobe they sort of remind me of the ear muffs of the brain again this is anterior so this would be the frontal lobe the temporal lobe the parietal lobe and way back here the occipital lobe and us we would have a central sulcus which is going to be harder to find on a sheep there's a salsa yard that's well defined this may be one right here so this may be the central sulcus it goes all the way straight up so if you remember all right and let's Orient ourself again this is the anterior this is posterior Central sulcus goes all the way towards the medial longitudinal fissure but does not quite get into it so if this were the central sulcus some of this right here should be the premolar cortex and some of this should be the post sensory cortex pre-motor gyrus that is some post-centric sensory gyrus all right okay so let's um stop that for us we're going to stop that for a second and all right so let's Orient our silver again so this is the anterior portion and this is the posterior portion we're looking at the superior surface all right well one should normally not point with the knife like I just did but we're going to do coronal Cuts right now so Chrono Cuts remember we'll give you an anterior and a posterior and when we do these we're going to lay them down so that we know what we cut all right so we're going to make each one maybe close to uh 10 millimeters or so and size so I'm going to slice them out just straight down [Music] so if you were getting an MRI of a brain and someone did chroma Cuts they would look like this way I've left my Dura on this one too take that dirt off all right and I'm going to cut through this last part of cut that brain stem off [Music] so right now I've got mostly the cerebral hemispheres all right and I'm going to turn this again this is anterior this is posterior and I'm going to lay them out so we can take a look at what happens as we go from anterior to post here [Music] grab my probe here so I can point with a probe all right we might be able to see the difference between gray and white matter so if we look it sort of looks a little grayer on the outside now it looks a little wider on the inside all right and that's how they got their name gray matter and white matter gray matter is unmyelinated structures and so the biggest on myelinated structure is the cell body so cell bodies or any neurons that are unmyelinated may be in the gray matter the white matter is myelinated tract so these are mostly axons that are traveling now if we look through here we can see that there's a big white matter track that connects the two hemispheres and so we named it that the Corpus for body colosum the Colossal big track corpus callosum let's see what we can see down here look now we have some spaces in here so we got a couple of spaces right here so these are our ventricles the word ventricle means little belly so we would have a lateral ventricle here and another lateral ventricle here by by tradition the right lateral ventricles called ventricle number one and the left one is ventricle number two we have a structure here that's coming into it look at this next one here this looks like this is probably the conduct nucleus we're going to come down here to this next structure all right and here's our ventricles again and right here is this big structure all right this big structure's name means inner chamber this is the thalamus so again you can see some of the ventricle here and some of it here this big structure is the thalamus and you actually can see this little structure right here which is the third ventricle so the two lateral ventricles will drain into the third ventricle we come on further and we've actually cut down here is a structure that's called the cerebral Aqueduct so the third ventricle up here is now draining into the cerebral Aqueduct and here we got our midbrain so this now we're starting into the brain stick brains brain stem and the first portion is the midbrain back here we still have a little bit of occipital lobe so these are axial cuts the important thing again is to notice the difference between white matter and gray matter to notice that there's a big corpus callosum connecting the two that there are some matters that are gray matters this right here looks like the caudate nucleus this belongs to the basal ganglia all right and we come down even further we can get the big thalamus all right and the ventricles usually should sit underneath that corpus callosum and we can follow those on down they those lateral ventricles drain into the third which drains in the cerebral Aqueduct which drains into the fourth so we're going to push those over to the side here we're going to take what we still have left over here so here still is the Imperial portion of the brain stem and again we might be able to find that cerebral Aqueduct there he is right there all right so that's Ripple Aqueduct is going to drain into the fourth ventricle and the fourth ventricle is going to sit in that space right here so if we look at it from the top there you can see it down in there is our fourth ventricle and actually we can see some of that spider web-like structures that is actually part of the arachnoid the spider web of the arachnoids so there is a fourth ventricle you might be able to see the pineal gland it looks like we have a little portion of the plug in the old ground right here and we'll try and find that in another so this is a good way to see the fourth ventricle all right the Palms is the middle structure of the midbrain I always think of it as looking kind of pregnant so I put my peas together pregnant pons all right here was the midbrain here's a pons here is the medulla oblongata down here again the fourth ventricle would sit the the pons would sit anterior to the fourth ventricle and the cerebellum sits posterior to it all right we're going to take these aside now and we're going to take this other section and we're going to cut him in a mid-sagible cut all right so to review again orienting ourself is so important this is anterior this is posterior here's the brain stem this little part right here maybe the spinal cord all right and this is the cerebellum here so we're going to take a mid sagittal cut right down the middle remember sageable Cuts give you a right and left side so I'm going to cut straight down the middle and flip it around so I can cut away from my fingers there you can see some arachnoid again I always cut away from your fingers all right Put The Knife Down and now we have mid-sizeable cut here all right so if we Orient ourselves again anterior posterior here is our cerebellum all right now we got another view of the corpus callosum here's the corpus callosum right here all right underneath the corpus callosum it's a ventricle and I've just poked through a part called the septum pellucidum so that you could see Into The ventricle so there's a ventricle right there The Floor Of The ventricle is the thalamus sitting right there here's a few of the pineal gland there's a pineal gland this would be the midbrain this would be the pons this would be the medulla all right our fourth ventricle would have been sitting right in here in that space all right so let's go over this one more time anterior posterior corpus callosum lateral ventricle this being my left hemisphere this would be the left lateral ventricle or ventricle number two the thalamus makes up most of the floor of the ventricle all right midbrain here pineal gland think about what the pineal gland does all right pawns right here all right fourth ventricle right there medulla oblongata if we look I'm going to pull like this other side so now we're looking at the right side now anterior's over here and posters over here okay we have another view of the pineal gland right there all right but what's interesting here is here's the cerebellum and you can see this tree like structure so this tree-like structure of white matter you can see coming out that's called The Arbor Vitae Arborvitae means tray of life and it's just connections of white matter in the cerebellum but it tells you you're in the cerebellum so again this is a saddle lookup our other one was a Corona cut you also could do an axial cut but these are the two most informative cuts so now that we're done please review all your structures then carefully bag everything up wash your tools and let them air dry and we'll be back for the next dissection