hey everyone welcome to professor long's lectures in anatomy and physiology i'm professor bob long today we're going to be going over some of the external anatomy of the brain if you've watched the video of me doing the drawings of the external anatomy of the brain while the drawings are not um you know they're not works of art and they're certainly not necessarily drawn to scale they give you an overall idea of the layout of the external parts of the brain we're going to cover them on the model which is how you'll be tested so i got four brain models here we refer to these sort of the clown brains because they're brightly colored like a clown we call this the puzzle brain because it comes apart into three different uh comes apart in multiple parts like a three dimensional puzzle and we call this the brain on the half shell because it's like sitting on this little shell or at least half of a shell um i'm going to start with the clown brains and i'm going to go over the anatomy and then i'm going to go over these two which are the main ones that we really use but occasionally you'll see these for certain details so if you're following along on your list of things to know we're actually going to toggle between page 32 and page 33. i don't necessarily go in the order of the list i go in an order that makes sense to my brain to make it easier to learn so if you look at this simple puzzle brain here actually this is one of our clown brains the nice thing about this one is it shows you a couple of things one is it shows you the lobes of the brain that we covered so this would be the frontal lobe this would be the parietal lobe here in green this is the temporal lobe in yellow this is the occipital lobe back here in blue sitting above the cerebellum i could also see the pons and the medulla the parts of the brain stem that we discussed i'm going to flip it around here and you can see a lot of other structures but we don't use them for this model or use this model to demonstrate those structures simply because it's too hard to see them but one other thing that you can see is this on our models for the most part there are exceptions to the rule we may not go over them but for the most part if it's painted white there's two types of brain tissue that we find in the brain when the brain is sitting in a jar and been pickled with some uh formalin or some kind of preservative some of the brain material appears a very light gray almost a white color some of it appears a much darker gray when this was being done they didn't know which was which or what it what was indicated by the colors so they just called it gray matter and white matter so anywhere on the brain if the structure is painted white it's probably white matter if it's not painted white it's probably covered in gray matter okay you really see this when you get to dissect the brain but nonetheless so if i ask you what kind of tissue is found we're talking about white matter and gray matter and i'm going to show you where we'll ask that in a little bit now kind of done with that model this model is a repeat of that one okay i'm gonna take out half of it and the lobes are color coded here in this sort of funky looking i don't know magenta fuchsia mauve i'm a dude i don't know colors but this color here this would be the frontal lobe all the way back including this red one right here and then all of this in blue would be the parietal lobe everything in yellow would be the temporal lobe and everything here in this sort of orange tan looking color is the occipital lobe you can see the cerebellum where the lines on its surface called folia i can see the pons and the medulla and if i flip it around i can really see those structures i see the pons right here this little belly-like structure and i see the medulla there's a structure up here referred to as the diencephalon and this large arch which is called the corpus callosum and we'll see the white matter inside the cerebellum here called the arbor vt all the white lines now again i may not cover all that on these models we really like to see use these models for the lobes now one of the things that we learned previously from the drawings is that every bump or surface that sticks out of the brain is called the gyrus and every groove on the surface of the brain on either side of a gyrus there's a groove each groove is called a sulcus a sulcus is a low spot spot or a depression gyrus means to gyrate or stick out so you can see the entire cerebrum is covered with gyro and sulci there's one particular groove or sulcus that goes from what would be called let me move this over here the longitudinal fissure is this groove right down the middle now what what we would call the longitudinal fissure there's a groove that goes from the longitudinal fissure runs uninterrupted all the way down to the temporal lobe that specific groove is called the central sulcus because it's about halfway back from front to back so it's about in the center of the brain sort of so that's called the central sulcus this specific gyrus anterior to it because let me pull this out of the model again or out of the stand this is anterior this is posterior the cerebellum is always posterior that specific groove is anterior to that central sulcus so this is called the pre-central gyrus pre meaning before the central sulcus so this is called the pre-central gyrus here in red the one in blue would be after the central sulcus that is called the post-central gyrus and we'll talk about this in lecture but the pre-central gyrus is what we call the primary motor cortex and the post-central gyrus is the primary sensory cortex so if i could reach with my right hand and go touch something those neurons would come from my right hand into the spinal cord through the brain stem and then branch out and end up synapsing somewhere here in the post-central gyrus and actually with synapse on the opposite side of the brain because the right half of our brain wires the left side of our body and vice versa so if i touch something with my left hand then those neurons would come in through the spinal cord from a nerve in my arm into the spinal cord all the way up into the brain stem and then they will project out over here to this postcentral gyrus and of course my hand area would be somewhere over here but it's all pretty well mapped out anyway that's the pre and the postcentral gyrus also the primary motor cortex the primary sensory cortex for lecture okay now um one of the other things i want to show you while i exchange my models here is this i like to use this brain model a whole lot this is what we call our puzzle brain it's sitting on a cradle that represents your spinal cord and the base of the skull again if i look at the the brain now i'm just going to lift it off the model and these do fall apart quite a bit because we take them apart and put them back together if i take it out you see the cerebellum here underneath i see the pons this little belly-like structure would be the pons and i have the medulla and all of this up here would be the cerebrum so our brain has some major regions cerebrum cerebellum pons and medulla there's another area inside called the diencephalon we're not going to see that just yet so if i know this is anterior and this is posterior this would be my frontal lobe this would be my parietal lobe right above the cerebellum if i can hold on to it right above the cerebellum here there's a little area it's kind of outlined by a little arch this little dome-shaped area would be your occipital lobe and this would be the temporal lobe on the surface i can see multiple gyri and sulci every bump is a gyrus every groove is a sulcus okay if i go through the longitudinal fissure about halfway back i have a sulcus that runs into it and runs uninterrupted to the temporal lobe that would be the central sulcus so this bump would be the precentral gyrus that would be the post-central gyrus okay so that's a lot of the external anatomy of the brain now eventually we're also going to go over the 12 pairs of cranial nerves which start on the cerebrum and run along the brain stem and we'll go over some other anatomy here okay so let me make sure i'm going to check my list and make sure i covered a lot of what i wanted to cover yeah so far so now um i'm going to take the cerebellum off for a second and if we look at it we notice on the surface there's all these fine lines those little fine lines are actually folds the surface of the cerebellum is folded on itself and if you could run an instrument across it it would fan out and close back up so those little folds or lines are called folia folia those are the folia of the cerebellum if i look down the center of the cerebellum there's a little worm-like structure right in the middle there and we can also see it on top here it kind of looks like a butterfly but the body of the butterfly right here in the middle would be called the vermis v-e-r-m-i-s vermis means worm and then i have two cerebellar hemispheres so from this model i can see the vermis here and here the folia and the two cerebellar hemispheres now the cerebrum itself is divided into two hemispheres hemisphere means half of a sphere hemi and sphere or half of a round thing so if i look here where the longitudinal fissure is that's going to divide the brain into a right hemisphere and the left hemisphere if i ask you for this entire half of the brain you would have to say right hemisphere or this half of the brain would be the left hemisphere okay every bump is a gyrus every groove is a sulcus you should be able to find the central sulcus the pre and the postcentral gyrus and the lobes of the brain as well as the cerebellum ponds and medulla so you can see the ponds the little belly-like structure and the medulla like some little legs okay now one other thing i want to show you here i was talking about on this other model if it's painted white it's probably white matter if it's painted gray it's probably gray matter there are two different types of brain tissue and i literally word my questions sometimes like id the type of brain tissue found here so now if i break the cerebrum open remove the two top parts of the cerebrum i can see this little arching structure right down the middle it's got these green stripes and has some white lines running back and forth across here that's called the corpus callosum the corpus callosum is a bridge from the front of the brain to the back of the brain and also from the right and left halves now this would be anterior facing up this would be posterior so this would be the right half of the brain over here this would be the left half over here the right half of the brain and the left half of the brain and the front and back of the brain have centers areas that process different types of information and for us to make sense of the world those areas have to communicate so their axons are connected to each other so that they can synapse and release neurotransmitter they're connected through these through the corpus callosum it connects the front of the brain to the back of the brain and the right and left hemispheres would send axons down across here and back up okay so this is the corpus callosum another thing that you can see from this model and we may repeat this in another video is that i can see how there's a lot of white matter here it's all painted with some fuzzy white lines and then the edge is very nice and flesh colored and you can see how deep the sulci run in here but these would be the gyrus and the groove would be the sulcus that little edge of tissue is where we would find some gray matter that edge the that structure is called the cerebral cortex cortex means bark like a tree bark and so this outer covering i could take my fingernail and literally scrape it off that would be the cerebral cortex the type of tissue found in the cerebral cortex if i point to that same layer and say what kind of tissues found here you would say gray matter if i ask you what kind of tissues found here you would say white matter and we'll see white matter all over the brain the gray matter is the thinking part of your neurons our neurons process information from the dendrites through the soma through the axon hillock out the axon if you've covered the neuron anatomy for lab and lecture now um an axon is like a little wire that sends an electrical impulse called an action potential and causes us to release a neurotransmitter a chemical on another cell that um those axons are usually myelinated and that's what makes the white matter white is the myelinated axons running from a group of cells here all the way to the front of the brain maybe communicating something to another group of cells so you're seeing the connectivity in the white matter the white matter is the wiring the gray matter is the processing centers so anyway all right now one last model i want to show you before i finish up this video and we move on to the next one is our brain on the half shell essentially it is the same stuff every bump is a gyrus every groove is a sulcus if i go a little bit more than halfway back i have the central sulcus with the pre and the postcentral gyrus because they're so hard to see on these models a lot of time we like to ask them on the models that show the color coding you can see the frontal lobe the parietal lobe the temporal lobe and then way back here above the cerebellum would be the occipital lobe now this model where the longitudinal fissure is breaks completely in half and i can see all the white matter in the brain stem there would be the medulla there's the pons up here would be the diencephalon here's the inside of the cerebellum which has the arbor vt the white tree-like structure that is the white matter connecting all of the cerebellum and connecting to other parts of the brain so that shows us most of the external anatomy of the brain the internal anatomy we're going to start with this model move on to that one and cover a lot of detail so i hope you had some fun i hope you had as much fun as i did now download one of these pictures and practice labeling it and touching it and saying the names until you can't stand it only 4 four five things at a time repeat them in the same order do it to you can't stand it do it till you understand it and then do it until you could pick up a brain and teach it to me the same way that i taught it to you if you can do that you're ready to make an a on your test thanks for watching see you in the next video