Overview of the Brain

hi everybody dr mike here in this video we're going to take a look at an overview of the brain we're going to have a look at the development of the brain and also important structures of the brain and the relevant functions but to begin you need to understand that the brain with all of its convolutions and complexities actually began as a hollow tube so at around about three weeks gestation we have this hollow tube called the neural tube that will ultimately become the brain brain stem and spinal cord now from three weeks till around about five weeks you'll find that various aspects of this tube begin to swell and they form vesicles you can see that there's one two three four five vesicles that you need to understand because they become really important landmarks of the brain so let's start at the top move our way down so the very first vesicle you need to be aware of is that of the tel encephalon now when we have a look at these words they look a bit funny importantly the suffix the part at the end is going to be encephalon all the way through for all of these vesicles so the first is tel encephalon encephalon means brain the first part the prefix that's the important part so tel encephalon telos in greek actually means the end the endpoint so telencephalon means end of brain which makes sense because it's the end of the neural the developing neural tube if we were to have a look at this neural tube continually developing you'll find that the telocephalon actually begins to or continues to swell and folds over like that and again ultimately becomes this massive structure right here that makes up most of the brain that we call the cerebrum so the telecephalon actually produces the cerebrum so let's take a quick look at the cerebrum again the cerebrum is the largest part of the brain and is comprised of two hemispheres you can see these two hemispheres here the two hemispheres are actually separated out by what we call a fissure or a splitting down the middle here and this is what we call the longitudinal fissure the longitudinal fissure separates out the left and right hemispheres of the brain importantly the left hemisphere controls what's happening on the right hand side of the body and the right hemisphere controls what's happening on the left hand side of the body right controls left left controls right and another important point is that some functions of the brain actually sit more so on one hemisphere than the other so for example for most of us language being able to understand and comprehend language sits predominantly on the left hemisphere now this is termed laterality where functions predominantly sit on one side compared to another laterality now structurally if we were to look at the cerebrum again even though it's the biggest part of the brain you'll find that the outer one to five millimeters of the cerebrum is termed the cortex so cortex just means outer layer right so this is what we call the cerebral cortex and the cerebral cortex is the seat of consciousness it is the substrate for consciousness let's write this down right the cortex equals consciousness that's really important for you to become consciously aware of anything it must get to that outer one to five millimeters so the fact that you are understanding and comprehending what i'm saying to you right now is because information that i'm delivering to you is reaching your cortex and you can actually separate the cortex out into various lobes various functional lobes so roughly the separating lines for these lobes are like this so you've got the frontal lobe sitting at the front unsurprisingly the parietal lobe the occipital lobe and the temporal lobe sitting around about your temple your ear now in actual fact if you were to lift up your temporal lobe and have a look there's going to be another lobe called the insula some recognize it as a lobe some don't but it is a functional lobe let's write these lobes down here and just talk very briefly about what they do i have done a video on each lobe if you want more detail so the frontal lobe has a couple of important functions first of which is that right here in the frontal lobe is what we call our primary motor cortex so the frontal lobe contains the motor cortex this is where we want to consciously initiate movement the fact that i can consciously write and draw is because information is beginning here at the motor cortex sitting in the frontal lobe the frontal lobe also has particularly if we look more anteriorly more towards the front this is the seat of higher understanding higher integration high degrees of consciousness what am i saying here i'm saying that basically it controls really complex behavior you knowing how to act in a particular situation how to act socially amongst one person compared to another person for example it's a higher order reasoning that's another thing that sits on the frontal lobe higher order reasoning really important parietal lobe let's take a look the parietal lobe doesn't have a motor cortex but right here opposing the motor cortex it has a sensory cortex called the somatosensory cortex so think about it signals initiating in the motor cortex of the frontal lobe go down to our motor neurons into our muscles to say to move but the somatosensory cortex is receiving signals coming up so you can understand what's happening in your environment whether it's your internal environment or external environment so it's going to pick up signals on touch pain temperature pressure vibration proprioception whole bunch of sensory pieces of information and if it gets to this somatosensory cortex you become aware of it so parietal has the sensory or somatosensory cortex really important occipital lobe the occipital lobe simply allows for us to be able to see so it's important for vision temporal lobe is important for us to be able to hear and lifting that temporal lobe up and having a look at the insular is important for taste gustation gestatory but let's just write taste so that's a quick overview of the various lobes now this is only the outer one to five millimeters of the cortex or i should say the outer one to five millimeters of the cerebrum there's deeper structures within the cerebrum this includes parts of the basal ganglia and parts of the limbic system as well which i think we need to briefly mention let's write this down parts of the basal ganglia and again parts not all and limbic system again parts and not all now what do i mean by parts and not all i'm saying that other aspects or structures of these systems here actually sit within other vesicles or basically arise from these other vesicles what does the basal ganglia limbic system do well to put it simply the basal ganglia is important for initiating and smoothing out motor movement so initiating initiating and smoothing out motor movement or motor activity motor movement's a bit redundant motor activity an example of this is if i want to walk and walk smoothly that's the basal ganglia smoothing that out people who have deficits in the basal ganglia specifically dopamine that's the neurotransmitter used here if that's diminished or gone people find it hard to initiate a movement and they also have a resting tremor so they don't have that smooth movement that's why the basal ganglia is important there limbic system really important in emotion other things as well but let's just highlight emotion all right so this is basically the cerebrum let's then move on to the next part that's the telecephalon this next part highlighted in blue is called the diencephalon diencephalon so again encephalon suffix meaning brain dye means between or within why is that well you can see again as this neural tube continues to develop it becomes encased or sits within or between the telencephalon as it begins to fold in and again that's looking at it from a front on view let's look at it from a side on view like we've got here you can see it's sitting inside here there's the diencephalon now the diencephalon has two really important structures it has the thalamus the thalamus and the hypothalamus what do these two structures do so thalamus and hypothalamus in actual fact most of that there is the thalamus and the hypothalamus is basically going to be sitting like that and it has a protrusion like that called the pituitary gland which we'll talk about in a sec so thalamus hypothalamus what do they do firstly let's look at the thalamus the thalamus let's put it over here the thalamus is the sorting center or relay center it's the post office of the brain it takes information and decides where it needs to go let me give you an example somebody were to tickle my hand or tickle my finger that signal will move down the nerves in my arm into my spinal cord and continue to move up it moves up the spinal cord through the brain stem and gets to the thalamus the thalamus goes okay what is this signal where did it come from where does it need to go it goes oh it came from your hand and it's a sensory signal i need to send it to the somatosensory cortex in the parietal lobe we spoke about that before right in actual fact all of this area here within that parietal lobe all this area here has a map of the whole body on it that can pick up sensation and there's going to be a part map to the hand the thalamus knows this and will throw this tickling sensation that it received up to the relevant area of that somatosensory cortex it will do that with all types of sensation that you need to become consciously aware of so for example pain somebody pricks my finger to the thalamus throws it to the part of the parietal lobe that deals with experiencing pain of that part of the body brilliant so that's why it's called the sorting center or relay center what about the hypothalamus well hypo means below thalamus sitting below the thelma so you can see that in what i've drawn up here the hypothalamus sitting below the thalamus the hypothalamus is actually what we call the master regulator master regulator of two important things master regulator of the endocrine system and the master regulator of the autonomic nervous system so the endocrine system is hormones hormones that can control growth and development and functioning of the body the hypothalamus can control this by producing and releasing its own hormones it can also stimulate this pituitary gland that sits underneath it to release its hormones as well and there's a whole range of hormones that can be released hormones like oxytocin involved in milk let down and bonding antidiuretic hormone for holding on to fluid in times of dehydration or low blood pressure it can also involve releasing hormones associated with the thyroid with the adrenal gland with our sex glands as well so our testes and our ovaries a whole wide range of hormones autonomic nervous system is the sympathetic and the parasympathetic sympathetic fight or flight and parasympathetic rest and digest again all controlled by the hypothalamus all right so that's the thalamus and hypothalamus in the diencephalon let's look at the next part the next part is the mesencephalon again encephalon means brain mes means middle it's the middle of the brain and you can see it is there right middle of the brain middle of the brain the mesencephalon actually comprises of the midbrain the midbrain is the most superior or upper aspect of the brain's stem i'm not going to talk about its function at the moment because i want to talk about all aspects of the brain stem together as one i've done a very specific video on the individual aspects of the brain stem feel free to watch that so we've got the midbrain part of the mesencephalon sitting here as well next part is the met encephalon and the metaencephalon met encephalon met actually means behind so behind the brain why is that well let's take a look that's part of the mediencephalon and that's part of the metincephalon let's look at it from a lateral view it's here and here you can see that's the pons and that's the cerebellum which is sitting behind the brain so the metaencephalon contains the pons which is the next part of the brainstem pons but also the cerebellum so let's take a look now at the cerebellum over here what does the cerebellum do well the cerebellum does three really important things and again i've done a video on the cerebellum looking at the specifics but here's an overview it's important for tone balance and coordination tone balance and coordination of what well obviously motor activity the tone how contracted it needs to be the balance where should you be in your space and coordination what pattern of firing needs to occur the cerebellum fine-tunes information that's coming from the motor cortex so if i want to initiate the ability to move i need to check with the cerebellum that it's doing the right thing an example i like to give to my students is i'm helping a friend move house they say mike there's a heavy box there be careful when you lift it i go sure i'm strong i can do this i walk up to it i bend with my knees not with my back grab the box lift it and when i immediately i realize that the box is empty it's not heavy at all so signals are now going from my motor cortex to the cerebellum and they're firing through the cerebellum says whoa you need to change the tone balance and coordination of these muscles in this movement so that's what the cerebellum does and again that's going to be part of the met encephalon so midbrain ponds brain stem last part is going to be the last part of the brain stem which is this lowest aspect here the deepest part here called the mild encephalon mile what's that referring to mile means marrow it means the pith the deepest part in actual fact it contains the medulla and the medulla also means the deepest part right specifically you could call the medulla oblongata but often just referred to as the medulla the deepest part you can see here here here it's the deepest aspect of the brain that's the medulla so now we've got the three parts of the brainstem we've got the midbrain the pons and the medulla what do they do what does the brain stem do it does a whole bunch it's really important in basic functioning of the body let's write it over here brain stem the brain stem has a couple of extremely important functions one of which is it's really important when it comes to heart rate breathing again breathing rate and breathing pattern blood pressure blood pressure certain reflexes of the head and neck that can include the cough reflex for example and the corneal reflex but also houses the nuclei of the cranial nerves nuclei of the cranial nerves nuclei is just where they live right the home of the cranial nerves there's 12 pairs these are nerves that shoot in and out of the brain and brain stem and they control what's happening at the head and neck and a little bit below so when it comes to sensation of the head and neck cranial nerves when it comes to motor movement of the head and neck cranial nerves and many of the nuclei of these cranial nerves live in the brain stem itself and the brain stem's also the conduit for information coming from the brain down and going from the body up to the brain all right so what we've gone through telencephalon diencephalon mesencephalon metincephalon myelin cephalon now sometimes you'll see these two put together right as the prosencephalon and you'll see the meta and myelin cephalon put together is the rhombencephalon all right but this is the five important vesicles you need to know the important substructures or landmarks of the brain they produce and their various functions as an overview i hope that helps hi everyone dr mike here if you enjoyed this video and want to watch more please hit the like and subscribe button

Channel: Dr Matt & Dr Mike

Views: 113,797

Keywords: brain, overview, summary, stem, brainstem, midbrain, pons, medulla, oblongata, telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon, rhombencephalon, prosencephalon, development, embryology, cerebrum, cerebral, hemispheres, lobes, cortex, cortical, frontal, temporal, occipital, parietal, insula, cerebellum, function, activity, anatomy, physiology, nursing, medicine, college, university, lecture, best, dr mike, dr matt, nervous, system, central, spinal, cord, neural, tube, thalamus, hyporthalamus, endocrine, ans, autonomic

Id: xXk5BOAO7rc

Length: 19min 19sec (1159 seconds)

Published: Mon Dec 06 2021