Introduction to Neuroanatomy - Learn the Basics - Neuroanatomy Playlist

hello wonderful people it's medicosis perfect Snus where medicine makes perfect sense welcome to a new playlist medicosis neuroanatomy making sense of one of the most challenging subjects in medicine if you watch this playlist neuroanatomy in its entirety I promise you you will understand the subject better than 95% of doctors first let's get organized we have central nervous system and peripheral nervous system the central nervous system is made of two things only the brain and the spinal cord the peripheral nervous system is anything else how about the nerves that come out of the brain well they

are outside the brain so they are peripheral nervous system how about the nerves that come out of the spinal cord also peripheral nervous system so the cranial nerves and the spinal nerves are peripheral nervous system only the brain and the spinal cord are central nervous system now smash that like button click the Subscribe button and let's get started so please make sure to say save this neuroanatomy playlist here are my Ten Commandments of neuroanatomy thou shal understand the difference between motor and sensory draw your Line in the Sand between anterior motor and posterior sensory motor

is eent sensory is aent why is sensory AER because it goes to the brain why is motor eent because it leaves the brain and goes somewhere else number two th shall understand the difference between CNS and pns central nervous system versus peripheral nervous system central nervous system is brain and spinal cord pns is everything else any nerve is pns with one exception that we'll discuss later there is only one cranial nerve that is part of the central nervous system rather than the peripheral one third thou sh understand the difference between brain and spinal cord and

between cranial versus spinal between somatic and autonomic autonomic is also known as visceral or splank Nick these words are used interchangeably of course you know that the autonomic nervous system includes what oh sympathetic and parasympathetic only and that's it shut up it is sympathetic parasympathetic and don't forget for your gut the enteric nervous system or ens that's why you always talk about your gut feelings so to speak your gut has its own brain next understand the difference between melinated and unmyelinated melinated fiber appear white in color unmarinated fibers appear gray in color hence white matter

versus gray matter hence white rayus communicans versus gry Rus communicans if you want them in plural white RI communicantes and gray RI communicantes my goodness commandment number seven thou shall understand the meanings of these terms nucleus gangan tract nerve liscus synapse decoation Kiser exteroceptive proprioceptive epilat contralateral bundle fulus peduncle pathway and much more in other words Thou shalt study hard as mediocre students get on my nerve see what I did there next Thou shalt understand the distinction among proen cilon mesen cilon and renon you also need to learn about tanyon versus dilon and meanon versus

myelin sephon you need to understand the organization of nuclei in the brain stem how many nuclei does the facial nerve have how about the ocula motor nerve the 10th commandment thou shal not covet your neighbor's taste buds thou shall understand the difference between the anterior 2/3 of the tongue and the posterior 1/3 of the tongue when it comes to the name of the nerve the name of the nucleus the name of the gangion the difference between General Sensations and taste sensations which salivary glands etc etc and bonus if you can understand the distinction between these

here is General somatic eant this is branchial eant General visceral ephant when I say ephant I mean Mortor I mean we're going to leave the brain and go somewhere else versus those who end in a which are aent General sensory aent special sensory aend special visceral aend General visceral aend if you can understand these Ten Commandments today you'll be in a very good shape to dig into the cranial nerves which is the topic that comes next in this neuroanatomy playlist in this doozy playlist you'll learn about the brain spinal cord cranial nerves spinal nerves the

menes the cerebral spinal fluid arterial Supply Venus drainage the internal structures of the brain the nuclei the tracts and tract Loy now let's go over these Commandments one by one first motor versus sensory draw your Line in the Sand in embryology this was called the sulcus limit hands which limits the anterior from the posterior anterior during embryology was called the basil lamina the posterior was the AAR lamina the anterior became motor the posterior became sensory for the most part of course there are Exceptions there always are but that's the most important big picture let's practice

I want to move my biceps well well to move your biceps that's SM look where it starts in front of the line which passes by the central sulcus okay let's say that I want to feel the feather of my arm oh to feel something is Sentry look where it is cool I want to move my eye to the right to the left up and down this is frontal eye field look where it is in front of the line but I want to see you oh to see me Vision that sensation primary visual cortex look where

it is behind the line posterior baby let me talk and articulate my thoughts to talk is to move therefore look at me I am here and this is broke as area but I want to hear you and understand you well look at that that is Vern's area surprise surprise the hearing area and the understanding area are very closely related which makes perfect sense there are hundreds of thousands of students who go through school they just memorize this stuff like the sunshines they are and they never take a second to understand why are they located this

way it's all because of your embryological development anterior is motor posterior is sensory please take a moment to pause and review move my extremities feel my extremities move my muscles of articulation to talk hear and understand you move my eyeball versus see you and the same exact concept applies to the spinal cord here's the lovely spinal cord cross-section anterior is here posterior is there you draw your Line in the Sand anterior is motor posterior is sensory let's say that I felt a feather touching the skin of my back feeling the feather oh that is sensory

so look where I'm going I'm going posteriorly aparent because I'm sensory so I'm going to the back of the spinal cord okay but let's say that I want to contract my biceps if I want to contract my biceps I better start here at the anterior horn cell which is anterior to the imaginary line and I go forwards like this eent until I reach the beautiful biceps to contract it what's the name of the nerve that supplies the biceps muscle please comment below embryology review this is your sulcus limitans this is the basil lamina and this

is the ALR lamina another important fact is that motor is eent which means it starts in the center nervous system and goes somewhere else let's say it starts here in the brain and decides to leave the brain this way however sensory is apher it's the opposite it starts somewhere else and ends up in the brain like this motor is eent but sensory is aent next CNS versus pns brain and spinal cord are part of the central nervous system everything else is peripheral nervous system so the cranial nerves the spinal nerves any other nerve that you

can imagine is peripheral nervous system so the radial nerve Nar nerve sciatic nerve you name it or peripheral nervous system how about ocular motor nerve vagus nerve facial nerve also peripheral nervous system how about the nerves of the brachial plexus or lumbosacral plexus these nerves are peripheral nervous system next brain versus spinal cord oh that one is easy the brain is upstairs spinal cord is downstairs the brain is made of forbrain midbrain hind brain the Hind brain consists of the ponds the Milla and the cerebellum but what's the brain stem brain stem is three things

on top of one another midbrain ponds and medulla then the medulla is continuous with the spinal cord so let's say that the brain is cerebrum cerebellum and brain stem the brain stem is midbrain pawns and middle then the spinal cord has many segments about 31 segments eight segments in the cervical area then 12 in the thoracic area five lumbar five sacral and one coxal talking about the spinal cord and not about your vertebral column if I was talking about your vertebral column you'll have seven vertebrae in the cervical area 12 thoracic five lumbar five sacral

and four fused coxal then we talk about the cranial nerves and spinal nerves they are part of the peripheral nervous system the cranial nerves are 12 pairs 12 on the right 12 on the left spinal cord are 31 pairs 31 on the right 31 on the left and they follow the same segments so you have eight pairs of cervical spinal nerves 12 pairs of thoracic five pairs of Lumbar five pairs of Sac and one pair of coxy spinal nerve you'll learn more about the spinal cord in a separate video titled anatomy of the spinal cord

what's the structural unit of the nervous system it's the neuron made of a Soma or cell body and an axon some axons are melinated like this one and they will appear white in color others are unmyelinated and they appear gray in color that was the structural unit how about the functional unit that's the reflex arc we start with a stimulus which will be felt by a receptor then I have an a ferent fiber then I have a center such as the spinal cord then I have an eent fiber an eector organ like my biceps which

causes a response so if I touch the candle that's the stimulus it's going to be felt by a receptor for heat or Thermo receptor and then it will travel through an aent fiber towards my spinal cord which is the center then I have an eent fiber which will go to the eector organ such as my biceps to flex my arm away from the candle next somatic versus autonomic somatic is voluntary which you can control but autonomic is involuntary you cannot control the word autonom is synonymous with visceral or spanic the somatic could be motor or

sensory the autonomic also could be motor or sensory what is a mixed nerve it's a nerve that has more than one thing it has motor fibers and sensory fibers or motor and sensory and autonomic what are the types of autonomic nervous system we have sympathetic nervous system parasympathetic nervous system and enteric nervous system the enteric nervous system is subdivided into myenteric plexus and submucosal plexus we have talked about all of these in great detail in my physiology playlist next myelinated versus unmyelinated some neurons have milin and they appear white and we call this the white

matter other neurons are not melinated and they appear gray we call this the gray matter in the spinal cord the gray matter is on the inside but the white matter is on the outside so if I look at this oh this is white matter which means the nerve f fibers here are melinated but let's look here oh it's gray so the nerve fibers here are unmated the opposite is true for the brain look the gray matter is not Central anymore it is peripheral ooh what does that mean it means that I have unmarinated fibers here

or it could simply be that I have the Somas here the cell body there because the cell bodies are not covered by m only some axons are so it could be that the fibers are re ranged like this so I have a Soma and a axon s axon Soma axon so to recap in the spinal cord the gray matter is on the inside but in the brain the gray matter is on the outside how is this important well it is very important indeed because we agreed that this white matter means melinated so let's just draw

some milin so look at this this is milin fibers milin milin and milin so these fibers are milin that's how they appear white okay what if I have a disease known as multiple sclerosis it demines the fibers of the central nervous system only so who's going to suffer only the brain and spinal cord and nothing else okay what's going to happen here what's going to happen is that you will destroy your myin o so where will be the disease on the outside or on the inside the disease is where the myin is it will be

on the inside part of the brain and that's why on MRI you will see oligo colonal bands signs of demolation and when you find them on MRI in a patient with Ms these oligoclonal bands are on the inside and not on the outside because the oligoclonal bands are where the milin used to be cos medicine makes so much sense once you understand what the french toast you're talking about so white matter is melinated okay who melinated these fibers if they are in the central nervous system the aligo dendrocytes melinated those fibers but if these fibers

are in the peripheral nervous system let's say the nner nerve or the radial nerve they were melinated by the Schwan cells next a matter of definitions if you wish to converse with me said voler define your terms so let's define our terms remember that this is a neuron it's made of Soma or cell body and axon a collection of Somas in the center nervous system is a nucleus a colle collection of Somas in the peripheral nervous system is a gangion but a collection of axon fibers in the CNS is a tract and a collection of

axons in the pns is a nerve that's why you hear of the sciatic nerve allar nerve radial nerve muscular cutaneous nerve all of these are nerves because they are collection of axons what if I told you that 99% of doctors cannot give you these simple definitions how about the definition of a facular or a bundle that's a group of nerve fibers usually in the CNS but they have different Origins terminations and functions they just happen to be in close proximity to one another what's a ponal oh I'm glad you asked here is my lovely forbrain

and here is the midbrain followed by the pawns followed by the medulla if the midbrain wants to communicate with my cerebrum it does so by a cerebral peduncle but if the same midbrain here wants to communicate with with the cerebellum behind it it does so by means of superior cerebel peduncle then the pawns to the cerebellum is Middle cerebel peduncle the Medela with the cerebellum is inferior cerebella peduncle let's do it again this is a cerebral peduncle Superior middle and inferior cerebellar pedones so a peduncle is a thick bundle that supports part of your brain

and usually communicates between two structures what's a pathway pathway is a series of neurons transmitting impulses inside or outside the CNS and you will learn about Pathways in the next video which talks about the olfactory nerve and the olfactory pathway you'll also learn about the visual pathway in an upcoming video the auditory pathway etc etc etc what's a kisher oh look at this here are your two cerebral hemispheres who communicates between them aisher you can have a gray kisher made of gray matter or white kisher made of white matter a commer connects part of your

CNS on one side to the same part on the opposite side you look at this that's a tract when two tracts cross like this we call this a decussation or crossing what's a liscus a liscus is a band of ascending fibers always going upstairs until they reach the thalamus Alum nisus has to be a group of fibers in the brain stem and they have to end up in the thalamus how many lmis Kai do you need to know four medial and lateral spinal and trigeminal medial liscus lateral liscus spinal liscus and trinal liscus next epilat

versus contralateral well if I'm referring to the right cerebral cortex and let's say the right half of my face they are on the same side so they are epilat but the right cortex with the left half of my face are contralateral on the opposite side last set of definitions today is exteroceptive versus proprioceptive if I'm feeling touch or pain or temperature these Sensations are called exceptive Sensations but if I'm feeling the position of my muscles or ligaments or joints in space this is proprioception please do not continue watching this video if you do not fully

grasp the definition of all of the following terms nucleus ganglion tract nerve bundle or fasiculus peduncle pathway kisher decussation liscus exceptive versus proprioceptive and epilat versus contralateral next do you remember the trilaminar embryo endoderm mesoderm and ectoderm yes I do where did the nervous system come from only from the ectoderm the ectoderm is subdivided into neuroectoderm and surface ectoderm the surface ectoderm is for the epidermis of your skin hair nail Etc forget it but the neuroectoderm is the one that actually gives us the nervous system and it will give us two structures neural tube and

neural crest the neural tube will give us the CNS but the neural crest will give us the pns neural tube will give us the cells that mate the CNS known as the oligodendrocytes but the neural crest will give us the cells that myelinate the peripheral nervous system namely Schwan cells don't forget that all of the ganglia by definition are a collection of Somas in the peripheral nervous system that's why the ganglia are made by the neural crest so the CNS and the cells that mate the CNS come from the neural tube but the pns and

the cells that mate the pns come from the neural crest both of which come from the neuroectoderm which is ectodermal in in origin here is a tough question for you can you name one ganglion that is not in the peripheral nervous system and instead it's in the central nervous system please comment below now let's talk about proen cilon mesen cilon and romlon during embryological development do you remember the neural tube yeah the neural tube will give us spinal cord and brain the spinal cord is called the posterior neuropore and up here is the anterior neuropore

anterior end posterior end which later become the upper end and the lower end this is the tip of your forebrain and this is the lowest part of your spinal cord these are the three vesicles that will make up your brain proen cilon mesen cilon and rumen cilon the word proen cilon reminds me of a protrusion look at this protrusion that's your forbrain the word meso means what it means in the metal if you remember in organic chemistry we had something called that meso compound which looked akin to this it was a compound that had a

central I mean internal plane of symmetry so that I can divide it with a knife like this and I will have two mirror images that was called a miso compound meso because there is a mirror in the middle meso means middle hence mesen sephylon midbrain the midbrain is mid it's in the middle between the forebrain and the hind brain after this I have the rilon or the hind brain penlon will give me telen cilon and dilon mesan cilon will give me the midbrain and rilon will give me mtin and milin mentin is the ponds and

the cerebellum milin is the medulla how do I remember that milin is the medulla and not the other way around easy the word Milo means core referring to the spinal cord what's the continuation of the spinal cord as I go up through the foran Magnum it is the Mida and you will learn about telen cilon dilon mid brain and all of this in upcoming videos but for now I want you to know this penlon is the four brain it will give you telen cilon appear here on the outside and dlon which is deep on the

inside the dlon is anything that has the word Thalamus in it including Thalamus and it's metalmusic and subthalamus the tanyon on the outside will give you the cerebral hemispheres on more the outside and basal ganglia towards the inside outer cover followed by this middle cover followed by this inner cover your brain and spinal cord are surrounded by cerebral spinal fluid who made that cerebral spinal fluid ventricles endal cells lining the choid plexus in the ventricles lateral ventricles Mak CSF and then that CSF goes to the third ventricle this CSF leaves the third ventricle and goes

to the fourth ventricle and then leaves through manif foramina to surround your brain and Surround your spinal cord what's the name of The ventricle of the the Talen cilon lateral ventricle what's the name of The ventricle between the dilon or between the thalami third ventricle near the mezan sephylon you have the cerebral Aqueduct of sylvus and for the ren sealon what do we have we have the fourth ventle in the next videos we'll talk about the cranial nerves for now just remember that cranial nerve one and two come out of the midbrain three and four

come out of the midbrain 5 6 7 and 8 exit through the ponds 9 10 11 12 come out out of the medulla and this is the total of 12 pairs of cranial nerves when you think of emotions and behavior think of your lyic system such as the amydala when you think of your hypothalamus think regulation regulation of temperature regulation of glucose regulation of a hepatite thermostat glucostat epistat respectively when you think of your midbrain remember the IE reflexes like the corneal reflex light reflex Etc they have their Center in the midbrain as for the

the middle it has four famous centers that you cannot forget heart and lungs get it in get it out cardiovascular respiratory swallowing and vomiting heart and lungs get it in get it out Mr spinal cord has the mtion reflex defecation reflex and the center for erection remember again that we have somatic and autonomic the autonomic could be sympathetic nervous system parasympathetic or anic the anic is in your gastrointestinal tract subdivided into myeric plexus for motility and submucosal plexus for secretions the M goes with the m and the S with the S recall that your sympathetic

is thorac lumbar but the parasympathetic is cranio sacral what do you mean by cranial I mean cran nerves 3 7 9 and 10 oculomotor facial glossop Fingal and vagus nerves what do you mean by sacral I mean S2 S3 S4 s234 keeps my PP of the floor if you understood this pneumonic please comment below explain it recall if I am somatic motor I'll leave the anterior horn cell but if I am autonomic motor I'll leave the lateral horn cell and then I will leave this go to the eend and then reach the spinal nerve and

then I'm here but I got to go through a ganglion because I'm autonomic I'll have pre ganglionic fibers and postganglionic fibers pre goes to the ganglion post whereas post leaves the gangion usually the preganglionic fibers are melinated so they appear white and we call this the white Rus communicans the post ganglionic fibers leave the gangion they are unmyelinated they appear gray hence the gray Ramos communicants the gangion is a relay station for regulation so if I want to draw this this will be the Soma that I will start with okay dendr beautiful and then here

is the axon amazing and then as I race the ganglion that's the end of the axon in the ganglion there is a synapse so another neuron starts and the cell body and we have the axon going this way if you want to learn more about the difference between preganglionic and postganglionic and how ganglia work etc check out my physiology playlist especially the series on the autonomic nervous system for now remember that preganglionic is mated postganglionic unmated preonic appears white postganglionic appears gray pre Gonic are B fibers they are thin and melinated post Gonic are C

fibers thin and unmated where's the cell body for this prionic it was all the way in the lateral horn cell as we have just discussed but where is the cell body for the postganglionic it's inside the freaking ganglion next let's talk about the organization of nuclei in the brain stem here's your brain stem this could be midbrain ponds or middle if a cranial nerve is leaving and this cranial nerve is purely somatic motor it will leave and medially very close to the midline for example the abducent nerve it is purely motor somatic so it leaves

intermediately but if you are mixed if you're not pure blood motor like this if you're mixed if you're motor and sensory motor and autonomic motor sensory autonomic bran all kinds of mixture you will be more anthrol lateral and not just that you could be lateral or even posterior anything but intram medial this trick will save you tons of hours on your studying and it's not have Hazard either this is how your brain was organized during embryological development you will learn more about the extraocular muscles but for now just remember that the nerves that Supply the

muscles that move your eye are crayon nerves three four and six keep this in mind so they move my eyeball but what if I want to see oh sensory not motor then that's CR nerve too the optic nerve for you so here is Vision which is sensation here is movement of the eyeball which is motor another important trick if I want to feel the feather that touch my face I use Crane nerve number five which is trigeminal nerve but if I want to move my facial muscles i e motor that's the facial nerve or the

seventh cranial nerve and last let's talk about the anterior 2/3 versus the posterior 13 of your tongue now none of this is going to make sense to you today but keep watching my videos on the cron nerves and you will Master this topic like it's nobody's business anterior 2/3 of the tongue here posterior 1/3 of the tongue is there separating between the two portions is the sulcus terminalis and you have a foran seeum in the middle anterior 2/3 of the tongue who's going to help me feel the touch that's V3 the lingual branch of the

mandibular nerve which belongs to the trigeminal nerve but who's going to help me taste the cord tempy nerve of the facial nerve which is the seventh cranial nerve let's switch to the posterior 1/3 of the tongue who's going to help me feel the pain and the touch ninth nerve which is the glossop Fingal who's going to help me taste the same nerve the glossop forel oh so there is a difference in the anterior but there is no difference in the posterior that's correct anterior 2/3 is V3 for General sensation and seven for Taste sensation I.E

special sensation General versus special how about posterior General and special are by the glossop Fingal nerves all right now tell me about the gland the salivary gland what does the facial nerve Supply IT Supplies submandibular glands and sublingual glands but the glossop fenel supplies the pared gland okay now please name the gangan well I am submar gland so I relay in submar gangion but I am a pared gland which literally means parallel to your ear parotic so iay in tic gangion amazing since this is saliva and this is saliva which nucleus in the brain stem

should I start in you should start in a salivatory nucleus to salivate to secrete saliva the one that controls the facial nerve anterior is the superior salivary nucleus but the one that contains the gloss ofel which is posterior is the Superior salivatory nucleus the superior salivatory nucleus is called Superior because it exists in the ponds which is located superior to the medulla the medulla is inferior to The Ponds anatomically speaking so anterior before posterior Superior salivatory is before or above inferior salivatory the facial is above the glossop Fingal in position and the ponds is anatomically

superior to the medulla in position I know this is a difficult topic right now but if you can memorize these distinctions it's going to help you tremendously as we go forwards but I forgot to tell you something all of this was sensory parasympathetic Etc but let's say that I want to move my tongue up and down right and left this is the function of the glossu Fingal nerve which is the 12th cranial nerve and there you have it the Ten Commandments of neuroanatomy how about the bonus you will learn about this in the upcoming videos

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