Full transcript
0:08hi ninja NES in this video we're going
0:09to talk about the structure of the
0:10eyeball all right so let's go ahead and
0:12get started with this because it's
0:13important before we start going into all
0:15the photo transduction and going into
0:18the retina and looking at all the cells
0:19layers of the retina and how these optic
0:21pathways are even occurring going to the
0:23central nervous system we really need to
0:25just get a good idea about the anatomy
0:27of the eye right so if you guys have
0:29watched some of our Anatomy videos we
0:31have a model that we actually go through
0:33the eye but this is just going to go to
0:35a little bit more detail and apply some
0:37physiology to it okay so let's go and
0:40get started so the what are we going to
0:41try to cover in this video let's come
0:42over here and let's get our little
0:43outline set up first thing we're going
0:46to talk about is the tunics of the eye
0:48okay then I want to talk about these
0:49things called segments like anterior
0:51segments and posterior segments and what
0:53separates them and what's in
0:55them then after that we're going to talk
0:57talk about the flow of this substance
0:59called aquous humor and you know we
1:01might even throw in another thing called
1:03the lacrimal flow okay we might even
1:04talk about the lacrimal flow and then
1:06we'll throw in a tiny little tidbit in
1:08there about clinical correlations
1:09nothing really insane all right so let's
1:11go ahead and start about tunics so
1:13there's actually going to be three main
1:15tunics of the eye three main tunics what
1:18are those three main tunics
1:21okay one tunic that we're going to talk
1:23about is actually called the fibrous
1:25tunic that's the first one we'll start
1:27with the fibrous tunic and this this is
1:30made up of two things okay so the
1:31fiberous tunic is made up of two things
1:34one of them is going to be the
1:37Scara and we'll talk about the Scara and
1:39the other big component is actually
1:42going to be the
1:45cornea okay the other one's going to be
1:46the cornea so the fibrous tunic we're
1:48going to talk about is actually going to
1:49be made up of two things one is the
1:51Scara and the other one is the cornea
1:53then after that we'll talk about what's
1:55called
1:57the vascular tunic or the uvia okay the
2:02vascular
2:04tunic sometimes they even call it the
2:07uvia uvia all right we'll talk about
2:09that and this is made up of three
2:11different components right so this is
2:13made up of What's called the choroid
2:15which is a nice dark pigmented membrane
2:17that is important for basically
2:18preventing the scattering and of Light
2:20by absorbing that because it contains a
2:22lot of melanin in that area also has a
2:24lot of blood vessels so it gives a nice
2:25good vascular Supply to some of the
2:26layers of the retina okay then there's
2:30going to be What's called the iris and
2:31the iris is important for being being a
2:33to control specifically the pupil hole
2:35size all right and what's called the
2:40ciliary body which is made up of two
2:42things the ciliary body if you guys know
2:44is made up of two components one of the
2:46components is called the
2:47ciliary muscles so we're just going to
2:50call it the ciliaris right and the other
2:52one is called the
2:55ciliary processes which are the
2:57structures that actually make the
2:59aqueous humor
3:01and then we'll talk about one more tunic
3:03and we're actually going to have another
3:04video specifically digging into that
3:06into more detail but then the last one
3:08we're going to talk about is actually
3:09going to be the sensory tunic the
3:12sensory tunic and this is basically the
3:16retina okay so we'll talk about that one
3:19and they even include into the sensory
3:21tunic we actually throw into this not
3:22only the retina we also throw into this
3:24a little bit of the vitous humor because
3:26it's it's kind of in that area but it's
3:28more of what's called in a segment but
3:30we're going to kind of throw it in there
3:31a little bit with the sensory
3:33tunic okay all right so what do we have
3:36here we have the fibbr tunic which is
3:38made up of the Scara and the Cornet
3:40let's start with that first where would
3:41you find the Scara in here and what is
3:43the Scara made of all right so if you
3:47look here we're going to have this outer
3:49part of the eye and the outer part of
3:51the eye is actually made up of this nice
3:53you know there's actually three layers
3:54of this Clara so if we actually kind of
3:56I'm not going to go through every single
3:58uh component of each one but I'm going
3:59to say that they're is three layers to
4:00the Scara so if we actually have the
4:02Scara here there's actually three layers
4:04of the Scara one is called the episclera
4:07so that's the outermost part of the scar
4:09and it's made up of a really nice dense
4:11uh
4:13fibrous connective tissue right very uh
4:17rich and dense fibrous irregular
4:19connective tissue then underneath that
4:21you're actually going to have another
4:22one it's called the
4:24Scara
4:25proper and the Scara proper is also
4:28important because the Scara proper is
4:29actually going to be made of a lot of
4:31collagen so a lot of collagen fiber so
4:33it makes it very tough right very very
4:35um
4:36resilient and the last one is actually
4:38going to be What's called the
4:40lamina fusa and this is basically very
4:43pigmented so it's pigmented so it
4:46actually is going to have a nice color
4:47to it okay so we have the lamin fusa and
4:51then you're going to have the episclera
4:52the Scaro proper and the lusco right so
4:54there's three layers Ty Scar and it's a
4:55really really important layer and again
4:57it's made of like an opaque connective
4:59tissue there is clinical correlation to
5:00this because sometimes in certain
5:01situations like jaundice certain Billy
5:04ribon types of molecules can accumulate
5:06within the Scara and it can actually
5:07cause off like a nice little jaundice
5:09like color they say right so you can
5:10actually see that in Scara uh and also
5:12very very prevalent in people who have
5:14what's called Gilbert's Disease which is
5:15basically they produce too much Billy
5:17ruin and accumulates there all right
5:19anyway that's the scare then what's the
5:22other part we said it was the cornea
5:24this big old orange sucker here right so
5:27the cornea is also important so let's
5:29write over here the cornea so the other
5:31super super important component here is
5:33going to be the cornea now the cornea is
5:36important because it's actually made up
5:38of you never you never believe it uh
5:41it's actually made up of five layers
5:42it's five layers uh just to make it
5:45really simple there's one 2 3 4 five
5:51there's an epithelial layer and this is
5:53actually probably of the most important
5:56one so it's a very very thin epithelial
5:58layer okay so there's an epithelial
6:01layer and this is the outermost so we're
6:03actually going from the
6:05outer all the way to the inner
6:07layer okay so this is going from Outer
6:10to the inner part of the
6:11cornea this is the epithelial layer the
6:13epithelial is actually rich in a lot of
6:15what's called No acceptors or pain
6:17receptors okay so it's also rich in a
6:19lot of what's called No acceptors or
6:22pain receptors why is this important
6:24because you know whenever you have
6:26something irritating the cornea what are
6:28you going to want to do there's
6:29irritation of the coret that's going to
6:31be sending signals to cause you to want
6:33to Blink right so we have pain receptors
6:35there to help us to let us know if
6:37there's any type of irritation to the
6:39cornea also you're going to have other
6:41layers underneath you know not super
6:44super simp U important but there's
6:46What's called the Bowman's
6:47membrane there's three layers of
6:49connective tissue the Bowman's membrane
6:51then after that there's actually What's
6:53called the stromal layer this is a very
6:55thick layer this is made up with some
6:57connective tissue here and there's also
6:59going to be another one called the
7:00Desmond's membrane and this is another
7:02connective tissue layer
7:04here so you have What's called the
7:06epithelial layer the Bowman's membrane
7:07the stromal layer the Desmond's membrane
7:09and there's also one more layer called
7:11the
7:12endothelial layer
7:16okay all righty now what's interesting
7:19about the coin is that it doesn't really
7:20have a lot of blood supply okay it
7:21doesn't really have a lot of blood
7:22supply specifically the epithelial layer
7:24too so because of that that's kind of
7:26interesting that's why you whenever you
7:27can do cornal transplants you can
7:29actually do a Coral transplant from one
7:30person to another without having any
7:32type of rejection because there is no
7:33immune um molecules in that vicinity
7:36really okay so again the corny is made
7:38up of five layers epithelial layer
7:40Bowman's membrane stromal layer
7:41Desmond's membrane and the endothelial
7:43layer and this is where a lot of the
7:44blood flow is actually coming in through
7:46to give Supply to some of the other
7:47structures okay so I did a little bit of
7:49blood supply coming here near the
7:51endothelial lay okay to give a little
7:54bit of nutrition to the actual layers
7:56around this area okay all right that's
7:59the cornea what is important about the
8:01cornea you know the cornea is important
8:02for doing what's called it's helping to
8:04actually allow for the light to pass
8:07through here so it allows for the
8:10movement of light so let's say here is
8:11actually going to be
8:13light it allows for light to pass
8:16through the cornea so it's very very
8:19good at allowing for light rats to pass
8:21through okay so that's one function of
8:23the cornea it allows for light rays to
8:24pass through all right sweet so we've
8:27gotten a a part of the Fibber tunic
8:28which is made up of the Scara and the
8:30cornea let's move on to the next
8:32part the next part we said is the
8:34vascular tunic and the vascular tunic is
8:36made up of what three components the
8:38choid the iris and the ciliary body
8:40which is made up of the ciliaris and the
8:42ciliary process let's talk about that
8:45okay so let's start here first with this
8:47big old maroon uh structure right there
8:51okay what is that big old maroon
8:52structure right here called this one
8:53coming down this way this one coming
8:55down this way that's called the iris
8:57okay so it's called the iris so if you
8:59guys have seen it like looking at from
9:01an anterior view you can kind of imagine
9:02it like this let's say here's the pupil
9:05which is the hole between Iris like this
9:06right here this is actually the pupil
9:08right here it's a little hole between
9:11the iris right around it you're going to
9:13have all of these actual muscles so this
9:16right here that I'm drawing with these
9:17lines is supposed to represent the iris
9:20and that's made up of a lot of muscles
9:21you know there's two muscles that make
9:22up this right here so again what is this
9:24structure here
9:25called this structure here is called the
9:28iris
9:30and the iris is actually made up of two
9:31different muscles okay so one of the
9:34muscles is actually going to be What's
9:35called the
9:38dilator
9:41pupila okay so one of them is called I
9:43think that's actually I put the P let's
9:45put the pupila so the dilator
9:49pupila another one is going to be it's
9:51called the
9:53sphincter
9:55pupila the reason why I'm mentioning
9:57this is because the dilator pupila is
9:58underneath
9:59what's called sympathetic nervous system
10:03innervation whereas the sphincter pupula
10:05is underneath parasympathetic nervous
10:07system innervation so what do I mean
10:10here if the dilator pupila is activated
10:13it'll cause the actual Iris muscle to
10:15relax which will cause what what will it
10:17do to the pupil hole so if you imagine
10:19here let's say that I have the pupil
10:22here is expanding okay it's getting
10:25bigger if it's expanding that means that
10:27it's dilating the muscles are going to
10:29be be causing that dilation of the pupil
10:31that's the the job of the dilator pupila
10:34okay but let's say for whatever
10:38reason the parasympathetic nervous
10:41system fibers are innervating the
10:42sphincter pupila and it's causing the
10:44actual Iris to contract and constrict
10:47that pupil hole and it's acting like
10:49ainter that's called the Shiner pupila
10:52okay so again dilator pupila dilates the
10:55pupil sphin your pupila constricts the
10:57pupil simple as that and again it's made
11:00up of a nice muscular layer so it's made
11:02up of muscle there right the dilator and
11:03the kinter but you know what else is
11:05important it's also pigmented so it's
11:07also having some pigmentation to it so
11:10it also has pigmentation it's what
11:12basically determines the color of a
11:15person's eye so for example you might
11:18have brown eyes you might have some
11:21hazel eyes you might have green
11:24eyes or you might have blue right and
11:28all that's detered in these darker
11:30colors are just the accumulation of more
11:31of this actual pigments you know when
11:33actually we were born most of us almost
11:36all of us are born with like kind of
11:37like a slate gray or bluish pigment
11:40right and then over time the actual real
11:43pigment of our actual Iris comes out
11:45okay all right sweet so we got the iris
11:48then we're going to go into the next one
11:50this big big structure right here you
11:52see all this part right here this whole
11:54thing right here all of this big chunk
11:58of muscle right there is called the
12:00ciliaris so what is this big chunk of
12:02muscle right here this big chunk of
12:04muscle here is called the ciliaris all
12:07this right here this is called the
12:10ciliaris okay so the ciliaris muscle
12:12what is it doing what happens is it's
12:14actually I'm going to show you here in a
12:15second it's connected to the lens right
12:18so it when it contracts it
12:22changes the
12:25shape of the lens
12:29okay here's another interesting point
12:31here the ciliaris muscle is under two
12:34different types of inovation it's under
12:37parasympathetic nervous system inovation
12:39and sympathetic nervous system inovation
12:41we'll talk about this in more detail
12:43when we do What's called the pupilary
12:44light reflex which involves the
12:47accommodation reflexes too but the
12:48silarus muscle is involved in What's
12:50called the accommodation so we can even
12:52put that which is basically this
12:54changing in the shape of the lens so
12:56accommodation right these accommodation
13:00reflexes which is important for distance
13:03vision and close Vision all right just
13:06to give you a tiny little tidbit
13:08whenever the ciliaris muscle contracts
13:10so here I'll put it like this
13:13parasympathetic nervous system it
13:14actually will cause the ciliaris muscle
13:17to contract when it contracts you see
13:19these little things right here these
13:20little black lines they look kind of
13:22like strings from a guitar these things
13:24right here are
13:25called you can call them two things you
13:27can call them ciliary zonals so you you
13:29can call them ciliary zonals or you can
13:32just call them like suspensory
13:34ligaments
13:37suspensory
13:41ligaments what's why these are important
13:43is because when the ciliaris muscle
13:44contracts these weirdly these ciliary
13:47zonals become very
13:49loose and when they become very loose
13:52what happens is this lens starts bulging
13:56so it actually starts bulging and when
13:58it bulges that's for a very very close
14:00Vision so short distance Vision but if
14:04the ciliaris muscle relaxes so because
14:06of what system this would be the
14:09sympathetic nervous system the
14:10sympathetic nervous system actually
14:12relaxes the ciliaris muscle so it
14:14relaxes it if it relaxes it weirdly The
14:18sary Zone will become really tight and
14:20when they become really really tight it
14:22actually causes this lens to flatten and
14:25when the L lens flattens that's for very
14:27far distance Visions we'll talk talk
14:29about that when we get into the um
14:31specifically the pupilary light reflex
14:33okay just introducing a piece of it now
14:36all right cool now what's the other part
14:39so we got the iris we got the ciliaris
14:41there's these little cells here okay you
14:43see these tiny little cells here that's
14:45kind of lining right over the ciliaris
14:46muscle so there's some cells right here
14:49and there's some cells right here these
14:51little bad boys right
14:53there these are called your ciliary
14:55processes so what are these little
14:56structures they're called they're called
14:57your ciliary
15:01processes and they're a tiny little
15:03layer of epithelial cells so they're a
15:05tiny little layer of epithelial
15:09cells epithelial cells some sort of
15:13cuboidal epithelial cells right and what
15:15they do is they secrete that humor that
15:18aquous humor so they secrete what's
15:21called that
15:23aquous
15:25humor okay so look what happens here
15:29they secrete this humor right so they're
15:31going to be making this aqueous humor
15:33because there's going to be nearby blood
15:34vessels right so they're going to be
15:35having blood vessels serving this area
15:36so if you imagine here for just a second
15:38let's say I remove out this part here
15:40and I put a little blood vessel in here
15:42because there's going to be blood
15:43vessels running all in this area it
15:46gives off little connections all right
15:48it gives off little connections and what
15:51happens is these ciliary processes could
15:53take some of the substances from the
15:54blood and make this aquous humor now
15:57what happens is is this aquous humor and
16:00these cells could be over here too right
16:02so they could even have some lining this
16:03side too I'm just showing it here what
16:06happens is let's actually kind of bring
16:08this stuff up here it moves upwards and
16:11as this aquous humor starts moving it
16:14actually comes up through the back of
16:15the iris Right comes up the back of the
16:17iris and then it moves through this
16:19little hole here what is this hole here
16:20called the pupil and it moves into this
16:23little chamber right here which we're
16:24going to talk about later and then from
16:26here it can provide some certain types
16:28of lubrication to to different
16:29structures in that area and can pick up
16:31metabolic waste and it can drain into
16:33this little hole right here that hole is
16:36called the canal of slim or schlim or
16:39you can I like to call it the sclero
16:40venosus because it just sounds weird
16:42sounds like I'm saying something like I
16:44shouldn't be saying right so again this
16:45structure here is called the
16:49scleral
16:50Venus sinus or the canal of
16:54schlim okay and so again what happens
16:56these ciliary processes are making this
16:59humor moves up through the you know
17:01there's actually a chamber here I'll
17:02mention it now I might as well cuz I'm
17:04already talking about what is this
17:05chamber here there's two Chambers here
17:07there's a chamber here and a chamber
17:10here this whole thing though if I were
17:12to make this whole distance here let's
17:13do this in pink so it's nice and bright
17:16here this whole distance here from the
17:19cornea all the way to the lens so from
17:21the cornea all the way to the lens there
17:24is a specific this whole thing is a
17:27segment what is this segment here called
17:30this segment is called the post I'm
17:31sorry posterior there should be anterior
17:35segment
17:37anterior
17:40segment now there's two chambers of the
17:43anterior segment separated by the
17:47iris this chamber back here is called
17:49the posterior
17:53chamber and then this one right here is
17:56actually called the anterior
18:01chamber now truthfully it's hard to show
18:04it in this this diagram here but what
18:06happens is this lens is actually much
18:07much closer here and the ciliary process
18:10is whenever they're secreting this this
18:12acre humor what happens is the sary's
18:15muscle has to contract to kind of move
18:16the shape of the lens a little bit so
18:18that this aquous humor can move
18:20underneath the lens and then from the
18:24posterior chamber it moves into the
18:26anterior chamber through the pupil then
18:29from that it goes into the anterior
18:30chamber and moves from the anterior
18:32chamber and drains into this area here
18:34this little hole here called the scarel
18:36Venice sinus or the canal schlim okay
18:40just so that we got that so the flow of
18:41vacuous humor sary processes are
18:43secreting this humor it moves kind of
18:45underneath the lens because the silary
18:48muscles have to actually control that
18:50the accommodation reflex to allow for it
18:52to move underneath the lens then it
18:54moves through the pupil hole it moves
18:57from the posterior chamber into the
18:59anterior chamber through that pupil hole
19:01and then it drains into the Scaro Venus
19:04sinus alrighty sweet deal okay so let's
19:08just recap this real quick because we
19:10basically covered these parts here we
19:11got one more layer but again Scara has
19:14episclera Scara proper and lamin fusa
19:17and if I'm being very specific to kind
19:19of go along with this how I said that
19:20the corny you had an outer layer to
19:22Inner layer this would be the same thing
19:25so from
19:26Outer to Inner layer
19:30we're moving downward so the outer layer
19:32is the episclera then the middle layer
19:34is the Scara proper and then the middle
19:36innermost layer is going to be the
19:37lamina
19:38fusa all right sweet now let's go to the
19:41next part of the uvia or the vascular
19:45tunic one more part here all right so
19:47this posterior extension that's coming
19:49from the C body see this posterior
19:50extension here that's moving all here
19:52this maroonish like structure here this
19:54is all called the
19:57choroid it's called the choid so what is
20:00this structure here
20:01called this structure here is called the
20:04[Music]
20:06choroid now the choroid is important
20:08because the chid is actually going to be
20:09a very pigmented membrane so it's a
20:12pigmented membrane now I'm mentioning
20:15that because that has a important
20:17physiological function when light
20:20rays because you know light rays is
20:22coming from many many different
20:23directions through here when the light
20:26rays are coming out here and they could
20:27be hitting different parts of the retina
20:30this light rays could actually be
20:31scattered throughout the I which can
20:32cause different problems with vision
20:34right we don't want that we don't want
20:35this actual light to be scatter to
20:37through all different areas because it
20:38could affect the visual field processing
20:40so what happens is the choroid absorbs
20:44some of those light rays that are being
20:46reflected okay so what is this guy doing
20:48here what is this choid doing he's
20:51basically
20:54absorbing any light rays
20:59to
21:01prevent
21:05reflection and
21:09scattering of light because that could
21:12affect the actual visual pathway and
21:15what we see within our visual fields we
21:17don't want that also really important
21:19I'm going to do it in red it has a
21:22nice vascular Supply a lot of blood
21:24vessels that are running in this area
21:26Okay so it has a nice little vascular
21:29Supply okay so a very rich in vascular
21:31Supply which is going to nourish a lot
21:32of different structures including the
21:34retina so it's actually going to have a
21:35nice vascular Supply that can give blood
21:37supply to the retina and it's going to
21:40be a pigmented membrane which can absorb
21:41a lot of different light rays to prevent
21:43that refle reflection of that light and
21:45the scattering of those light rays so
21:47that we have very
21:48very uh very precise and very very good
21:52visual pathway without any different
21:54types of uh you know Illusions or
21:56anything that could come from it okay
21:58all right sweet so we covered that now
22:01all right now let's move on let's get
22:03rid of these light rays here let's move
22:05on to the next part what's the next part
22:07so we've covered what we've covered the
22:09fibers
22:10tunic this part's done here we covered
22:13the vascular tunic that part's done
22:15there now we're going to cover the
22:16sensory tunic so the sensory tunic which
22:19is actually going to be consisting of
22:20the Rea and we said that we wanted to
22:21talk about something else
22:23here all right if you look here we were
22:26going to talk about this vitus humor
22:29from here if you look here from the back
22:31of the lens go from the back of the lens
22:34the posterior part of the lens all the
22:37way back to the retina okay so all the
22:40way back to the
22:42retina this whole thing makes up another
22:45segment so the anterior segment was from
22:46the anterior part of the lens to the
22:48cornea this segment the posterior
22:53segment is going to be from the
22:56posterior part of the lens all the way
22:57back to the red
22:59now I talked about shame on me I talked
23:01about the sary zonals and dispensary but
23:03I didn't really talk about the lens I
23:05said that it's important for basically
23:06helping to refract light rays and
23:08helping to control our distance vision
23:10and our short like close Vision but I
23:12didn't really talk about it enough so
23:14let me actually just real quickly talk
23:15about this this is actually the lens
23:17right now what's important about the
23:19lens we said it's responsible for
23:21refracting light rays so whenever light
23:24is coming in here it helps to be able to
23:26bend the light right and helps to be
23:28able to allow for the to focus those
23:30light rays specifically onto the retina
23:32so it's helping to refract these light
23:35rays okay so that's one of his functions
23:39But the lens is actually made up of
23:40different things if I were to say here
23:42we have the lens there's actually two
23:43components of the lens the lens is
23:46actually consisting of what's called
23:48crystallin like protein molecules they
23:50call them crystallins which are just
23:52proteins and that makes up what's called
23:54the lens fibers so the lens fibers is
23:58actually going to be made up
24:00of crystallin proteins and then you have
24:03another component which is called the
24:06lens
24:09epithelium epithelium and this is
24:12actually going to be consisting of some
24:13like a cuboidal epithelial tissue cells
24:15so it's actually going to have a little
24:16bit of cuboidal cells okay so this
24:20cuboidal cells so this is important to
24:24understand that the lens is actually
24:25made up of two things what is the lens
24:26made up of it's made up of lens
24:29fibers and lens
24:32epithelium okay two components here the
24:34reason I'm mentioning this with this
24:36whole lens fibers and the crystallin
24:37proteins is because in certain
24:39situations there is a uh you probably
24:42heard of it called
24:44cataracts they're called cataracts and
24:46cataracts are basically just
24:49accumulation or clumps of these
24:50crystallin
24:52proteins uh you know and cataracts can
24:54be due to many things one of the common
24:56causes is diabetes so in people who have
24:58diabetes this could actually be a cause
25:00smoking actually accelerates this
25:02process and what else it could even
25:06be congenital right so sometimes just
25:09congenital you know another weird
25:11one it's it doesn't make any sense but
25:14it could be due to if you consume too
25:16much vitamin C so if you take too much
25:18vitamin C like through supplementation I
25:20actually take Vitamin C that's why it's
25:22weird if if you actually take too much
25:24vitamin C this could actually accelerate
25:26the process of cataracts too so it's a
25:30unfortunate thing here right so that's
25:31why I'm mentioning the lens is because
25:32there is certain clinical correlations
25:34that whenever there's accumulation of
25:35these crystallin proteins it can cause
25:37cataracts which can definitely make a
25:39huge difference in Your Vision because
25:41what is it was responsible for helping
25:43to refract some of those light rays onto
25:45the retina to focus those light rays
25:46onto the retina to help within our our
25:48distance vision and our close-up Vision
25:51okay and you can actually do surges to
25:53replace the actual uh lens nowadays so
25:56that's pretty cool all right so we
25:58covered the lens now let's get back to
25:59the posterior segment sorry for being
26:01off track there okay now in the
26:03posterior segment it's going to be made
26:05up of all of this pink stuff now what's
26:09interesting about this pink stuff
26:11here is that you make it during
26:14embrionic development and you never make
26:15any more of it for the rest of your life
26:18whatever you have that's what you got
26:20forever so what is this jellylike
26:23material here called which it has some
26:25types of proteins also within it as well
26:28as other different types of molecule
26:29like hyaluronic acid and stuff like that
26:31what is this substance here called this
26:34whole substance pretty much occupying
26:36the entire posterior segment is called
26:38the vitous humor so the pretty much this
26:42whole posterior segment is occupied by
26:44the structure called the vitous
26:48humor there's actually a Remnant like
26:50structure that can actually run through
26:52here called the hyoid Canal we're not
26:54going to mention it but it can actually
26:55uh run right within the v's humor we're
26:57not going to talk too too much about it
26:58just saying that there is another
26:59structure that can run in it the
27:01posterior segment which is called the
27:02hyoid Canal but primarily it's going to
27:05be made up of this vitous humor now
27:08what's the function of this vitous humor
27:09what does it do well the vitous humor is
27:13really good at being able to transmit
27:16the light rays so it's good at
27:20transmitting the light
27:23rays so any light rays that are coming
27:25in here this vitous humor is very very
27:28very good at being able to allow for the
27:29light R to move through that jelly-like
27:30material and onto the retina also it's
27:34very kind of like a a strong jelly like
27:37material so it actually you see how
27:39right here we have this like black
27:40lining here this black lining here with
27:43all this like baby blue underneath it
27:46all this part here the black line all
27:48the way back to that Brown Line there
27:50this is going to be made up of the
27:51neural layer of the retina so we'll talk
27:53about these two things there's two parts
27:54of the retina the inner neural layer of
27:56the retina and the outer Pig layer of
27:58the retina what this actual vitous humor
28:01does is it holds the retina together so
28:04it holds the retina the neural layer and
28:07the pigmented layer close to one another
28:09okay so it holds the neural layer and
28:11the pigmented layer close to one another
28:13that's another function so it holds
28:14retina in
28:19place and know another thing that we
28:22didn't really talk too much about but we
28:23talked about in other videos you know
28:25what's actually connecting over here on
28:27the eye like for example let's say that
28:28I have a muscle right here the inferior
28:31rectus let's say that I have a muscle
28:33back here up here I mean superior rectus
28:36and then you have other ones medial
28:37rectus lateral rectus all those
28:38different muscles right what are they
28:39doing they're called extraocular eye
28:41muscles and they're changing you know
28:42they're moving the eyes whenever these
28:45extraocular muscles are Contracting and
28:46pulling on the eyes they can change the
28:49intraocular pressure but you know the
28:51vitous humor is very very good at doing
28:53it's helping to maintain it's
28:55contributing to the intraocular pressure
28:57to prevent any excessive changes in the
29:00intraocular pressure that is occurring
29:02whenever these extraocular muscles are
29:04Contracting so again one more time when
29:07the extraocular muscles are Contracting
29:09the vitous humor helps to be able to
29:11maintain the actual intraocular pressure
29:15that's its function when the extrinsic
29:16ocular muscles are Contracting it helps
29:18to maintain the intraocular pressure so
29:21we can say it
29:24contributes to I'm going to put in inra
29:28ular pressure IOP okay so it contributes
29:31to intraocular
29:33pressure sweet now we get on to the
29:35freaking good stuff the meat and
29:37potatoes all right so let's talk about
29:39this one right here we're going to
29:40actually zoom in on later when we go
29:42through the layers of the retina but I'm
29:44just going to take a tiny little piece
29:45out for just a second here so let me
29:48pretend that I'm doing this for a second
29:50I'm taking a slice of this a little
29:52chunk of this right here and I'm going
29:54to zoom in on it okay I'm going to take
29:55a little chunk of that and I'm going to
29:56zoom in on it so let's come over here
29:58for just a second all right so let's say
30:02right here let's say that this is that
30:04actual part there and that was kind of
30:07separating what would this structure be
30:08right here this would be where the
30:11vitous humor is so let's say this is
30:12where the vitous humor is okay that's
30:14all vitous
30:15humor then there was the part of the
30:17retina that we had here in blue all this
30:19part here what is this made up of what
30:22is the retina made up of we'll go over
30:24its cell layers in more detail but I'm
30:25going to give you a brief little
30:27discussion minute very very
30:30brief this is the outer pigmented layer
30:33of the retina there's two parts of the
30:37retina okay what is this blue layer here
30:39called this blue layer is the inner
30:42neural layer of the retina the
30:45neural
30:47layer of
30:49retina this is made up of three
30:52different types of cells well there's
30:53actually more we'll we'll discuss these
30:56in more detail like I said but there's
30:57going to be what's called called photo
30:59receptors photo receptors and these are
31:01like your rods and your cones there's
31:03going to be what's called bipolar cells
31:06or bipolar neurons there's going to be
31:09what's called gangon
31:11cells and then there's going to be
31:13what's called
31:15Amrine and horizontal cells which are
31:18basically helping to modify the the
31:20visual pathway so a lot of different
31:23cells within this area that are making
31:25up this neural layer of the retina photo
31:27receptors which you can consisting of
31:28rods and cones bipolar neurons gangon
31:31cells and Amrine and horizontal cells
31:33this is important because we talk about
31:34phototransduction we'll see this flow
31:37okay so that's make up in the neural
31:39layer of the retina the next one that we
31:41said this brown
31:43layer is the outer pigmented layer of
31:45the retina so this is the
31:48outer
31:51pigmented
31:53layer of
31:56retina and this is actually made up of
32:00these actual epithelial cells these
32:02epithelial cells it's actually made up
32:03of epithelial cells kind of like a
32:05single layer of epithelial
32:08cells rich
32:10in
32:13melanin very rich in melanin and that is
32:16important for basically being able to
32:18help to contribute to preventing the
32:19scattering of light Ray so it absorbs
32:21some of that light to prevent the
32:22scattering and the actual reflection of
32:25these different types of light rays
32:26another thing what do we say it runs
32:29right around this area the choid so the
32:32choid runs in very very close proximity
32:34to this actual outer pigmented layer why
32:37is that important because you see these
32:40epithelial cells that are actually rich
32:42in me melanin we call them um pigmented
32:45epithelial cells these pigmented
32:47epithelial cells they basically act like
32:50uh kind of like the part of the
32:51bloodbrain barrier in a similar way
32:53these cells
32:55here they filter whatever is actually
32:57coming
32:58out of this choid V vessels and
33:01determine what actually goes into the
33:02retinal area Okay so these cells here
33:04that are making up this outer pigmented
33:06epithelium they're very special and the
33:08reason why is they're controlling what's
33:10leaving the blood from the choid vessels
33:13and coming out here into the neural
33:14layer of the retina the reason I'm
33:16mentioning this is because in certain
33:17types of severe trauma or shifting of
33:20movement you can actually kind of
33:23dissect this layer here kind of dissect
33:28this layer right here and when you
33:29dissect this layer right here what can
33:31happen
33:32is some of this vitous
33:35humor can actually leak in between these
33:38spaces so some of this vitous humor can
33:41leak in between these spaces when some
33:44of this vitous humor leaks in between
33:45the actual neural layer of the retina
33:48and the outer pigmented layer of the
33:49retina that's called a retinal
33:50detachment and if not treated very
33:52quickly it can lead to blindness okay so
33:54in certain situations in which there is
33:56the separation of the internal layer of
33:58retina and the outer pigmented layer of
34:00the retina Vitus hum can come into that
34:02little space and cause retinal that's a
34:04retinal detachment and if not treated
34:06quickly it can lead to
34:08blindness all right that's that part one
34:12other thing I want to mention here let
34:14me actually get rid of this part here
34:17because I want to mention something else
34:20with relation to the eye I'm going to
34:22draw another mini eyeball here real
34:23quick another mini
34:25eyeball because I want to talk about
34:27these things called your eyelids your
34:29palra so let's see here I draw another
34:31mini eyeball here's the actual Cora
34:35here's the pupil and then here's your
34:37optic nerve right we're not going to
34:38draw everything in there it's not super
34:40important ah freck it we'll do it real
34:42quick do this
34:44here and then that there
34:47okay now coming right around this area
34:50you're going to have the lower eyelid so
34:53you're going to have a little area right
34:54here called the lower eyelid then coming
34:57over here we have another one which is
34:58going to be the upper ey let's actually
35:00make this one look like that one let's
35:02actually do it like
35:04this okay so look you'd have some
35:06beautiful eyelashes coming off there and
35:08some beautiful eyelashes coming off like
35:11that right why am I mentioning this two
35:14things one there's a little layer here
35:17let's do this one in Orange o
35:20orange there's a little layer here
35:22lining right underneath this thing what
35:25do we call this we call this the palpa
35:28so this is the inferior palpa the lower
35:30eyelid this is the superior palpa the
35:32upper eyelid there's a
35:34little tissue here that's
35:37lining not only the eyelid but it's
35:40giving off a little double layered
35:42membrane here that kind of covers a
35:43little bit of the Cora okay so there's a
35:45little layer here that's actually
35:47covering underneath the palpar and then
35:50there's a layer that's actually covering
35:51onto the bulb of the eye here a little
35:53bit on the bulb of the eye so again same
35:55thing over here there' be a little layer
35:56here covering the
35:58inner surface of the palpar and then
36:00giving off a little layer here that kind
36:01of covers a little piece of the Coria
36:03like the bulb of the cornea right what
36:05is this called This is called the
36:07conjunctiva all right so this part here
36:10that part there that's actually lining
36:12the inner part of the palpa that's
36:14called the palpal conjunctiva palpal
36:18palpa
36:21brl
36:24conjunctiva and then this inner one here
36:26that's actually lining the little parts
36:28of the cornea there that's called the
36:30bulbar
36:31conjunctiva okay the
36:33bulbar
36:37conjunctiva the reason why I'm
36:38mentioning that is that certain bacteria
36:41or viruses can accumulate in this area
36:44people always joke around and say like
36:45oh dude I'm going to fart on your pillow
36:47and you're going to get pink eye it's
36:49partially kind of true if certain types
36:51of bacterial molecules or viral
36:53molecules get into that little space
36:55there and cause inflammation and
36:56infection of that area that can lead to
36:58what's called conjunctivitis pink eye
37:01right that's why it's important to
37:03little know a little bit about that is
37:05that if there's the inflammation of the
37:06Papo conjunctiva and then the bulbar
37:09conjunctiva this could lead to what's
37:10called pink ey or
37:13conjunctivitis all right so don't go
37:16farting on people's pH pillows and stuff
37:18all right now next thing there's another
37:20two more important structures in here
37:22right in here if I kind of draw in Black
37:25here there's a little plate
37:28a little plate right here it's called
37:30the tarsel plate so what is that little
37:33thing I'm making like a u that's called
37:34the tarel plate this has two functions
37:38one function is there's two muscles that
37:40connect to it one muscle is called the
37:43the actual the palpa muscles right so
37:46for example you could have the palp
37:47muscles if there's one up here that' be
37:49a connection of the levator palpa
37:51superioris also it's also a nice
37:53connection for the orbicularis oculi so
37:57two different muscles can attach to the
37:58Taro plate right so if I kind of draw it
38:00like this over here too let's say I draw
38:02it like
38:05this I bring it like this right
38:08here right there's a tarel plate right
38:10there and again there you have the
38:12levator Papa Superior is attaching and
38:14then the orbicular is oculi attaching
38:17okay that's one function of the Taral
38:19plate all right so there's two muscles
38:21that are attaching to the tarsel plate
38:23one could be the orbicularis
38:27oculi and if we were to be really
38:29specific there would be another one
38:30that's actually attaching up here called
38:34the L levator palp
38:37superioris okay so this one up here
38:39would be the levator palp I'm not going
38:42to write all levor palp
38:45Superior all right that's one function
38:47of the Taro
38:48plates another function there's these
38:51actual glands in here called the tarso
38:53glands so there's glands kind of like
38:55inside of that tarso plate there called
38:57called the tarso glands what happens is
39:00these are basically like sebaceous
39:02glands and they produce kind of like
39:03oily secretions on the eyelid to keep
39:06the eyelid and some of the structures on
39:08the eye nice and moist and prevent
39:09basically the eyelids from sticking
39:11together or sticking to the eye okay or
39:13the cornia in this case so there's
39:15little Taro glands inside of the Taro
39:17plate that producing sebum an oily
39:19secretion to basically keep the palpa
39:22nice and lubricated prevent them from
39:24sticking together and prevent it from
39:25sticking to like the corneal area okay
39:27all right guys I just wanted to take in
39:29a little bit of time and pre-draw this
39:30structure here because I want to talk
39:32really briefly about the lacrimal flow
39:34okay because that's kind that's kind of
39:36important so laa flow are basically the
39:38production of Tears which is what Conor
39:40McGregor is going to be doing when he
39:41fights Mayweather on August 26th all
39:43right anyway what happens here if we
39:46look at an anterior view of the eye
39:48here's your um upper palpa the superior
39:51palpa here's the inferior palpa you see
39:54this kind of like V like part here
39:58that v- like part there is actually
39:59called the lateral commissioner and this
40:02part over here is actually called the
40:04medial commissioner but don't get that
40:06confused with the space between the
40:09superior paler and the inferior paler
40:10that's actually called the pal feser
40:12okay so this little V part over here is
40:14actually called the lateral commissioner
40:16V part over here is the medial
40:17commissioner and the space between the
40:19palpar is called the palpal
40:21Fisher now this right here is the eye
40:24I'm just showing an anterior view of the
40:25nose like this is the nasal sep
40:27and this is the lateral wall of that
40:29nose and this is the lateral wall of
40:31that nose Okay that side of that nose
40:33all right sweet so let's go here in a
40:36step-by-step process first thing is the
40:39lacrimal glands if you remember the
40:41facial nerve the facial nerve cranial
40:43Nerf 7 cranial Nerf 7 was actually one
40:45of the big guys there that was going to
40:48inovate this guy right and caused this
40:50actual lacrimal gland to start producing
40:52lacrimal fluid and that lacrimal fluid
40:55if you remember it comes out and moves
40:58across the eyeball so it moves across
41:01the eyeball nourishing the cornea and
41:04basically picking up any types of
41:05metabolic waste products and it starts
41:08moving medially towards that medial
41:10commissure there's actually a little
41:11fleshy part here a little fleshy part
41:14here actually called the lacrimal corle
41:17a little area right there called the
41:18lacrimal corle little fleshy part there
41:20what happens is there's these tiny
41:23little holes here tiny little holes
41:25right there around that medial
41:26commissure called the lacrimal Puna so
41:29the first step is it lacrimal glands
41:30secrete it they move medially then the
41:33third step is they move into this holes
41:35here called the lacrimal Puna then from
41:38there they move to these tiny little
41:40canaliculi called the lacrimal
41:43canaliculi then from that they move into
41:45this big Old Sac here called the
41:47lacrimal Sac then the lacrimal Sac
41:51empties this stuff through this duct
41:53here called the naso lacrimal duct and
41:56it goes under underneath you see how
41:58this is the superior con Superior nasal
42:00cone middle nasal cone inferior nasal
42:03cone and in between it this is the
42:05superior meatus middle meatus and
42:07inferior meatus the nasal lacrimal duct
42:09empties in just around the inferior
42:12meatus into the nasal cavity okay so to
42:15recap that what's it all doing here
42:18first one lacrimal gland
42:22secretes okay
42:25fluid second step
42:28moves
42:29across
42:32cornea
42:35medially then third step what goes into
42:38the lacrimal Puna
42:40moves into
42:43lacrimal
42:46Puna then fourth step goes through these
42:48tiny little canaliculi then it goes into
42:51the
42:53lacal
42:55canaliculi then from there it goes into
42:58the lacrimal
43:02Sac then from there it goes into the
43:05nasal lacrimal
43:10duct and then from there goes into the
43:12nasal cavity through the inferior meatus
43:16so I'm going to put inferior
43:19meatus of
43:21nasal
43:25cavity holy sweet goodness we did it all
43:29right now one more thing I want to talk
43:32about and then we're going to go ahead
43:33and stop all right there's another
43:36little thing that I forgot to mention
43:37here probably probably one of the more
43:38important things here is that if you're
43:40looking here you see this whole big
43:41sucker right there what do you think
43:43this is this right here is called the
43:45optic nerve okay this is called the
43:48optic nerve so what is this structure
43:50here called it's called the
43:53optic nerve or cranial nerve two this is
43:57also called cranial nerve
43:592 the reason why I'm telling you that is
44:02because if we look at the eye if you do
44:04like it's called opthalmoscope so you
44:06look at the eye from actually doing an
44:07opthalmoscope you look into their eye
44:09you're going to see in the back of the
44:11eye you're going to see this structure
44:12here called the optic disc that little
44:14part there the optic disc is where the
44:17actual optic nerve is piercing through
44:19the back of the Scara then you'll see
44:21kind of a little bit near it you'll see
44:22another structure called the macula
44:26right where the fob and tralis where the
44:28highest concentration of cones are okay
44:30but right here is the
44:32optic disc so if I do what's called a
44:35fundoscopy where I'm looking at the back
44:37of the eye there's the optic disc and
44:39then there's What's called the
44:41macula
44:43ludia kind of a little bit more lateral
44:45to that the optic disc is where the
44:47actual optic nerve pierces through the
44:49back of the Scara now when I say
44:50piercers through the black of the scare
44:52we we said oh wait I thought the scare
44:53was the episer the Scara proper the
44:55lamin ausa yeah it gives a little
44:57extension downwards here and whenever
45:00the optic nerve is piercing through the
45:02back it moves these little holes so the
45:04optic nerve which the axons of the gang
45:06gland cells they're moving through these
45:07holes what are these holes here in the
45:08Scara called these holes in the Scara
45:11are called the lamina
45:15kosa
45:17cribrosa okay and it's running these
45:20little holes within the scare where the
45:21optic nerves are piercing through the
45:23back all right all right Niners we
45:26covered a lot of information this video
45:27I I really hope you guys enjoyed I hope
45:29it made sense if you guys did like it
45:31please hit the like button comment down
45:32in the comment section and please
45:34subscribe in the next video we're
45:35actually going to take a look more
45:36specifically at the retina zoom in on
45:38the retina all the cells of the retina
45:40and then talk about the photo
45:41transduction process I hope to see you
45:42guys there all right Ninja nerds until
45:44next time