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Lecture Comments (2)

1 answer

Last reply by: Bryan Cardella
Sun Nov 17, 2013 1:03 PM

Post by Melika Shayegh on November 17, 2013

I was wondering if otoconia is the same thing as otoliths
thank you


  • The external ear includes the auricle (pinna), external acoustic (auditory) meatus, hair, ceruminous glands, and the tympanic membrane (eardrum)
  • The middle ear contains the middle ear bones: malleus, incus, and stapes (hammer, anvil, and stirrup), and muscles associated with them
  • The inner ear contains the boney labyrinth (cochlea, vestibule, and semicircular canals)
  • The cochlea is filled with various ducts (vestibular/cochlear/tympanic) and membranes (basilar/tectorial) that help transfer vibrations into electric signals in hair cells
  • Sound waves hit the tympanum, vibrating the auditory ossicles to amplify the sound, which hits the oval window and moves the fluid/membranes within the cochlea to stimulate hair cells, which send their signals to the brain through the cochlear nerve
  • Sound is measured in Hz for frequency (pitch) and decibels for loudness (amplitude)
  • The vestibule contains the utricle and saccule (each one has a macula), which are needed for telling the brain how your head is oriented in space
  • The semicircular canals have ampullae that are analogous to the three dimensions in space and their relative movements tell the brain how your head is rotating in space
  • Hearing conditions/disorders include tinitis, motion sickness, and ear infections
  • Did you know…
    • Q: What does the round window of the cochlea do?
    • A: The round window, which is inferior to the oval window, allows sound waves to dissipate out of the cochlea
    • Q: Is it true that you’re not supposed to use cotton swabs (Q-Tips) to clean out your earwax?
    • A: It is recommended that you do not use Q-Tips. It’s possible to do worse damage, such as pushing wax (cerumen) further against the tympanum, or even damaging/puncturing the tympanum! There are other ways to clean out your ears without putting a long hard object into your ear canal.


Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • External Ear 0:04
    • Auricle
    • External Acoustic Meatus
    • Hair
    • Ceruminous Glands
    • Tympanic Membrane
  • Middle Ear 5:31
    • Tympanic Cavity
    • Auditory Tube
    • Auditory Ossicles
    • Tympanic Muscles
  • Auditory Ossicles 12:02
  • Inner Ear 13:06
    • Cochlea
    • Vestibule
    • Semicircular Canals
  • Cochlea 13:57
    • Organ of Corti
    • Vestibular Duct
    • Cochlear Duct
    • Tympanic Duct
    • Basilar Membrane
    • Tectorial Membrane
    • Hair Cells
    • Nerve Fibers
  • How Sounds Are Heard 21:30
    • Sound Waves Hit the Tympanum
    • Auditory Ossicles are Vibrated
    • Stapes Vibrates Oval Window
    • Basilar Membrane is Vibrated in Turn
    • Hair Cells are Moved with Respect to Tectorial Membrane
    • Cochlear Nerve Fibers Take Signals to Temporal Lobes
  • Frequency and Decibels 23:30
    • Frequency Deals with Pitch
    • Decibels Deal with Loudness
  • Vestibule 27:54
    • Contains the Utricle and Saccule
    • Maculae
  • Semicircular Canals 31:05
    • 3 Semicircular Canals = 3 Dimensions
    • Movement Gives a Sense of How Your Head is Rotating in 3 Dimensions
    • Each Contains an Ampulla
  • Hearing Conditions / Disorders 33:20
    • Conductive Deafness
    • Tinnitus
    • Otitis Media
    • Motion Sickness
    • Ear Infections

Transcription: Hearing

Welcome back to

This is the lesson on hearing.0001

When we look at the ear, we are going to start at the outermost portions, the most superficial, lateral part of the ear.0003

In the anatomy and physiology course, when you say the ear you are not just talking about this.0013

You are talking about all the stuff in the inside too.0018

The outer part of the ear that has the lobe, that typical look that we see on human beings, that is called the auricle.0021

The way that I remember that is the term aura.0029

Have you heard someone say your aura is green.0033

Aura is something that is emanating from you, projecting from you, and the auricle is emanating or projecting from your skull.0038

The lobes of your ear or the auricles you can call them pinna or pinnae.0049

You may have heard the term pinna peds which relates to sea lions but pinna - that is another name for the auricle.0056

It is made up of mostly cartilage and fat.0065

A lot of it is soft bone which skin on top of it.0070

They are shaped like little satellite dishes and they are angled in a way where you can hear mostly what is on the sides and in front of you.0073

Think of it our ears are not facing backwards, they are facing side and forward.0084

If you do this little tapping action on the sides of your head, you are exaggerating the action of your ears.0090

Something you cannot hear very well and you go like that it is like you are extending that little satellite shaped.0098

If you hear something behind you, you are going to turn so you can perceive it better through your auricles.0102

If you go to that hole which is primarily formed by that passageway meatus in the temporal bones, that you may have heard in the skeletal lessons.0108

The external acoustic meatus or external auditory meatus in certain books, is the whole that goes through the temporal bones 0120

and this part of the picture here that is spongy bone of the temporal bone.0129

This would be the periosteum on the sides and the compact bone.0134

This hole that leads into the middle and inner ear, there is going to be skin lining and on the top you are going to have hair and ceruminous glands.0139

What is an ear hole without hair?0151

Everybody got hair in the inside of the ear even if we cannot see it there are hairs in there and that is normal.0154

Like with hairs in the nose, they are catching that dust, those particles that are going in and preventing them from causing ear infection.0160

You do no want to lose your hearing when there is something going on inside of there.0168

A hair is going to protect that.0171

Excess hairs some people will trim them.0173

It is funny when you age those hairs get more obvious in certain individuals.0176

The ceruminous glands are a kind of gland similar to sebaceous glands but modified in the sense 0183

so that these ceruminous glands are producing something that is called cerumin.0192

Cerumin is a very waxy substance that is causing the build up of ear wax inside of your ear canal.0197

The purpose of that to make that sticky waxy stuff is to catch bacteria and particles and things coming into that ear canal 0207

into that external auditory meatus and preventing it from getting to the eardrum and beyond that wax accumulates in they are ways to clean it out.0217

Some people produce more than others and there are probably genetic and dietary factors that have to do with that.0226

The tympanic membrane is what separates the external and outer ear from the rest of the stuff inside.0232

The tympanic membrane is better known as the ear drum.0239

It is also called the tympanum.0242

It has 3 different names.0244

Ear drum is a great term because it is like a snare drum in terms of how sound waves vibrate it.0246

It is a very rigid set of membranes with a very thin layer of skin on the external portion of it, on the lateral side of it.0254

On the one that is facing the external part of your body.0266

When you go inside of a pool and you got water in your ear, the water is not actually inside of your ear but it is still in the external ear.0269

If you can see this with the blue, when water goes inside of your ear, sometimes it is just resting right here against that ear drum.0281

A simple shaking can get that water out.0293

You cannot get water in here and if you do your chances of infection are going to go up.0296

The tympanic membrane or ear drum actually vibrates when sound waves come in.0303

That is the first structure that is being impacted by sound waves entering your ear and that is going to transmit those vibrations further in.0311

It is going to amplify them based on what is connected to them, to the tympanum and further on in the inner ear.0321

That is the external ear.0327

The middle ear is from the inside of the tympanum or ear drum all the way to the bony labyrinth which is made up of cochlea and these other parts.0330

All in here is the middle ear.0343

You can call it the tympanic cavity if you want.0346

The auditory tube is a hollow passageway that is going to connect the middle to the nasal pharynx.0349

That is a technical term for the top of the throat.0357

The pharynx is the throat and the top of the throat is right next to the nasal conchae.0360

It is important that we have this tube there that is also called the auditory tube or station tube.0365

Anytime you get that change in pressure inside of your head like you are going up in an airplane or up 0371

or down in elevation in a car where you bit there is little bit of pressure.0377

Getting rid of that pressure and equalizing it you can thank your station tube.0386

For instance, you are getting high up in a mountain in a car, the atmosphere pressure will gradually drop.0390

At sea level the atmosphere pressure is 1 ATM but if you get up higher and higher it will get to .8 or .7.0398

As that air pressure drops, the air pressure outside of your ear drum is what is dropping but 0406

the air pressure inside in the middle is staying how it was from where you are coming from.0415

That is creating a pressure difference.0422

The pressure outside of your head is dropping but the pressure inside your ear is greater than what is outside of your head.0424

That is going to push on the ear drum and push it.0430

Depending on whether you are dropping in elevation or going up it is going to push the ear drum one way or another.0436

That can be very uncomfortable, that build up of pressure.0442

When you open and close the opening of the station tube inside of your upper throat, 0444

that is going to allow the pressure to move in and out to equalize it with respect to what is outside of your head.0450

You probably heard that chewing gum or gnawing like that or swallowing is going to open and close the opening of the station tube and equalize the pressure.0456

You can get rid off that uncomfortable feeling.0468

When we look at what is next, what is connected to the ear drum that is going to amplify the reception of those sound waves is 3 auditory ossicles.0470

Ossicles is a fancy term for bone ossification is the formation of bone.0483

Auditory ossicles are your middle ear bones.0488

There are 3 ear bones.0491

Maleus, inquis, and stapes comes from Latin terms but in English we can say hammer, anvil, and stirrup.0492

The hammer is first one directly attached to the inside of the tympanum.0499

Next is the anvil named after, you see them on cartoons dropping on people’s heads.0503

There is an anvil.0509

A stapes or stirrup looks a lot like where you put your foot in when you are riding a horse.0511

That looks very similar to that, we will see on the next slide.0519

These 3 middle ear bones are amplifiers.0524

It is like when you plug a guitar to an amp you are making the sound from the electric guitar a lot louder because of the amp.0528

If you look at reptiles oftentimes they will have one middle ear bone connecting their ear drum to the inner ear, we have 3 as a mammal. 0534

If you look at the animal kingdom, mammals in general have very good hearing.0543

We are taking little vibrations against this ear drum and making them a lot louder.0549

They tympanic muscles are the stapes that are attached to this middle ear bones.0557

They help keep them in place and also one of them prevents the stapes from running into the cochlea too hard.0563

This will make more sense in a couple of slides.0571

The cochlea is this snail shell shaped body, it is a hard body that contains the sensitive cells inside of it that are allowing you to hear.0574

The stapes is that middle ear bone that is vibrating in the cochlea.0584

The moment that the stapes hit it that gives us the different pitches we hear, high versus low, the loudness we hear, loud versus faint sounds.0589

If we hear a loud decibel noise, the stapes will run hard into the cochlea.0597

Those very loud noises are likely to damage the cochlea.0605

One of those muscles will tend up and prevent the stapes from hitting it too hard.0610

That is a nice notation to have.0616

A quick side note.0618

I saw this amazing documentary about the Eskimos up north, they live in an area 0620

that typically you do not hear as much of the noise you would in the city or even suburbia. 0630

It is very quiet.0636

There are very few noises in the environment.0637

You are going to hear glaciers moving and falling into the ocean but on a daily basis they are not hearing traffic, construction, etc.0641

A lot of those people still go out and hunt for seals.0653

They will go and use rifles.0657

The rifle will be right next to their head.0660

They start hunting from a very young age, from adolescents.0661

The amazing thing is that just hearing the rifle noise daily, that loud bang they are not used 0665

to having that tensor muscle pull on the stapes and prevent it from running into the cochlea with loud noises.0675

Those loud bang noises were causing this group of people to have deafness by the time they were 0682

in their 30’s or 40’s and by the time they hit 50 they cannot hardly hear anything.0690

Someone who lives in the city who goes and shoots rifles occasionally they muscles are more adapted to being use to pulling on that stapes from running in the cochlea.0695

There are adaptors that adapt to this Inuit tribes and they were giving them ear plugs.0707

When they will hunt, they will wear ear plugs.0714

It is going to prevent that onset of deafness at a very young age.0716

When we look very close at these auditory ossicles these 3 middle ear bones.0720

This one is the hammer and if you use your imagination you can picture that.0726

If you grab this part of it here is the head of the hammer like you can bang on something.0730

This look somewhat look like an anvil if you use your imagination.0735

There it is.0738

What a blacksmith would use or what a cartoon character would use to injure another character.0741

Inquis or anvil is that middle bone of the middle ear drums. 0747

Here is the stapes of stirrup.0752

It does look like something you put your foot in.0762

This is what is hitting the oval window of the cochlea which we are going to see in a little bit.0765

These 3 bones amazingly if you take them out of a person’s body you could fit them all on your thumb nail.0772

It is the smallest bone in the human body.0781

The inner ear, that deepest part of how the ear works, is made up of a bony labyrinth.0784

Labyrinth is like a maze within here.0793

It is bony because it is hard all through out.0797

It is made up of 3 basic parts.0800

The cochlea is that classic looking snail shell type part, that have to do with your ability to hear.0802

The vestibule which is made up of section called utricle and saccade.0809

The semicircular canals these 3 loops.0814

These all have to do with your equilibrium.0817

Your brain gets information from these areas so that you know how your head is moving in space and that is important to know.0821

We are going to start on the cochlea then we are going to move on to the other sections.0831

Imagine that we took that snail shell shaped cochlea and unravel it.0836

It is crawled up and unravel it.0843

This is an image of what it would look like if this was unraveled.0845

This part right here is known as the oval window.0848

This will be important in a little bit.0853

Number 4 here this is called the round window.0858

The way that I keep them straight is it is alphabetical if you go down the R.0865

I think of oval window being on top or superior to the round window because O comes before R.0873

The organ of corti is where all the action is going on inside the cochlea.0881

This is a zoom in of this organ of corti.0887

When we look at the cochlea in terms of the fluid layers inside this bony snail shell shaped part there are 3 ducts.0890

There are couple of ways to name them.0899

The vestibular duct is also called the scala vestibule.0901

This and this are the same.0907

The cochlear duct is also known as the scala media.0909

In purple we are going to label the tympanic duct also called the scala tympany.0916

It is a kind of fluid inside of the cochlea and depending on how the fluid shakes it vibrates membranes 0924

inside of the scala media or cochlear duct which contains the organ of corti.0934

We will get to those membranes in a second.0940

Think of it this way.0942

Stapes is just responding to what those other bones are doing and if we look back at the hammer that is responding to how sound waves are vibrating against it.0943

As sound waves come in depending on how the stapes hits against the oval window of the cochlea that is going to vibrate the fluid 0953

in such a way that is going to vibrate the membranes and change how this little neurons are either being depolarized or repolarized.0964

That gives you ability to hear amazingly.0974

When you look at the inside of the scala media you got the organ of corti.0978

Here is the parts that are inside of the organ of corti.0984

The basilar membrane is at the base of the organ of corti, below these little accessory cells and below these little hair cells.0987

Another term for this is stereo cilia.1004

The hair cells it is not these but it is a little modified neurons with cilia on top of them.1008

The reason why I have my hand here is there is a membrane resting on top of them.1016

If you look carefully here are little cilia, those little black lines.1022

This orange section which I am highlighting in red is the tectorial membranes sitting on top of them.1026

In orange here are those hair cells.1035

These are the outer hair cells and this one right here is an inner hair cell.1039

These are found all through the cochlea from this region all the way to the edge here.1045

The hair cells at this region close the stapes are more sensitive to high frequency noises.1052

Those kinds of noises.1059

At this end of the cochlea, that sensitive to low bass noises which as we can perceive but the way that 1062

I remember what part responds to which frequency is a garden hose.1073

If I take a garden hose and go like this with the garden hose, picture this in my hand and I am going like this, 1080

there are little waves in the beginning of the garden hose that you are not going to notice at the very end of it like 40ft further.1086

It is a high frequency noise.1094

A high frequency noise is the sound waves are vibrating air molecules very quickly with respect to each other.1096

It is a matter of second.1104

The cycle is very high.1105

We will talk about that more in a second.1108

With low frequency noises the frequency there is not as much in terms of the number of vibrations that are happening in a seconds time.1109

Back to the garden hose example.1119

A low frequency is if I did with the hose, you would see this arc go down the entire hose all the way to the edge.1121

That is how a low frequency noise is going to stimulate this further edge or the inside of the snail shell shaped.1132

That is how I remember it.1141

The high frequency will send all the way to low frequency.1143

Another application of this is as you age you do not hear high frequency quite as well.1146

Young folks who have cell phones maybe familiar with this.1154

There is a cell phone ring tone that is so high pitched that the average adult cannot here it anymore.1158

When you are born, you can hear up to 20,000hz and I am going to show you more about that on a slide in a future.1167

As you age, as your stirrup is hitting the cochlea the hair cells that tends to get damaged first are 1173

the ones at this end of the scala media that are sensitive to the high frequency ones.1184

The ones at the low end you tend to keep those longer.1188

By the time you are like 50, 60, 70, you have lost virtually all of these hair cells and you cannot regenerate them.1192

Once you lose the hair cells, they do not come back.1200

Maybe in the future some treatment will be able to regenerate them but my students did a test to me once1203

where I found out that a student in my class had this ring tone.1210

I have said sometimes next week I want that ring tone go off class and let us see if I can hear it because 1214

I was convinced at the time that I was in my late 20’s that I can hear it.1220

One day I am teaching and all of a sudden they are all looking at me and I said what is going on?1225

You do not hear that, no I did not hear it.1229

By the time that I was in my late 20’s I have already lost a bunch of the hair cells in terms of their functionality at this end.1233

I could not hear 20,000 hz anymore.1240

Maybe I can only hear 15,000 or 14,000.1243

That is the little tale that relates the hair cells in the cochlea to the different frequencies.1246

There are nerve fibers connected and you can see that here is a cochlear nerve connected to all of these hair cells.1254

These fibers down here run together and come into contact with the cochlear nerve.1261

It all comes into one nerve that connects all of these hair cells to each other.1270

That cochlear nerve goes to the temporal lobes so that you can actually perceive hearing.1276

There is a separate nerve called the vestibular nerve that has to do with the vestibule and the semicircular canals.1281

This is related to what I was talking about in the previous slide.1289

How sounds are heard?1294

This is step by step relating sound waves coming into your ear canal all the way to the cochlea and how it communicates with the temporal lobe.1295

Low frequency noises if you imagine that image that allows computers have with raising the volume and bringing the volume down.1304

Low frequency is like this and high frequency is like this.1313

It is a lot more of this vibration in that span of time of high to low frequency noise.1321

Sound waves depending on their frequency and how loud they are, the amplification of them, 1329

whatever sound waves they are, they are going to hit the ear drum in certain patterns.1337

They hit the tympanum then the auditory ossicles are vibrated because they are attached to the tympanum.1341

It amplifies the sound.1348

The stapes connected to the oval window right here is going to vibrate against the fluid here that in turn 1350

are going to vibrate the basilar membrane which is right below the hair cells just posterior to them.1357

Those hair cells are moved because they are just next to the basilar membrane and depending on how cilia moves 1366

that opens up channels for sodium and potassium and going to depolarize and repolarize action potentials just like neurons.1375

Depending on which combinations of hair cells are stimulated, that is going to give you the sensation of hearing.1385

All the different kinds of noises you hear and all the different pitches.1393

A tectorial membrane moving with respect to those cilia is going to stimulate certain neurons, and those cochlear nerve fibers take those signals into the temporal lobes.1396

When it comes to frequency and decibels, this like what I have mentioned before.1408

Every different sound waves has a wave length.1415

Some physicist do not like that term because wave length is better when you talk about light.1420

Waves looking like that in terms of electromagnetic radiation, those radio waves, microwaves, the visual spectrum.1425

It is better to think of it in terms of this, which is like air molecules are vibrating against each other.1434

That is how sounds gets inside of your ear.1442

You may have heard that in space you would not be able to perceive sound because if you are out in space there are no air molecules for sound to vibrate against.1445

But if you are on Earth, you do need to worry about that.1454

The number of how often the molecules are bumping against each other per second is going to give you the different frequencies.1456

On top of that you got decibel level or how loud the sound is or how faint the sound is.1466

You can have a high pitch sound that is very loud.1473

There are also high pitch sound that is not very loud.1477

You can those different decibel levels.1481

When it comes to frequency, we use hertz.1487

Hertz is the cycle per second named after a scientist.1491

20hz is the lowest end of the frequency.1494

20,000 is the max that humans can hear.1500

Dogs can hear beyond that, that is why there are dog whistles that no human can perceive but the dogs can hear it.1504

20,000hz a child or newborn can typically perceive that but by the you are an adolescence and teenage years you have already lost some of that.1511

When you get to 20’s or 30’s you are losing more and more when you age.1522

As I told you before, the stapes hitting that part of the cochlea.1525

When it comes to decibel levels in terms of loudness, it is a logarithmic scale.1529

When you look at 20 decibels versus 10, 20 decibels is 10× louder than 10.1535

30 decibels is 100× louder than 10 and that means 40 decibels is 1,000× louder than a 10.1544

Here are some examples.1552

0 will be the lowest audible level, the tiniest noise.1553

40 is just a quiet office and that is a lot louder than a 0 but a quiet office where people are not talking 1561

you just hear those general noises maybe an air conditioner or water cooler, computer sounds.1573

It is a very peaceful atmosphere.1579

A 100× louder than that is how I am talking to right now, a typical conversation.1582

I am at 60 decibel right now.1587

A lot louder than that is a chain saw.1589

If you are using a chain saw without protection, that can damage your hearing over time.1593

120 is a loud rock concert and a band like the WHO has set records in terms of loudness.1601

That is going to be damaging your hearing over time.1608

Pete Thompson has said that he should wear ear protection because he has partial deafness from years of rocking on 1612

and having those amplifiers blare noises into his skull.1621

160 is going to make you deaf.1625

If you are there for a rocket launch right next to the rocket or under a plane.1629

A plane landing is probably going to be more like 140 but still without ear protection from 120 to 160 you are risking permanent damage and deafness.1635

I do want you to think that 100 is not a problem or 90 is not a problem.1644

If you listen to 100 decibel sound over a long period of time that can be as bad as 1 or 2 seconds of 160.1650

It is all relative in terms of what the exposure is.1659

When you get up on this range not only you are going to be having a lot of pain and ruptured ear drums but you are risking permanent damage to your hearing.1662

When you look at the vestibule, the inner part of the ear, that has to do with equilibrium, there are 2 main sections.1672

There is the utricle and the saccuole. 1681

If you remember the image where you have the semicircular canals, we are not talking about the canals right now, 1685

we are talking about the middle region between the canals and cochlea.1690

It is bony.1694

It is well protected and housed but inside of the vestibule this utricle and saccuole each has something called a macula.1696

The plural is maculae.1705

This is what a macula looks like.1707

This is the whole macula of either the utricle or saccuole.1710

What the vestibule does is if your head is till and you get up in an elevator, even your eyes are closed you know that you are going up or down.1714

You just have a sense of it and it is because of the vestibule.1726

Based on how the gravity pushes on the macula or if you have an opposite feeling of gravity that you are rising up, 1728

that is another action that is going to affect the macula and allow you to perceive that.1735

It is the same thing where I am sitting in a car and I am not moving my head around, I can have my eyes closed 1742

and just know when the person is speeding up or slowing down.1747

I just have that sense of it because that linear acceleration is pushing on part of the macula.1751

That gravitational force or linear acceleration or deceleration is going to affect the audilyst.1758

Audilyst basically means ear stones.1767

They are these tiny, hard, crystals that sit on top of this gelatinous layer which is going to be having these hair cells embedded in it.1770

If I am going up in an elevator I am going to sense that it is the opposite of gravity.1783

It is going to feel like I am pushed on and even though I am rising up I am going to feel that I am pushed on, that is going to affect the audilyst.1792

That is going to action of those tiny stones moving and their movement is going to affect this gelatinous layer which is going to manipulate these little cilia 1801

and just like with cochlea that is going to cause depolarization and repolarization that is going to activate these nerve fibers.1812

This is the same when I am accelerating forward in a car, if the front of your face is that way, if I am accelerating forward 1822

the audilyst are going to move this way and is going to drag the gelatin layer and that is going to affect the hair processes.1836

If you are body is on a rollercoaster and your body is still but you are being moved around, 1848

you will get a sense of that because of the actions that are happening within the vestibule.1858

The semicircular canals there are no coincidence here that there are 3 of them.1864

It is perfect.1870

There are 3 canals that correspond to the x, y, and z axis.1871

If you think about geometric graphs and 3 dimensional space, x, y, and z each of those canal correspond to the 3 planes.1878

That is great because depending on how your head moves in space that is going to change what is going on in certain canals 1 or sometimes all 3.1888

Here are the planes.1896

There is this one, this one, and this one.1898

Depending on how you move your head you are going to manipulate 1 or more of them.1903

Each one of the semicircular canals, if you look at the canal being shaped like this, 1908

there is a lymph fluid inside the canal and at the base of each of these 3 canals is something called and ampoule.1915

Within one ampoule there is a lot going on.1926

The crysta is pretty much this region.1932

That is made up of epithelium and then modified neurons with stereo cilia, those cilia poking up in a gelatinous layer.1936

It is very similar to the macula in the previous slide.1947

The crystal is there.1950

The hair cells that is the stereo cilia and the copula is this.1952

It is surrounding the purple region that is where the cilia are.1960

The gelatinous layer it is going to be manipulated based on how the fluid is moving in the semicircular canals.1969

The fluid slashes based on how your head is moving, that moves the copula and then that is 1976

going to manipulate certain hair cells or modified neurons within this ampoule.1982

The endolymph is that fluid that is surrounding the copula.1987

The paralymph is the rest of the fluid on the outside.1992

That is how your semicircular canals are going to function.1995

When it comes to hearing conditions and disorders, one of the forms of deafness is conductive deafness which can be cured.1998

It is not necessarily permanent.2010

That is usually something in the outer in the external or middle ear that is preventing the transmission of sound waves to the cochlea.2013

Many with conductive deafness could have a cochlea that is working perfectly fine but it might be a problem with milliard bones.2021

It might be swelling or blockage in their external auditory canal or ear canal.2029

Conductive deafness covers a range of reasons why you are not getting those sound waves coming all the way to the cochlea.2035

Tinnitus is a ringing in the ear.2045

We have all experienced it.2048

It could be a result of over stimulation of those hair cells and sometimes you will find yourself sitting in a quiet room 2050

and there is like that ringing that does not go away and after several minutes it does.2059

There are cases where people with tinnitus that lasts for a month or year.2065

Sometimes it could be a pressure problem.2070

It could be swelling or blood pressure problems that are affecting the cochlea.2074

Even there is no sounds hitting the cochlea and stapes is what is responsible for transmitting those sound waves to the cochlea.2078

It will give you the illusion that there is this sound.2085

Otitis media is when there is something coming to the middle ear and cause the problem.2088

It could be bacteria, some kind of infection, and even could be some kind of micro organism like a tiny insect or a protist 2095

or something that is come up to your middle ear and cause swelling and inflammation.2108

That is something you do not want.2116

Motion sickness is because what your eyes are telling your brain and what the semicircular canals and vestibule are telling your brain are not in sync.2118

An example is if you are reading in a car and I can do that in no problem, other people cannot.2128

They will be in a car reading and after a little bit they get nausea.2134

That is because your eyes are telling you that you are not moving, you are just reading a book as if you are in a chair at home.2139

Your vestibule and your semicircular canals are telling your brain there is a movement going on.2146

It is some kind of mixed set of information that has something to do mesoncephalon that is what I have heard is the theory behind that.2153

We still do not know all the reasons why it results in nausea and vomiting.2162

As time goes on we are going to figure more and more about that.2167

Another source of motion sickness would be for people who are on a cruise ship.2170

They will be doing something inside the boat and their eyes are telling them that their body is still but the boat is moving.2177

It is impacting those little hair cells inside your vestibule or semicircular canals.2185

Finally, ear infections.2191

Ear infections they happen if bacteria, viruses, etc, get to the tympanic membrane and can cause a lot of swelling and inflammation.2193

It is going to be very painful.2206

An ear infection can cause deafness if they are not treated.2207

If you have ear pain go and see a doctor.2212

Thank you for watching 2214