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Ear Anatomy and Hearing

Ear Anatomy and Hearing

Author: Amanda Soderlind

This lesson will give an overview of the anatomy of the human ear.

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Ear Anatomy

Source: Video and Images Created by Amanda Soderlind

Video Transcription

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Welcome to this lesson today on ear anatomy. Today we will be discussing the structure and function of the ear.

So, the function of the ear is to be able to detect sound. And sound travels as a wave. So your ear has several structures within it that are able to detect sound waves and then interpret them. And sound is measured in a unit called decibels.

So, we're going to take a look at the three main areas of the ear and then take a look at the structures located within those three main areas.

So, the first main area of your ear is called the outer ear. And the outer ear is composed of the part of your ear that you can see from the outside as well as the auditory canal. And the auditory canal, it's purpose is to direct sound waves inward. So, a sound wave will enter your ear and then be directed through the auditory canal towards the inner part of your ear.

The next part of the ear we're going to take a look at is the part here in purple and this is your middle ear. So there are several components that compose your middle ear. The middle ear is made up of the tympanic membrane, which is also commonly known as the eardrum. So, we have our tympanic membrane right here.

So basically, a sound wave will enter the ear, be focused through the auditory canal, and then cause this tympanic membrane to vibrate, which then vibrates your three ear bones, which are located in the middle ear.

So, you have a total of three ear bones, and they're called the hammer, the anvil, and the stirrup. So, this is the-- oops, I'm sorry --this is the hammer, the anvil, and the stirrup. So, these are the three bones of the inner ear.

The next part of the ear we're going to take a look at is the inner ear. So, we have our outer ear, our middle ear, and our inner ear in green. So, everything labeled in green here is a part of our inner ear. Hope you can see that OK.

So, our inner ear is, again, composed of several different structures. One here that we're talking about first is the cochlea. So, the cochlea here is a coiled structure. So this here is the cochlea. And the cochlea contains several different structures, including the organ of Corti and the tectorial membrane. So, the organ of Corti has little hair cells, which are mechanoreceptors, and they interact with the tectorial membrane, which helps to detect the intensity of a sound.

So, the cochlea itself is composed of a few different structures as well. We have the round window, which is this little, if you can see the darker green little circle right here, is our round window. And the round window basically acts as a pressure release valve if too much pressure builds up in the ear. And we also have another structure in our ear that allows for pressure release as well.

And then, if we take a look here, this in the darker green is our auditory nerve. And our auditory nerve will basically send signals to the brain. So, as sound waves travel through our ear they travel through all these different signals, signals are interpreted, and then auditory nerve will send those signals up to the brain to process that information.

And above our auditory nerve we have our semicircular canals. So, we actually have three of them. There's one here, one here, and one here. So, semicircular canals.

So, the semicircular canals and vestibular apparatus play roles in balance and equilibrium. The vestibular apparatus is composed of the semicircular canals and two fluid filled sacs, which will help maintain equilibrium. Otolith organs are bits of calcium carbonate within the fluid filled sacs of the vestibular apparatus that move as the head's position in space changes. So, for example, if you were to turn your head to the side, the otolith organs shift to the side as well, allowing the head's movement and position in space to be detected.

So, this lesson has been an overview on anatomy of the ear.


Source: Video and Images Created by Amanda Soderlind

Video Transcription

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Welcome to this lesson today on hearing. Today, we will be discussing how the structures within your ear allow for you to be able to hear. So the first thing we're going to do is identify the three main parts of the ear, which are the outer ear, middle ear, and inner ear. So this part of the ear right here is considered the outer ear, most of which you can see from the outside of your body.

This is the middle ear. The middle ear is the location where sound waves are amplified. So the outer ear is where sound waves enter, the middle ear is where sound waves are amplified. And then the inner ear is where sound waves are sorted.

So in the process of hearing, the first thing that needs to happen is that sound must enter the ear. So sound is a type of mechanical energy, and sound travels as a wave. And it's measured in a unit called decibels. So sound will enter the ear, it will be funneled through this auditory canal towards the tympanic membrane.

And the tympanic membrane is also commonly referred to as the ear drum. So when these sound waves enter the tympanic membrane, it will cause the tympanic membrane to start to vibrate. And as the tympanic membrane vibrates, it will cause these three bones of the middle ear to vibrate as well. So these three bones of the middle ear are called the anvil, the hammer, and the stirrup.

So the vibrating of the panic membrane causes the three bones of the middle ear to vibrate. And then that energy is then sent to the cochlea. So the cochlea is this coiled structure right here. So energy from the sound waves will create pressure waves in a fluid of the cochlea. And those waves will then be transmitted to the organ of Corti within the cochlea. And hair cells are mechanoreceptors for sound. And these hair cells are found in the organ of Corti, which is found within the cochlea.

So pressure waves will push these hair cells against something called a tectorial membrane. And this tectorial membrane is a jelly-like structure. So once these hair cells get pushed against the tectorial membrane, a neurotransmitter will be released, which will then trigger an action potential in the neurons of the auditory nerve. So this here is the auditory nerve. So the auditory nerve will then carry those signals to the brain for interpretation. So that's the process of hearing.

We're going to talk briefly about a couple other structures of the ear that don't directly relate to the process of hearing, but play more of a role in balance and equilibrium. So these three structures right here, one, two, three, are called the semicircular canals. And these semicircular canals contains sensory receptors that detect the head's position in space.

And the vestibular apparatus-- the vestibular apparatus also is a structure that plays a role in balance and equilibrium. So the vestibular apparatus is actually composed of the three semicircular canals plus two fluid-filled sacs, which can be found within here. And these two fluid-filled sacs are called the saccule and the utricle. So those two fluid-filled sacs, in addition to a semicircular canals, compose the vestibular apparatus.

Now these two fluid-filled sacs include an otolith organ. And otolith organs contain hair cells and bits of calcium. So as your head moves position in space, these bits of calcium will also move back and forth as well. So again, it's helping to monitor your head's position in space, and it plays a role in balance and equilibrium. So this lesson has been an overview on the process of hearing.

Video Transcription

Terms to Know
Auditory Canal

Otherwise known as the ear canal and a part of the outer ear; the auditory canal guides sound waves toward the tympanic membrane.

Auditory Nerve

The nerve that projects auditory information detected by the hair cells in the cochlea to the primary auditory cortex of the temporal lobe.


The organ of hearing found within the inner ear; contains the sensory receptors for hearing (hair cells/stereocilia), Organ of Corti, tectorial membrane, round window, and the auditory nerve.


A unit of measurement which indicates the loudness of a sound.

Hair Cells

The actual receptors for hearing within the cochlea; the hair cells bend due to mechanical fluid vibrations within the cochlea. The bending of the hair cells causes them to depolarize and generate action potentials. The hair cells are also called stereocilia.

Inner Ear

The inner portion of the ear deeply embedded within the temporal bone; contains the organs of hearing and balance/equilibrium. Organs within the inner ear are the cochlea, the vestibular system, Organ of Corti, tectorial membrane, hair cells (stereocilia), round window, otolith organs, auditory nerve, and the semicircular canals.

Middle Ear

The middle portion of the ear that is primarily designed to mechanically amplify the sound waves that enter the ear. Anatomic structures included are the tympanic membrane (ear drum), auditory ossicles (malleus, incus, stapes), and the eustachian tube.

Organ of Corti

A highly specialized organ found within the cochlea that contains the hair cells/stereocilia and their supporting structures (tectoral membrane, basilar membrane).

Otolith Organs

The saccule and utricle, each with an otolith (hard bits of calcium carbonate).

Outer Ear

Anatomically the outer part of the ear that traps and funnels compressed air inward toward the middle ear. Anatomic structures included are the auricle/pinna, auditory canal.

Round Window

A structure in the cochlea that acts to dampen the mechanical fluid vibrations within the cochlea to prevent damage to the hair cells.

Semicircular Canals

A system of canals in the vestibular system of the inner ear that provide feedback about body position.


Mechanical energy that travels in the form of a wave detected by our ears.

Tectorial Membrane

One of two gel membranes located within the cochlea of the ear and is part of the organ of Corti. The two gel membranes contribute to the mechanical process of hearing.

Tympanic Membrane

A thin, highly innervated tissue at the end of the auditory canal that is attached to the auditory ossicles. When sound waves strike the tympanic membrane it vibrates, which causes the auditory ossicles to shift and press against the cochlea. Commonly referred to as the "eardrum."

Vestibular Apparatus

A system within the inner ear that provides us with feedback about our body position and balance; consists of the semicircular canals and the otolith organs.