Welcome back to my channel, in today’s video we are going to go over the structure
and function of the human ear. The human ear is an organ that
is responsible for hearing and balance. There are three general areas the ear
can be divided into; the outer ear, the middle ear, and the inner ear.
The outer ear includes the part visible on the outside of the body, the auricle,
as well as the ear canal and the ear drum. The auricle, also known as the pinna,
is the fleshy visible part of the ear and has many areas to it.
It has a lobule at the bottom which is what we call the ear lobe.
The helix is the outside area that is folded over. The tragus is a pointed area near the entrance of
the ear canal, opposite this is the anti-tragus. The deep area near the ear canal is the concha,
up from here is the arching anti-helix. Between the anti-helix and helix is the scapha
posteriorly and the fossa triangularis anteriorly. The function of the auricle is in capturing,
amplifying and directing sound from the external environment towards the ear canal.
The ear canal, also known as the external auditory meatus, is the tube that goes from the outside of
the ear ending with the eardrum. The entrance to the ear
canal is called the aperture. The function of the ear canal is as a pathway
for sound to go from the auricle to the eardrum. The eardrum, also known as the tympanic
membrane or the myringa, is a membrane that separates the ear canal and the middle ear.
This membrane’s function is that is vibrates when the sound coming through the ear canal reaches it
and transmits these vibrations to the middle ear. The next section of the ear is the middle ear.
Behind the eardrum there is a cavity that is full of air called the tympanic cavity,
the other components of the middle ear are found within this cavity.
Inside the tympanic cavity are the auditory ossicles.
There are three auditory ossicles, which are actually small bones.
The first ossicle is the malleus, also known as the hammer due to its hammer like shape.
The malleus is connected to the eardrum. It is also connected to the second ossicle,
the incus also known as the anvil because of it’s anvil like shape.
The incus is connected to the third ossicle, the stapes, also known as the stirrup due to
the stirrup like appearance of the end portion that joins to the oval window.
These ossicle are attached via several stabilizing ligaments.
The function of these ossicles it to receive the vibrations from the eardrum
and transmit them through the ossicles where they are amplified before entering
the inner ear through the oval window. The oval window is a membrane covered
opening between the middle ear and the inner ear. In the middle ear there is also the round window,
this is another membrane covered opening between the middle ear and the inner ear.
The round window’s membrane will move towards the middle ear to balance out the pressure caused by
the oval window when the stapes causes the oval window to move towards the inner ear.
Leading down from the tympanic cavity is a tube called the eustachian tube
also known as the auditory tube. This tube lead from the middle ear
down into the nasopharyx area. The final section of the ear is the inner ear.
The components of the inner ear are all found within the bony labyrinth.
Inside this bony labyrinth is a duct systems known as the membranous labyrinth, inside the ducts that
make up the membranous labyrinth is a fluid called the endolymph and outside between itself and the
bony labyrinth is a fluid called the perilymph. The membranous labyrinth
consists of three general parts. The first of these is the vestibule, the vestibule
has two parts; the utricle and the saccule. There are also the semicicular canals,
these consists of three interconnected tubes; the anterior/superior canal, the
lateral/horizontal canal and the posterior canal. The function of the semicircular canals
is in maintaining balance. The third area is the cochlea.
The cochlea is spiral shaped and itself consists of three areas; the vestibular
duct and tympanic duct that contain perilymph and the cochlear duct that contains endolymph.
Another important part of the cochlea is an area called the organ of corti,
this is the area where you find the hair cells. The vibrations that have come through the oval
window into the inner ear move through to the cochlea and the movement of the fluid
inside the inner ear from these vibrations cause movement of the hair cells in the organ of Corti.
Attached to the inner ear is a nerve called the vestibulocochlear nerve
which runs from the inner ear to the brain, where it receives signals for both balance and sound.
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