Ma3 - Ear

Front 1

What is included in the Outer Ear?

Back 1

Outer Ear-Pinna (auricle) and external auditory meatus to tympanic membrane, which is the boundary between the outer and middle ear

Front 2

What is included in the Middle ear?

Back 2

-Middle ear-tympanic membrane to orifice of auditory (eustacian) tube.

-Auditory (Eustacian) tube is a diverticulum off the middle ear cavity that communicates with the pharynx.

-Middle ear cavity contains the three ossicles.

Front 3

What is included in the Inner ear?

Back 3

Inner ear-membranous labyrinth

e. Inner ear is a complex, closed vesicular epithelium that contains patches of innervated neuroepithelium where the mechanotransducers are found.

Front 4

What do the neuroepithelial cells in the inner ear do and what are they called?

Back 4

The ear has a system of neuroepithelial cells in the inner ear that are highly specialized for the transduction of movement into electrical activity. These are Mechanoreceptors.

Front 5

What is caused by the deflection of hair cells and how?

Back 5

-Either movement of the head or the tympanic membrane causes the deflection of hair cells.

-Via the mechanoreceptors, movement of these hair cells sends electrical signals towards the brain for interpretation of sound and movement of head.

Front 6

What type of receptors are hair cells and they are a modified form of what?

Back 6

-Hair cells are special sensory receptors like those of the eye and nose.

-These special sensory receptors are a modification of the apical cilia and project from the epithelial cells – highly specialized epithelium.

Front 7

Pinna functions as a...

Back 7

-Pinna functions as a funnel for sound. It catches it, amplifies it and projects it into the external auditory meatus.

-The shape of your pinna is essential for this function – it is shaped as a parabolic mirror with a focal point at the external auditory meatus.

-Animals with exceptional hearing have extremely large pinnae – dogs.

Front 8

Ceruminous glands - located where, produce what, function of what is produced?

Back 8

Within the external auditory meatus is highly modified skin that not only has hair follicles and sebaceous glands but also modified apocrine sweat glands called ceruminous glands, which produce earwax.

-Most probable function of earwax is as an insect repellent – it has an acrid flavor that is designed to keep insects from crawling into the ear and parasitizing the head (i.e. Bot flies).

Front 9

Middle Ear Cavity - contains what, connected to what via what

Back 9

-Contains Malleus (attached to TM), Incus, and Stapes (attached to oval window)

-Connected to pharynx by auditory (eustacian) tube

Front 10

Middle Ear Cavity - Auditory tube's function and epithelium

Back 10

It allows the middle ear cavity to equalize the air pressure. The auditory tube has a varied epithelium.

Front 11

Middle Ear Cavity - Near the opening into the nasopharynx, the epithelium is nasopharyngeal epithelium consisting of...

Back 11

Pseudostratified ciliated columnar epithelium with goblet cells.

Front 12

Middle Ear Cavity - Tubal tonsils - located where, function, what infection can arise in middle ear cavity?

Back 12

-Tubal tonsils are located in the eustacian tube at the orifice of the nasopharynx.

-They protect the oral bacteria from ascending into the middle ear.

-Otitis media, or middle ear infection, is extremely common in children because they have a short eustacian tube. It is treated with antibiotics.

Front 13

Middle Ear Cavity - When the tympanic membrane is driven by sound waves, the motion of the membrane causes...

Back 13

When the tympanic membrane is driven by sound waves, the motion of the membrane causes the Malleus to displace medially, pushing on the Incus, which pushes on the Stapes.

Front 14

Middle Ear Cavity - What is the function of the three ossicles?

Back 14

-The ossicles, within the middle ear, act as an amplification system

-The three ossicles form a lever system with a mechanical advantage of about 9:1 producing a 9-fold amplification.
1.A force of unit one that deflects the tympanic membrane will be conveyed as a force of 9 units at the oval window.
2.(thus far we have discussed 2 amplification systems: the pinna and the ossicles).

Front 15

Inner Ear - found where?

Back 15

Inner ear is a cavity in the petrous portion of the temporal bone called the Bony Labyrinth.

Front 16

Inner Ear - Within the boney labyrinth is the epithelial-lined...?
What type of epithelium?

Back 16

Within the boney labyrinth is the epithelial-lined Membranous Labyrinth.
i.Membranous labyrinth is congruent in shape to the bony labyrinth.
ii.Mostly simple squamous epithelium with specialized patches of neuroepithelium, which contain mechanotransducers and supportive cells.
iii.Patches of neuroepithelium are innervated by CN VIII