Auditory Anatomy Review

Earwax

What is cerumen?

Ceruminous glands

What glands produce cerumen?

function of cerumen

Protects the ear canal, traps debris, repels water, and prevents infection

pinna

the visible external portion of the ear

Function of the pinna

Collects and funnels sound into the ear canal

helix

The outer curved rim of the pinna

concha

Bowl-shaped depression that directs sound into the ear canal

lobule

the soft ear lobe

no cartilage

What is unique about lobule?

trigs

Cartilaginous projection in front of the ear canal

antitragus

cartilaginous projection opposite the trigs

Eardrum

What is another name for the tympanic membrane?

Pars tensa and pars flaccida

What are the two major regions of the tympanic membrane?

Pars tensa

Which portion of the tympanic membrane is larger?

Pars flaccida

Which portion of the tympanic membrane is smaller and located superiorly

Outer epithelial, middle fibrous, inner mucosal

What are the three layers of the tympanic membrane?

Middle fibrous layer

Which layer of the tympanic membrane provides strength?

umbo

What is the deepest point of the tympanic membrane?

the manubrium (handle) of the malleus

What attaches to the umbo?

cone of light

What is the triangular reflection seen during otoscopy?

healthy tympanic membrane

What does the cone of light generally indicate?

ossicles

What are the three bones in the middle ear?

Malleus, Incus, Stapes

What are the ossicles in order?

Malleus

Which ossicle attaches to the tympanic membrane?

Incus

Which ossicle is the middle bone?

Stapes

Which ossicle attaches to the oval window?

function of the ossicles

Transmit sound vibrations to the inner ear

Eustachian tube

What is the tube that connects the middle ear and nasopharynx?

equalize air pressure

What is the primary function of the Eustachian tube?

Drain fluid

What is the second function of the Eustachian tube?

Cochlea

What is the spiral-shaped organ of hearing?

Temporal bone

In what bone is the cochlea located?

2.5

How many turns does the cochlea make?

35 mm

Approximately how long is the cochlea if uncoiled?

Modiolus

What is the central pillar of bone within the cochlea?

Modiolus

Around what structure does the cochlea spiral?

Scala vestiboli, scala media, scala tympani

What are the three chambers of the cochlea?

Scala vestibuli

Which chamber is the upper chamber of the cochlea?

Scala media

Which chamber is the middle chamber of the cochlea?

Scala tympani

Which chamber is the lower chamber?

Scala media

Which cochlear chamber contains endolymph?

Scala vestiboli and scala tympani

Which cochlear chambers contain perilymph?

Basilar membrane

What membrane supports the Organ of Corti?

Tectorial membrane

What membrane sits above the hair cells?

Basilar membrane

Hair cells bend and generate neural signals when what moves?

Inner hair cells and outer hair cells

What are the two types of hair cells?

one row

How many rows of inner hair cells exist?

three rows

How many rows of outer hair cells exist?

3,500

Approximately how many inner hair cells are present?

12,000

Approximately how many outer hair cells are present?

Inner hair cells

Which hair cells are the true sensory receptors?

Outer hair cells

Which hair cells act as cochlear amplifiers?

function of outer hair cells

Increase sensitivity and sharpen frequency tuning

tonotopic organization

Frequency mapping within the cochlea

Base

Which end of the cochlea responds best to high frequencies?

Base

Which end of the cochlea responds best to high frequencies?

Apex

Which end of the cochlea responds best to low frequencies?

Basilar membrane is narrow and stiff

Why does the base respond to high frequencies

Basilar membrane is wide and flexible

Why does the apex respond to low frequencies

CN VIII (Auditory/Vestibulocochlear nerve)

What cranial never carries auditory information from the cochlea?

Cochlear nucleus

What is the first auditory structure after the auditory nerve?

Medulla

Where is the cochlear nucleus located?

Superior olivary complex

What auditory structure follows the cochlear nucleus?

Pons

Where is the superior olivary complex located?

Superior olivary complex

What is the first auditory structure to receive input from both ears?

Lateral lemniscus

What auditory structure follows the superior olivary complex?

lateral lemniscus

Major ascending auditory tract

Inferior colliculus

What auditory structure follows the lateral lemniscus?

Midbrain

Where is the inferior colliculus located?

Medial geniculate body

What auditory structure follows the inferior colliculus?

Thalamus

Where is the medial geniculate body located?

Primary auditory cortex

What auditory structure receives information from the medial geniculate body?

Heschl’s gyrus

What is another name for the primary auditory cortex?

Temporal lobe

In which lobe is the primary auditory cortex located?

Wenicke’s area

Language comprehension center

Temporal lobe

In which lobe is Wernicke’s area located?

function of Wernicke’s area

Understanding spoken and written language?

Wenicke’s aphasia

What disorder results from damage to Wernicke’s area?

Fluent but nonsensical speech

What is the hallmark symptom of Wernicke’s aphasia?