Auditory System Flashcards by monica toth

Major parts of the auricle composed of this

Elastic cartilage, sebaceous glands

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Regions of auricle

Helix/ antihelix, tragus/antitragus, concha/lobue

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What are the ceruminous glands?

Found in the external acoustic meatus. Aprocrine-type gland.

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What is ear wax?

Mixture of cerumen, sebaceous gland secretio, and desquamated meatal cells

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Innervation of the tympanic cavity

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What are the ceruminous glands?

Found in the external acoustic meatus. Aprocrine-type gland. Not to be confused with sebaceous glands- these are associated with the vellus hairs

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Innervation of the middle ear

Glossopharyngeal (IX)

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Innervation of eterna ear and external acoustic meatus

3- Greater auricular, lesser occipital, auriculotemporal- part of temperomandibular (V3)

Facial (VIII), Vagus (X)

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Innervation of the middle ear (tympanic cavity)

Glossopharyngeal (IX)

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Difference in pressure between eustatian tube and external meatus may be relieved by this action

swallowing- opens eustatian tube to the pharynx

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What muscles open the eustatian tube via the tubal cartilage

Levator palati, Tensor palati, salpingopharyngeus

air gets to enter the inner ear
they also pull up the soft palate

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Function of ossicles

Amplify sound from vibrations of the tympanic membrane

-Malleus, Incus, Stapes: decrease in surface area

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Tensor tympani muscle function

Dampens ossicle movement- low frequency

Sits in eustatian tube and meets up to the handle of the malleus

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Stapedius muscle function

Attaches stapes- pulls on stapes when there is extreme vibrations

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Chorda tympani- how, where it moves, what source

Goes through temporal bone. Branches from facial nerve (VII) and joins V3

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Tensor tympani is innervated by

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Stapedius is innervated by

VII- facial

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Function of chorda tympani

Sensory- taste from anterior 2/3 of tongue

Parasympathetic- submandibular and sublingual salivary glands

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Chorda tympani- how, where it moves, what source

Goes through temporal bone- passes by tympanic membrane, and leaves bone to meet with lingual nerve. Branches from facial nerve (VII) and joins V3

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Function of chorda tympani

Sensory- taste from anterior 2/3 of tongue

Parasympathetic- submandibular and sublingual salivary glands

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Otitis media

infection affecting chorda tympani, ossicles, tympanic membrane

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Otitis media symptoms

Decreased taste and decreased salivation

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Otitis media

infection of middle ear affecting chorda tympani, ossicles, tympanic membrane
Negative pressure pulls tympanic membrane into the tympanic cavity

Tegmen tympani

When otitis media infection perforates tympanic membrane- results in meningitis or brain abscess

Otitis media symptoms

Decreased taste and decreased salivation. | Pain by negative pressure moving membrane in (V3)

Tegmen tympani

When otitis media infection perforates tympanic membrane- results in meningitis or brain abscess. This is the area that connects the middle ear to the meninges.

Spaces in cochlea

Scala tympani, cochlear duct, scala vestibuli

Cholesteatoma

Perforation in the tympanic membrane- permits entry of skin cysts. This damages the middle ear and mastoid (can cause eruptions of the air cells in this part of the skull). Cllot of dead cells and sebum

Cochlea is composed of these spaces

Cochlear duct- scala tympani (media), cochlear duct, scala vestibuli

Perilymph vs Endolymph

Perilymph- same as CSF. A filtrate of blood. High K+ Endolymph- fluid inside cochlear duct made by stria vascularis. High Na+ There is a change of electrical potential between the 2 fluids

Perilymph vs Endolymph

Perilymph- same as CSF. A filtrate of blood. High K+ Endolymph- fluid inside cochlear duct made by stria vascularis. High Na+ There is a change of electrical potential between the 2 fluids

This medium stimulates receptor cells

Fluid in cochlea

Order of sound conductance

Ear drum-> malleus, incus, stapes-> oval window-> perilymph of scala vestibuli-> perilymph of scala tympani-> Round window

Order of sound conductance

Ear drum -> malleus, incus, stapes -> oval window- > perilymph of scala vestibuli -> perilymph of scala tympani -> Round window -> auditory tube

Organ of corti cell types, location, tectorial membrane

Basilar membrane, tectorial membrane, receptor hair cells, sensory neurons

Tectorial membrane location

Between Organ of Corti and Endolymph containing portion of cochlear duct

Ear ringing caused by

Malleus tensing tightly to protect ear from heavy vibration. When moved away from low-frequency (dangerous) sounds, you can only hear high and mid frequency since the contraction is still happening

Ear ringing caused by

Malleus tensing tightly to protect ear from heavy vibration. When moved away from low-frequency (dangerous) sounds, you can only hear high and mid frequency since the contraction is still happening

This membrane protects receptor cells of organ of corti

Tectorial membrane

Stereocilia are these and are located here

Microvilli "hair" cells that are located on the basilar membrane and contact the tectorial membrane

Sensory nerve of organ of corti

VIII- vestibulocochlear

How the cochlea encodes sound frequencies

Hair cells move in response to sheer forces on tectorial membrane. This depolarizes receptor cells --> K+ channels open (Endolymph). This releases vesicles to the afferent nerve

Sound waves vibrate the full length of this

Basilar membrane

Tonotopy is the frequency of sound coded by difference of this

Basilar membrane as it widens and ascends- produces complex sound waves

Resonance frequency

The frequency at which the membrane vibrates best

Inner hair cells transmit sound info to

CNS

Inner cells respond to movements from this membrane

Basilar membrane

Signal is transmitted to this part of the brain

Medulla- via the cochlear nuclei

Signal is transmitted to this part of the brain

Medulla- via the cochlear nuclei

Outer hair cells function as this

Mechanical amplifiers

Prestin does this

Moves outer hair cells by the movement of the basilar membrane

Hearing loss is mainly due to the destruction of this

The outer hair cells

Conductive deafness is due to

Damage of the tympanic membrane

Acoustic neroma is this

A tumor of schwann cells (schwannoma)

Subjective tinnitus is

Sensation of sound without external stimulation- a phantom perception

This area of the auditory pathway has abnormal activity

- Dorsal cochlear nucleus- increases spontaneous activity | - Primary auditory cortex