Outer Ear Review Flashcards by Libby Sarra

What are the 4 parts of the temporal bone?

mastoid portion, tympanic area, squamous portion, petrous portion

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What is the organization of the somatotopic mapping of the body on the S1 and M1 areas

Head closest to the temporal lobe, arms, legs dipping into the longitudinal sulcus

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CN VIII and CN VII enter or exit the brainstem at the

cerebellopontine angle

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Parts of a cell and what they do:

soma (cell body containing the nucleus), dendrites (provide more area for neuron reception, branch like), axon (long cable, where impulses from the nerve travel away to be received by other neurons)

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What nerves and artery course through the internal auditory canal?

CN VII facial nerve, CN VIII (cochlear division), SVN, IVN, Labyrinthine artery

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Function of sodium-potassium pump for muscles and neurons

Helps to maintain equilibrium and membrane potential in cells
Maintains the gradient of a higher concentration of sodium extracellularly and a higher level of potassium intracellularly
for every 3 sodium pumped out, one potassium is pumped in

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outer ear skin’s protective mechanisms:

maintains the environment in the canal and minimizes chances of infection

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narrowest portion of the canal is the __

isthmus (6mm from the TM)

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cerumen properties

water repelling, lubricates, antimicrobial, protects TM

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what amount (in dB) does the ear canal resonate at?
(take into consideration the outer ear structures…)

17 dB!!! (2700 hz)

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sound pressure gain

External ear is a passive amplifier that increases the high frequency SPL at the TM

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since average length of canal is 2.5 cm, what is the resonance of the EAC? (excluding the effects of the concha/pinna)

about 3500 Hz

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what does the concha do as an “end correction” of the resonant tube? What happens when the ear canal and pinna are combined?

lowers the frequencies to a peak around 2700 Hz and a peak at 5000 Hz

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what do the bends in the canal do?

reduce occlusion effects (ex: deeper hearing aids make less sound waves –> our own voices sound louder

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roof of ME

tegman tympani

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floor of ME

jugular wall

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medial wall of ME

labyrinthine wall (prominatory)

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anterior wall of ME

carotid wall

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3 divisions of the ear

outer, middle, inner

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the outer ear includes:

pinna & ear canal

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is the skin of your outer ear the same as other skin on our body?

yes

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14 terms of the pinna:

helix, crus of helix, concha (cavum and cymba), triangular fossa, antihelix, crura of antihelix, darwin’s tubercle, scaphoid fossa, tragus, intertragal notch, antitragus, lobule

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average length of the canal:

2.5 cm

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cranial nerve innervation of the outer ear:

V VII & X (trigeminal, facial, vagus

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how many turns does the canal have?

2.5

name of fissures in the cartilage of the canal:

fissures of santorini

what type of glands are in the external canal?

ceruminous (modified apocrine sweat gland, also sebacious)

which side of the canal runs longer than the other?

the floor is longer than the roof (due to obliqueness of the TM)

how do the hairs in the canal protect it?

point outward to act as a filter for incoming objects

3 neuro-reflexes

vagus, trigeminal, lymphatic

what is the vagus reflex?

causes coughing, gagging, eye watering

What is the trigeminal reflex?

"red reflex" causes thickening of the TM and vascularization (hearing aid wearing, otoscopy, otoblocks, etc)

another name for Vagus reflex

Arnold's reflex

What is the lymphatic reflex?

slow reflex that is doe to over-wearing of aids, or an allergic reaction that causes swollen lymph and soreness around canal

more medial canal hairs lie ___ ; more lateral canal hairs lie __

flat, oblique

a sexual characteristic in males causes hairs over the tragus to become _____

thicker and longer

2 types of glands found in the outer ear

sebaceous (oil) and ceruminous (apocrine/sweat)

self cleaning ear canal function is called?

epithelial migration

2 patterns of epithelial migration:

radial (center of TM outward), and horizontal (laterally along the canal

how much does the external ear amplify sound pressure?

10 dB (resonant peak at 5,000 Hz)

inverse square law

from the sound source, as sound moves outward, it spreads out the distance it is covering and it loses intensity over that space energy twice as far from the source is spread over four times the area, hence ¼ the intensity

tympanic membrane components:

pars flaccida, pars tensa, manubrium of the malleus, umbo, cone of light, tympanic annulus, notch of rivinus, anterior + posterior malleolar folds

quadrants of the TM

anterior superior, anterior inferior, posterior superior, posterior inferior

which quadrant has the cone of light?

anterior inferior

a right ear has the malleus at what degree?

1pm

the TM has how many layers? describe them

4 layers! 1. epithelial 2. radial fibrocartilaginous 3. concentric fibrocartilaginous 4. mucous membrane

What nerve supplies the helix, antihelix and lobule

greater auricular nerve (C2 C3) (Blue on image)

What nerve supplies concavity of concha and floor of EC?

auricular branch of vegas (CX) (purple on image)

What nerve supplies Tragus, Crus of the helix & adjacent part of helix?

Auriculotemporal nerve (branch of V3) (green on image)

What nerve supplies Auricle in depression of the concha and over its eminence?

facial nerve (C7) (Yellow on image)

What is outer half of external auditory canal made of?

supported by cartilage thin skin with dermal papillae

What nerves innovate EAM?

CN V, CN VII and CN X

What are the neural innervations for Vagus Reflux

Pacinian corpuscles Arnold's branch of vagus Facial nerve Glossopharyngeal

What nerve supplies upper part of cranial surface?

lesser occipital nerve (C2, C3) (orange in image)

What are the neural innervations for Lymphatic reflex

Facial nerve Pacinian corpuscles Meissner's corpuscles Hair follicles

What are the neural innervations for Trigeminal reflex

Pacinian and Meissner's corpuscles Facial sensory and motor neurons

Describe the External Ear canal

2.5 cm length oval or elliptical shape S-shape with 1st bend and 2nd bend cartilaginous outer ~1/2 and boney medial ~1/2, floor inferior wall is longer than ceiling/superior wall due to slant of TM

Why is the fissure of santorini a concern?

provide a potential path for infection or neoplasm to spread between the parotid gland and the external ear canal.

What contributes to the protective function of the ear canal?

it's anatomy (s shape) arrangement of the hairs (slanted laterally) cerumen

Sympathetic and parasympathetic vascularization at TM when pressure applied in outer 1/3 of canal

trigeminal reflex

Sympathetic motor reflex caused by light touch upon the superior-inferior and anterior meatal wall

cause of vegas reflex

May appear to be due to allergies

lymphatic reflex

Evidenced by swelling of tissues and soreness while wearing a custom fitted earmold or hearing aid

lymphatic reflex

A slow reflex which may result from over-wearing of hearing aids during adaptation period

lymphatic reflex

Can cause excessive vascularization and thickening of the TM during otoscopy, otoblock insertion, and during hearing aid wearing

trigeminal reflex

Sometimes called the "red reflex"

trigeminal reflex

Also known as Arnold's reflex or the ear-cough reflex.

vagus reflex

This reflex is evidenced by coughing, gagging, and/or watering of the eyes

vagus reflex

This reflex may be evoked during insertion of an otoblock used in making earmold impressions, cerumen removal, and rarely, with hearing aid use

vagus reflex

What is the auditory function of the outer ear?

sound pressure gain

What acts as a cavity resonator?

concha

What does cerumen contain?

lipids, proteins, free amino acids, and mineral ions

What is resonant frequency based on?

tube length

What is the average gain and resonant peak at TM due to concha? Why are the effects of the concha important?

Important in increasing high-frequency SPL at the TM with an average gain of 10 dB and a resonant peak at 4500 – 5000 Hz acts as a cavity resonator

what is the resonant frequency for an average ear canal?

3500 Hz

The concha resonance blends with the EAM resonance, producing what?

composite curve with two peaks one at 2700 and another at 5000

Outer Ear Review Flashcards

Exam 2 (76 cards)