Lecture 11-Ear Flashcards by Vibha Shaji

What are the possible signs and symptoms of ear disease?

otalgia (ear pain)
discharge
hearing loss
tinnitus
vertigo
facial nerve palsy

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What makes up the external ear?

Pinna, external auditory meatus and lateral surface of tympanic membrane

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What is the purpose of the external ear?

Focuses sound waves onto tympanic membrane

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What can the pinna also be called?

Auricle

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What is the pinna made of?

Skin, cartilage and fatty tissue

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What is Ramsey-Hunt syndrome?

Shingles of the facial nerve (reactivation of varicella zoster virus within the geniculate ganglion) -> ipsilateral facial weakness and vesicles in pinna and ear canal

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What is a pinna haematoma usually secondary to?

Blunt injury eg contact sports

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What is a pinna haematoma?

Blood accumulates between cartilage and perichondrium which deprives the cartilage of its blood supply -> pressure necrosis of the tissue

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What happens if a pinna haematoma is left untreated?

Fibrosis and new asymmetrical cartilage forms = cauliflower deformity of the ear

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What is the external acoustic meatus (EAM) lined with?

Skin

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What is the shape of the EAM and what implication does this have when trying to examine the ear?

Sigmoid

Need to pull ear back and up to straighten

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What are the two parts of the EAM?

Outer 1/3 = cartilage

Inner 2/3 = bone

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What is present in the cartilaginous part of the EAM and why?

Hairs and wax to prevent objects entering deeper

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How long is the EAM?

2.5 cm long

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What is otitis externa?

Inflammation of EAM caused by infection

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What is otitis externa also called?

Swimmer’s ear

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What makes up the middle ear?

Ossicles and air filled cavity

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What are the three ossicles and what is their function?

Malleus, incus and stapes

- Amplifies vibration from tympanic membrane to cochlea via oval window

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True or false: the ossicles are connected via synovial joints

TRUE

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Which two muscles tamper the movement of the ossicles and why?

Tensor tympani and stapedius

- If there is excessive vibration due to loud noise, these muscles contract = acoustic reflex

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What is hyperacousis?

Sensitivity to noise

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What is otosclerosis?

Fusion at the articulations of the ossicles, especially in between the stapes and oval window. Sound vibrations can no longer be transmitted and this can cause deafness

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What is the function of Eustachian/pharyngotympanic tube?

Equilibrates pressure of the middle ear with atmospheric pressure

What leads to a negative pressure in the middle ear?

Mucous membrane of the middle ear continuously reabsorbs air

What is otitis media with effusion also called and what is it?

- glue ear | - build up of fluid and negative pressure in the middle ear, not due to infection

What can glue ear lead to?

Decreased motility of the tympanic membrane and ossicles which can affect hearing

How can a persisting glue ear be treated?

Grommets to ventilate the middle ear and equilibrate pressure

What is acute otitis media?

Acute middle ear infection

What are the symptoms of acute otitis media?

Otalgia High temperature Red, bulging tympanic membrane

Why is acute otitis media more common in infants?

Their Eustachian tube is shorter and more horizontal so easier passage for infection

What are the complications of acute otitis media?

- tympanic membrane perforation | - mastoiditis, meningitis, brain abscess, sigmoid sinus thrombosis but these are rare

What is mastoiditis?

Middle ear cavity communicates with mastoid air cells via mastoid antrum which is a potential route for infection to spread to the mastoid bone -> red, swollen ear which is turned forward

What is cholesteatoma?

Abnormal skin growth in middle ear, can erode through and damage ossicles, mastoid and cochlea

What are the symptoms of cholesteatoma?

- painless, smelly otorrhoea | - hearing loss

Why is the eardrum sucked inwards in cholesteatoma?

Negative pressure

What forms the inner ear?

Vestibular apparatus and cochlea (fluid filled tubes)

What does the cochlea do?

Converts vibrations to action potentials which are perceived as sound

What does the vestibular apparatus do?

Maintain sense of position and balance

How is an action potential generated in the cochlea?

Movements at the oval window set up movements of fluid in the cochlea and waves of fluid causes movement of stereocilia (special sensory cells) in the cochlear duct which generates an action potential in CN VIII

What is included in the vestibular apparatus?

Semicircular ducts, saccule and utricle

What is Meniere’s disease?

Too much fluid in the cochlear duct -> vertigo, tinnitus and hearing loss

What is benign paroxysmal positional vertigo?

Crystals form in fluid and every time the head moves, crystal dislodges and moves so fluid moves -> stereocilia move -> sensation of movement

What is labrynthitis?

Inner ear infection -> vertigo, hearing loss, feeling or being sick

Describe how we hear

Auricle and external auditory canal focuses sound waves towards the tympanic membrane which vibrates -> vibration of ossicles (stapes at oval window) sets up vibrations in cochlear fluid -> sensed by stereocilia in the spiral organ of Corti in the cochlear duct -> movement of stereocilia in the organ of Corti triggers an action potential in the cochlear part of CN VIII -> primary auditory cortex in temporal lobe

What do the Rinne’s and Weber’s tests differentiate between?

Conductive and sensorineural hearing loss

How do you perform a Weber’s test?

Tap tuning fork and put it on the head and ask if the sound is different in each ear Normally, it should sound the same on each side

How do you perform a Rinne’s test?

Ring the tuning fork over the mastoid process of each ear and then in front of the ear and ask whether it’s loudest on the bone or in front of the ear Normally, it should be louder in front of the ear because air conduction is better than bone conduction

Describe the results of a Rinne’s and Weber’s test in someone with sensorineural hearing loss

Rinne’s: air conduction > bone | Weber’s: louder in normal ear

Describe the results of a Rinne’s and Weber’s test in someone with conductive hearing loss

Rinne’s: bone conduction > air | Weber’s: louder in affected ear

State some conditions which cause conductive hearing loss

Conditions involving external/middle ear: otitis media, glue ear, otosclerosis

State some conditions which cause sensorineural hearing loss

Conditions involving the inner ear or CN VIII: presbyacusis, Meniere’s, acoustic neuroma

Which nerve innervates the lower 2/3 of the ear, both anteriorly and posteriorly?

Greater auricular nerve (branch of cervical plexus)

Which nerve innervates a small portion of the helix?

Lesser occipital nerve

Which nerve innervates the concha and most of the area around the auditory meatus?

Auricular branch of vagus nerve

Which nerve innervates the anterosuperior and anteromedial aspects of the auricle?

Auriculotemproal nerve (branhc of CN Vc)