Functional Anatomy An Disorders Of The Ear

Question 1

Which nerves carry general sensation from the ear

Answer 1

• Branches of
• cervical spinal nerves (C2/C3)
• vagus
• trigeminal (auriculotemporal n.)
• glossopharyngeal (tympanic n.) (the internal surface of the tympanic membrane and middle ear cavity is supplied by the glossopharyngeal nerve (CNIX)
• small contribution from CN VII

Question 2

What does otalgia with a normal ear suggest

Answer 2

The overlapping sensory innervation of the ear with other parts of the body can lead to misdiagnosis in patients suffering from otalgia.
(there are many non-ontological causes for otalgia).
If ear aim and ear is normal - is it referred pain from something that shares the same innervation. Eg lerynx and pharynx - sensory rom vagus.

Question 3

What comprises the inner ear and what is its role

Answer 3

The External Ear: pinna, external auditory meatus and lateral surface of tympanic membrane
Collects, transmits and focuses sound waves onto the tympanic membrane

Question 4

What is Ramsay hunt syndrome

Answer 4

If someone has a facial palsy check early - rare condition called Ramsay hunt syndrome - shingles affecting the canal nerve. Facial nerve has sensory ganglion (genuiculate) - dormancy viruses in ganglion ca cause shingles. Facial nerve does carry some gs from ear 0 can see shingles in ear in Ramsay haunt

Question 5

What is a pinna haematoma and what are the consequences

Answer 5

Accumulation of blood between cartilage and its overlying
• Secondary to blunt injury to the pinna
• Common in contact sports
Cartilage is avascular - it is stuck up against perichondrium to be blood supply.. in haematoma, blood collects between cartilage and perichondrium covering. Deprives cartilage of blood supply. Pressure of haematoma.
• Subperichondrial haematoma deprives cartilage of its blood supply + pressure necrosis of tissue
• Prompt drainage & measures to prevent re- accumulation/re-apposition of two layers - eg a dressing that ensures there is pressure keeping perichondrium on cartilage
• Untreated leads to fibrosis and new asymmetrical cartilage development -> cauliflower deformity

Question 6

Describe the external acoustic meatus

Answer 6

• Lined with keratinising, stratified squamous epithelium continuous onto lateral surface of tympanic membrane
• Cartilaginous (outer 1/3) and bony (inner 2/3) - bony less mobile
• Sigmoid shape
• Hair, sebaceous and ceruminous glands line cartilage part: barrier to foreign objects
• Ceruminous glands produce ear wax • Bony part lacks these glands and hairs
• Desquamation and skin migration out of canal
Epithelium shed - moved along by escalator to outperform, mixed with wax

Question 7

What are some common conditions involving the EAM

Answer 7

See slide

Question 8

Describe the middle ear

Answer 8

Air Filled Cavity Between Tympanic Membrane and Inner Ear Containing Ossicles
• Ossicles connected via synovial joints
• Amplify and relay vibrations from the
tympanic membrane to the oval window of the cochlea (inner ear)
• Transmitting vibration to waves in a fluid- medium
•movement is tampered by 2 muscles tensor tympani and stapedius
• Muscles contract if potentially excessive vibration due to loud noise (protective; acoustic reflex)

Question 9

What are the ossicles

Answer 9

Malleus - sitting against tympanic membrane. Malleus vibrates - causes incus to vibrate - abuse stapes to vibrate. Transmit airwaves at tympanic membrane - to fluid in inner ear. Ossicles amplify the vibration as they relay it from tympanic membrane to the oval window. Stapedius tampers this

Question 10

What is otosclerosis

Answer 10

One of most common causes of Acquired Hearing Loss in Young Adults
• Both genetic and environmental causes
• Exact cause unknown (?viral ?hereditary triggers?)
• Ossicles fused at articulations due to abnormal bone growth particular between base plate of stapes and oval window
Sound vibrations cannot be transmitted effectively to cochlear
• Present with gradual unilateral or bilateral conductive hearing loss
Bony growth usually between stapes and oval window - fusion - transmission of vibrations is impeded

Question 11

What is the pharyngotumpanic tube

Answer 11

Mucous membrane of middle ear continuously reabsorbs air in middle ear causing negative pressure - builds up 
Pharyngotympanic tube (Eustachian Tube) allows equilibration of pressure within middle ear cavity with that of the atmosphere. It also allows for ventilation of and drainage of mucus from the middle ear

Question 12

What is a cholesteatoma

Answer 12

Sac of Trapped Epithelial Cells that Proliferate and Erode
• Rare, but should not be missed!
• Retraction of an area of pars flaccida (TM) forms a sac/pocket
Pulls part of TM up into middle ear cavity - epithelial cells get trapped and start to proliferate
• Trapping epithelial cells
• Proliferate forming cholestatoma
• Usually secondary to chronic Eustachian Tube (ET) dysfunction
• negative pressures pull the pocke into middle ear
• Painless, often smelly otorrhea (ear discharge) +/- hearing loss
• Not malignant but slowly grows and expands
– Potentially more serious consequences due to enzymatic bony
destruction e.g. erode ossciles, mastoid/petrous bone, cochlea

Question 13

What is glue ear

Answer 13

Otitis media with effusion (glue ear)
– Not an actual infection
– Build up of fluid and negative pressure in middle ear - transudate
– Due to Eustachian tube dysfunction: can predispose to infection
– Decreases mobility of TM and ossicles (cant vibrate as well)-> affecting hearing
– Most resolve spontaneously in 2-3 months.. but some may persist
• Require grommets (tympanostomy tube) to maintain equilibration of
pressures - equilibriate s pressure - ales sure there is not increasingly negative pressure

Question 14

What is acute otitis media

Answer 14

• Acute Otitis media
– Acute middle ear infection
– More common in infants/ children than in adults
• Signs and symptoms include
– Otalgia (infants may pull or tug at the ear)
– Other non-specific symptoms e.g. temperature
– Red +/- bulging TM and loss of normal landmarks
Haemophilus influenzae, strep pneumoniae Haemophilus influenzae, staph aureus, pseudomonas a - common amuses

Question 15

Why are fangs more likely to get acute otitis media

Answer 15

Pharyngotympanic tube is shorter and more horizontal in infants
In infants therefore:
• Easier passage for infection from the nasopharynx to the middle ear
• Tube can block more easily, compromising ventilation and drainage of middle ear, increasing risk of middle ear infection

Question 16

What are the complications of acute otitis media

Answer 16

• Tympanic membrane perforation
• Facial nerve involvement
• Rarer but potentially life-threatening complications include
– Mastoiditis
– Intracranial complications
• Meningitis 
• Sigmoid sinus thrombosis 
• Brain abscess

Question 17

What is mastoiditis

Answer 17

Middle ear cavity communicates via mastoid antrum with mastoid air cells. Provides a potential route for middle ear infections to spread into the mastoid bone (mastoid air cells)
Intravenous antibiotics. May have to clear out air cells. Osteomyelitis of mastoid bone

Question 18

Decsribe teh relationship between the facial nerve nd middle ear

Answer 18

Ss

Question 19

Decsribe teh innear ear

Answer 19

Vestibular apparatus (semicircular canals) and cochlea: fluid filled tubes
The cochlea converts vibration into an electrical signal (action potential) which is perceived as sound The vestibular apparatus is involved in maintaining our sense of position and balance
Semicircular canals joined to cochlear all one lucid filled canal  - stuff transmitted as movement of fluid

Question 20

What is the cochlea

Answer 20

`Fluid-filled tube with specialized hair cells that generate action potentials when moved
The cochlea is the organ of hearing. It is fluid filled tube. Movements at the oval window set up movements of the fluid in the cochlea. Waves of fluid cause movement of special sensory cells (stereocilia) within the cochlear duct which generate action potentials in CN VIII

Question 21

Give an overviews of how hearing occurs

Answer 21

Auricle and external auditory canal focuses and funnels sound waves towards tympanic membrane which vibrates
Vibration of the ossicles (stapes at the oval window) sets up vibrations/movement in cochlear fluid
Sensed by stereocilia (nerve cells) in the cochlear duct (part called the spiral organ of Corti)
Movement of the stereocilia in organ of Corti trigger action potentials in cochlear part of CN VIII
Primary auditory cortex (make sense of the input)

Question 22

Describe the vestibular apparatus

Answer 22

Fluid-filled tubes with specialized hair cells that generate action potentials when moved
Vestibular apparatus includes the semicircular ducts, the saccule and utricle: these are a fluid-filled tubes sacs containing stereocilia
Fluid movements due to moving position or rotation of head (Semicircular canals in 3 planes - fluid move depending on how head is tilted ), bends stereocilia which generate action potentials via CN VIII -> brain
Perceive and maintain our sense of balance

Question 23

What is labrynthistis

Answer 23

Inflammatory condition affecting the labyrinth in the cochlea and vestibular system of the inner ear.

Viral infections are the most common cause of labyrinthitis. Bacterial labyrinthitis is a complication of otitis media or meningitis.

Typical presentation includes vertigo, imbalance, and hearing loss.

Diagnosis is supported by history, physical examination, and audiometry.

Treatment is typically symptomatic and primarily involves the use of vestibular suppressants and anti-emetics.

Question 24

What is Menieres disease

Answer 24

Episodic auditory and vestibular disease characterised by sudden onset of vertigo, hearing loss, tinnitus, and sensation of fullness in the affected ear. Earlier in the disease process, all symptoms may not be present.

The cause is unknown, but results in an over-production or impaired absorption of endolymph in the inner ear.

Diagnosis is made on clinical history and detailed audiological tests; other investigations may be required to exclude other causes.

Dietary changes and diuretics may control symptoms in early stages of the disease; specific medical therapies for vertigo control can be tried if required.

If symptoms persist despite maximal medical therapy, several surgical interventions are available.

Question 25

Wha this bppv

Answer 25

-Common, often self-limiting condition, but can be chronic and relapsing.

Diagnosis is based on a suggestive history and physical examination with a positive Dix-Hallpike manoeuvre or a positive supine lateral head turn. Other tests are not usually required.

Medication is not an effective treatment option.

Repositioning manoeuvres are highly efficacious in resolving an episode of BPPV.

Surgery is highly effective but is reserved for intractable and severe cases.

Question 26

What happens when a patient presents with wearing lsos

Answer 26

History • Examination
– Inspection and palpation of external ear
– Otoscopy • Gross hearing assessment (whispering a word or
number and patient repeating back while masking the ear not being tested)
• Tuning forks tests (512 Hz)
• Weber’s and Rinne’s test
• Referral for more formal audiometry testing

Question 27

What is Weber and Rennes testing

Answer 27

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