HEENT notes review prior to first quiz

[liveonearth]

ANATOMY AND FUNCTION OF OUTER, MIDDLE AND INNER EAR

outer ear:
funnels sound into external auditory canal
protects TM, secretes cerumen

middle ear:
behind the TM the ossicles mechanically transmit sound to inner ear
TM-->malleus, incus, stapes-->round window
air filled cavity in temporal bone connecting to nasopharynx via Eustachian tube

inner ear:
cochlea: senses sound via hairs (organ of Corti) from pulsations in the endolymph (fluid)
semicircular canals: for balance
between those two: the vestibule, incl the utricle and saccule, for balance

STRUCTURE AND FUNCTION OF LABYRINTH, STRIA VASCULARIS AND ORGAN OF CORTI

labyrinth:
functions in hearing and balance
bony/osseous labyrinth is lined with the membranous labyrinth
layer of perilymph fluid between them
three parts of bony: vestibule of the ear, the semicircular canals, and the cochlea

stria vascularis:
in the upper portion of the spiral ligament (where periosteum connects to outer ductus cochlearis)
capillary loops and small blood vessels
produces endolymph for the scala media (1 or 3 compartments of cochlea)
pseudostratified columnar vascularized epithelium with melanocytes
helps maintain the high potassium concentration of the endolymph

organ of corti:
contains specialized hair-like receptors that respond to fluid-borne vibrations in the cochlea
shear on the hairs opens ion channels-->neural action potentials to auditory cortex

DDX OF EAR PAIN
dermatitis (seborrheic/contact/atopic), lichen simplex chronicus, cellulitis, erysipelas
trauma to jaw, ear, neck, teeth, surgical trauma
TM rupture or damage
barosinusitis
barotitis
infection
abscess of tonsils, gingiva, mastoid
local furuncle
ethmoid sinusitis
ethmoid sinusitis
myringitis
OM, chronic or acute
acoustic neuritis/neuronitis
bullous myringitis
Otitis, chronic external
carcinoma in the region
infx chondritis, relapsing polychondritis (AI)
thyroiditis, granulomatous, subacute
foreign body, ear
impacted cerumen
migraine headaches/syndrome
trigeminal nerve lesion (5th)
cholesteatoma, middle ear
TMJ arthritis/synovitis
lots more variants

OSTEOMA
bony growth in ear canal
usudt cold water exposure

ASOM VS OME
hx: ? vs swim, qtip, dermatitis
PE: red & bulging TM vs swollen canal
tympanometry: positive pressure (flat line) vs normal midline peak

OTITIS EXTERNA
risks: alkaline ph, incr temp and humid, trauma (qtips)
hx: swim, traum, dermatitis, qtips
sx: ear canal inflamed, tender, mb tender to throat, canal mb blocked, v painful

MALIGNANT OTITIS EXTERNA
rare but dangerous, only in immunocompromised esp DM, alc, malnourish
slow moving, invasion of cartilage
sx: pain, purulent discharge, lacks fever and swelling
loc: usu where canal enters temporal bone, see granulation tissue
etio: usu p.aeruginosa
complic: osteomyelitis, hearing loss, facial nerve paralysis, death
pe: test facial nerve fx
tx: refer to ENT!

OTITIS MEDIA = ASOM
etio: usudt URI
incidence: mc in kids under 10
sx: usu begins as blockage sensation, hearing loss, then fever, pain worse at night, insomnia, irritability, anorexia
pe: rectal temp over 100.4, oral over 99.5
pe: TM: bulging, red, loss of landmarks, light reflex distorted
pe: fever, LAD

OTIC BAROTRAUMA
inflam of middle ear dt pressure
risk: poor eustacian tube fx
etio: air travel, scuba diving
sx: pain, fullness, worse yawning, hearing loss, dizziness
TM: may perforate, round window membrane can rupture