W8: Inner Ear, Outer and Middle Ear Flashcards
Describe the epithelial lining of the external ear canal and middle ear.
The middle ear will show non-keratinized stratified squamous epithelium.
The external auditory canal also has keratinized stratified squamous epithelium that covers the external tympanic membrane as well.
Describe the structure of the tympanic membrane.
PARS TENSA = drumskin, translate sound waves
LATERAL/HANDLE OF MALLEUS
PARS FLACCIDA = maintain pressure
CONE of LIGHT = reflection of light dependent on angle of TMembrane
* distortions in the cone of light can also be a sign of increased middle ear pressure or otitis media.
Discuss the importance of the Eustachian tube in middle ear function.
aerates the middle ear system and clears mucus from the middle ear into the nasopharynx
Describe the inter-connection of the middle ear, mastoid air cell system and post nasal space
The mastoid antrum communicates with the middle ear via the aditus to mastoid antrum.
The mastoid air cells act as a ‘buffer system‘ of air – releasing air into the tympanic cavity when the pressure is too low.
Describe the inter-connection of the middle ear, mastoid air cell system and post nasal space
The mastoid antrum communicates with the middle ear via the aditus to mastoid antrum.
The mastoid air cells act as a ‘buffer system‘ of air – releasing air into the tympanic cavity when the pressure is too low.
*allows communication of mucus and air/pressure into the nasopharynx
Describe the course of the facial nerve in the middle ear cavity and its importance to the surgeon.
The motor and sensory roots of the facial nerve (pons) travels in close proximity to the inner ear and through the internal acoustic meatus. Progresses to the facial canal.
*gives off stapedius nerve
=> will progress to the distal branches of the facial nerve: significant sens and motor innervation
Middle ear bones
AUDITORY OSSICLES:
MALLEUS + head: articulates with incus and transmits oscillations produced from sounds
INCUS:
STAPES: (smallest bone): articulates with INCUS and the OVAL WINDOW
Describe the basic principles of pure tone audiometry and tympanometry.
PURE TONE = conduction thus subjective
TYMPANOMETRY = middle ear assessment and objective by assessment of pressure
standard clinical test for BPPV
Dix-Hallpike maneuver
= rotatory nystagmus with latency and limited duration is considered pathognomonic
BPPV aetiology and management
- calcium crystal dislodged from urticle = to posterior semilunar canal = supercharged AP = NYSTAGMUS
- FLEETING, triggered by postural changes
> EPLEY MANOUEVRE = crystals move back
Vestibular neuritis
Acute onset and LONGER than BPPV; N/V
- viral aetiology
- hearing loss RARE = mumps, measles
> nervous system will compensate over a few weeks
Bell’s Palsy
CN VII: compression, irritation = dysfunction
= facial paralysis
* loss of forehead wrinkles and nasolabial fold = IPSILATERAL NATURE
often idiopathic or HSV or herpes zoster
> 3-4mos recovery
ensure eye hydration
corticosteroids
?acyclovir
Adult: Otitis Ext
pain, discharge, h. loss
- ext. meatus inflamm
- pseudomonas; granulation, pain+++, +/- CN palsies
> topical
abx/steroid eardrops +/- suction eardrop
can progress to malignant = TEMPORAL OSTEOMYELITIS
*elderly, DM picture
> ciprofloxacin
Signfiicance of foreign bodies in ears for adults
URGENCY SCALE:
button size/ battery > organic > inorganic
Significance of cauliflower ear
Auricular Haematoma d/t trauma resulting in necrosis of cartilage
> incision and drainage
?abx
