Defense & Barriers: Otitis Flashcards
EXTERNAL ear canal…
function?
contains what 3 things?
VERTICAL ear canal?
HORIZONTAL ear canal?
= CONDUCTS AIR VIBRATIONS TO THE TYMPANUM
contains…
1. hair follicles
2. sebaceous glands
3. ceruminous glands (MODIFIED APOCRINE)
VERTICAL ear canal?
= FIRST part of the canal that’s CONTINUOUS WITH THE PINNA
HORIZONTAL ear canal?
= starts after ANNULAR CARTILAGINOUS PROMINENCE
CERUMEN…
secreted by what? (2)
made of what?
2 functions?
what happens if TOO MUCH cerumen (clinical sign & why it happens)?
secreted by…
1. CERUMINOUS glands
2. SEBACEOUS glands
made of SLOUGHED EPITHELIAL CELLS
2 functions?
1. TRAPS debris, parasites & microorganisms (immune)
2. PROTECTS TYMPANUM from DESSICATION
if TOO MUCH CERUMEN = NUTRIENT-RICH MEDIUM FOR MICROORGANISMS, prone to CHRONIC EAR INFECTIONS
label…
white arrow?
blue arrow?
yellow arrow?
WHAT STRUCTURES ARE THESE (1 main, 1 other)?
white arrow = PARS FLACCIDA
blue arrow = PARS TENSA
yellow arrow = STRIA MALLEARIS
TYMPANIC MEMBRANE & STRIA
TYMPANIC MEMBRANE…
what landmark should we look for?
2 portions, their functions, appearance, what happens if one is damaged? (2 for each)
landmark = TUFT OF HAIR?
2 portions…
1. PARS FLACCIDA = DORSAL portion
–> VARIABLY prominent depending on PRESSURE IN MIDDLE EAR CAVITY
–> FLATTER in cats
- PARS TENSA = “EAR DRUM”
–> TRANSLUCENT, GRAY MEMBRANE that TRANSMITS SOUND WAVES
–> if it RUPTURES –> CHRONIC OTITIS –> FIBROSIS –> LOOKS MORE OPAQUE
STRIA MALLEARIS…
= what/where is it?
where is the TIP of the bone pointing?
= C-SHAPED BONE located on the MEDIAL PART of TYMPANIC MEMBRANE that ATTACHES IT TO THE MANUBRIUM/HANDLE OF THE MALLEUS (acoustic ossicles)
TIP points to the NOSE (rostral)
A = ??
B = ?? (pathologic)
A = normal pars TENSA (ear drum)
B = BULGING pars FLACCIDA
what structure is this?
NORMAL TYMPANIC MEMBRANE
MIDDLE EAR CAVITY…
alternative name?
lined by what?
DORSAL portion?
–> contains what 3 things?
MIDDLE portion?
–> location?
–> what main structure is here?
VENTRAL portion?
–> name?
–> function?
–> unique feature in cats?
what TUBE is present/what does it CONNECT?
alternative name = TYMPANIC cavity
lined by RESPIRATORY EPITHELIUM
DORSAL portion?
–> contains ACOUSTIC OSSICLES (malleus, incus, stapes) & TYMPANIC NERVE
MIDDLE portion?
–> located ADJACENT TO TYMPANIC MEMBRANE
–> contains PROMONTORY (bony shelf) = opposite mid dorsal aspect of TYMPANIC MEMBRANE, and its CAUDAL END is called the ROUND WINDOW
VENTRAL portion?
–> called BULLA (largest bone)
–> function = acts as SINK for STERILE EFFUSION/INFECTION in middle ear cavity
–> in CATS = tympanic bulla SEPARATED BY BONY SEPTUM
AUDITORY/EUSTACHIAN TUBE connects the NASOPHARYNX to the MIDDLE EAR CAVITY
what should we AVOID when rupturing tympanic membrane? where is it located?
AVOID the ROUND WINDOW
located at the CAUDAL END of the PROMONTORY in the MIDDLE EAR CAVITY
which part of the middle ear cavity is the LARGEST?
VENTRAL portion, BULLA
INNER ear…
contains what TYPE of structures?
3 main structures present?
relation to middle ear infection (& alternative name)?
adverse effect of a medication?
contains NEUROLOGIC structures
3 main?
1. COCHLEA = HEARING apparatus, looks like spiral
2. VESTIBULE & SEMI-CIRCULAR CANALS = BALANCE apparatus
3. VESTIBULOCOCHLEAR NERVE (CN VIII)
if OTITIS MEDIA, then can lead to INNER EAR INFECTION
can have INNER EAR damage from OTOTOXIC MEDICATIONS, causing BALANCE/HEARING issues
PRIMARY causes of otitis…
= definition
overall DDXs? (5, 3 sub)
= occurs when something DIRECTLY INITIATES INFLAMMATION & cause alterations in MICROENVIRONMENT/SECONDARY INFECTIONS
DDxs?
1. ectoparasites
2. obstructions (foreign bodies, polyps, tumors)
3. allergic dermatitis
4. autoimmune disease
5. cornification disorders
4 ECTOPARASITES that can cause OTITIS?
- OTODECTES CYNOTIS = ear mite, MOST COMMON CAUSE OF OTOTITIS EXTERNA in cats, ESPECIALLY YOUNG CATS/CATS IN SHELTERS
- DEMODEX (demodicosis)
- OTOBIUS MEGNINI = SPINOUS EAR TICK, found in WESTERN US
- CHIGGERS = BRIGHT RED & usually found around PINNA
ALLERGIC DERMATITIS in EAR CANAL…
= what is it/what species is it most common in?
what can cause it?
what 3 signs would indicate it (irritant contact dermatitis)?
2 examples of medications that cause this? (one of the medications is found in what?)
= ALLERGIC SKIN DISEASE that’s the MOST COMMON CAUSE OF OTITIS EXTERNA in DOGS
what can cause it?
can be caused by anything that can CONTACT SURFACE or INSIDE of ear
irritant contact dermatitis?
1. starts AFTER starting APPROPRIATE (based on C&S) therapy
2. cytology shows INCREASED INFLAMMATORY cells
3. see SCALING/BURNS on CONCAVE ASPECT OF PINNA
medications?
1. NEOMYCIN
2. PROPYLENE GLYCOL is an INACTIVE INGREDIENT found in OTIC MEDICATIONS
identify
ALLERGIC DERMATITIS