Exam Flashcards
Layers of TM
- epidermal layer
- lamina propria
- muscosal layer
Four quadrants of TM
- antero-superior
- posters-superior
- antero-inferior
- posters-superior
Thickened ring around TM
-annulus
Hearing loss as little as ? Can have a significant impact on speech and language development
15 db hl
Main resonant frequency of outer ear
2.5khz
What is impedance matching?
Sound waves travelling through a different elasticity and density will reflect off
Middle ear impedance matching methods
- buckling of the TM
- the lever ratio of the ossicles
- area ratio of the TM to oval window
Two middle ear muscles
Tensor tympani - contracts prior to volcalisation (innervated by trigeminal)
Stapedius tendon - contracts in response to loud sounds (stapedial branch of facial nerve)
Where is endolymph created
Stria vascularis
Masking goes to over ear on supra aural headphones
-40db hl
Masking leak of interaural
60db at or below 1khz
50 bd above 1khz
Acute otitis media
Red ear Middle ear fluid Suppurations infection Sudden onset, fever, bulging of TM resolves in 30 days
Chronic suppurations otitis media
Runny ear
Discharge from ear through TM perforation for more than 6 weeks
Antibiotics and surgery
TM buckling
The curvature of the TM buckles means that the point of the TM to which the umbo is attached to moves less than the rest of the TM, increasing the force
Lever ratio
The long crus of the incus is 1.3 times shorter than the manubrium of the malleus, causing a corresponding increase in force
