3 - ENT - Otology - Anatomy

Question 1

2 main structures of outer ear

4 main structures of middle ear

Answer 1

outer - auricle (pinna), EAM

middle - TM, Occicles, openings, round window

Question 2

inner ear - consists of? lined with? filled with?

forming the 3 parts of inner ear?

Answer 2

consists of bony labyrinth, line with periosteum, filled with perilymph

forming - semicircular canals, vesticule, cochlear

Question 3

What is suspended within the inner ear structures? - filled with? - 4 parts of this?

Answer 3

membranous labyrinth - filled with endolymph

semicircular ducts, utricle, saccule, cochlear duct

Question 4

what is the cochlear ?

- innervation?

Answer 4

organ of hearing

cochlear branch of VIII - enters through internal acoustic meatus

Question 5

when does the stiffness of the cochlear change? what does this mean?

Answer 5

decreases towards centre

high freq heard best at outer portions and low freq heard best centrally

Question 6

briefly describe how the cochlear works

Answer 6

sound transduced through cochlear duct fluid > causes shearing of tectorial membrane > bending of stereocilia on outer/inner hair cells > AP generated

Question 7

what if sounds are too loud

Answer 7

tensor tympani muscle contracts (attached to malleus)

+/or stapedius muscle (attached to stapes) dampens vibration

Question 8

what are the organs of balance and movement - what do they judge

Answer 8

semicircular ducts - movement in any direction
utricle - centrifugal and vertical acceleration
saccule - linear acceleration