Lecture 12 (EARS)

Question 1

cranial nerves involved in hearing

Answer 1

5 (trigeminal) - tensor tympani
7 (facial) - stapedius muscle
8 (vestibulocochlear) - hearing and balance
10 (vagus) - sensory to auditory canal

Question 2

external ear anatomy

Answer 2

• aurical
• external auditory canal
• tympanic membrane (ear drum) seperates external and middle

Question 3

middle ear anatomy

Answer 3

• Tympanic cavity
  Ossicles:
• malleus (connects to tensor tympani)
• incus
• stapes (connects to stapedius)

Question 4

inner ear

Answer 4

• oval window (behind stapes)
• vestibular and tympanic canals t w/ parilymph fluid
• cochlear duct w/ endolymph fluid
• tectorial membrane (covers organ of corti)
• organ of corti (consists of hair and supporting cells, transmits info to CNVIII)
• round window

Question 5

purpose of inner ear muscles

Answer 5

tensor tympani - dampens ossicle movement when chewing
stepedius - dampens ossicle movement during loud sounds

Question 6

upper respiratory tract infection can cause

Answer 6

build up of pressure in auditory tube, can lead to rupture of ear drum, infection into mastoid air cells (matoiditis), erosion of temporal bone (meningitis)

Question 7

location of frequencies

Answer 7

closer to oval window is higher

Question 8

auditory neural pathway

Answer 8

Medulla - synapses in cochlear nuclei then crosses over
Pons - lateral leminiscus (acoustic startle reflex)
Midbrain - inferior colliculis and thalamus
Cortex - auditory

Question 9

types of deafness

Answer 9

conduction - wax buildup, rupture eardrum, damaged ossicles
sensory - inner ear or CNVIII

Question 10

vestibular apparatus anatomy

Answer 10

Semicircular ducts (all at right angles):
- anterior (sagittal)
- lateral (transverse)
- posterior (coronal)
Utricle (horizontal acceleration)
Saccule (vertical acceleration)
*filled with endolymph