14 - Ear - Stephens

Question 1

what provides GSA innervation to the pinna?

Answer 1

auricotemporal (V3), lesser occipital (C2-3), greater auricular (C2-3)

Question 2

what can trauma to the pinna cause? what can this lead to?

Answer 2

auricular hematoma, cauliflower ear (failure to evacuate and bandaged)

Question 3

why is a furuncle so painful?

Answer 3

due to it’s close adherence of the skin to the underlying periosteum

Question 4

what is the middle fibrous layer in tympanic membrane?

Answer 4

pars tensa

Question 5

what does the absence of the pars tensa in the antero-superior quadrant form?

Answer 5

pars flaccida

Question 6

what is the innervation of the inner mucous membrane of the tympanic membrane?

Answer 6

GVA of glosspopharyngeal n. via tyrannic plexus

Question 7

what is the name for the central concavity of the tympanic membrane?

Answer 7

umbo

Question 8

what are the v-shaped folds that form the borders of the pars flaccida?

Answer 8

anterior and posterior mallear folds

Question 9

what nerve courses thru the pars flaccida?

Answer 9

chorda tympani n.

Question 10

what is otitis media? why is it more common in infants?

Answer 10

inflammation of the middle ear cavity, may result in accumulation of fluid and mucous and decreased hearing; infants auditory tubes horizontal, adults are downward

Question 11

fractures of the petrous temporal bone can be caused by? what does this result in?

Answer 11

severe head trauma (basilar fxs- transverse or longitudinal fractures of temporal bone); otorrhea, otorrhagia, vestibular disturbances, deafness, or Bell’s palsy

Question 12

what makes the floor of the tympanic cavity?

Answer 12

superior bulb of the internal jugular vein

Question 13

what does a lesion of the greater petrosal n. result in?

Answer 13

absence of lacrimation in the ipsilateral eye

Question 14

what does a lesion of the facial n. cause?

Answer 14

bell’s palsy

Question 15

what does a lesion of the n. to the stapedius m. result in?

Answer 15

hyperacusis

Question 16

what does a lesion of chorda tympani result in?

Answer 16

loss of taste sensation from the ant 2/3 of tongue and decreased salivation from the SM and SL glands

Question 17

what does a lesion of the nerve to the posterior digastric result in?

Answer 17

lower jaw deviating toward normal side when mouth is opened wide

Question 18

what does the footplate of the stapes articulate with?

Answer 18

fenestra vestibuli

Question 19

what is otosclerosis? what does it prevent?

Answer 19

ossification or scarring of small ossicular joints; prevents transmission of sound from tympanic membrane to the fenestra vestibuli—> hearing impairment (bone conduction normal, nerve conduction is reduced)

Question 20

what does the stapedius do?

Answer 20

pulls stapes out of the fenestra vestibuli—> protective mechanism, prevents excessive movement of stapes due to loud sound

Question 21

what provides the sensory innervation to the middle ear? blood supply?

Answer 21

GVA sensory branches of glossopharyngeal n via tympanic plexus; stylomastoid branch of the posterior auricular a. and the anterior tympanic artery

Question 22

where is the inner ear apparatus embedded?

Answer 22

petrous temporal bone

Question 23

what are the functions of the inner ear?

Answer 23

1. cochlear receptors for hearing
2. receptors in the semicircular ducts: detect angular acceleration
3. receptors in the sacculus and utricle: detect linear acceleration

Question 24

where is the cochlea in relation to the facial n.?

Answer 24

anterior

Question 25

what does the cochlear division of CN 8 innervate? convey?

Answer 25

organ of Corti; auditory info

Question 26

what does the vestibular division of CN 8 innervate? conveys?

Answer 26

maculae utricle and saccule and the cristae ampullaris of the semicircular ducts; conveys static and dynamic position-sense info (equilibrium)