Ear

Question 1

what are the contents of the external ear?

Answer 1

auricle
external auditory meatus
external surface of tympanic membrane

Question 2

what are the contents of the middle ear?

Answer 2

internal surface of tympanic membrane
tympanic cavity
ossicles
pharyngotympanic (eustacian) tube

Question 3

what are the contents of the inner ear?

Answer 3

auditory and vestibular apparatus
internal auditory meatus
vestibulocochlear nerve (CN VIII)
oval and round windows

Question 4

what type of cartilage forms the auricle?

Answer 4

elastic cartilage

Question 5

what provides lymphatic drainage of the auricle?

Answer 5

parotid and cervical nodes

Question 6

what gives arterial supply to the auricle?

Answer 6

posterior auricular
anterior auricular
superficial temporal
…and their perforating branches (all from ECA)

Question 7

what innervates the auricle of the ear?

Answer 7

CN VII, IX and X (facial, vestibulocochlear or vagus)
auriculotemporal (CN V3)
lesser occiptal and great auricular (from cervical plexus)

Question 8

what forms the lateral 1/3rd and medial 2/3rds of the external auditory meatus?

Answer 8

lateral 1/3rd: elastic cartilage, hair follicles, sweat and sebaceous glands
medial 2/3rds: bone lined with stratified squamous epithelium

Question 9

what innervates and gives arterial supply to the external auditory meatus?

Answer 9

blood: auricular branches of ECA
innervation: auriculo-temporal (CN V3), auricular branches form CN VIII and X

Question 10

what shape and size is the tympanic membrane?

Answer 10

roughly circular

8mm diameter

Question 11

what lines the medial and lateral layers of the tympanic membrane?

Answer 11

medial: mucous membrane
lateral: stratified squamous

Question 12

what runs across the medial surface of the tympanic membrane and what attaches to it?

Answer 12

across: chorda tympani
attaches: malleus

Question 13

what innervates the lateral and medial surfaces of the tympanic membrane?

Answer 13

lateral: auriculotemporal (CN V3) and auricular branch of CN X
medial: tympanic branches of CN IX

Question 14

what muscles are present in the tympanic cavity of the middle ear and what is their combined function?

Answer 14

tensor tympani and stapedius

reduce vibration passing to inner ear

Question 15

where is tensor tympani and what is it’s function?

Answer 15

wall of auditory tube –> handle of malleus

function: tense tympanic membrane

Question 16

what innervates tensor tympani?

Answer 16

CN V3

Question 17

where is stapedius and what is it’s function?

Answer 17

pyramid of middle ear –> neck of stapes

pull ‘footplate’ of stapes laterally

Question 18

what innervates stapedius?

Answer 18

CN VII

Question 19

what gives sensory supply to the tympanic cavity (incl. medial surface of tympanic membrane)?

Answer 19

CN IX

Question 20

what supplies blood to the tympanic cavity?

Answer 20

tympanic branches of posterior auricular, ascending pharyngeal and maxillary arteries

Question 21

what is the route of the chorda tympani?

Answer 21

crosses medial surface of tympanic membrane and handle of malleus
exits tympanic cavity via petrotympanic fissure
joins lingual nerve

Question 22

what does the chorda tympani supply?

Answer 22

parasympathetic: sublingual and submandibular salivary glands
taste: anterior 2/3rds tongue

Question 23

what does the pharyngotympanic tube connect?

Answer 23

nasopharynx and tympanic cavity

Question 24

what is the pharyngotympanic tube formed of and lined with?

Answer 24

lateral (1.2cm): bony canal lined with mucosa

medial (2.5cm): cartilaginous and membranous

Question 25

the auditory tube is normally closed but the contraction of what muscle causes the lumen to open?

Answer 25

tensor veli palatini (i.e. when swallowing, yawning etc.)

Question 26

what is the role of the pharyngotympanic tube?

Answer 26

equalising pressure on both sides of the tympanic membrane

Question 27

what innervates the pharyngotympanic tube?

Answer 27

sensory from CN IX

Question 28

what supplies blood to the middle ear?

Answer 28

``` anterior tympanic (glaserian) artery from 1st part of maxillary artery also from ascending pharyngeal (inferior tympanic), middle meningeal (superior tympanic), posterior auricular (stylomastoid, posterior tympanic), artery of the pterygoid canal and caroticotympanic branch of the ICA ```

Question 29

what is the role of perilymph and endolymph?

Answer 29

conduct sound vibration and respond to mechanical forces (movement and acceleration)

Question 30

what is found in the bony labyrinth and what is it?

Answer 30

contains cochlea, vestibule and semicircular canals | system of canals filled with perilymph

Question 31

what surrounds the bony labyrinth?

Answer 31

otic capsule | very dense bone within the petrous temporal bone

Question 32

what is the membranous labyrinth?

Answer 32

continuous system of ducts and sacs inside the bony labyrinth suspended in perilymph but contains endolymph

Question 33

where are the semicircular canals?

Answer 33

posterior and lateral to the vestibule

Question 34

what are the names given to the canals and what are the positions of each relative to one another?

Answer 34

anterior, posterior and lateral | anterior and posterior are at right angles, lateral is horizontal

Question 35

what do the semicircular canals contain and what are the names given to the swellings at the end?

Answer 35

contains the semi-circular ducts | swellings = ampullae

Question 36

what does each ampullae contain and what is their function?

Answer 36

equilibrium receptors called crista ampullaris | respond to rotational movements of the head

Question 37

what is the vestibule and what does it contain?

Answer 37

bony labrynth, 5mm long | contain two membranous sacs - the utricle and saccule

Question 38

what house the maculae and what do they respond to?

Answer 38

the utricle and sacule house the maculae respond to pull of gravity and chages in the head position due to the presence of otoliths (calcium carbonate crystals that respond to gravity)

Question 39

what innervates the cochlea?

Answer 39

spiral (cochlear) ganglion from the cochlear nerve from CN VIII

Question 40

what innervates the utricle, saccule, semicircular duct and vestibule?

Answer 40

axons of the vestibular ganglion from the vestibular nerve from CN VIII

Question 41

what gives arterial supply to the inner ear?

Answer 41

Internal auditory branches (labyrinthine, form the cochlear and vestibular arteries arising as a branch of the anterioinferior cerebrallar artery (80%) or basilar artery (20%))