15: Ear

Question 1

function of external ear

Answer 1

collection of sound waves

Question 2

function of middle ear

Answer 2

translation of sound waves into mechanical energy (vibration of membranes and bones)

Question 3

function of inner ear

Answer 3

translation of mechanical energy to electrical (neural) energy in the cochlea; also for balance in the vestibular apparatus

Question 4

external ear parts

Answer 4

auricle, external auditory meatus, tympanic membrane

Question 5

auricle blood supply

Answer 5

superficial temporal a.

posterior auricular a.

Question 6

auricle innervations

Answer 6

SENSORY: auriculotemporal V3
auricular branch of Vagus X
Facial
Great auricular
Lesser occipital

MOTOR: facial

Question 7

tympanic membrane

Answer 7

separates the external auditory meatus from the middle ear - covered with skin externally and mucus internally

Question 8

tympanic membrane blood supply

Answer 8

deep auricular (from maxillary a.) for external surface of membrane

anterior tympanic (from maxillary a.) for internal surface of membrane

Question 9

roof of the middle ear

Answer 9

tegmen tympani - a thin plate of bone separating the middle ear from the middle cranial fossa

space beneath it is the epitympanic recess

Question 10

floor of the middle ear

Answer 10

thin layer of bone separating the middle ear from the jugular foramen (posterior) and carotid canal (anterior)

Question 11

posterior wall of the middle ear

Answer 11

aditus antrum - entrance to mastoid air cells
pyramid - entrance of the stapedius m. to insert on stapes
foramen for entrance of chorda tympani n.

Question 12

innervates the stapedius m.

Answer 12

facial n.

Question 13

aditus antrum

Answer 13

middle ear, entrance to the mastoid air cells (posterior “wall”)

Question 14

anterior wall of the middle ear

Answer 14

tensor tympani m.
entrance of the pharyngo-tympanic tube
exit of the chorda tympani n.

Question 15

innervates tensor tympani m.

Answer 15

V3 (trigeminal)

Question 16

lateral wall of the middle ear

Answer 16

tympanic membrane

Question 17

medial wall of the middle ear

Answer 17

promontory
oval window
round window
facial nerve
lateral semicircular canal prominence

Question 18

promontory

Answer 18

produced by the first basal turn of the cochlea; tympanic plexus of nerves on it

Question 19

oval window

Answer 19

membrane of the cochlea covered by the foot plate of the stapes

Question 20

round window

Answer 20

membrane the sound travels through after it has gone through the cochlea. next it heads through the eustachian/auditory tube

Question 21

lateral semicircular canal prominence

Answer 21

located in epitympanic recess

Question 22

contents of the middle ear

Answer 22

malleus
incus
stapes
tensor tympani m.
stapedius m.
chroda tympani n.

Question 23

tensor tympani m.

Answer 23

inserts on malleus

innervated by trigeminal V3

Question 24

stapedius m.

Answer 24

inserts on stapes

innervated by facial VII

Question 25

pharyngo-tympanic tube (auditory tube)

Answer 25

cartilage + bone | equalizes air pressure on each side of the tympanic membrane

Question 26

mastoid air cells

Answer 26

accessed through the aditus antrum | increase the volume of the mastoid process without increasing its weight (??)

Question 27

inner ear

Answer 27

a series of canals with an auditory and a vestibular portion | between the internal auditory meatus and the middle ear

Question 28

auditory portion of inner ear

Answer 28

cochlea and modiolus

Question 29

cochlea

Answer 29

auditory part of inner ear; contain hair cells for transduction of vibration into neural electrical signals for hearing

Question 30

modiolus

Answer 30

central bony pillar of the cochlea; contains spiral canals for housing the spiral ganglion and passage of the cochlear n.

Question 31

vestibule

Answer 31

between the cochlea and the semicircular canals; contains saccule/utricle for transduction of linear motion into neural electrical signals

Question 32

3 semicircular canals

Answer 32

anterior, lateral, posterior: dilation called the ampulla; contain crista ampullaris for transduction of angular (rotational) motion into neural electrical signals (BALANCE)

Question 33

facial nerve VII is associated with

Answer 33

``` internal auditory meatus geniculate ganglion (cell bodies of SS and GSA fibers) stylomastoid foramen (GSA - concha of pinna; SVE - muscles of facial expression) branches of facial nerve near ear - greater petrosal (SS-taste, preganglionic parasympathetic GVE to pterygopalatine ganglion), stapedius chorda tympani (SS taste; preganglionic parasympathetic (GVE) to submandibular ganglion ```

Question 34

branches of facial nerve that are SS - special sensory

Answer 34

geniculate ganglion greater petrosal n. - concha of pinna and taste chorda tympani - taste

Question 35

branches of facial nerve that are GSA - general sensory afferent

Answer 35

geniculate ganglion | stylomastoid of foramen - concha of pinna

Question 36

branches of facial nerve that are GVE - preganglionic parasympathetic

Answer 36

greater petrosal nerve to pterygopalatine ganglion | chroda tympani to submandibular ganglion

Question 37

vestibulocochlear nerve VIII innervates

Answer 37

internal auditory meatus (SS - auditory from cochlea SS - balance from vestibular apparatus)

Question 38

tympanic plexus

Answer 38

from CN 7, 9, and 10

Question 39

CN 9 from tympanic plexus

Answer 39

give rise to lesser petrosal n. which contains preganglionic parasympathetic fibers that pass through foramen ovale with V3 to synapse in the otic ganglion

Question 40

postganglionic parasympathetic fibers leave otic ganglion

Answer 40

and join the auriculotemporal nerve (of V3) for a bit and then hop off to innervate the parotid gland

Question 41

arterial supply to the ear

Answer 41

PA and ST | posterior auricular and superficial temporal

Question 42

sensory innervation to ear

Answer 42

top: auricular temporal from V3 middle: CN 7 and 10 (also 9) bottom: lesser occipital and greater auricular from cervical plexus

Question 43

facial nerve VII has these branches/parts in the ear

Answer 43

greater petrosal geniculate ganglion nerve to stapedius muscle chorda typmani *travels from stylomastoid foramen to internal acoustic meatus*