16-A Ear

Question 1

What is the mandibular fossa,

Answer 1

space where the mandible articulates with the temporal bone

Question 2

Contrast the embryologic origins of the external/middle ear with the inner ear

Answer 2

the external and middle ear develop from the branchial arches, and first cleft and pouch, where as the inner ear develops from the otic placode

Question 3

What embryonic tissues fuse to form the tympanic membrane?

Answer 3

endoderm, mesoderm and ectoderm

Question 4

What nerves provide the innervation for the external ear?

Answer 4

CN VII (dots) lesser occipital and greater auricular– cervical plexus (posterior) auriulo-temporal– CN V3 (anterior) and CN IX and X (indside)

Question 5

Which nerves innervate the external auditory meatus?

Answer 5

CN V3, VII, IX and X

Question 6

Describe the innervation for the outer and inner tympanic membrane.

Answer 6

outer: CN V3, VII and X inner: (mucous membrane CNIX

Question 7

What is another name for swimmer’s ear?

Answer 7

inflammation of the external auditory meatus– otitis externa

Question 8

Where is the middle ear in relationship to the internal carotid

Answer 8

ME is posterior to route of ICA

Question 9

Name the two cavities that the middle ear is open to anteriorly and posteriorly.

Answer 9

mastoid air cells (sinus like) and the auditory tube

Question 10

Which window the round or oval window does the stapes sit on?

Answer 10

the stapes footplate sits on the oval window

Question 11

Describe the paths of the tensor tympani and the stapedius: where is the canal, to what does the muscle attach?

Answer 11

tensor tympani canal runs next to the auditory canal and teaches to the malleus while the stapedius is embedded near the mastoid process and attaches tot eh stapes

Question 12

Describe the chorda tympani? What fibers does it carry? Between which to bones does it travel?

Answer 12

the chord tympani, a branch of CN VII that carries parasympathetic preganglionic and special vicerosensory (taste); travels between the malleus and incus then exits the petrotympanic fissure

Question 13

Which nerves enter and exit the tympanic plexus, where is the tympanic plexus?

Answer 13

tympanic plexus on the promontory of the medial middle ear wall: tympanic nerve (branch of CN IX) enters carrying parasympathetic and general somatosensory and meets with caroticotympanic sympathetics (post ganglionic), exiting is the lesser petrosal nerve which consists of parasympathetics continuing on to the otic ganglion and parotid gland

Question 14

Which embryonic tissue forms the membranous labyrinth of the inner ear and sensory neurons of cranial nerve VIII?

Answer 14

the otic placode

Question 15

Which forms first the membranous labyrinth or the bone incasing the inner ear?

Answer 15

the membranous labyrinth forms first NOTE the cochlea and vestibule/semicircular canals are under separate genetic control— must set up appropriate axes

Question 16

Which part of the inner ear is most anterior?

Answer 16

the cochlea followed by the vestibule and the semicircular canals

Question 17

Where can you find endolymph and perilymph in relation to the membranous labyrinth?

Answer 17

endolymph is within ducts, perilymph is outside ducts

Question 18

Name the two compartments int he cochlea that contain perilymph.

Answer 18

scala vestibule and scala tympani

Question 19

What is the cochlear/spiral ganglion

Answer 19

sensory connector between the hair cells and the cochlear nerve

Question 20

How are alcohol and balance related (at least in part).

Answer 20

alcohol changes the density of cupola, which will change how movement is percieved

Question 21

Where is the vestibular ganglion located?

Answer 21

at the base of the vestibular system before continuing on as the vestibular nerve

Question 22

Name the 3 systems that contribute to balance?

Answer 22

the vestibular system, vision and proprioception

Question 23

What is the cause/symptoms of acoustic neuroma?

Answer 23

caused by a tumor of schwann cells near and if it occurs near the internal auditory meatus which can lead to hear loss, balance problems and tinnitus due to impinging on CN VIII and CN VII as they enter the internal acoustic meatus

Question 24

Name the branches of the facial nerves that enter the internal auditory meatus.

Answer 24

parasympathetics to lacrimal gland and glands in the oral nasal cavities, chorda tympani and branchiomotor and general somatosensory to the face

Question 25

What are the two nerves that come together to form the deep petrosal nerve

Answer 25

greater petrosal nerve and deep petrosal nerve

Question 26

Branchiomotor and general somatosensory to the face leave the temporal bone is the ____.

Answer 26

stylomastoid foramen

Question 27

What is included in the geniculate ganglion?

Answer 27

contains the cell bodies of the special viscerocensory neurons that innervate the taste buds of the anterior 2/3 of the tongue as well as general somatosensory to the external ear

Question 28

Parasympathetics destined for the parotid gland sort out from the tympanic plexus and after a long journey exit this hole on their way to the otic ganglion

Answer 28

foramen ovale