16-A Ear Flashcards
What is the mandibular fossa,
space where the mandible articulates with the temporal bone
Contrast the embryologic origins of the external/middle ear with the inner ear
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
What embryonic tissues fuse to form the tympanic membrane?
endoderm, mesoderm and ectoderm
What nerves provide the innervation for the external ear?
CN VII (dots) lesser occipital and greater auricular– cervical plexus (posterior) auriulo-temporal– CN V3 (anterior) and CN IX and X (indside)
Which nerves innervate the external auditory meatus?
CN V3, VII, IX and X
Describe the innervation for the outer and inner tympanic membrane.
outer: CN V3, VII and X inner: (mucous membrane CNIX
What is another name for swimmer’s ear?
inflammation of the external auditory meatus– otitis externa
Where is the middle ear in relationship to the internal carotid
ME is posterior to route of ICA
Name the two cavities that the middle ear is open to anteriorly and posteriorly.
mastoid air cells (sinus like) and the auditory tube
Which window the round or oval window does the stapes sit on?
the stapes footplate sits on the oval window
Describe the paths of the tensor tympani and the stapedius: where is the canal, to what does the muscle attach?
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
Describe the chorda tympani? What fibers does it carry? Between which to bones does it travel?
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
Which nerves enter and exit the tympanic plexus, where is the tympanic plexus?
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
Which embryonic tissue forms the membranous labyrinth of the inner ear and sensory neurons of cranial nerve VIII?
the otic placode
Which forms first the membranous labyrinth or the bone incasing the inner ear?
the membranous labyrinth forms first NOTE the cochlea and vestibule/semicircular canals are under separate genetic control— must set up appropriate axes
Which part of the inner ear is most anterior?
the cochlea followed by the vestibule and the semicircular canals
Where can you find endolymph and perilymph in relation to the membranous labyrinth?
endolymph is within ducts, perilymph is outside ducts
Name the two compartments int he cochlea that contain perilymph.
scala vestibule and scala tympani
What is the cochlear/spiral ganglion
sensory connector between the hair cells and the cochlear nerve
How are alcohol and balance related (at least in part).
alcohol changes the density of cupola, which will change how movement is percieved
Where is the vestibular ganglion located?
at the base of the vestibular system before continuing on as the vestibular nerve
Name the 3 systems that contribute to balance?
the vestibular system, vision and proprioception
What is the cause/symptoms of acoustic neuroma?
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
Name the branches of the facial nerves that enter the internal auditory meatus.
parasympathetics to lacrimal gland and glands in the oral nasal cavities, chorda tympani and branchiomotor and general somatosensory to the face
