ear Flashcards
which is true?
A Facial nerve supplies sensory to external ear canal
B Vagus supplies the sensory innervation of the internal ear canal
C Major blood supply is from the great auricular artery –branch of internal carotid artery
D External carotid and maxillary vein lie immediately ventral to the bulla
A facial –> motor
B vagus –> sensory–> EXTERNAL ear canal
C external carotid –> great auricular–> caudal auricular
D TRUE (external carotid and maxillary v ventral to bulla)
what Two membranes are found within the mesotympanic chamber:
the tympanic membrane and the secondary cochlear (or round) membrane on the promontory
stapes footplate –> vestibular window = oval window (dorsal to promontory)
What forms the tympanic plexus
tympanic branches of cranial nerve IX= glossopharyngeal and the caroticotympanic nerve.
The vascular supply to the middle ear—the tympanic artery—where does it come from and by what path?
external carotid –> MAXILLARY –> enters via a small foramen caudal to the temporomandibular joint.
origin within superficial temporal passes rostromedially beneath the TMJ medial to the retroarticular process in its course to the alar canal
What is different in the cats middle ear compared to dogs?
hypotympanum + rostrolateral component = epi+mesotymp w/SEPTUM separation
tympanic plexus distributes widely across bony promontory but is reported to be more exposed +/- sensitive to iatrogenic trauma
True/false: Medial to the bulla is external carotid and the retroglenoid vein
False INTERNAL carotid is medial to bulla Retroglenoid vein is immediately ROSTRAL to the osseous ear canal
maxillary vein and carotid are ventral to bulla
what 2 muscles dampen sound vibrations?
tensor tympani m. and stapedius m.
What structure/organ is responsible for conversion of sound waves to neurological signal?
hair cells in organ of Corti
(in basilar membrane of cochlea) –> cochlear nerve –> vestibulocochlear nerve –> brain
what are the cartilages associated with the external ear canal?
osseous auditory meatus –> annular cartilage –> scutiform cartilage –> conchal cartilage–>scapha(pinna)
which glands are more superficial and which are deeper in ear canal tissue?
sebaceous = superficial ceruminous = deeper
describe the path of the facial nerve from the pons-medulla oblongata junction to the external ear canal?
internal acoustic meatus –> facial canal of petrous temporal bone through the middle ear (exposed in the dorsal aspect of the tympanic cavity near the vestibular window)–> stylomastoid foramen
where is the facial nerve in respect to the canal?
caudoventral to the canal at the level of the terminal horizontal canal
Stray dissection should be avoided around the bulla for these structures… rostrally? Ventrally?
Rostrally = retroglenoid vein Ventrally = external carotid artery, maxillary vein
what are the 3 chambers of the tympanic cavity in dogs?
epitympanum (smallest), mesotympanum, hypotympanum (ventral)
True/ false? The inner ear is innervated by the vestibulocochlear nerve
true: membranous labyrinth (vestibule, cochlea and semicircular canals)
