Lecture 54 - Ear and Eye Anatomy & Phys Flashcards
what species is the third eyelid an active protrusion
cat
what is the function of the third eyelid
spread tears over the cornea
contains superficial glands
what is cherry eye
prolapse of the superficial gland of the 3rd eyelid
T/F: Cherry eye is considered to be caused by a genetic defect
TRUE
T/F: excision is the most effective way to treat cherry eye
FALSE
____ of tear production is by the lacrimal gland while ____ is done by the superficial gland of the 3rd eyelid
60%; 40%
describe the anatomical structures of tear drainage
- dorsal/ventral lacrimal puncta
- dorsal/ventral lacrimal ducts
- lacrimal sac
- nasolacrimal duct
- rostral nasal cavity
what is the periorbita
cone of connective tissue and smooth muscle surrounding extraocular mm., nn., etc.
what structure completes the rim of the orbit
orbital ligament
the oculomotor nerve (CN III) innervates what muscles
dorsal, vental, and medial rectus mm.
ventral oblique mm.
levator palpebrae superioris
the abducens nerve (CN VI) innervates what muscle
lateral rectus mm.
retractor bulbi mm.
the trochlear nerve (CN IV) innervates what muscle
dorsal oblique mm.
what are the 3 tunics of the bulbus oculi
- external fibrous tunic
- middle vascular tunic
- inner nervous tunic
is the cornea or sclera avascular
cornea
what is the choroid
posterior part of the uveal tract, pigmented, and highly vascularized
what is the tapetum lucidum
specialized reflective layer that increases dim light vision
what two structures does the ciliary body connect
connects the choroid to the iris
give the components of the ciliary body and their functions
ciliary processes - ridges that extend from body
zonular fibers - connect processes to lens
ciliary mm. - contraction changes tension of lens
the constrictor pupillae m. is _____ and the dilator pupillae m. is _____
parasympathetic; sympathetic
what are the two major layers of neuroepithelium
- pigmented retinal epithelium (PRE)
- nervous layer (light receptors and transmitting neurons)
what are the 3 chambers of the eye
- anterior chamber
- posterior chamber
- vitreous chamber
describe the vitreous chamber
- gel-like
- holds retina against choroid
- constant in volume
- not continuously replaced
describe the external vestibulocochlear system
pinna to tympanic membrane
describe the middle vestibulocochlear system
ear ossicles to inner ear openings
encased by tympanic bulla
describe the internal vestibulocochlear system
receptors for hearing/balance/etc.
within petrous temporal bone
what are the 3 ear ossicles
- malleus
- incus
- stapes
what is the function of the eustachian tube
pressure equalizer
musculotubal canal
what species is the septum bullae more prominent in
the cat
what divides the tympanic cavity into two compartments
septum bullae
what is the organ of hearing
cochlea
what are the two components of the vestibular system
- semicircular canal
- utricle and saccule
describe the sound pathway in 8 steps
- pinna
- external aoustic meatus
- tympanic membrane
- ear ossicles
- vestibular window
- cochlea
- CN VIII
- auditory pathways in the brain
describe the route that soundwaves take to create auditory input
- ear canal
- tympanic membrane vibrates in response to sound waves
- malleus, incus, and stapes vibrate
- transmit to oval window of cochlea
- fluid movement in the cochlea creates nerve impulse
what are the 3 chambers of the inner ear
- scala media
- scala tympani
- scala vestibuli
which chambers contain perilymph
scala tympani and vestibuli
what is the difference between perilymph and endolymph
endolymph is enriched with potassium for auditory receptor cell depolarization
what is the organ of Corti
arrangement of hair cells in the cochlear duct
where are vibration-sensitive hair cells located
basilar membrane
T/F: depolarization occurs when deflection occurs towards the thickest cilium
TRUE
what contributes to frequency detection
degree of specificity in individual hair cells
what is the “place principle”
different types of hair cells responding to different frequencies of sounds
summarize the vibration of basilar membrane in 5 steps
- sound vibrations in liquid cause vibrations of basilar membrane
- displacement of the organ of corti (displacing hair cells)
- movement of stereocilia causes depolarization (longest) and inactivation (shortest)
- glutamate is released
- transmitted into electrical impulse on the auditory nerve
T/F: the auditory pathways are uniquely bilateral
TRUE
list the innervations from the auditory pathway in the order in which they are innervated
- cochlear nuclei
- nucleus of the trapezoid body
- caudal colliculus
- medial geniculate nucleus
- auditory cortex
the rostral (anterior) canal is important for what motion
sagittal plane; “yes” movement
the horizontal canal is important for what motion
horizontal plane; “no” movement
the caudal (posterior) canal is important for what motion
transverse plane; side-to-side
what is responsible for detecting linear motion
utricle (vertical) and saccule (horizontal)
otolith
crystals of calcium carbonate embedded in gelatinous mass
T/F: vertigo and nausea are caused when the left and right vestibular nerves are both active
TRUE
vestibulo-ocular reflex
semicircular canals exert control over the eye muscles so when the head is turned you can stay focused
