Lab 3: Cranial Nerves part 2 (vision, hearing/balance) Flashcards
name foramina of bony orbit
sof
optic canal
supraorbital notch/foramen
describe all bones of bony orbit and what they make up
frontal
zygomatic = lateral and floor
maxilla = floor and medial wall
lacrimal = lateral wall
ethmoid = lateral wall
sphenoid = posterior and lateral walls
palatine = contributes to posterior wall
can also see lacrimal duct
what passes through supraorbital foramen
branches of frontal nerve
what passes through optic canal
cn ii = optic nerve
what passes through superior orbital fissure
3,4,5,6
cn v1 = ophthalmic (lacrimal, frontal)
cn vi = abducens
cn iv = trochlear
cn iii = oculomotor
describe levator palpebrae superioris
eyelid - on top of superior rectus
describe superior rectus
deep to levitator muscle - underneath
elevates, rotates superiorly
intorsion (up) towards nose
ADDuction
describe inferior rectus
depresses
rotates inferiorly
extorsion - down
ADDuction
describe medial rectus
ADDuction
towards midline
describe lateral rectus
ABDuction
away from midline
describe superior oblique
depresses
ABDucts
intorsion
attachment = trochlea provides redirection - helps with compensation
describe inferior oblique
elevates
ABDuction
extorsion
Visible form front
describe origin of all eye muscles
SR, IR, MR, LR = all rectus muscles, from tendinous ring origin, anterior aspect at 4 cardinal points
SO = also from tendinous ring, through trochlear, more posterior aspect
IO= from maxillary (inferior orbital wall, underneath eye, goes to inferior aspect, more posterior, inserts between inferior and lateral rectus)
name orbit cranial nerves
cn ii = optic
cn iii = oculomotor
cn iv = trochlear
cn vi = abducens
cn v = ophthalmic
describe cn ii
optic nerve
huge
describe cn iii
innervates superior rectus, inferior rectus, inferior oblique and levatator palpebrae superioris
describe cn iv
trochlear
goes straight into superior oblique
describe cn vi
abducens = innervates lateral rectus
describe v
Ophthalmic division of trigeminal = 3 branches off
nasociliary nerve= runs with medial rectus (runs medially along superior border of medial rectus)
frontal nerve = above muscle (runs superior to levator palpebrae superioris)
lacrimal nerve = not into muscle, into lacrimal gland, runs with/above lateral rectus (runs laterally along superior border of lateral rectus)
Where in the temporal, approximately, would you find the middle ear cavity and inner ear?
petrous portion
Which of the openings leading into/out of middle ear cavity are patent (open) in real life, and which are normally covered/filled with membranes or structures?
tympanic opening = membrane
oval window = stapes fills (footplate of stapes in oval window)
round window = covered with membrane
opening (ostium) of auditory tube = stays open (connects middle ear, equalize pressure, closed on one side)
which fluids are found in bony vs membranous labyrinth spaces
bony = perilymph
Membranous = endolymph
describe bony labyrinth
2 parts = cochlear (hearing) and vestibular apparatus (balance also with utricle and saccule)
cochlear duct = membranous labyrinth - tube within tube
cochlear canal = bony labyrinth
How are they 3 semicircular canals oriented relative to each other, and how does this relate to their roles in detecting angular motion
perpendicular = helps pick up head rotation in space in all 3 planes
Semicircular duct = membranous labyrinth, ends in ampulla = where cells are that sense movement of endolymph
describe anatomy of middle and inner ear
3 semicircular canals = end in ampulla –> utricle (membranous labyrinth) –> saccule
endolymph = linear acceleration and head position in space
hair cells located in thickening of endolymphatic duct
describe entire process of sound transduction - start to finish
sound waves push tympanic membrane –> vibrates chain of ossicles (malleus, incus, stapes) –> footplate of stapes in oval window (changes sound waves to pressure waves), moves perilymph up scala vestibuli - distance up spiral proportional to frequency of sound –> perilymph in scale vestibuli pushes down on cochlear duct (stimulates spiral organ receptors at that level – compresses perilymph and presses on spiral organ) –> pressure waves on floor of cochlear duct passed on to scala tympani (endolymph pushes perilymph in scala tympani)–> move down cochlear canal to be dissipated at round window membrane
what do superior and inferior obliques do
Compensate
SO –> IR
IO –> SR
Sequence of middle ear ossicles
malleus incus stapes
