Lab 3: Cranial Nerves part 2 (vision, hearing/balance)

Question 1

name foramina of bony orbit

Answer 1

sof
optic canal
supraorbital notch/foramen

Question 2

describe all bones of bony orbit and what they make up

Answer 2

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

Question 3

what passes through supraorbital foramen

Answer 3

branches of frontal nerve

Question 4

what passes through optic canal

Answer 4

cn ii = optic nerve

Question 5

what passes through superior orbital fissure

Answer 5

3,4,5,6
cn v1 = ophthalmic (lacrimal, frontal)
cn vi = abducens
cn iv = trochlear
cn iii = oculomotor

Question 6

describe levator palpebrae superioris

Answer 6

eyelid - on top of superior rectus

Question 7

describe superior rectus

Answer 7

deep to levitator muscle - underneath
elevates, rotates superiorly
intorsion (up) towards nose
ADDuction

Question 8

describe inferior rectus

Answer 8

depresses
rotates inferiorly
extorsion - down
ADDuction

Question 9

describe medial rectus

Answer 9

ADDuction
towards midline

Question 10

describe lateral rectus

Answer 10

ABDuction
away from midline

Question 11

describe superior oblique

Answer 11

depresses
ABDucts
intorsion
attachment = trochlea provides redirection - helps with compensation

Question 12

describe inferior oblique

Answer 12

elevates
ABDuction
extorsion
Visible form front

Question 13

describe origin of all eye muscles

Answer 13

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)

Question 14

name orbit cranial nerves

Answer 14

cn ii = optic
cn iii = oculomotor
cn iv = trochlear
cn vi = abducens
cn v = ophthalmic

Question 15

describe cn ii

Answer 15

optic nerve
huge

Question 16

describe cn iii

Answer 16

innervates superior rectus, inferior rectus, inferior oblique and levatator palpebrae superioris

Question 17

describe cn iv

Answer 17

trochlear
goes straight into superior oblique

Question 18

describe cn vi

Answer 18

abducens = innervates lateral rectus

Question 19

describe v

Answer 19

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)

Question 20

Where in the temporal, approximately, would you find the middle ear cavity and inner ear?

Answer 20

petrous portion

Question 21

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?

Answer 21

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)

Question 22

which fluids are found in bony vs membranous labyrinth spaces

Answer 22

bony = perilymph
Membranous = endolymph

Question 23

describe bony labyrinth

Answer 23

2 parts = cochlear (hearing) and vestibular apparatus (balance also with utricle and saccule)
cochlear duct = membranous labyrinth - tube within tube
cochlear canal = bony labyrinth

Question 24

How are they 3 semicircular canals oriented relative to each other, and how does this relate to their roles in detecting angular motion

Answer 24

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

Question 25

describe anatomy of middle and inner ear

Answer 25

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

Question 26

describe entire process of sound transduction - start to finish

Answer 26

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

Question 27

what do superior and inferior obliques do

Answer 27

Compensate
SO –> IR
IO –> SR

Question 28

Sequence of middle ear ossicles

Answer 28

malleus incus stapes