eye and orbital anatomy

Question 1

frontalis action

Answer 1

moves scalp and raises eyebrow

Question 2

what nerve innervates frontal

Answer 2

CN 7

Question 3

corrugator action

Answer 3

pulls medial eyebrow inf. and med. (forms 11s)

Question 4

what nerve innervates corrugator

Answer 4

CN 7

Question 5

procurus action

Answer 5

pulls forehead & eyebrow inf. - forms “bunny lines”

Question 6

what innervates the procures muscle

Answer 6

CN 7

Question 7

forehead and brow muscles

Answer 7

fantails, corrugator, procerus

Question 8

eyelid muscles

Answer 8

levator, obricularis

Question 9

action levator

Answer 9

elevates the eyelid

Question 10

innervation of levator

Answer 10

CN 3

Question 11

action of orbicularis

Answer 11

closes the eyelid

Question 12

innervation of orbicularis

Answer 12

CN 7

Question 13

periosteum anteriorly

Answer 13

fuses with septum at Marcus marginalus; septum important to prevent spread of infection into posterior orbit

Question 14

periosteum posteriorly

Answer 14

fuses with dura of ON

Question 15

where is the periosteum attached

Answer 15

firmly at orbital and suture lines

Question 16

extra ocular muscles

Answer 16

superior rectus
inferior rectus
medial rectus
lateral rectus
superior oblique
inferior oblique

Question 17

superior rectus - action & innervation

Answer 17

elevates; CN 3

Question 18

inferior rectus - action and innervation

Answer 18

depress; CN 3

Question 19

medial rectus - action and innervation

Answer 19

adduct; CN 3

Question 20

lateral rectus - action and innervation

Answer 20

abduct; CB 6

Question 21

superior oblique - action and innervation

Answer 21

intort; CN 4

Question 22

inferior oblique - action and innervation

Answer 22

extort; CN 3

Question 23

what allows for slack of optic nerve in orbit

Answer 23

distance from globe to optic foramen (18 mm)

Question 24

what is a sign of brain aneurysm

Answer 24

palsy of CN3

Question 25

what cranial nerve is responsible for pupillary light reflex

Answer 25

CN 3 - oculomotor nerve

Question 26

what does the oculomotor nerve innervate

Answer 26

medial rectus, superior rectus, inferior rectus, inferior oblique, levator palpebrae

Question 27

what does the trochlear nerve innervate

Answer 27

superior oblique

Question 28

what is the easiest cranial nerve to damage in head trauma

Answer 28

trochlear nerve (CN 4)

Question 29

palsy of CN 4

Answer 29

causes head tilt

Question 30

CN 5

Answer 30

trigeminal nerve

Question 31

V1

Answer 31

ophthalmic branch

Question 32

what can V1 be affected by

Answer 32

Zoster

Question 33

what branches are part of V1

Answer 33

lacrimal branch, frontal branch, nasocilliary branch

Question 34

sensation to the cornea

Answer 34

V1: ophthalmic branch

Question 35

CN6

Answer 35

abducens nerve

Question 36

abducens nerve innervates

Answer 36

lateral rectus

Question 37

palsy of CN6

Answer 37

common in small strokes

Question 38

cause of double vision

Answer 38

CN 6

Question 39

easily affected by intracranial pressure

Answer 39

CN6 because it does not travel the wall of the cavernous sinus so easily affected by increased intracranial pressure

Question 40

CN 7

Answer 40

facial nerve

Question 41

CN 7 innervates

Answer 41

muscles of facial expression

Question 42

CN 7 stimulates ____

Answer 42

tear production

Question 43

Bell's palsy

Answer 43

see difficulty with eyelid closure due to obicularis occuli paralysis

Question 44

annulus of zinn

Answer 44

four rectus muscles originate from a ring of fibrous tissue attached to the posterior orbit

Question 45

which nerves enter the orbit within the annulus of zinn

Answer 45

optic nerve (CNII), the superior and inferior divisions of the oculomotor nerve (CN III), the abducens nerve (CN VI), and the nasociliary branch of the ophthalmic branch of the trigeminal nerve (CN V1)

Question 46

what does not pass through the annulus of zinn

Answer 46

trochlear nerve and the frontal and lacrimal branches of the ophthalmic branch of the trigemnical nerve (CN V1) do not pass through the annulus of Zinn

Question 47

lateral wall

Answer 47

thickest and strongest wall; rarely affect in trauma

Question 48

medial wall

Answer 48

thinnest; level of cribriform plate; floor of anterior cranial fossa; anterior and posterior ethmoidal arteries; lamina papyracea

Question 49

lamina papyracea

Answer 49

thinnest bone; often fractures; can be site of cellulitis extension

Question 50

superior orbital fissure nerves

Answer 50

``` lacrimal n (V1) frontal n (V1) trochlear nerve (CN4) sup div of CN3 nasociliary N (V1) abducens N (CN6) inf. div of CN3 ``` Lazy French Tarts Sit Naked and Inviting

Question 51

ophthalmic artery

Answer 51

a branch of the internal carotid artery, enters the orbit through the optic canal then travels along the medial wall of the orbit

Question 52

first branch of ophthalmic artery

Answer 52

central retinal artery; penetrate the optic nerve and enters the eye through the center of the nerve

Question 53

superior and inferior ophthalmic veins

Answer 53

drain the orbit

Question 54

branches of the superior and inferior ophthalmic veins

Answer 54

exit through the superior and inferior orbital fissures before draining into the cavernous sinus

Question 55

puncta

Answer 55

where tears exit the ye

Question 56

canaliculus

Answer 56

pipe that leads to lacrimal sac

Question 57

lacrimal sac

Answer 57

tear reservoir - often site of infection if outflow is blocked

Question 58

nasolacrimal duct

Answer 58

outflow into the nose for tears