Lecture 21 + 22: Eye and Orbit

Question 1

what are the 3 tunics of the eye

Answer 1

• fibrous (sclera) outermost
• vascular (vascularized, composed of choroid, ciliary body and iris)
• neural

Question 2

what muscle constricts the pupil

Answer 2

constrictor pupillae
contained within the anterior layer of the iris

Question 3

what muscle changes lens shape

Answer 3

ciliary muscle
contained w/in the ciliary body

Question 4

what layer of the ye contains blood vessels

Answer 4

choroid

Question 5

what muscle dilates the pupil

Answer 5

dilator pupillae
contain within the posterior layer of the iris

Question 6

pathway of light through the eye

Answer 6

Cornea
aqueous humor
iris
lens
vitreous body
Retina

Question 7

what part of the eye contains photosensitive rods and additional layers of specialized neurons

Answer 7

retina

Question 8

photoreceptors that allow for vision in low light

Answer 8

rods
- only one type

Question 9

photoreceptors that allow for vision in color and visual acuity

Answer 9

Cones

Question 10

what are the 2 types of cones

Answer 10

short and medium wavelength sensitivities (blue vs green) in carnivores and artiodactyls

Question 11

what is tapetum lucidum

Answer 11

functions as a reflector, redirects photons back through the retina
provides an additional chance for photoreceptors to capture photons

Question 12

what does the optic disk serve as an exit for

Answer 12

retinal gangilon cell axons

Question 13

what is the optic nerve formed from

Answer 13

bundles of axons from the retinal ganglion cells

Question 14

pupil constriction reduced light entering the eye whereas _______ increases it

Answer 14

dilation

Question 15

the lens is contained within a _____ ?

Answer 15

lens capsule

Question 16

a rounder lens is for focus on ______ objects

Answer 16

nearer

Question 17

a flatter lens is for focus on ______ objects

Answer 17

more distant

Question 18

what muscles control the pupil diameter

Answer 18

• dilator pupillae (sympathetic)
• sphincter / constrictor pupillae (parasympathetic)

Question 19

what is the purpose of tarsal glands embedded within the tarsal plates

Answer 19

tarsal glands are modified sebaceous glands that secrete an oily substance that increases the viscosity of tears and decreases tear evaporation from the surface of the eye

Question 20

what is Chalazion

Answer 20

inflammation / blockage of the meibomian glands

Question 21

what are commissures

Answer 21

meeting of upper and lower eyelid

Question 22

what gland secretes tears

Answer 22

lacrimal gland
under automatic control

Question 23

what cranial nerves are in the orbit

Answer 23

CN II - optic
CN III - oculomotor
CN IV - trochlear
CN V1 - opthalamic division of trigeminal
CN VI - abducens

Question 24

CN II enters the orbit via the _______

Answer 24

optic canal

Question 25

CN III, IV V1 and VI enter the orbit through the...

Answer 25

orbital fissure

Question 26

how many extrinsic eye muscles attach to the eye and move it

Answer 26

7 (4) are recti (2) obliques (1) retractor bulbi

Question 27

what extrinsic eye muscle pulls the eye back into the orbit

Answer 27

retractor bulbi

Question 28

what nerve gets sensory info from the cornea and sclera

Answer 28

sLong ciliary nerve

Question 29

what nerves get sensory info from the nasal cavity

Answer 29

Anterior and Posterior ethmoidal nerves

Question 30

what nerve sends parasympathetic innervation to the pupillary sphincter and ciliary muscles

Answer 30

short ciliary nerves

Question 31

what nerve gets sensory input from the lacrimal gland, conjunctiva and upper eyelid

Answer 31

Lacrimal n.

Question 32

what produces the glycoprotein component of the tear film

Answer 32

goblet cells of the conjunctivae the tarsal glands produce the oily superficial layer of the tear film

Question 33

what cranial nerve innervates the Orbicularis oculi

Answer 33

CN VII

Question 34

what cranial nerve innervates the levator palpebrae superioris

Answer 34

CN III

Question 35

what cranial nerve distributes sensory innervation to the cornea and sclera, nasal cavity and face

Answer 35

CN V1 (ophthalmic division of trigeminal)

Question 36

what nerve provides sensory info from the nasal cavity, cornea and sclera

Answer 36

Nasociliary n

Question 37

what nerve provides sensory info from the skin of the forehead and the scalp

Answer 37

Frontal n.

Question 38

what nerve provides sensory info from the lacrimal gland, conjunctiva, and upper eyelid

Answer 38

Lacrimal n.

Question 39

what nerve provides sensory info from the cornea and sclera

Answer 39

long ciliary nerves

Question 40

what nerves bring sensory info from the nasal cavity

Answer 40

anterior and posterior ethmoidal nerves

Question 41

what nerve provides parasympathetic innervation to the pupillary sphincter and ciliary muscle

Answer 41

short ciliary nn.

Question 42

what eye muscle does the trochlear nerve innervate

Answer 42

dorsal oblique muscles

Question 43

what eye muscles does the abducens nerve innervate

Answer 43

lateral rectus and retractor bulbi

Question 44

what 4 cranial nerves carry parasympathetic innervation

Answer 44

Oculomotor (III) - ONLY Facial (VII) - FANS Glossopharyngeal (IX) - GETS Vagus (X) - VIEWS

Question 45

What ganglia does CN III innervate

Answer 45

Ciliary ganglia

Question 46

what ganglia does CN VII innervate

Answer 46

Pterygopalatine (lacrimal) and Submandibular ganglia (salivation)

Question 47

what ganglia does CN IX innervate?

Answer 47

Otic ganglion (parotid gland salivation)

Question 48

what is the direct light reflex

Answer 48

pupil constricts in eye stimulated by light

Question 49

what is the consensual light reflex

Answer 49

pupul constricts in contralateral eye

Question 50

what are sinuses

Answer 50

small gaps between the folds of the dura and skull they receive venous blood draining from the brain which then gets drained to the vertebral and internal jugular veins

Question 51

What are the extrinsic eye muscles that CN III innervates

Answer 51

Ventral oblique Dorsal rectus Medial rectus Ventral rectus

Question 52

what extrinsic eye muscle does CN IV innervate

Answer 52

dorsal oblique

Question 53

what extrinsic eye muscles does CN VI innervate

Answer 53

lateral rectus retractor bulbi (pulls eye backward into orbit and causes nictitans to protrude)

Question 54

what extrinsic eye muscles are used to look up

Answer 54

dorsal rectus and ventral oblique

Question 55

what extrinsic eye muscles are used to look down

Answer 55

ventral rectus and dorsal oblique

Question 56

what extrinsic eye muscle ADDucts the eye

Answer 56

medial rectus

Question 57

what extrinsic eye muscle Abducts the eye

Answer 57

lateral rectus