Basic Ophthalmology Anatomy

Question 1

what are the 7 bones of the orbit?

Answer 1

frontal
zygomatic
maxilla
lacrimal
ethmoid
sphenoid
palatine bones

Question 2

what are the important entrance/exit points in the bony anatomy of the orbit?

Answer 2

supraorbital foramen/notch
infraorbital foramen
superior orbital fissure
inferior orbital fissure
optic canal

Question 3

what passes through the supraorbital foramen/notch?

Answer 3

supraorbital nerve and vessels

Question 4

what passes through the infraorbital foramen?

Answer 4

infraorbital nerve and vessels

Question 5

what passes through the superior orbital fissure?

Answer 5

CN III
CN IV (trochlear - superior oblique)
CN V1
CN 6 (abducens - lateral rectus)

Question 6

what passes through the optic canal?

Answer 6

CN 2

Question 7

where is the optic canal found?

Answer 7

on posterior wall

medial to superior orbital fissure

Question 8

what is the area where the iris meets the sclera called?

Answer 8

corneal limbus

Question 9

how many lacrimal puncta are there and where do they lead to?

Answer 9

2

• one on upper lid - drains into superior lacrimal canal > nasolacrimal duct
• one on lower lid - drains into inferior lacrimal puncta > nasolacrimal duct

Question 10

where is the lacrimal gland found?

Answer 10

superior and lateral to the eye (brow bone)

Question 11

what are the 2 types of conjunctiva?

Answer 11

tarsal conjunctiva = lines inner surface of eyelid

bulbar conjunctiva = lines sclera up until the corneal limbus

Question 12

what are the 2 cavities of the eye and what do they consist of?

Answer 12

anterior cavity
- anterior chamber = between cornea and iris
- posterior chamber = between iris and lens
posterior cavity
- contains vitreous chamber

Question 13

what are the 3 groups of extraocular muscles?

Answer 13

rectus muscles
oblique muscles
levator palpebrae superioris

Question 14

what are the 3 intraocular muscles?

Answer 14

ciliary muscles
sphincter pupillae
dilator pupillae

Question 15

where is the trochlea found?

Answer 15

superior nasal aspect of the frontal bone within the orbit

Question 16

on which side of the eye does the inferior rectus attach?

Answer 16

lateral

Question 17

2 main actions of the superior oblique?

how can this be tested?

Answer 17

moves eye ball down and in which leads to looking down and out
intorsion when looking straight ahead
tested by making patient look down and in

Question 18

3 main actions of inferior oblique?

Answer 18

extorsion
elevation
abduction

Question 19

how is the action of inferior oblique tested?

Answer 19

make patient look up and in

Question 20

why does testing of the oblique muscles not match their function?

Answer 20

as their elevation/depression functions are strongest on adduction

Question 21

the ciliary muscles are part of what?

Answer 21

part of ciliary body

Question 22

what do the ciliary muscles do?

Answer 22

act as part of accommodation reflex
contraction causes relaxation of suspensory ligaments and allows lens to thicken allowing focus to shift to close up objects

Question 23

what do the sphincter pupillae muscles do?

Answer 23

also activate in accommodation reflex as well as the light reflex to constrict the pupil

Question 24

what do the dilator pupillae muscles do?

Answer 24

increase diameter of the pupil

Question 25

are the intraocular muscles under sympathetic or parasympathetic control?

Answer 25

ciliary and sphincter pupillae muscles = parasympathetic

dilator pupillae = sympathetic

Question 26

what nerve is responsible for special sensory (vision) in the eye?

Answer 26

CN 2 (optic)

Question 27

sensory innervation of the eye?

Answer 27

CN V1

Question 28

motor innervation of the eye?

Answer 28

CN III
CN IV (trochlear = superior rectus)
CN VI (abducens = lateral rectus)

Question 29

how is the autonomic nervous system involved in the eye?

Answer 29

sympathetic fibres from internal carotid plexus

parasympathetic fibres from edinger westphal nucleus, carried in CN III to ciliary ganglion

Question 30

sign of CN III palsy?

Answer 30

eye fixed in down and out position

dilated (blown) pupil

Question 31

sensory control of the cornea?

Answer 31

CN V1

Question 32

how does CN II provide special sensation of vision?

Answer 32

both optic nerves converge at the optic chiasm where information is exchanged, dividing visual information into right and left visual field, rather than right and left eye
nasal retinal fibres (temporal visual field) cross over to the contralateral side of the brain and join temporal retinal fibres (nasal visual field) which do not cross
these mixed fibres form the optic tract

Question 33

how do the optic tracts travel to the primary visual cortex?

Answer 33

information on the left and right visual fields continue to the lateral geniculate nucleus of the thalamus
from here information is split again into superior and inferior visual fields
- superior visual fields reach the primary visual cortex via the temporal lobe (Meyers loop)
- inferior visual fields will reach the primary visual cortex via the parietal lobe

Question 34

what are the 3 parts of the accommodation reflex?

Answer 34

convergence
thickening of lens
pupillary constriction

Question 35

what nerves mediate the pupillary light reflex?

Answer 35

afferent pathway = CN II (optic)

efferent pathway = CN III (oculomotor)

Question 36

2 divisions of pupillary light reflex?

Answer 36

direct

consensual

Question 37

what is the corneal reflex?

Answer 37

eyes should close in response to a physical stimuli stimuli applied to the cornea

Question 38

what nerves mediate the corneal reflex?

Answer 38

afferent pathway = CN V1

efferent pathway = CN VII

Question 39

describe blood supply to the eye

Answer 39

ophthalmic artery branches off internal carotid (1st branch)
ophthalmic artery branches to:
- central retinal artery = enters via optic nerve and supplies inner retinal layers
- posterior ciliary artery = enters eye outside of optic nerve and supplies middle and outer retinal layers