How does the eye see (anatomy)

Question 1

What protects the eye from a direct blow from any object of diameter greater than that of the orbital rim?

Answer 1

The orbital margins

Question 2

Which parts of the orbit are most often affected in an orbital blow out fracture?

Answer 2

The medial wall of the orbit and the orbital floor (extremely thin 0.5-1mm)

-orbital rim remains in tact

Question 3

When might the infraorbital canal/infraorbital NVB be damaged and what does this mean?

Answer 3

When the fractured zygoma rotates medially

-this will result in a general sensory deficit of the facial skin

Question 4

Sphincter of the eye

Fibres surround the eyelids used to “screw up the eyes”

Answer 4

Orbicularis oculi

-used in blinking

Question 5

Orbicularis oculi

Answer 5

Screw up the eyes

-within the eyelids, used in blinking

Question 6

What is the purpose of the orbital septum?

Answer 6

Helps prevent the spread of infection from superficial (periorbital cellulitis) to deep (orbital cellulitis)

Question 7

Muscle which raised the eyelid?

Answer 7

Levator palpebrae superioris

-contains skeletal and smooth muscle

Question 8

Function of the tarsal glands?

Answer 8

Lipid secretion

Question 9

What is the conjunctival formix?

Answer 9

Where the conjunctiva is reflected off the sclera and onto the internal aspect of the eyelid

Question 10

Sympathetic nerve supply to the lacrimal gland?

Answer 10

CN VII

Question 11

This ducts carries tears to the inferior meatus of the nasal cavity

Answer 11

Nasolacrimal duct

Question 12

The 2 corneal reflections and their significance

Answer 12

The nasal and temporal (used clinically to track the symmetry of bilateral eye position/movements)

Question 13

The 2 layers of the fibrous layer of the eye

Answer 13

The sclera

Cornea

Question 14

Protective/attachment for the extra-ocular muscles

Answer 14

The sclera

Question 15

Provides 2/3rds of the eye’s refractive power

Answer 15

The cornea

Question 16

Controls the iris, the shape of the lens and the secretion of aqueous humor

Answer 16

The ciliary body

Question 17

What is the choroid responsible for?

Answer 17

Nutrition and gaseous exchange for the other layers

Question 18

is the common location of “floaters” caused by areas of liquefaction of the gel & clumping of collagen fibres/cells

Answer 18

Vitreous body

Question 19

What is the anterior chamber?

Answer 19

The space between the cornea and the iris: contains aqueous

Question 20

What is in the posterior chamber?

Answer 20

Contains the lens and aqueous humor

Located between the iris and the ciliary body

Question 21

What is in the posterior segment of the eye?

Answer 21

Sclera, choroid, retina, vitreous body

Question 22

The 3 layers of the retina

Answer 22

1) photoreceptors
2) ganglion cells (anterior to the photoreceptors)
3) The axons of the ganglion cells (lie anterior to photoreceptor cells and ganglion cells)

The retinal veins and retinal arteries lie anterior to the retina

Question 23

Where are the visual cortices?

Answer 23

In the occipital lobes

Question 24

Function of levator palpebrae superioris?

Answer 24

Lifts the upper eyelid

Question 25

Where do all of the rectus muscles originate from?

Answer 25

The common tendinous ring (attached to bones surrounding the optic canal)

Question 26

This muscle attaches to the anteromedial floor of the orbit

Answer 26

The inferior oblique

Question 27

LR6

Answer 27

Lateral Rectus

CNVI (abducent nerve)

Question 28

SO4

Answer 28

Superior oblique

CNIV (trochlear nerve)

Question 29

AO3

Answer 29

All others

CNIII (oculomoter nerve)

Question 30

Secretes aqueous

Answer 30

Ciliary body

Question 31

Route of aqueous

Answer 31

1) circulates around lens within posterior chamber
2) Then into pupil and anterior chamber
3) Then reabsorbed into the scleral venous sinus (Canal of Schlemm) at the iridocorneal angle

Question 32

Where is CNII formed from all of the axons leaving the retina?

Answer 32

Formed at the optic disc

Question 33

What is the fundus?

Answer 33

The retina + macula + fovea centralis + optic disc

Question 34

The opthalmic artery is a branch of which artery?

Answer 34

The internal carotid

Question 35

How to tell the difference between the internal and external carotid artery? e.g. if they gave you a prosection of just the neck and you couldn’t tell?

Answer 35

The internal carotid has no branches in the neck!

Question 36

The opthalmic artery travels in which canal?

Answer 36

The optic canal

Question 37

Nasal branches of which artery contribute to Kiesselbach’s area?

Answer 37

Nasal branches of the opthalmic artery

Question 38

The only vein draining the retina?

Answer 38

The central vein of the retina

Question 39

What is an end artery?

Answer 39

An artery with insufficient anastamoses to maintain viability of the tissue supplied if arterial occlusion occurs

Question 40

What is the danger triangle of the face?

Answer 40

The upper lip and the external nose

-here you can have retrograde spread of infection via superficial veins into the cranial cavity

Question 41

The inferior opthalmic vein drains into which vein?

Answer 41

Drains into the superior opthalmic vein

-this then drains posteriorly into the cavernous sinus (via the superior orbital fissure)

Question 42

Which arteries and veins are responsible for the “red eye” appearance in flash photography?

Answer 42

The ciliary arteries and veins of the uvea

Question 43

The blind spot of the visual field corresponds to this

Answer 43

The optic disc

Question 44

The only point of entry/exit from the retina for blood vessels and the axons of CNII?

Answer 44

The optic disc

Question 45

Retinal artery occlusion and retinal vein occlusion

Answer 45

complete interruption of flow in a retinal artery branch/”branch” retinal vein = loss of an area of visual field corresponding to the area of ischaemia
b) complete interruption of flow of the central artery (end artery) or vein = monocular blindness