Self Study

Question 1

Where does the retina end anteriorly?

Answer 1

At the Ora Serrata, just in front of the equator of the eye

Question 2

Function of the Humours of the eye?

Answer 2

Aqueous humor maintains intraocular pressure

Vitreous Humor cushions the retina

Question 3

Describe the passage of the Aqueous Humor?

Answer 3

• Produced in ciliary body
• Feeds into posterior chamber
• Passes into anterior chamber throught he pupil in front of the lens
• Passes out the angle of the anterior chamber through the trabecular meshwork
• Finally drains out Schlemm’s canal into the episcleral veins

Question 4

What pathologies are visible in relation to the orbital fat?

Answer 4

Starvation/malnutrition - If the eyes look sunken it can mean the person is using up their orbital fat which is one of the last stores to go

Thyroid disease - Orbital fat hypertrophy -> Staring protruding eye appearance

Question 5

What glands exist in the eyelid?

Answer 5

Sebaceous glands at the base of the eyelashes (blockage = external stye)

Meibomian Glands (in the tarsal plate) produce the oily layer of the tear film

Question 6

What is the tarsal plate?

Answer 6

A layer of dense connective issue that gives the eyelid shape

Question 7

What is conjunctiva?

Answer 7

A thin vascular membrane covering the inner surface of the eyelid and the sclera (but not a cornea)

Question 8

Whats the reason for the conjunctiva not covering the cornea?

Answer 8

Its very vascular (and capillaries leak) so it would obstruct the transparent nature of the cornea

Question 9

Where is the lacrimal gland and how is it innervated?

Answer 9

Lateral roof of the orbit

Parasympathetic fibres from the Facial Nerve

Question 10

Where do the lacrimal ducts open into the orbit?

Answer 10

The superior conjuncitval fornix (reflection)

Question 11

How do excess tears drain?

Answer 11

Through punctae on the medial side of each eyelid into the lacrimal sac (over lacrimal bones) and down the nasolacrimal duct into the Inf meatus

Question 12

Explain the innervation of the intrinsic eye muscles

Answer 12

Ciliaris & Constrictor Pupillae = Parasympathetic fibres from Cr N III

Dilator Pupillae = Sympathetic fibres from a plexus around blood vessels

Question 13

Where do the extraocular muscles originate?

Answer 13

Levator Palapebrae Superioris - Roof of orbit
Recti - Annular Fibrous (tendinous) ring
Sup Oblique - Lesser Wing of sphenoid
Inf Oblique - Medial orbital floor

Question 14

What does the oculomotor nerve carry?

Answer 14

Mostly somatic motor innervation to the extraocular muscles.
Some Parasympathetic (Autonomic Motor) fibres --> Synapse at ciliary ganglion --> Ciliaris/Constrictor Pupillae

Question 15

What are the branches of the ophthalmic nerve to the orbit and what do they do?

Answer 15

Enters through Sup Orbital Fissure

• > Nasocilliary nerve
• > Lacrimal nerve
• > Frontal Nerve

Supplies general sensory info to most of the orbit

Question 16

How is the maxillary nerve related to the orbit?

Answer 16

It supplies sensory information to the floor of the orbit and the eyelids.

It passes through the inferior orbital canal into the orbit and out the infraorbital foramen as the infraorbital nerve

Question 17

How does the ophthalmic artery reach the orbit?

Answer 17

Through the optic foramen alongside the optic nerve

Remember its a branch of the ICA

Question 18

What branch of the ophthalmic artery supplies the retina

Answer 18

Central Retinal Art
Travels within the optic nerve
Supplies inner retinal layers (remember outer layers are supplied by the choroid)

Question 19

What arteries supply the choroid?

Answer 19

Short posterior ciliary arteries (branches of the ophthalmic)

Question 20

What arteries supply the ciliary body and iris (and anterior choroid)?

Answer 20

Long Posterior Ciliary Arteries

Question 21

Summary of ophthalmic artery and branches:

Answer 21

Branches from ICA and enters orbit via the Optic Foramen

1) Central Retinal Art –> Travels within optic nerve –> Inner Retinal layers

2) Posterior Ciliary Arteries:
short - Choroid
Long - Iris/ciliary body/ant choroid

3) Ant/Post Ethmoidal Arteries -> Nasal cavity/septum superiorly
4) Muscular Arteries

Question 22

What can we see using an ophthalmoscope and how do we divide it up

Answer 22

The optic disc (a physiological blind spot) and coming off it the central retinal artery and vein

The fovea centralis

We divide the image into 4 quadrants with the intersection on the optic disc:

• Inferonasal
• Superonasal
• Superotemporal
• Inferotemporal

Question 23

What veins drain the eye and to where?

Answer 23

Sup & Inf Ophthalmic veins drain to the cavernous sinus via the sup orbital fissure

Question 24

What lines the intracranial venous sinuses?

Answer 24

Squamous epithelium (Endothelium)

Question 25

What nerves sit in the walls of the cavernous sinus?

Answer 25

Cr N 3,4,5,6 (2 sits just behind it)

Also the ICA passes through the sinus