Neurovascular Structures of the Orbit and Development of Eye

Question 1

How does the optic CN leave the orbit?

Answer 1

Via optic foramen

Question 2

How does the trochlear, oculomotor and abducent CNs leave the orbit?

Answer 2

Via superior orbital fissure

Question 3

Which nerve supplies the eye with general sensory innervation?

Answer 3

Trigeminal nerve

(trigeminal nerve provides general sensory innervation for all of head and neck and anterior scalp)

Question 4

Which branches of the trigeminal CN go into the orbit?

Answer 4

V1- ophthalmic branch
V2- maxillary branch

Question 5

Describe the innervation of the V1 ophthalmic branch of the trigeminal nerve.

Answer 5

Enters through superior orbital fissure.
Provides general sensory innervation to upper eyelid and and upper eyeball.

Question 6

Describe the innervation of the V2 maxillary branch of the trigeminal nerve.

Answer 6

Enters through inferior orbital fissure.

Question 7

There is a small branch of the maxillary branch of the trigeminal CN called in the infraorbital nerve. How does this leave the orbit?

Answer 7

Via infraorbital foramen
Supplies general sensation to eyeball

Question 8

What is the main blood supply of the orbit?

Answer 8

Ophthalmic artery

Question 9

Which artery is the ophthalmic artery a branch of?

Answer 9

Internal carotid artery

Question 10

Which two structures enter the optic foramen.

Answer 10

Ophthalmic artery
Optic nerve

Question 11

Name the first branch of the ophthalmic artery.

Answer 11

Central retinal artery

Question 12

What does the central retinal artery supply?

Answer 12

Inner layers of retina

Question 13

There are more branches of the ophthalmic artery known as posterior short ciliary arteries. What do they supply?

Answer 13

Choroid and therefore the outer layers of the retina.

Question 14

What do the long posterior arteries of the eyes supply?

Answer 14

Anterior aspect of choroid
Ciliary body
Iris

Question 15

If using an ophthalmoscope, you will see a round yellow disc at the back of the eye. What is this?

Answer 15

Optic disc- start of the optic nerve

Question 16

Where do all the veins of the eyeball get drained into?

Answer 16

Superior or inferior ophthalmic veins

Question 17

What then do the superior and inferior ophthalmic nerves drain into?

Answer 17

Cavernous sinus

Question 18

Where does the eye develop from?

Answer 18

Part of the neural tube

Question 19

Where do optic vesicles come from?

Answer 19

Grow outwards from the diencephalic part of neural tube

Question 20

What happens once the optic vesicles reach the surface ectoderm?

Answer 20

Cells of surface ectoderm thicken and the lens placode is formed

Question 21

The lens placode starts to push inwards (invaginates). What does the invagination form?

Answer 21

Two layered optic cup

Question 22

As the optic cup is forming, blood vessels pass through forming a fissure. What is this fissure called?

Answer 22

Choroid fissure

Question 23

Which parts of the eye does the surface ectoderm form?

Answer 23

Eyelids
Conjunctiva
Corneal epithelium

Question 24

Which parts of the eye does the mesechyme form?

Answer 24

Choroid
Stroma of cornea
Sclera
Extraocular muscles

Question 25

Which parts of the eye does the lens fibres form?

Answer 25

Epithelium of lens vesicle

Question 26

RECAP- where is the mesenchyme derived from?

Answer 26

Mesoderm and neural crest cells