Neurovascular Structures of the Orbit and Development of Eye Flashcards
How does the optic CN leave the orbit?
Via optic foramen
How does the trochlear, oculomotor and abducent CNs leave the orbit?
Via superior orbital fissure
Which nerve supplies the eye with general sensory innervation?
Trigeminal nerve
(trigeminal nerve provides general sensory innervation for all of head and neck and anterior scalp)
Which branches of the trigeminal CN go into the orbit?
V1- ophthalmic branch
V2- maxillary branch
Describe the innervation of the V1 ophthalmic branch of the trigeminal nerve.
Enters through superior orbital fissure.
Provides general sensory innervation to upper eyelid and and upper eyeball.
Describe the innervation of the V2 maxillary branch of the trigeminal nerve.
Enters through inferior orbital fissure.
There is a small branch of the maxillary branch of the trigeminal CN called in the infraorbital nerve. How does this leave the orbit?
Via infraorbital foramen
Supplies general sensation to eyeball
What is the main blood supply of the orbit?
Ophthalmic artery
Which artery is the ophthalmic artery a branch of?
Internal carotid artery
Which two structures enter the optic foramen.
Ophthalmic artery
Optic nerve
Name the first branch of the ophthalmic artery.
Central retinal artery
What does the central retinal artery supply?
Inner layers of retina
There are more branches of the ophthalmic artery known as posterior short ciliary arteries. What do they supply?
Choroid and therefore the outer layers of the retina.
What do the long posterior arteries of the eyes supply?
Anterior aspect of choroid
Ciliary body
Iris
If using an ophthalmoscope, you will see a round yellow disc at the back of the eye. What is this?
Optic disc- start of the optic nerve
Where do all the veins of the eyeball get drained into?
Superior or inferior ophthalmic veins
What then do the superior and inferior ophthalmic nerves drain into?
Cavernous sinus
Where does the eye develop from?
Part of the neural tube
Where do optic vesicles come from?
Grow outwards from the diencephalic part of neural tube
What happens once the optic vesicles reach the surface ectoderm?
Cells of surface ectoderm thicken and the lens placode is formed
The lens placode starts to push inwards (invaginates). What does the invagination form?
Two layered optic cup
As the optic cup is forming, blood vessels pass through forming a fissure. What is this fissure called?
Choroid fissure
Which parts of the eye does the surface ectoderm form?
Eyelids
Conjunctiva
Corneal epithelium
Which parts of the eye does the mesechyme form?
Choroid
Stroma of cornea
Sclera
Extraocular muscles
Which parts of the eye does the lens fibres form?
Epithelium of lens vesicle
RECAP- where is the mesenchyme derived from?
Mesoderm and neural crest cells
