Hi, this is Dr. Kingston,
and in this video, we'll be discussing
the vascular supply of the orbit.
The objectives for this video are to trace
the branches of the ophthalmic artery and vein,
and then to describe the relationships of
the orbital neurovasculature within
the cavernous sinus, within the cranium.
The arterial supply for
the orbit comes from the ophthalmic artery.
The ophthalmic artery is
a branch of the internal carotid.
So here's the internal carotid
and here's the ophthalmic artery.
It's going to branch off that internal carotid,
right as it emerges from the cavernous sinus.
It's then going to travel with the optic nerve through
the optic canal and into the posterior orbit.
Once it arrives in the orbit,
it's going to start to give off branches.
The first branch that it gives off
is the central retinal artery.
And this one is a little
bit different from all the others.
It's going to pierce the dura
that surrounds the optic nerve.
And it's going to travel through
that optic nerve to reach the eye.
The subsequent branches that come off then are going
to share the names of branches of V1 that they run with.
So we have a lacrimal artery,
we've got a supratrochlear artery.
And if I had a little bit more on this picture here,
we would see a supraorbital as well.
There are two opthalmic veins that drain the orbit,
and these are both going to drain
into the cavernous sinus.
So the cavernous sinus, remember,
is this cranial dural sinus
that runs right next to the sphenoid here.
And then will eventually drainby
the inferior petrosal sinus down to the jugular vein,
The superior ophthalmic artery,
so this one here, is going to drain the superior orbit,
the eye, the ethmoid air cells
and even a little bit of the forehead.
It also has connections to
the facial vein via the angular vein.
So that's the one that runs right
up to the bridge of the nose there.
The inferior ophthalmic vein,
this one down here, is going to drain
the inferior orbit and part of the face.
It also has connections to the facial vein and also down
into the pterygoid plexus of
veins that sit in the infratemporal fossa.
These connections are important
to remember because they can
be a pathway for infection to spread.
And they're especially important here because
those ophthalmic veins drain
directly into the cavernous sinus,
which sits around the brain inside the cranium.
Now that cavernous sinus also has
some important relationships to
the nerves that supply the orbit as well.
In this picture here we can see
the cavernous sinus within the dura.
And in this image here,
the dura has been peeled off so we can
see the pathway that these nerves travel.
So traveling through parts of the cavernous sinus,
we have the oculomotor nerve,
the trochlear nerve,
the ophthalmic nerve, the abducens nerve.
All right. I've included maxillary
here because you can see it.
So that's V2.
Ophthalmic, remember, is V1 right there.
Now some of these are going to travel through
the wall of the cavernous sinus.
And if we look down here, we can
see which ones those are.
We have the oculomotor nerve, trochlear nerve,
ophthalmic nerve, and a little bit
of the maxillary nerve as well.
The abducent nerve is a little bit special.
I should say, we're going to call this the abducens.
Some texts call it abducent,
as you can see right here,
we're going to stick with abducens.
And that travels right through the sinus itself.
So it is bathed on all sides by blood.
So if you were to get
an infection in your cavernous sinus,
it would most likely affect your abducens nerve first.
I will note too that all of these nerves might be
affected by a infection within the cavernous sinus.
We call that a cavernous sinus thrombosis.
The ones that are traveling through
the wall are just likely to
be affected after the abducens nerve.
All right.
I have given you guys so many
hard practice questions for this session,
but I'm going to end it with giving you an easy one.
And the correct answer is C,
the central retinal artery.
This is the branch of
the ophthalmic that is going to pierce the dura that
surrounds the optic nerve and travel
right through its center to enter the eyeball.
And that is the end of that.
Thank you guys for watching.