This is the second tutorial on the foramina of the skull.
In this tutorial, I'm going to be looking at the different structures that pass through
the foramina in the skull, so the vessels and nerves that pass through these little
holes.
It's quite important to know because -- well, medical schools love asking about which structures
pass through which foramina.
I'm assuming you've watched the tutorial before and it would also be quite useful if you've
watched the tutorial on the cranial nerves or if you've read up a little bit about the
cranial nerves.
It makes it a bit easier to understand.
So looking from the outside, starting inferiorly, we've got the mental foramen, foramina.
You can see these nerves and vessels emerging.
You've got the mental nerves and the mental vessels that emerge from here.
You've got these foramina just below the orbit, the infraorbital foramen and you've got the
infraorbital vessels and nerves that come out of here.
And then you've got these little notch here called the supraorbital notch.
So you can see these supraorbital vessels and nerve runs through this notch.
And then we've got the foramina in the orbit of the eye, the optic canal and the superior
orbital fissure.
So what I think I'm going to do is I'm going to switch to an intracranial view.
So that's the base of the skull, wrong view.
Here we go.
This is the view we were looking at the previous tutorial, but now we're going to be looking
at nerves and vessels that pass through these holes.
So starting anteriorly -- so this is looking from behind.
If I just rotate around, this is anterior (this end) and posterior is this side -- you
could see here this big nerve.
So now we're looking from the front directly at the brain stem and the nerves that are
emerging from it.
You can see this big, fat nerve, which crosses over.
This is the optic nerve.
You can see this bit here, which is the optic chiasm.
This nerve passes through the optic canal.
We can look that from -- this is cranial nerve II and you can see it passing through this
hole here, so the optic chiasm lies here and the optic nerves run out through the optic
canal.
So that's cranial nerve II that goes through the optic canal.
And if we look at it from the front, you can see it coming out.
So also, what runs through the optic canal is the ophthalmic artery.
We've got the optic nerve and the ophthalmic artery that run through the optic canal.
So next, we've got the superior orbital fissure.
This is this big opening in the skull here.
You can see it from the trunk.
Anteriorly, you've got this superior orbital fissure.
And if I zoom in quite a bit, you can see that quite a few little nerves emerge from
this fissure.
I'll just flick back to the other view and we'll take a look at what those nerves are.
This is where knowledge of the cranial nerves is quite useful for learning what passes through
the foramina.
So you've got a couple of nerves, quite a few nerves that pass through the superior
orbital fissure.
You've got the ocular motor nerve, the trochlear nerve, the ophthalmic branch of the trigeminal
nerve, the abducent nerve and you've got ophthalmic veins that pass through here.
So a lot of structures to remember, but here, we're just going to be looking at the cranial
nerves.
So if I just rotate around, you can see this nerve here which is the ocular motor nerve.
So that runs through the superior orbital fissure.
Just remember, these are all nerves to do with the eyes.
So the ocular motor nerve has to do with the movement of the eyes, trochlear nerve has
to do with the movement of the eyes, ophthalmic nerve is a branch of the trigeminal nerve,
which has to do with sensation around the eye region and the abducent nerve is the nerve
responsible for abducting the eye.
So these are all eye muscle and eye sensation nerves that pass through the superior orbital
fissure.
So if you just think of the muscles of the eye and which nerve supplies them, these are
generally the nerves that pass through the superior orbital fissure.
So you can see this nerve here, which emerges just medial and inferior to the inferior colliculus
and winds around and passes through the superior orbital fissure.
This is the trochlear nerve.
And then you've got this nerve, which comes right from the base of the pons.
If I zoom in, you can see that.
This nerve coming from the base of the pons, this is the abducent nerve and that passes
through the superior orbital fissure.
And then you can see this thick trunk here.
This is the trigeminal nerve.
It's got three branches.
You've got the superior branch here, which is the ophthalmic branch, you've got the maxillary
branch and the mandibular branch.
So trigeminal nerve is cranial nerve V and the branches are labeled V1, the ophthalmic;
V2, the maxillary; V3, the mandibular.
So you've got the ophthalmic branch of the trigeminal nerve passing through the superior
orbital fissure.
So again, it's related to the eyes because it supplies sensation around the eye region.
So those are the four nerves which you can see passing through.
Just to go over, you've got the ocular motor, the trochlear, the abducent nerve and the
ophthalmic branch of the trigeminal.
And you've also got ophthalmic veins which pass through the superior orbital fissure.
So next, we're going to go down to this.
We just looked at the superior orbital fissure.
Just to show you again, that was this fissure here.
That's the superior orbital fissure.
And now, we're going to be looking at this little hole here, the foramen rotundum, which
you've got obviously on either side.
So that's that little hole just inferior to the superior orbital fissure.
It's this hole here.
And what you've got, as you can see, you've got the second branch of the trigeminal, which
passes through this.
The foramen rotundum allows the maxillary branch of the trigeminal nerve to pass through.
You can see that on either side, this branch here.
The maxillary branch passes through the foramen rotundum.
And then just looking at the next branch of the trigeminal, the mandibular branch, you
can see that passes through this foramen here.
So that's this one, the foramen ovale.
The mandibular branch V3 of the trigeminal passes through the foramen ovale.
There's quite a lot to remember with all these different structures passing through all these
foramen.
I actually remembered it using really silly mnemonic, which may not make any sense, but
it helps me remember stuff.
The more stupid things they are, the easier they are to remember.
I had a friend called Max who was pretty fat.
So I thought of Max as 'rotund'.
So the maxillary branch passes through the foramen rotundum.
My fat friend, Max, Max is 'rotund'.
The maxillary branch passes through the foramen rotundum.
I didn't have a friend called Mandy, but I imagined she was oval.
Mandy is oval and Max is rotund.
So the maxillary branch of the trigeminal passes through the foramen rotundum and the
mandibular branch of the trigeminal passes through the foramen ovale.
So Mandy is oval and Max is rotund, that's how I remembered it.
It sounds stupid, but it helped me remember.
So that may be useful or may just be a load of rubbish.
So we've gone through the superior orbital fissure, the foramen rotundum, the foramen
ovale and we've done the optic canal.
So next, we're going to keep working our way back.
So just to show you this view, the optic canal, the superior orbital fissure there, the foramen
rotundum, the foramen ovale, and now we've got this lateral foramen, which is the foramen
spinosum.
So what we've got passing through here is the middle meningeal artery.
So that's that artery that lies behind pterion and is often damaged by blows to the temple.
So if we just take a look -- no, not that view.
So this is the foramen spinosum lateral to the foramen ovale.
So I think the best way to show you this is from the base of skull view.
Let's just see what I'm doing.
I've got the skull here, I'm just rotating it so you can see...