Hello, everyone! This is Joao from Kenhub, and welcome to another anatomy tutorial where, this time, we’re going to be talking about the orbit, specifically the different blood vessels that you can find in the orbit.
So what we’re going to be doing here on this tutorial is going to this part of your body, specifically the orbit, and we’re going to be describing the different arteries and also veins that we find in this area.
We’re going to start off with this one that you see here on the screen, highlighted in green, because this is one of the main arteries of the orbit that will, then, offer the different branches that you’re going to be seeing here.
Now, this one is known as the internal carotid artery. This is a major paired artery, so you have one on each side of your head. And in general, this artery is going to be supplying the brain but gives off many branches which supply other areas.
The next one that we’re going to be talking about that you see here highlighted in green, this one is the ophthalmic artery. And the ophthalmic artery is the first branch of the internal carotid artery, that artery that we saw on the previous slide.
And keep in mind that right now, we’re looking at a superior view of the orbit where we cut the skull in a way to expose this area of your body, and then here you see the superior view of the ophthalmic artery.
Now, branches of the ophthalmic artery will be supplying all the structures in the orbit as well as some structures in the nose, face, and meninges.
Now, one important point that I want to make here is that the ophthalmic artery will be, then, splitting into different branches, numerous branches that we’re going to be covering here on this tutorial.
There are two main images that we see here throughout this tutorial. The first one I already told you about, which is the superior view. But this one that we also saw in the beginning, this is the lateral view of the orbit where we can expose these structures.
You’ll also see other structures here, like some nerves as you can see here that are usually or they are closely nearby these arteries that we’re going to talk about.
We’re now… right now, the main focus is this one here, the ophthalmic artery which is highlighted in green, which gives numerous branches, such as the central retinal artery, the ciliary, the lacrimal, the supraorbital, the anterior and posterior ethmoidal, the supratrochlear, the dorsal nasal, and finally, some muscular branches that we’re going to be seeing as well.
Let’s start off with the very first one here on the list.
Now again, from a superior view, we see here this highlight, this tiny structure here. This one is then the central retinal artery.
And as I mentioned before, this is a branch of the ophthalmic artery running inferior to the optic nerve within its dural sheath to, then, the eyeball.
The central retinal artery supplies all the nerve fibers that form the optic nerve that carries visual information to the lateral geniculate nucleus of the thalamus, including those that reach over the fovea
The next set of arteries that we’re going to be talking about are known as the ciliary arteries which you now see from a lateral view, these structures highlighted in green here. But here on this tutorial, we’re going to be focusing mainly on the posterior ciliary arteries.
However, it’s important to highlight that the ciliary arteries are divided into three groups: the long posterior, the short posterior, and the anterior ciliary arteries. However, we’re going to be focusing on the major group, which is the posterior ciliary arteries.
So the first thing I would like to say about the posterior ciliary arteries is that they arise from or they’re branches of the ophthalmic artery, and they will be supplying such structures as the iris, the ciliary body, choroid, and the ciliary processes.
Moving on to the next structure, the next artery that we’re going to be seeing here, this is known as the lacrimal artery.
And you probably have guessed because this artery is going all the way to, then, this structure here, which is the lacrimal gland.
The lacrimal artery arises from the optic foramen and is one of the largest branches derived from the ophthalmic artery.
Now, the branches of the lacrimal artery will be anastomosing with other arteries. In other words, they’re going to be, the lacrimal artery is going to be connecting with the medial palpebral arteries, the deep temporal arteries, the transverse facial arteries, and also a branch of the middle meningeal artery.
The lacrimal artery is going to be supplying different structures, including the gland that it pierces, the lacrimal gland. And you can also see here on this lateral view. Notice here the lacrimal gland and how the lacrimal artery is then piercing this structure.
Now, another one will be the eyelids. It will be also supplied by this artery and the conjunctiva.
We’re going to move on and talk about this structure that you see now highlighted from a superior view. This one is known as the supraorbital artery, which is also a branch of this structure here, this artery, which is known as the ophthalmic artery.
Notice here how the supraorbital artery, highlighted in green, is then branching off of this artery, the ophthalmic.
Now, as the vessel is crossing over the medial side of the optic nerve, this is when it’s going to be branching off.
And when passing through the supraorbital notch, it divides into a superficial and deep branch.
Its terminal branches will be anastomosing with other structures, other arteries known as the supratrochlear artery and also will be anastomosing with the superficial temporal arteries.
Now, the supraorbital artery will be supplying a lot of structures, including the levator palpebrae superioris (so a muscle), also the diploë of the frontal bone. The frontal sinus will be supplied by the supraorbital artery as well. The upper eyelid or the superior eyelid, and the skin of the forehead and the scalp.
So all these structures will be supplied by the supraorbital artery.
We’re going to move on to a group of two arteries that you see now from a superior view highlighted in green. These are the ethmoidal arteries.
And on the left image, you’re seeing the anterior ethmoidal artery, and on the right side, we’re seeing the posterior ethmoidal artery.
And we’re going to also show you these structures from a lateral view, as you can see here where we remove the eye and a lot of the structures here so you can see just the anterior ethmoidal artery here and, posteriorly, the posterior ethmoidal artery.
And notice here that this is the front of your skull—so this is the anterior portion of your skull—and how these two are, then, positioned.
And again, we’re looking at a lateral view of the orbit.
An important point I would like to add about the ethmoidal arteries is that they are branches of the ophthalmic artery, which you can clearly see here. This is the ophthalmic artery and how these two are branching out of the ophthalmic artery.
They enter the orbit but do not supply any relevant structures of the orbit. Therefore we will not get into details on these two arteries.
We’re moving on to another artery that you see here highlighted from a lateral view. We’re looking at the supratrochlear artery.
Now, the supratrochlear artery also called frontal artery is one of the terminal branches of the ophthalmic artery. And similarly, it passes through the orbit but only supplies structures outside the orbit, such as the pericranium and some of the face muscles.
Ready to move on to a next artery here, also from a lateral view. We’re looking at the dorsal nasal artery.
And the dorsal nasal arteries are arteries of the head, and they are the terminal branches, also one of the two terminal branches of the ophthalmic artery.
The dorsal nasal artery emerges from the orbit above the medial palpebral ligament and then will be supplying part… the upper part of the lacrimal sac and some parts of the nose as well.
We’re going to finalize the list of arteries with these that you see here highlighted in green from a lateral view. We’re looking at the muscular branches of the ophthalmic artery.
And as you probably guessed by the name, these will be then branching off of the ophthalmic artery and supplying the extra ocular muscles.
We’re ready to move on to the next set of blood vessels that you see now from a superior view.
We’re going to be talking about the veins now, and the list is the pterygoid plexus, the vorticose veins, the inferior ophthalmic, the superior ophthalmic, the cavernous sinus, and this is the list that we’re going to be looking at.
And we’re going to, of course, start with the first one on that list that you see here highlighted in green. From this lateral view, we’re looking at the pterygoid plexus.
Now the pterygoid plexus is a venous plexus of considerable size and is located partially between the two pterygoid muscles.
It receives blood from numerous veins and drains it into the maxillary vein.
The next set of veins that we’re going to be talking about are these tiny ones that you see from a lateral view. These are known as the vorticose veins. They’re also called, sometimes, as vortex veins, and they collect blood from the ocular choroid and drain it into the inferior and superior ophthalmic veins.
Now, let’s talk about this one that you see here highlighted in green, which you remember from the previous slide. This is where the vorticose veins will be draining into, and yes, this is the inferior ophthalmic vein, and you can also see here the vorticose veins and how they connect here with the inferior ophthalmic vein.
We’re still looking at a lateral side of, a lateral view of these structures.
Now, the inferior ophthalmic vein begins in the venous network at the most anterior part of the floor and medial wall of the orbit.
And as I mentioned, it receives blood from some vorticose veins and also the rectus inferior muscle, the inferior oblique muscle, the lacrimal sac, and also from the eyelids.
Then, it drains into the superior ophthalmic vein and the cavernous sinus.
If there is an inferior ophthalmic vein, there should be this one that we’re going to be talking about that we’re looking now from a superior view. This is the superior ophthalmic vein.
Now, the superior ophthalmic vein begins at the inner angle of the orbit. It receives blood from the ethmoidal veins, the vorticose veins, and also the inferior ophthalmic vein. And then the superior ophthalmic vein will be draining into the cavernous sinus.
And we’ve been talking about this next structure throughout this tutorial. It’s time to just talk about it. And you see here highlighted, this is an important structure which is known as the cavernous sinus.
Now, the cavernous sinus is a large collection of thin-walled veins creating a cavity bordered by the temporal bone of the skull and the sphenoid bone.
This structure will be receiving blood from the middle cerebral vein, the sphenoparietal sinus, and the superior and inferior ophthalmic veins.
Then it will drain the blood into the inferior and superior petrosal sinuses.