Video: Muscles of the orbit

Hello, everyone! This is Joao from Kenhub, and welcome to another anatomy tutorial where, today, we’re going to be talking about the muscles of the orbit. On this tutorial, we will take a look at the muscles and related structures of the orbit. We will be focusing on the muscles that control the movement of the eye and the related structures.

Now, without keeping you waiting, I’m going to show you the first structure that we’re going to be talking about, this muscle that you see here, highlighted in green, which is known as the levator palpebrae superioris. And keep in mind that we’re looking at the muscle from a lateral left view.

Now, as the name suggests, this is the muscle responsible for lifting of the upper eyelid. So the contraction of this muscle elevates your eyelids.

And in terms of innervation, the muscle is going to be innervated by the oculomotor nerve or cranial nerve number three.

And if you take a closure look here at this image, you notice that this muscle originates from the lesser wing of the sphenoid bone. And I can also show you here this image that we can look at the muscle from a superior view. If we were to section the skull and expose the orbit from a superior view, then this is how the levator palpebrae superioris would be seen.

And you can also see here the lesser wing of the sphenoid section and the origin point for this muscle.

We’re now ready to move on to the next muscle that you see here, highlighted in green, laterally. This is the superior oblique muscle, which is innervated by the trochlear nerve or cranial nerve number four. It has its origin from the body of the sphenoid bone, as you can also see here, and passes through the trochlear, inserting in the posterolateral part of the sclera.

Now, the contraction of this muscle abducts, depresses, and medially rotates the eye. And you can see, also here, an image from a superior view of the superior oblique muscle.

Next muscle that we’re going to be talking about is this one, seen also highlighted. This is known as the superior rectus muscle. And the superior rectus muscle elevates and medially rotates the eye. It is innervated by the oculomotor nerve or cranial nerve number three. It has its origin from the common tendinous ring, and it inserts on the sclera of the eye, as you can see. So origin point here, and then the insertion point on the sclera of the eye.

We’re now looking at this muscle that you’re seeing here, highlighted in green. And now we’re looking from an anterior view of the eye. This is known as the medial rectus muscle. And the contraction of the medial rectus muscle adducts the eye. It has an origin from the common tendinous ring.

This muscle is innervated by the oculomotor nerve, so cranial nerve number three. And the contraction of the medial rectus muscle adducts the eye. It has its origin from a common tendinous ring along with the other extrinsic muscles of the eyes.

So as you can see here, this is going to be the origin point for the medial rectus.

We’re now ready to move on to the next one that you see here, highlighted. This is, then, the lateral rectus muscle. We’re looking at the eye again from a lateral point of view, and you can clearly see now this muscle.

And this muscle is innervated by the abducens nerve, so cranial nerve number six.

The lateral rectus muscle is located on the lateral side of the eye, as you can clearly see here. Also has its origin from the common tendinous ring, this common tendinous ring that you see here. And it functions to abduct the corneal pole.

We’re now ready to move on to the next muscle that you see here, also from a lateral view, highlighted in green. This is known as the inferior rectus muscle. And this muscle is innervated by the oculomotor nerve or cranial nerve number three.

And the inferior rectus muscle functions to depress and rotate the eye laterally. And similar to the other extrinsic muscles of the eye, the inferior rectus has its origin from the common tendinous ring.

The next muscle that we’re going to be talking about is this one that you see here. This is known as the inferior oblique muscle. And it is innervated by the oculomotor nerve, so cranial nerve number three.

The inferior oblique muscle functions to rotate the eye laterally as well as to elevate and abduct the eye. It has its origin point on the lateral side of the nasolacrimal canal, as you can see here on this image.

So we’re done covering the different muscles of the orbit to now cover or just mention this green structure that you... or this structure highlighted in green, which is an important structure that we talked about in a few muscles here. This is known as the common tendinous ring.

Now, the common tendinous ring works as a common origin for the recti ocular muscles. And this common tendinous ring is an annular ligament surrounding the optic canal on the medial part of the superior orbital fissure, as you can see here, also from a superior view.