Neurovasculature of the Orbit

00:01 Let's talk a little bit about the arterial supply to the orbit, which is largely coming from the internal carotid artery via the ophthalmic artery branch.

00:13 One of those branches will travel inside the optic nerve, hence the name central retinal artery.

00:21 Other branches include the lacrimal artery and lacrimal term referring to tears.

00:26 So this is going in the area of the lacrimal gland.

00:30 And there's going to be branches called the lateral palpebral arteries, palpebral referring to eyelid.

00:35 As well as zygomatic branches and we know where the zygomatic bone is to have some idea of that distribution.

00:43 We also have these long and short posterior ciliary arteries, which are going to go in and supply the choroid layer of the eye.

00:55 We're also going to have our super orbital artery, our posterior and anterior ethmoidal arteries.

01:03 Medial palpebral arteries, super trochlear arteries just medial to the super orbital artery.

01:14 We also have the infraorbital artery coming out of the infraorbital foramen which is going to be a branch of the maxillary division.

01:23 In terms of venous drainage, there are many veins that are going to drain back to one of two ophthalmic veins as superior inferior ophthalmic veins.

01:35 So much of the same area we saw in the superior aspects of the orbit will drain into the superior ophthalmic vein.

01:42 Include things like supraorbital veins, supratrochlear vein, dorsal nasal vein, lacrimal vein, various ethmoidal veins, as well as what are called vorticose veins that are draining the choroid the body of the eyeball.

01:59 The central retinal vein will also drain into the superior ophthalmic vein.

02:04 But sometimes it will also drain directly into the cavernous sinus.

02:08 Whoever the superior ophthalmic vein is draining into that anyway, so either way, it'll reach the same destination.

02:15 There's also an inferior ophthalmic vein draining the more inferior aspects of the orbit, including some of the more inferior vorticose veins as well.

02:23 And often it will have a communication with a different source of venous drainage known as the pterygoid plexus, closer to the pterygoid muscles.

02:34 Let's take a look at the innervation of the orbit.

02:38 You mentioned the ocular motor doing the majority of the extra ocular movements, but we also had the trochlear and abducens for superior oblique and lateral rectus respectively.

02:49 We also have a lot of sensory innervation in this area, mostly coming from the ophthalmic division of trigeminal.

02:57 We have the lacrimal branch going off towards the area of the lacrimal gland.

03:02 We have the frontal nerve, which divides into the supraorbital and supratrochlear nerves.

03:08 We have the nasal ciliary nerve and infratrochlear nerves and ethmoidal nerves, as well as the long ciliary nerve.

03:16 We also have the infraorbital nerve, which is coming from the maxillary division of trigeminal.

03:24 Here we see the long and short ciliary nerves in a little closer detail and they sit very close to the optic nerve and that's because they will enter the eye itself over the ciliary nerves are not for the processing of visual stimuli.

03:38 They're for sensory innervation and for innervating the small intrinsic muscles of the eyeball.