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.