00:01
Now we're going to
talk about the orbit.
00:04
The orbit is a very special
cavity within the skull
where we're going
to find the eyes.
00:11
The orbits are gonna be formed
by many different bones.
00:15
They're going to form a space
for other structures to fill in.
00:20
So after we talk about the
bones that outline the orbit,
we're going to start filling
in some of those structures.
00:25
Most importantly, we're going
to talk about the eyeball.
00:29
We're also going to talk about the
stuff that's found inside the eyeball,
things like the retina,
the lens and the iris.
00:37
We're also going to
zoom out a little bit
and look at the muscles in the
orbit that act upon the eyeball
to move it around and direct
where eyes are looking.
00:47
Then we're also going to look at
something called the lacrimal system,
which bays are
eyes in tear fluid
to keep them from drying out
naturally help us with our vision.
00:59
The other things is going to
protect our eyes or the eyelids.
01:02
So we're also going
to cover those
and talk about some of the
external and internal features
of the eyelids as well.
01:09
Now let's starting with the bony orbit.
01:13
Here we see parts
of the frontal bone,
maxillary bone,
ethmoid bone,
sphenoid bone,
lacrimal bone,
and zygomatic bone,
as well as a little bit
of the palatine bone
and they all contribute
to the orbit.
01:32
The orbit itself is
somewhat pyramidal shaped
with a very wide opening
or base anteriorly
and getting narrow as
it moves posteriorly
towards the apex.
01:45
Therefore, it also has a roof,
a floor,
a medial wall,
and a lateral wall.
01:54
If we take a closer
look at the roof,
we find the orbital
plate of the frontal bone
as well as the lesser
wing of the sphenoid bone.
02:05
We see some features
in this roof
such as a little depression
called the trochlear fovea,
which is where we're going to find a
little structure called the trochlea.
02:15
We also see a depression
called the lacrimal fossa,
which is we're going to
find that lacrimal gland.
02:22
If we look over at
the medial wall,
here, we find the lacrimal bone
and the orbital plate
of the ethmoid bone
as well as a bit of the
body of the sphenoid.
02:33
We also find some openings here
such as the anterior and
posterior ethmoidal foramena.
02:39
As well as a fossa for something
called the nasal lacrimal sac.
02:45
On the floor,
we have the orbital
plate of the maxilla
as well as some of
the zygomatic bone.
02:53
We also have the orbital
process of the palatine bone.
02:58
We have another space here,
this time called the
inferior orbital fissure.
03:03
And we can see that that's
going to lead to an opening
called the infra orbital canal
that opens up as the
infraorbital foramen anteriorly.
03:14
With the lateral wall,
we see more of
the zygomatic bone
as well as the greater
wing of the sphenoid.
03:21
We have openings here as well
such as the zygomaticotemporal
and zygomaticofacial phenomena.
03:29
We also see the superior
orbital fissure.
03:34
Now let's look at
those openings again.
03:37
We have a little opening at the
superior most aspect of the orbit
called the supraorbital
notch or foramen
depending on how
complete the hole is.
03:47
And this is where we're
going to find passageways
for our supraorbital
neurovasculature.
03:53
We also see an opening
called the optic canal
through which the optic nerve or
cranial nerve II is going to pass.
04:02
The much larger opening called
the superior orbital fissure
is going to contain
multiple nerves
such as cranial nerves
III, IV, V1, and VI.
04:16
We also have a corresponding
inferior orbital fissure.
04:20
That's we're going to find a
branch of the trigeminal nerve
called the maxillary
nerve or cranial nerve V2.
04:27
We also see the
infraorbital foramen again,
and that's going to
be the passageway
for the infraorbital
neurovasculature.
04:35
We see this nasolacrimal canal
which is going to be where we
find the nasolacrimal duct.
04:43
And the nasolacrimal
duct, as the name implies,
is gonna have something
to do with tear drainage.
04:50
We find the ethmoidal foramena,
the anterior and posterior ethmoidal
arteries passing through those.
04:59
And with the zygomatic
temporal foramen,
we have the zygomatic
temporal nerve
and similarly the
zygomaticofacial foramen
with the zygomaticus
facial nerve.