Welcome back, we're going to talk more about some of the
important, larger structures of the eye.
And to give you some anatomical landmarks, so that when we
get into the pathology of the eye,
you'll be able to understand what's going on,
not only from a kind of a structural point of view,
but also from a pathologic and cellular point of view.
Again, I want to acknowledge the hard work and efforts of
Dr. José Mata who made all of this possible.
We're going to look very briefly again, at the innervation
of the ocular muscles,
we will spend an entire session just talking about how the
and the various cranial nerve palsies that affect eye
It's going to be kind of creative redundancy, you'll see it
a couple different times.
But again, we're going to kind of review it very briefly
So, cranial nerve III , innervates a whole bunch of muscles,
it's the superior rectus, the inferior rectus, the inferior
oblique, and the medial rectus.
And if cranial nerve III, or any of its outputs are
defective, when a patient is staring straight ahead,
the net impact will be that there's no input bringing eye
back to the middle of the vision,
it's going to be pulled down and out largely through the
effects on the superior rectus.
So that's going to be a dominant effect.
And the eye will look like a lazy eye going down to -
down and out because of the residual superior oblique
If we, on the other hand, hit or nick or destroyed the
the trochlear nerve, that's going to be Cranial Nerve number
it's going to be supplying the superior oblique.
So now we cannot pull the eye down and out.
We really only see that mostly when we try to have the eye
So, the cranial nerve IV palsy, the patient is looking off
to the side.
And their right eye should have the actual iris and pupil
down more midline
in the mid palpebral fissure, just like the left eye is.
That right eye however because it cannot be pulled down and
out by the trochlear
is in the superior oblique, means that it ends up looking
Okay, that's that palsy.
And then, we can have a cranial nerve VI palsy,
cranial nerve VI is going to be innervating the lateral
which is going to be important for making the eye look
So, when you're looking straight ahead that eye will not be
able to pull to the outside
and so the cranial nerve palsy is reflected as kind of
looking a little bit cross-eyed with just one eye.
Again, until you play with this a little bit and think about
it a lot it can be a little bit confusing.
We will return, we will have a session that's almost
exclusively all about eye movement,
but just a brief kind of creative redundancy.