...buccinator.
So this muscle is a muscle that forms the muscular component of the cheek.
This is used when you're puffing out your cheeks and blowing air out of your mouth.
So when you're testing the patient's seventh nerve and you ask them to puff out their cheeks,
you're testing the function of the buccinator muscle.
So if you have to just remember four muscles from this tutorial, then try to remember these
ones, the occipitofrontalis (which I showed you at the beginning with its occipital and
frontal bellies), the orbicularis oculi (which closes the eyelids), the orbicularis oris
here (which purses the lips, closes the mouth) and the buccinator (which is the muscular
component of the cheek wall and which is used for forcefully expelling air from the mouth).
So now I'm just going to cover the remaining muscles in the oral group of the facial muscles.
I'll break it down into an upper group and a lower group.
So starting laterally, we've got the right risorius.
So just by looking at where the muscle inserts, you can get an idea of what the function of
that muscle will be.
You can see that the risorius inserts onto the corner of the mouth.
When it contracts, it will retract the corner of the mouth along this direction.
So that's the risorius and you've got these muscles on both sides just (so just that you're
aware of that).
So moving superiorly, we've got the zygomaticus major.
And again, looking at the point of insertion, you can see that when this muscle contracts,
it will draw the corner of the mouth in an upward and lateral direction.
And just adjacent to the zygomaticus major, you've got the zygomaticus minor.
What this muscle does is it inserts onto the upper corner of the mouth and it draws the
lip upwards.
Next, we've got the levator labii superioris.
And again, the name of this muscle indicates what the function and where it inserts.
So 'levator' means elevator/lifter, 'labii' is Latin for lips and 'superioris' means upper,
so it's the lifter of the upper lip.
So immediately, it tells you what the muscle function is.
And if we just look a bit closer, we can see the muscle that lies underneath it.
This is the levator anguli oris.
So remember, 'oris/orifice' refers to the mouth, 'anguli' means corner in Latin, so
it's the lifter of the corner of the mouth.
It raises the corner of the mouth.
And just medial to that, we've got levator labii superioris alaeque nasi.
Now that's a really long name and it's just Latin.
So it means lifter of the upper lip and of the alar cartilage of the nose.
So 'labii' is lips, 'superioris' is upper, 'alaeque' means and of the alar cartilage
and 'nasi' means of the nose.
So this has the function to lift the upper lip and it also opens the nostril, the alar
cartilage part.
That's quite a long one to remember.
So just to quickly go over those ones, you've got the risorius here (which is lateral and
it inserts onto the corner of the mouth and which retracts the corner of the mouth), you've
got the zygomaticus major and minor and then you've got the levator labii superioris and
the levator anguli oris.
So just moving on to the lower group of oral muscles.
There are a fewer muscles.
If you just replace 'levator' with 'depressor', you essentially get the muscle names for these
group of muscles.
So laterally, you've got depressor anguli oris.
So if you remember the Latin, 'anguli' means corner, 'oris' refers to mouth and 'depressor'
obviously means it depresses, so it depresses the corner of the mouth.
This is the most superficial muscle of the lower group of oral muscles and it depresses
the corner of the mouth.
So just moving slightly medially, we've got depressor labii inferioris, the counterpart
to levator labii superioris.
So this muscle depresses the lower lip.
Again, Latin 'depressor' means depressor, 'labii' means lip, 'inferioris' means lower.
So what this muscle does is it depresses the lower lip and the direction of the fibers
means that it also moves it laterally as well.
So that's just deep to the depressor anguli oris.
And then deep to this muscle, the depressor labii inferioris, you've got the mentalis
muscle.
What this muscle does is it helps to position the lip for instance, when you're drinking
from a cup or something like that.
Those are the muscles of the oral group of the mouth.
There are a lot of muscles and the names are quite long and complicated and if you just
try to memorize them off by heart, it becomes quite hard, so that's why I tried to explain
to you the meaning of the names because if you think about that, it's actually quite
simple.
So if you think of the corner of the mouth, anguli.
If you think of the position, which lip is it moving, upper or lower (so it would either
be superior or inferioris) and if you think of the action of the mouth, depressor (if
it's on the lower part because it's depressing it) and levator (if it's on the upper part
and it's elevating it).
So those are all the muscles which are involved in producing movements of the mouth, the oral
group of muscles.
So the final muscle group to talk about is this muscle around the ear.
These are the auricular muscles.
You've got three muscles.
You've got the auricularis posterior, the auricularis superior and the auricularis anterior.
Their function is pretty evident from their position.
So the posterior muscle pulls the ear backwards, the superior muscle elevates the ear and the
anterior muscle pulls the ear upwards and forwards.
So those are the auricular muscles.
So just to quickly recap, muscles of facial expression, you've got the occipitofrontalis
with its two bellies, occipital and frontal bellies and then you've got other muscles
of the face, which can be broken down into the orbital group, the nasal group and the
oral group.
If you're just going to remember four muscles, remember the occipitofrontalis, the orbicularis
oculi, the orbicularis oris and the buccinator.
And just remember when you're remembering any muscles, just trying to think of what
the name means, what the words actually means because they generally help you to remember
the position and the function of the muscle.
So that's the muscles of facial expression.