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.