So the muscle is responsible for facial expression.

So these muscles are innervated by the seventh cranial nerve, the facial nerve.

So when you're testing a patient's cranial nerves, and you get to cranial nerve.

Number seven, you ask them to wrinkle their forehead to close their eyes as tightly as they can as they can to show you their teeth by making a smile and um asking them to puff their cheeks out.

So this is a crude test of the muscles of facial expression.

So the way I'm going to do do this tutorial is that I'm gonna start superiorly and work through the the various muscle groups in the face.

So the um orbital muscle group, the nasal muscle group and then the muscles in the oral region.

So to begin with, um looking at the most superior muscle on the face, we you can see this muscle here, which is the frontal belly of the occipitofrontalis muscle.

Um and it's called the occipitofrontalis muscle because it consists of two muscle bellies.

So you've got the occipital muscle belly, so called because it's on the occipital region of the um skull.

And you've got the frontal belly of the oyo frontalis and connecting these two muscle bellies.

You've got this flat tendon sheath, this aponeurosis.

Um And if you, if you have covered the layers of the scalp, um you'll have been told that the aponeurosis of the o ccy frontalis makes up the third layer of the scalp.

So you've got skin connective tissue, aponeurosis, loose connective tissue and then the periosteum.

So the upper neurosis of the occ sept frontalis, um it's the third layer of the scalp.

So if we just look at the orbital region, um we can see these muscles which surround the eye.

Um and this muscle is called the orbicularis oculi.

And it's a, it's acts sort of as a sphincter of the eye.

And you've got an outer part um add an inner part to this muscle.

So this outer part here is called the orbital part and it's responsible for closing the eyelids forcefully.

If I just zoom in a little bit more, you can see that in a part of the orbicular circulate.

And this is called the palpable part and it resides inside the eyelid and it's responsible for closing the eyelid gently.

So that's the Abili oculi, this circular muscle responsible for closing the closing the eyelids.

So the next muscle is this muscle here, the corrugator super silly and it lies just um deep to the oculis ole and it draws the eyebrows immediately and downward.

There are three muscles associated with the um nasal muscles of the face and the nasal group.

Um So you've got the procerus, you've got the nasalis which consists of a transverse part and an um aar part.

And you've got this muscle in the midline, which is called the depressor septa nasa.

So, the procerus muscle here on either side, originates on the nasal bone and inserts onto the skin of the forehead.

And this muscle is active when an individual frowns.

And these muscles here, the na the nasal, sorry, the nasalis, which consists of the transverse part and the alar part is responsible for compressing and um flaring the nostrils, the nares.

So the transverse part compresses the nostrils and the alar part, um they are part of the nasalis.

Um flares helps to flare the nostrils, it opens them up.

Um And this muscle here that depresses sept NASA.

So the name kind of gives away what it does.

It depresses the nasal septum.

So it draws the nose down inferiorly.

Um So it actually inserts onto the nasal septum.

Um and it assists the A r part of the nasalis in widening the nostrils.

So those are the three muscles of the nasal group of the facial muscles, the procerus, the trans uh the nasalis and the depressor nasa septic.

So, the next group of muscles is the or group of muscles.

Um And as you can see, there's quite a lot of muscles which make up this group.

So if you're not interested in learning about all those in detail, then I'll just cover the two muscles that you need to know and you can switch off after that.

And then if you're interested, you can carry on listening uh to find out about the other muscles.

So what you need to know in the oral group, um If you are going to learn two muscles is that there's this big muscle here which forms a circle around the mouth.

Um And this is known as the UBI Iis Iris.

So just like you've got the circular muscles around the eyes, which constrict around the eyes, the Ubi oculi, you've got the UBI Iris.

So in Latin Oculus is an eye and Os oris is um a mouth.

So orifice oris help you to remember that.

So BIIS iis this circular mouth, circular muscle which um circles the mouth.

Um and you can kind of guess what the function is when it contracts, it narrows the mouth and closes the lips.

So you get this pursing action um which you get when you're whistling and that's brought about by this muscle, the orbicularis oris.