 Okay everybody, Dr. O here. In this video we're going to cover just the muscles of the head and the neck. So I covered some of these muscles in the major muscle overview, but I'm going to dive in deeper in all of them really. So I'm going to zoom in so we can see a little better here. But here we have the anterior view of the face. So the key muscles here are the orbicularis oculi. So anytime you see the word orbicularis, orbicularis means a circular muscle. And then oculi, I think oculi are around the eye. So the orbicularis oculi is that circular muscle around the orbit around the eye that closes the eye, plays a role in it. Next we have the frontalis. You'll see that called the frontal belly of the occipitofrontalis muscle here. Both are correct, but frontalis is easier to remember. Frontalis over the frontal bone and it raises your eyebrows. Orbicularis auris, circular muscle around the mouth, oral, orator, oral region. So the orbicularis auris around the mouth there compresses your lips. Then we have the zygomaticus, zygomaticus major and minor. They're going to retract and elevate the upper lip and the corner of your mouth. So think about a big smile is going to use these zygomaticus muscles. Remember the zygomatic bone is your cheekbone there. Lateral view, the epichranial aponeurosis at the top, that's what connects the frontal and occipital bellies of the occipital frontalis muscle. But I'll just call it the frontalis and then we have the occipitalis muscle there in the back. This is going to be, it's going to retract your scalp. So that's going to be over the occipital bone there. Orbicularis oculi already covered, circular muscle around the eye that closes the eye. Frontalis already covered. It's right there over the frontal bone and raises your eyebrows. Just said the occipitalis there. Next we have the temporalis and masseter. These two are considered your muscles of mastication or chewing, the temporalis muscle. I like to do this, put my thumb here and my finger here in this, clench my teeth. You feel both those muscles tighten up. Temporalis lays over the temporal bone and its job is to elevate the mandible during mastication or chewing. Masseter down here connects the upper and lower jaw. Plays a role in elevation of the mandible during chewing. Very powerful muscle. Probably the strongest muscle we have, pomper pound, give or take. The two muscles, so notice that both the temporalis and masseter elevate the mandible. There are no muscles that are needed to lower them. So chewing is a combination of elevation of the mandible with contraction of those muscles and then it depresses with gravity when those muscles relax. That's going to be elevation and depression of the mandible there. Orbicularis aureus, we already talked about. Circular muscle around the mouth that compresses the lips. Then we have the buccanator or buccanator. I've heard it called both the buccanator or buccanator muscle there. Its job is to compress the cheeks, which it's actually, buccanator basically comes from like a trumpeter. But so it does compress the cheeks if you're blowing into something. But the key reason it's important is the buccanator muscle compresses the cheeks against the teeth during chewing. So as you're chewing up food, it makes your teeth more effective at doing their job. Next muscles here, we have the zygomaticus already covered from the front. They're involved in smiling. They retract and elevate the upper lips. And you can see them there as well. Platysma is going to be this real thin plate-like or thin. That's what that's a platysma means. It's a plate-like muscle there on the front, very thin. It just tenses the skin in your neck. You generally don't know the muscle exists unless you get in a car accident, like a whiplash, hyperflexion, hyper-extension injury can pull that muscle and make the front of your neck really sore. But not much to know about the platysma. Then lastly we have, you can see the sternocleidomastoid. At least you can see the insertion. So I covered that in the overview video, but the sternocleidomastoid sterno means it originates on the sternum. Clidom means clavicle. Then you can see where it inserts here on the mastoid process. If both of them are contracting, it will flex the neck. If one is contracting, it will rotate the neck. That's why I put those motion images there. OK, those are all the key muscles I expect you to know of the head and the neck. I hope this helps. Have a wonderful day. Be blessed.