Alright guys, in this video we're going to talk about the muscles of the head and the neck. First thing we're going to look at is the muscles of mastication or the chewing muscles. Now remember, that's the muscles of mastication, not masturbation. Alright, so the first thing we're going to do is we're going to take a look here at the first muscle here. This is going to be called the temporalis muscle.
Now the origin of the temporalis muscle is going to be the fossa temporalis. and the temporal fascia and it does insert down here at the cornoid process and the ramus of the mandible its action is to be able to elevate the mandible okay so this is the temporalis muscle and just remember in general it's going to elevate the mandible Then I'm going to take and turn this guy over here to this side. So if you look here, 38, this is the masseter muscle. There is a superficial on the deep masseter, but this is just going to be our superficial masseter right here. And the masseter muscle, just like the temporalis, it helps to be able to elevate the mandible.
And you can tell that again because its origin is the zygomatic bone. It's also the zygomatic arch too. And then the insertion is right down here at the ramus of the mandible and the angle of the mandible.
And again, it elevates the mandible. If you look here, you can kind of see it here. This 35. that's the buccinator. Okay that's the buccinator and the buccinator is actually what it does is it helps to be able to compress the contents of the cheek and to move the food towards the middle for chewing and so this is the buccinator right there okay.
And then I'm gonna take there is two more muscles that you can't really see on this that are also part of the muscle somatication which is the lateral pterygoid and the medial pterygoid but they can't be seen on this model. Alright guys now we're gonna take a look at the muscles of facial expression. So first This one is going to be this muscle right here. It's actually the frontal belly of the occipital frontalis right here.
And then what I'm going to do here is I'm going to kind of turn it up like that. And you can see here this little connective tissue. This is actually called an aponeurosis.
It's the gallia aponeurotica or the epicranial aponeurosis. And it connects the frontal belly with the occipital belly back here of the occipital frontalis. All right.
Another muscle we're going to take a look at right here is going to be this one right here wrapping all the way around the occipital frontalis. the eye, it's a sphincter muscle, it's 25 right here. It's called the orbicularis oculi, the orbicularis oculi. And the orbicularis oculi is responsible for being able to, for the squinting action, so for being able to squint and blink the eyes, okay? That's the orbicularis oculi.
And then the occipital frontalis, the frontal belly, it'll actually pull the eyebrow up. And if you look here, 34, this muscle right there, this muscle is going to be called the levator labi superioris, and what it does is it elevates the upper lip. Now there is a tiny little muscle that you can kind of see right here, that muscle right there next to the levator labii superioris, it's called the zygomaticus minor. Okay, so the zygomaticus minor helps to be able to pull the upper lip also, kind of upwards and backwards to assist this muscle right here, which is called the zygomaticus major.
And the zygomaticus major is actually going to draw the angle of the mouth upwards and backwards for smiling. And if you look here, 30 coming across from this corner of the mouth right here, all the way over here to this lateral fascia of the cheek is actually going to be a little bit going to be called the risorius. The risorius pulls the actual corner of the mouth laterally and so that helps with the face of grimness.
Then if we look over here at 29, this is called the depressor anguli oris or they also call it the triangularis because it looks like it forms a triangle here. That is designed to be able to pull the angle of the mouth downward. So it helps to pull the angle of the mouth downward.
I'm going to turn it in here and you got this muscle right here. right there and this is called the depressor labi inferioris and it basically it pulls the lower lip downward so again the depressor labi inferioris pulls the lip downward the lower lip so right here is the mentalis and the mentalis is actually gonna be designed to be able to protrude the upper to protrude the lower lip right so it helps to be able to kind of make that sad face though so protrudes the lower lip right there so if you see 28 right here it's another sphincter kind of wrapping around the lips right here And this is actually going to be called the orbicularis oris. That's the orbicularis oris, and it helps with being able to close the mouth and keep the mouth shut.
So that's basically a sphincter muscle, and that's designed to be able to close the mouth. So that's the orbicularis oris. And another muscle that you can kind of see right up here around the cartilage of the nose, the hyaline cartilage, is called the transverse nasalis right there. So that's the transverse nasalis. So now we're going to cover a couple extra muscles here.
So this right here is called the auricularis anterior. It kind of helps to draw. the ear and the skin of the ear forward and then over here we're gonna have the auricularis superior, kind of draws the ear and the skin of the ear upwards and then this is the auricularis posterior back there and that's going to draw the ear and the skin of the ear backwards. Alright guys so now we're gonna take a look at the lateral neck muscles. So over here we have this big big huge muscle this is the SCM or the sternocleidomastoid.
Now the sternocleidomastoid has its origin situated here at the sternal end here of the basically the anterior surface of the manubrium and then it also has this clavicular head here that attaches to the medial third of the clavicle there and then its insertion point is going to be over here at the mastoid process and the latter part of the superior nuchal line and its function is to be able to flex the neck and assist in basically the forceful inhalations. Now we're going to go ahead and turn over here to the other lateral neck muscles. All right, guys. So now we're going to take a look at the scalenes. So if you look here, this is going to be our anterior scalene right here, number 44. Then over here, we're going to have the middle scalene, which is 42. And then we're going to have the posterior scalene right here, which is going to be 43. And all of these guys function to be able to flex the neck and to be able to assist in inhalation.
So now we're going to take a look at some of the posterior neck muscles. So if you look here, number 45, this is called our levator scapulae. So the levator scapula, it's actually going to be designed to be able to elevate the scapula. All right, and if you look here, number 19, this guy is going to be called the splenius capitis. This is the splenius capitis, and it's designed to be able to help extend the neck.
And then if you look here, this is called the semispinalis capitis, and it also helps to be able to extend the neck. So now we're going to take a look here at the trapezius. So if you look at the trapezius here, the trapezius has these fibers.
They're these descending fibers of the trapezius. And this trapezius is actually more superficial than these muscles over here that we talked about, the semispinalis capitis, splenius capitis, and levator scapula. The trapezius, because of its origin and insertion, it helps to be able to extend the neck and elevate the scapula.
I want to give you guys another look at the trapezius muscle here. If you look here, this is the trapezius muscle all right here. And what I wanted to show you is how you can tell it's such a superficial muscle. I'm going to pull this part here out and you can actually see these layers, these muscles right underneath it right here.
So you can see, like we talked about with the other, the herald head, you can see here that this is the spleenis capitis. You can see here's the levator scapula and you got the rhomboids down here that we'll talk about in the future. Alright, but again the trapezius muscle, it's a very, very superficial muscle. Alright, so that pretty much gives us everything we know about the posterior neck muscles and the lateral neck muscles on this model.
Alright guys, so now we're going to take a look at another muscle that we can only see it on this model here. It's just this muscle right here and this is called the platysma. And what the platysma does is it helps to be able to pull or depress the mandible down. So you can actually see this is the platysma. And you can see how it's such a superficial muscle right here, and it's lying over this pectoral, it has this pectoral fascia right there that it actually, or originates on.
And then again, insertion is the inferior border of the mandible there. So now we're gonna take a look at the suprahyoid muscle. So the suprahyoid muscles are gonna be all the muscles here above the hyoid bone.
All their insertion points are right there on the hyoid bone. So if you look here, we have two bellies of this muscle. This is called the digastric, but it's called the anterior belly of the digastric. And if you look here at number 47, this muscle right there, this is called the digastric posterior belly. So the digastric anterior belly and the digastric posterior belly, they both help to be able to elevate the high bone.
Now, if the high bone is fixed, the digastric anterior belly can also depress the mandible too. So let's come over here. So if you look here, guys, this is just the submandibular salivary gland, but 49 right here is going to be our myelohyoid.
This is another piece of the myelohyoid right there. And then 50 is the geniohyoid. And then we already said that 46 is the digastric anterior belly. And if you look here, 48, 48 is going to be the stylohyoid muscle.
And again, all of these muscles, all the ones that I've mentioned, all elevate the hyoid bone. The only thing that's a little different is that the digastric anterior belly can depress the mandible if the hyoid bone is fixed. All right, so now we're going to... Now we're going to look at the infrahyoid muscles.
So the infrahyoid muscles are all the muscles below the hyoid bone. And then again, these guys are going to depress, they're going to pull the hyoid bone down, so then their insertion points would be there. So if you look right here, 53, this is going to be the omahyoid, but it's going to be the superior belly. There's an intermediate tendon that you can't see, it's underneath the sternocleidomastoid that connects the two bellies. So again, this is the omahyoid superior belly, and this is the omahyoid inferior belly right here.
And again, the omahyoid inferior belly and superior belly are connected through what's called an intermediate tendon. We're going to take another. look here I wanted to show you guys you guys couldn't see the intermediate tendon between the superior omohyoid and the inferior omohyoid but if I remove the sternocleidomastoid out of this and so as you can see guys this structure right there that's the intermediate tendon again that's what connects the two omohyoid bellies together and while we're here we can also see a couple other structures if you look here number 26 26 right there is actually going to be the anterior scalene 25 is the middle scalene and 24 is going to be the posterior scalene you can see the levator scapula right there And if you look over here, you guys can see that 20 is the digastric posterior belly. You can see it also attaches right there to that mastoid notch there.
And then over here is 21. 21 is the stylohyoid. And again, it attaches to that styloid process there. So that just gives you guys another view of these neck muscles. All right, and the other infrahyoid muscle is going to be right here.
This is called the sternohyoid muscle. That's the sternohyoid muscle. And then over here, number 56, that's actually going to be the sternothyroid.
Okay, so that's going to be the sternothyroid. And so we got sternothyroid and we got the sternohyoid and then we got the omohyoid superior and inferior belly. And again, all of those are infrahyoid muscles, meaning that they depress the hyo bone. And all of these things with trying to change the depress and elevate the hyo bone all play a role in phonation or voice production. All right guys, this is pretty much going to finish up everything that we talked about for the head and the neck muscles.