Start learning the bones of the body. We're gonna start with the skull, and the skull is this complex bony structure. It's not a single bone, it is many bones. And to illustrate that, we have this skull over here. We have, side view and a frontal view of the skull, and you can see all the different bones there color coded. Now pretty soon, you're gonna be able to label and name every bone in that picture, and we're gonna get you there. Alright. We're gonna start off by talking about the cranial bones. The cranial bones are the bones that make up the bony house for the brain. Now I got a big old round head, and that big old roundness of my head is from my cranial bones. So that's because the cranial bones make up this hollow structure. Hopefully, it's not hollow. There's a big old brain in there, but the cranial bones are surrounding that brain, and they're protecting the brain inside. Next, we're gonna go through the facial bones, and the facial bones make up the structure of the wait for it. The face. Alright? Your face is this really complex three-dimensional structure that makes you look like you. Now I'll be honest, when I was learning the bones of the body, I found the facial bones particularly difficult. That's because the facial bones are it makes this kind of weird three-dimensional structure, and they fit together in this very puzzle like way that's kind of hard to imagine in your mind's eye. But don't worry. We'll get you there. Alright. We're also gonna learn some associated bones. The associated bones are gonna be bones that are used for hearing and swallowing. Alright. The bones for hearing, these are 3 tiny bones in your inner ear that connect the, the eardrum to the inner ear. Now we're not going to learn them learning about the skull. We're gonna learn those when we talk about the special senses. Now for swallowing, we're talking about the hyoid bone. The hyoid bone is this bone in your neck that's the base of the tongue and involved in swallowing. And even though it's not actually connected to the skull, its function is related to the functions of the skull, so we learn it with the skull. As we learn the skull, we're gonna learn about the different cavities the cavities and sinuses of the skull. These are the spaces in the skull. Right? You have your orbital cavity for your eyes, your nasal cavity inside your nose. You have your sinuses. These are spaces inside some of the bones of your of your skull. Those sinuses, if you've ever had a sinus headache or a sinus infection, you probably know where they are. Alright. Well, when talking about the skull, let's talk about what the skull does for you. It has several functions, and here we're breaking it down into 5 functions. Now like always, putting an exact number on this is a little bit difficult because it depends on how you count, but we're going with 5. First up, we're gonna say it protects the brain. And to illustrate that, we have a brain here wearing a helmet, and the cranium is really the helmet for your brain. It's there to protect what's inside. Now, if you're doing something especially dangerous, you might put a a helmet on top of that cranium to give it extra protection. But for the most part, your cranium does a pretty good job of protecting the brain. Alright. Next, we are going to say that it is there to, to produce facial structures. Right? You look like you do because of the bone structure of your face. Now to illustrate that, we have a person here, a little cartoon of a person making different faces. Now obviously, it's not just your bone structure that makes you look like you do. You also have, skin and muscles on it and a lot of your different facial expressions. That's obviously because of moving those muscles. But the underlying structure, the underlying basis of what you look like, that's the shape of those bones. We're gonna have some openings in the skull, and those openings are gonna be allow you to obtain air and food. Right? You breathe through your nose or through your mouth, and then you got your big old pie hole there that we can see here in our illustration, a big old mouth that looks like it's out ready to chomp down on a cheeseburger or something. Well, when you chomp down on the cheeseburger, you're gonna chomp down with your teeth. And one thing that your skull is doing, it's anchoring your teeth. We'll learn about the teeth in the digestive system, but that's a major job of the jaws. Right? Your upper and lower jaw is gonna hold those teeth in place. Now finally, we're gonna say that the skull is there to house your sense organs. Right? Your eyes, your nose, your ear, all these things in your head, and that's how you experience the world. It's largely through your skull, because that's where those really sensitive sense organs are. Alright. With that, now we know what the skull does. Let's go learn the bones.
2
Problem
Problem
True or False; if false, select the answer that best corrects the statement.
Associated bones provide a house for the brain.
A
True, the associated bones make up the cranium.
B
False, the associated bones provide the structure of the ear and nose.
C
False, the associated bones are involved in hearing and swallowing.
D
False, the associated bones create facial features.
3
concept
Overview of Cranial Bones
Video duration:
8m
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Video transcript
We're gonna start learning the bones of the body by learning about the skull. We're gonna start with the skull with the cranial bones. Now your cranium, that's the round part of your skull that houses your brain, the bones that protect the brain. So we're gonna start off just by saying that the cranium is made up of 8 bones, and those bones are gonna be connected by sutures. Now, we haven't gone over types of joints yet, but a suture just means that the bones have grown together in a way that they're still separate bone, but they're kinda interlocked, so it's not a movable joint. They're quite firmly together. Now before we go on, I just wanna note, we say here 8 bones. They're numbered, however, 1 through 6. That's because there's gonna be 2 parietal bones and 2 temporal bones and one of all the other bones. Now finally, let's just orient ourselves to the picture here. We have a side view of the skull with all the bones color coded. We're gonna be focusing on the cranium, these bones in the back. There. Alright. Our first bone that we are gonna talk about then is going to be the frontal bone. The frontal bone, well, in blue here, it's here making up the brow ridge, your forehead, up to the top of the sort of the top middle of your head. One of those, it's the frontal bone. It's the front of the head. I'm just gonna say here it is the forehead bone. Alright. Frontal bone, front of the head, pretty straightforward. Next, we have the parietal bone, and the parietal bone you can see in green here. There's 2 of these and they make up the upper side walls and the top of your head. So I'm gonna write here the upper side of your head or upper sides of your head. And parietal, the the word comes from Latin meaning wall, and so, it it makes up the walls of your head. But the way I remember it is if you make bad decisions in college, then your parents might grab their parietals. Parents grab the parietals. Those are the bones on the side of the head that you grab when you are in dismay. Alright. Next, we have the occipital bone, and there's gonna be one of these. The occipital bone is gonna make up the back of your head. And we can see it here in purple, the back of the head, but it actually comes up and it makes up a lot of the bottom of the cranium as well. You can't see it in this picture, but I'll show you here in this model of a skull. So we have the occipital bone all around here and then down and around this big hole in the bottom. Well, that big hole in the occipital bone, that is the foramen magnum, and that's how the spinal cord gets into the skull. Now foramen magnum literally means big hole. So the occipital bone has a big hole in it for the spinal cord to get in, the foramen magnum. Okay. Those first three bones are sort of the major flat bones of the cranium. The next one, the temporal bone, people often sort of group it in with those 3 because these are sort of the large flattish, at least, bones that make up the major sphere of the cranium that you can actually touch. The temporal bone, though, actually isn't a flat bone. It's a pretty irregular bone because it has these processes and holes in it, and I'm gonna talk about those now. So the temporal bone here, it's on the side in this sort of reddish color. And the first thing you'll note is that there's this hole here in the side, and that's because that is where your ears are. Temporal bone is right where your ears are, and that hole for your ear, your ear canal, your ear hole is called the auditory meatus. And on a skull, you can see it. So right behind where the jaw meets, right behind this arch, there's a little hole there and that goes into the skull and houses some kind of complex architecture of the inner ear. Now also helping you identify the temporal bone is gonna be that it has all these processes sticking off of it. Processes are things that stick off of a bone. So it's gonna have the styloid, mastoid, and zygomatic process. I'll show you these on this picture here. So the styloid process is this pointy thing that sticks down from the temporal bone. The mastoid process right behind your ear, you have this kinda big lump of bone, and you can feel that right behind your ear right here. There's a sort of lump of bone, that's the mastoid process. This muscle right here comes up and connects to it. And then finally, you have the zygomatic process, and that's right here. The zygomatic bone is actually its own bone. It's this cheekbone here in orange, but the zygomatic process comes up and it meets meets the zygomatic bone and creates this arch, and you can see that on your model skull here. I can just sort of stick my finger through there, and there's actually a muscle that goes through there. So all these different processes are quite easy to recognize, and helps you recognize that it is the temporal bone. So those are the bones that make up, again, the part of the cranium that you can feel. Now we're gonna move down to the bones of the inside front of the cranium. So you can't see or feel these bones because they're behind your face. The first one is gonna be the sphenoid bone, and there's one of these, and when you take the sphenoid bone out of the skull, it's kinda easily recognizable because it looks like a bat. And it makes up the sort of front and front bottom of the cranium, And we have a picture of it here. You can see here the shape of the bat. You can see it has these, wings here, the wings of the bat. And then the head of the bat would kind of be here and the body of the bat kind of there. So that's that bat shape that you can recognize as the sphenoid bone. It also has this feature called the sella turcica, and that is going to house the pituitary. And you can see that in the image, sort of right here. It comes up on either side, and there's this sort of groove in there that houses the pituitary. So if you imagine a bat and you put a saddle on the bat, that pituitary gland is riding that bat, and we can see it on the inside of the skull. I've outlined the sutures that make up the sphenoid bone here in black, and hopefully you can see that pretty decently. Well, the sphenoid bone there in black and the turcica sella turcica, this Turkish saddle. It's gonna be a little harder to see in the video than it is in a real skull, but it's that groove in there right there that's gonna house the pituitary gland. Okay. Our final bone of the cranium, it's not much of it is actually making up the wall of the cranium. A lot of it makes up to the architecture of the nasal cavity between the eye sockets. This is going to be the ethmoid bone, and we're going to say that this is sort of a sieve like bone. And by sieve, we mean it has all sorts of holes in it, and we'll talk about that in just one second. And it's gonna be between the eye sockets and, again, making up a lot of that nasal cavity. And and we can see as we look at the bone, just some features so you can orient yourself to it. Right here, this part that sticks down, that's part of your nasal septum, the the middle part of your nasal cavity. And here are these sides. Those are gonna make up sort of the walls of your nasal cavity. Now you'll notice here, though, we have 6 a. We have this part that, sticks up, kind of like a shark fin or a crest of a rooster, you could say, because the name of it is the krystagale, and krystagale literally means the rooster crest. So this part that sticks up, this is what kinda sticks up into the cranial cavity there, and it serves as an attachment point for brain membrane. So I'm gonna say brain membrane attachment. Oh, gotta spell it right though. And the other thing that you're gonna notice, this is where this idea of it being a sieve like bone comes from. We have something called the cribriform plate. And on either side of this cristagale here, it's gonna have all these little foramina, all these little holes where the olfactory nerves are gonna hang down into the nasal cavity so you can smell things, and you can see those and it's really identifiable. It's really this this complex shaped bone with all these little holes on the top really identifiable. So I'll show you here on this, model of a skull. I've outlined the suture that makes up, the ethmoid bone here in blue. You can see only a little bit of that bone is gonna stick into that cranial cavity, But you may be able to see on either side of that sort of crest like rooster crest or shark fin that sticks up, there's going to be all those little holes there, and those little holes are where the olfactory nerves come in, and that's why you can smell things. Alright. So that's 8 bones. I realize that was a lot of information. Don't worry. We're gonna practice it more in the example to follow and the questions after that. So I hope to see you there.
4
example
The Skull Example 1
Video duration:
2m
Play a video:
Video transcript
This example tells us that to remove the brain as part of an autopsy, the top of the skull will be removed by cutting roughly along the red line as shown in the diagram. And then just wants to know which bones would be cut as part of this procedure. Alright. So as part of an autopsy, sometimes they'll take out the brain, weigh it, do some tests on it, etcetera. To do that, you need to cut through the skull cap, and if you're familiar with a model skull or even a real one in lab, you'll see that a lot of times you can just take the top of the skull off to do that so that you can see inside. And it's this cut that we're talking about. What bones would you have to cut through to remove the skull cap just like this? Alright. So when we look at this red line here, the first thing that we can see that it goes through is this bone right here making up the front of the head and the forehead. So what bone makes up the front of the head and the forehead? The frontal bone. Alright. So the first bone that we're cutting through is the frontal bone and then as we follow it back, alright, we go cut through this bone right there. So what bone is that that makes up the side walls and the top of your head? Remember, we had a little memory tool. When you make bad decisions at college, your parents grab their parietal. Parents grab the parietal. So that's the parietal bone. So I'm gonna write down parietal and I'm just gonna put in parentheses here 2 because there's 1 on each side, so really you'd have to cut through both parietal bones to make this cut. Then finally, as we follow this cut all the way to the back, we're gonna be cutting through this bone in the back of the cranium that also goes up and makes up the bottom of the cranium as well. So what bone is that? Well, the back of the head, that's the occipital bone, and that's it. That's what we gotta cut through. The only bones that we didn't cut through as part of the cranium, we have the sphenoid and the ethmoid. Remember those are kind of behind the facial architecture and make up the front of the cranium, and then also, we did not cut through this temporal bone here that's making up the side of the skull. Now if this cut were a little lower, you could see that maybe it might cut through a little bit in the temporal bone. But in this picture, clearly, that cut is above that suture. Alright. With that, practice palms fall. Give them a whirl.
5
Problem
Problem
If a patient has a tumor on the pituitary gland, a surgeon will often make an incision in the nose before cutting into which bone to reach the pituitary?
A
Frontal
B
Sphenoid
C
Occipital
D
Temporal
6
Problem
Problem
Damage to which bone is most likely to cause problems with hearing?
A
Frontal.
B
Sphenoid.
C
Occipital.
D
Temporal.
7
concept
Overview of Facial Bones
Video duration:
6m
Play a video:
Video transcript
split the bones of the skull into 2 main categories. We have the cranial bones and the facial bones. Well, now it's time to learn the facial bones. We'll start just by saying that the face is made up of 14 bones, but many of them are paired. So when we look at our list here, we only have 8 names of bones that we need to learn. Before we learn them, let's just look at our image. We have a front view of a skull here, and you can see that each individual bone is color coded so that we can identify them. And then we also have an underside of the skull, at least the view of the front part of the underside of the skull with the lower jaw removed. So this row of teeth here that you're seeing, that's the upper row of teeth. Alright. First bones we're gonna learn, the maxilla. These are the main facial bones. And if you touch the front of your face right here, you're touching the maxilla. You can see it here in purple. It's kind of a large bone, at least for the face. It make it's making up part of the wall of the nasal cavity. It's making a part of the wall of the orbital cavity, this medial inferior wall of the orbital cavity, and then it's also holding that upper row of teeth. So you can sort of think of it as your upper jaw. This is so it's gonna say here, an attachment site for teeth. And as we look down, we can also see that it makes up the roof of your mouth, at least the front part of that hard palate. That front part of the roof of your mouth is going to be made by the maxilla. As we look down, we now come to the mandible. Well, if the maxilla is your upper jaw, the mandible, that's your lower jaw. And as a lower jaw is also an attachment site for teeth. Now it helps me to remember it. Remember the maxilla and the mandible together. These both start with that MA, maxilla mandible. That's your upper and lower jaw. Now the mandible is the only freely moving bone in your skull. All the other bones are fused together with these sutures, so none of them move, at least they shouldn't. The mandible though is really just attached back here just by some muscles and ligaments, and if those are gone in a skeleton, the lower jaw, the mandible will just fall right off. Alright. As we go down, we reach what I think is the most fun bone to say, the zygomatic. Alright. Your zygomatic bones, these are your cheekbones, and we can see them here in orange, the 2 cheekbones. They're making up part of the border of the orbital cavity, the lateral border of the orbital cavity. But also when we talk about the temporal bone, we said the temporal bone had that zygomatic process. And that zygomatic process with the zygomatic bone makes the zygomatic arch. And you can feel that as you start on your cheekbone. You sort of walk your fingers back to your ear. You're going along that zygomatic arch across the zygomatic process of the temporal bone and back to your ears, and you can see that in this underside view. That's that arch we're talking about right there on either side, that zygomatic bone. Alright. That brings us over here to bone number 4. This is going to be your nasal bones. Your nasal bones, 2 small bones that make up the bridge of your nose, hard part bridge of your nose right up there in the middle. Next, we have the lacrimal bones, 2 small lacrimal bones. Kinda hard to see here, but they're nice and small. These little pink bones right there are just gonna say this is sort of the inner wall of the eye or the eye socket, the orbital cavity here, kinda right in here. One way you can remember this, well, lacrimal fluid is another name for tears. Both lacrimal ducts and lacrimal glands, those all have to do with producing tears, and your lacrimal bones are right on the inside of your eyes there where tears come out. That brings us next to the inferior nasal conchae. So the conchae, some people say conchae or conchae, doesn't really matter. 2 of these, these are gonna be the walls of the nasal cavity. Inferior means they're gonna be the sort of the lower walls, And as we look in here, they're a little hard to see, but you can see these sort of folds of bone that come over into the nasal cavity there on this lower section here. Well, the conchae, that first part conch, that refers to a conch shell, that spiral shell that you might find on the beach. And as you look in the nasal cavity, it's the bone there is not smooth. There's these folds of bones that come down sort of in these little spirals. The inferior nasal conchae are their own bones that you can see right here that come in and spiral and give that nasal cavity a lot more surface area. Now there's other nasal, conchi up here at superior. You see the ethmoid bone, which we actually classified as a cranial bone because that a little part that went into the cranium. The, ethmoid bone here makes up those superior nasal conchae, but the inferior nasal conchae is its own bone, these spiral shaped things that protrude into the nasal cavity. Next, we have the vomer. The vomer, you can see here in purple on the bottom, and you can also just see a teeny bit sort of right there. The vomer, I sort of think of almost like a fin shaped bone, almost like a little shark fin that's sticking up, and it is making part of the nasal septum. And the nasal septum is the dividing part between the right and left parts of your nasal cavity. So you have 2 nostrils going into each side of your nose divided by the septum. The vomer makes up the lower and posterior part of the bony part of that nasal septum. The front part's made of cartilage. The top part of that nasal septum is going to be made, again, with the eth moid bone, that bone that we listed as a cranial bone, but still makes up a lot of this nasal architecture. Alright. Our final bone here is going to be the palatine bone. Palatine bones, well, these make up the back of the roof of your mouth, showing that right here, the roof of your mouth, the back of your hard palate. So your palate is made with your palatine bones. Of course, most of the palate here is your maxilla. It's just this back part that is the palatine bone. Now the palatine bone is a more complex bone than this. There's parts of it that sorta curve up, and they even reach up and touch sort of the inside part of the orbital cavity, right up there. But usually, the thing that you need to know about it is that it makes up the back part of the hard palate. Okay. With that, we've learned 14 more bones. We're well on our way. I'll see you in the next video.
8
example
The Skull Example 2
Video duration:
1m
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Video transcript
Our example tells us that in a cleft palate, the roof of the mouth or palate does not fuse properly during development. It says that without surgical correction, a cleft palate can lead to complications surrounding feeding, ear infections, and speech. And we see here a picture of a baby or a young child with a cleft palate, and then ask the question, what bones would you expect may be surgically repaired in the case of a cleft palate? So you may have heard of a cleft palate before or maybe a cleft lip. If that fusion only fails in the front lip part, it's called a cleft lip. If fusion fails going back further into the bones of the roof of the mouth, it's called a cleft palate. So this question really just comes down to what bones make up the roof of the mouth. So what bones are those? Well, there's 2 bones that make up the roof of the mouth or the palate. The first one is that major bone of the front of the face. It holds all your teeth. It makes up the side walls of some of your nasal cavity. It makes up the lower border of your eye sockets or your orbital cavities there. What bone is that? That is the maxilla, and it also makes up a major portion of the front part of that hard palate. Now, the second bone that's smaller and makes up the back part of the palate, that is the palatine bone. Now the palatine bone is more complex bone than just that little part in the back of the roof of the mouth, but that's the part you're more likely to get asked about that you know that it's part of the palate and makes up that hard roof of the mouth. So the maxilla and palatine bone make up the palate. Those are the bones that may need surgical correction in the case of a cleft palate. Alright. With that, practice problems at all. Give them a try.
9
Problem
Problem
During a baseball game, the batter hit's a line drive that strikes the pitcher directly in the face breaking a bone. Among the four bones listed, which bone would you expect to be the least likely to be the bone that is broken in this situation?
A
Zygomatic.
B
Mandible.
C
Maxilla.
D
Lacrimal Bone.
10
Problem
Problem
If you are moving the only freely moving bone in the skull, what activity are you doing and what bone are you moving?
A
Humming; the palatine bone.
B
Chewing; the mandible.
C
Crying, the lacrimal bone.
D
Sneezing, the ethmoid bone.
11
concept
Cavities of the Face
Video duration:
6m
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Video transcript
When learning about the bones of the skull, you may need to know which bones come together to make up specific structures. So here we're gonna talk about the bones that come together to make the cavities of the space. So we are going to say that the cranial and facial bones come together to form functional cavities, and those two cavities we'll preview before we go over all the bones. First off, we have the nasal cavity. The nasal cavity, well, that we're just going to say is going to be your nose holes. Right? That's inside your nostrils, what you breathe through, the holes that you breathe through through your nose. Now the other cavity we're gonna talk about is going to be the orbital cavity. And the orbital cavity, well, your eyes are round like orbits, so those are your eye holes or your eye sockets, as they're often called. Alright. With that, let's go through our, bones here 1 by 1. So first off, let's orient you to the picture. We have an image here showing the bones color coded. We have a front view of the bones that make up in the nasal cavity and also a midsagittal section, again, with all those bones color coded. First off, we have the maxilla. The maxilla, that major bone of the face, you can see here it's making up sort of the sidewall of the nasal cavity. It's also making up the palate. So the top of the roof of the mouth, that's the bottom of the nasal cavity. Next, we have the nasal bone. That's this bone here that makes up the bridge of the nose. We have the sphenoid bone. Remember, the sphenoid bone is that bat shaped cranial bone, and it's gonna make up some of the back of the nasal cavity, and you can see it in this, sagittal view here in yellow. We also have the vomer. The vomer here, you can see in the sagittal view again. It's sort of this fin like bone that makes up some of the nasal septum, the bottom part of the nasal septum. The septum's what divides the right and the left sides of the nose. We have the inferior nasal conchae. Now the nasal conchae, remember, these are these folds that come in into the nose and make sort of those nostrils kind of these complex three-dimensional structures. We can see the inferior nasal conchi sort of folding in right there. We have the palatine bone. Palatine bone doesn't make up a lot of this. You can see it right here. It's the back of the palate, so it's also gonna be the the bottom part of the, nasal cavity in the back. And it also sort of curves around some and even curves up into the, into the orbital cavities, as we'll see in a second. We then have the ethmoid bone. The ethmoid bone was that cranial bone, but really it makes up a lot of this nasal architecture. We can see here it makes up a lot of the septum in this sagittal view, and in the front we can see the septum, and we can also see some of these conchi coming down. Now to help you remember this, remembering just a list of bones like that is very difficult, so we put together a little memory tool. We say, my nose smells very interesting perfume extracts. And we have a little guy here smelling some perfume extracts to help you remember it. So my nose smells very interesting perfume extracts. That's the maxillanasal sphenoid vomer, inferior nasal conchae, the palatine, and the f one. Alright. The other part of the nasal cavity that you might need to know is which bones make up the septum. Now the septum, as we just said, it separates the left and right sides of that nasal cavity, and it's gonna be made of cartilage. And in our picture up here, you can see this light blue in the front. That's all cartilage, and that's why you can bend the end of your nose back and forth, because cartilage is flexible. But then the two bones that really make up the rest of this are going to be the ethmoid and the vomer. Now remember that piercing your septum nowadays is kind of popular. Now piercing your septum, you get a ring in your septum. You don't actually get it in the bones or the cartilage of your septum. You get it in the front here in the flesh of your septum. A lot of people get a ring, And nowadays, that's kind of popular, and you may think that getting a septum piercing is very exciting. So very exciting, the vomer and the ethmoid. Now I just have to say I'm a parent and my child happens to have a septum piercing, and I think that it's very embarrassing. Oh, well. Love you, kid. You do you. So very embarrassing or very exciting. The vomer and the f one. Alright. Let's go over the orbital cavities here. Orbital cavities are eye holes. Same thing. We have a picture of a skull zoomed in on one of the eye cavities, one of the orbital cavities here, and we're gonna label all the bones as we go. We have the maxilla. The maxilla is gonna, again, that major facial bone makes up the inside portion of this, margin of the, orbital cavity, and also a lot of the bottom of that orbital cavity. Next, we have the lacrimal. The lacrimal, this bone on the inside here, that small bone right on the inside of your eye. We have the ethmoid. Remember, the ethmoid makes up a lot of the nasal structure, but it's also coming in and making up just a little bit of that orbital cavity right there in green. We have the sphenoid bone, again, that bat shaped cranial bone. It's gonna make up a lot of the posterior part of the eye cavity, so a lot of the back of that orbital cavity. We have the palatine bone. Remember, the palatine bone is that bone in the back of your palate, and that's probably what you need to know it, know it for most, But a little bit of it does come up and you can see it right there. It touches and makes up a little bit of this orbital cavity. We have the frontal bone. The frontal bone, that's your forehead bone in the front of your head. It's gonna make up the top and the front margin of that orbital cavity. And then finally, we have the zygomatic bone. Zygomatic is your cheekbone here in orange, and it's making up the lateral side of the orbital cavity. Now again, just conjuring up a list of bones like that can be kind of difficult, so we've put together a memory tool for you. Our memory tool here is if ever as a kid you played that game, I spy with my little eye, well, we can say my little eye spies pretty fast zebras. And to illustrate that, we have someone spying a zebra here. So maybe you're playing that game in a zoo, or maybe you're in Africa. I don't know. But my little eye spies pretty fast zebras. It's the maxilla, the lacrimal, the ethmoid, the sphenoid, the palatine, the frontal, and the zygomatic. Okay. Again, remember those memory tools, because if you do need to know these structures, remembering just the list of bones can be very hard on its own. Like always, example and practice problems to follow. I'll see you there.
12
example
The Skull Example 3
Video duration:
3m
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Video transcript
Our example tells us that the following lists each have at least one bone that does not belong. We need to cross out any bones that don't belong to each list. And we have an image of a frontal image of a skull here with all the bones color coded if we need help for reference. Alright. So our first list is gonna be the bones that contribute to the nasal cavity. So take a look at those four bones. Do any of those not contribute to the nasal cavity? Well, remember we had a little memory device. We said my nose smells very interesting perfume extracts. Alright. And so as I look at that and I compare it to the letters, well, right away, that z, there is no z there. So I the zygomatic, I feel good about crossing out that, not the zygomatic. Alright. So let's check out our bones here. The zygomatic is this cheekbone that has nothing to do with the nasal cavity way off to the side. The ethmoid the ethmoid, that is this bone that makes up the top part of the internal structure of the nasal cavity. It's also part of your cranium, as well. So that's definitely there. The vomer the vomer is the bottom part of the nasal septum right there, so that's definitely part of your nasal cavity. And then the maxilla, the maxilla is your upper jaw, these purple bones here that make up the border of your nasal cavity. So feel very good about the rest of them? Let's check out our next list. We have bones that contribute to the orbital cavity. Alright. Take a look at that list. Do any of those bones not contribute to the orbital cavity? Well, we also had a mnemonic device, a little memory tool for this one. We said, my little I spies pretty fast zebras. Alright. So as I look here, all those letters are in my memory tool, but there is an issue here. This m is supposed to be for maxilla, and here we have d is the mandible. Remember, the mandible is your lower jaw. It has nothing to do with your orbital cavity. So feel pretty confident that it's not the mandible. Let's just check out our other options. Here, we have the lacrimal. Lacrimal, right, that makes up the inner border of your eye there, that little small pink bone right in here. The sphenoid. Sphenoid was that cranial bone that looks like a bat, but it makes up the back of the orbital cavity there. We can see it in yellow. It's also sort of sticks out in your temples right there. And then finally, we had the zygomatic. Well, the zygomatic, we just said was your cheekbones. Your cheekbones make up that lateral border of your orbital cavity. So the rest, definitely part of the orbital cavity. Alright. Our last list here is gonna be bones that anchor the teeth. So which of those don't anchor any teeth? Well, the bones that anchor the teeth, we said they both start with M. They're the maxilla and the mandible, and you could say maxilla and the mandible are for mastication. They're there for chewing. Yeah. So those are the bones that do, but the ethmoid, therefore, definitely does not. Remember the ethmoid, that's this bone of the, cranium and also making up the internal structure of the nasal cavity. It doesn't hold any cheap teeth. And then we have the palatine. Well, the palatine does make up the back of your mouth, makes up the roof of your mouth there, but all of the teeth are in the maxilla, not in the palatine bone, so it's not that. Alright. With that, I feel like we found the bones that don't belong in each list. Like always, practice problems to follow. We'll see you there.
13
Problem
Problem
One of the occupational hazards of boxing is a deviated septum, where the cartilage of the septum is damaged shifted to one side. What two bones may also be involved in a deviated septum?
A
The vomer, sphenoid, and ethmoid bones.
B
The sphenoid and ethmoid bones.
C
The vomer and sphenoid bone.
D
The vomer and ethmoid bone.
14
Problem
Problem
Which bone creates the lateral wall of the orbital cavity?
A
Zygomatic.
B
Lacrimal.
C
Sphenoid.
D
Maxilla.
15
concept
Overview of Sinuses
Video duration:
3m
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Video transcript
As we learn the bones of the skull, some structures that you're very likely going to need to know about are the sinuses. Now sinuses are just air filled cavities that are lined with mucosa, and mucosa is just a tissue that produces mucus. So these air filled cavities are gonna be really moist inside. They are going to be found inside of bones, but they're also going to be connected to the nasal cavity. So sometimes these are called the paranasal sinuses. Now these are doing a few things for you. First off, they are what going to lighten the skull. And by that, I just mean bone's a heavy tissue and air is lighter than bone. So if you have a cavity in the bone that's not filled with bone tissue, but instead it's filled with air, your head is just going to be lighter. And so to signify that, we have a little image here of some hot air balloons, showing how that makes your skull lighter. Next, we are going to say that they work to warm and humidify the air, and to show that, we have a little stove here with a fire showing it's warming and then a little humidifier next to it. Now when you breathe in, you're breathing air down into your lungs, which is really sensitive tissue. So the more surface area that you can get along the way that is warm and moist, well, the more evaporation into that air is gonna happen and just the warmer and more conditioned that air will be when it makes it down into your lungs. And the sinuses are doing some of that for you, as well as the rest of your nasal cavity. Finally, it is going to enhance vocal resonance. And by this, I mean, if you've ever seen like an acoustic guitar, it has this box on the back with a hole in it. That gives an acoustic guitar that nice loud rich sound. That box is a resonator box. If you compare that to an electric guitar that's not plugged in when you play it, it really doesn't sound very good. Now that's pretty similar to your voice. And to illustrate this, we have a guy singing here. But if you've ever tried to talk with a really bad cold where your nasal cavity is all blocked up, you can't use those resonance chambers of the sinuses. And so when you talk like this and you say you have a really nasally voice, it's because you're not getting the resonance of the nasal cavity and of the sinuses. Okay. So let's name our paranasal sinuses here. They're gonna be found in these four bones. First off, we have some in the frontal bone, and those are aptly named the frontal sinuses. And we can see here we have a picture of a woman showing the different sinuses that are color coded. And here we have the frontal sinuses in the frontal bone, that bone of the forehead sort of in your brow ridge right up here. Next, we have the ethmoid bone has the ethmoid air cells, and that's these little, marks here in green. Remember, the ethmoid bone, technically a cranial bone, but it makes up a lot of that internal architecture of the nasal cavity. Now these are called the air cells because you see over here there's a few of them. They're not just one cavity. The ethmoid air cells are a bunch of smaller little sinuses within this bone. After that, we have the maxillary sinus in the maxilla, and you see over here in purple, filling up a lot of front of the cheek here, all in here, the maxilla, those bones are hollow. They have these big sinuses in them. Lastly, we have the sphenoid bone has the sphenoid sinus, and you see in yellow here well, remember the sphenoid bone is a cranial bone. It's that bat shaped bone at the front of the cranium, so all the way in the back of the facial bone. So this is gonna be at the back of the nasal cavity. Now to remember these, we have just a real quick little word here. You can say fems. Where are my sinuses? Fems. They are in the frontal bone, the ethmoid bone, the maxilla, and the sphenoid bone. Alright. With that, those are the sinuses. We'll see you in the next video.
16
example
The Skull Example 4
Video duration:
2m
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Video transcript
Our example tells us that Dimitri is traveling on a plane while suffering from a cold. As the plane takes off, he begins to feel pressure and develops an intense pain just above the medial side of his right eye. Now, wants to know what might the source of this pain be. So what do you think? Well, we're in the section on the sinuses, and we have a picture of a skull here showing the sinuses color coded, so I'm pretty sure the answer is gonna have to do with the sinuses. But let's be a little bit more specific than that. What sinus is gonna cause pain just above the medial side of the right eye? Well, if you don't remember, we had an acronym to remember the sinuses. We had FEMs, And FEM stands for the frontal sinus, the ethmoid air cells, the maxillary sinus, and the sphenoidal sinus. So which one of those is just above the eye? Well, here, the right side of the skull is right here. We have this sinus right here in blue. That is a frontal sinus. So what might the source of Dimitri's pain be? I'm gonna say the frontal paranasal sinus, and you could just say the frontal sinus as well. Just for completeness, let's just label our other sinuses so that that we know them. So I'm just gonna outline each one here. The ethmoid air cells, those are here in green. Remember those, there's a few smaller ones rather than sort of just like one big cavity in the bone. Next, we have the m is the maxillary sinus. That's these in purple. I'll outline those sort of right in your cheeks there. And then finally, we have the sphenoidal sinuses. Those are here sort of in yellow, and remember the sphenoid bone is that bone of the cranium sort of shaped like a bat in the back of the nasal cavity. And this pain comes the fact. Right? These are cavities that are connected to the nasal cavity. And if they're clogged, if the connection is clogged, when you go up in a plane, you have a pressure change, and that can cause a lot of pressure in the sinus if it can't exchange air with the rest of the nasal cavity, and it can hurt like heck. If you've ever had it happen, you know what I'm talking about. Alright. Problems to follow. We'll see you there.
17
Problem
Problem
Which of the following bones is both classified as a facial bone and also contains a sinus?