Hey, in this video we're gonna look for the... Wait a minute. Have y'all seen Mortimer?
Hey, Mortimer! Dude, I'm here. What's up?
Dude, we can't do the bones of the skeletal system without you. Get over here. Wait, what did he say? It's time to do the bones of the skeleton video? I've been waiting for this my entire life.
I'm so excited I could cry if only I had tear ducts. I'm coming. I'm coming.
Here we go. I'm so excited. Alright, that's more like it. Like I said, we're going to learn all the bones of the skeleton in this video.
Mortimer's here and we're ready to get started. Let's do it. Alright, we're going to start from the top on the skull and work our way down through what we call the axial skeleton and then we'll move to the arms and the legs which we call the appendicular skeleton. And at the end of the video, we'll review all the bones again with Mortimer and you can take a quick self-quiz to see what bones you've learned and what you still need to practice.
Let's start with the skull at the top which is removable here. Sorry Mortimer. Whether it is noble in the minds of... Yeah, I don't know what that line is. So here's the skull, of course, and it houses your brain.
The main part of the skull here contains several bones that get sutured together whenever you're developing as a baby. You know how babies have a soft spot on their head? That's because a lot of this is cartilage, and then it fills in with bone over time as these bones grow together and form your adult skull.
The parts of the skull also match the lobes of the cerebrum. So if you know those lobes, the names of these parts of the skull will sound very familiar to you. First off, we have the frontal bone, which is going to cover this frontal part.
We have the parietal bones, which will be these bones right here on the top of your head. And we have the occipital bone around the back right here. On either side, we have what's called the temporal bone, like your temples. So again, those are the frontal bone, the parietal bones, the occipital bone, and then the temporal bones, one of which you have on each side. Like I said, the skull houses your brain, and you can see These kind of interesting shapes and that's where the brain sits in there and you see this big hole right here Which is where the brain connects to the spinal cord.
Did you know you had a big spike in your head? In case you didn't know that's not really there That's just for the model by the way If you do have a large metal spike in your head go to the doctor right now like seriously call 9-1-1 two more parts Of the skull this part right here that's superior to your mouth is called the maxilla and down here We have the mandible go ahead and take a moment stretch your mandible out there If you notice the mandible is actually not really attached to the rest of the skull except by the joint in the jaw right there. So it's able to move freely from the rest of the skull.
Much better. The next bone I want to talk about is the sternum. The sternum runs from here down to this tip at the bottom and you can feel your own.
There'll be a little notch in your neck right here and that's going to be that indentation between these two bones and your sternum. And if you go down from there, down sort of in the center, you should be at the bottom of your sternum. You can feel where it sort of like pokes down a little bit.
That's going to be the bottom of the sternum right here. Now, branching out of your sternum are a bunch of pieces of cartilage. You see those pieces of cartilage right here?
We call those the costal cartilage. And they connect your sternum to your ribs right here. As far as your ribs go, you've got 12 pairs of ribs. If I count in the front though, I won't count 12. I'll count 1, 2, 3, 4, 5, 6, 7, 8, sort of. So we can't really count them from the front.
So I'm going to spin Mortimer around in the back so you can see all of those ribs. We can count the 12 pairs a little bit better from the back here. We've got 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ribs.
And there's three categories that we use for the ribs. We've got true ribs, false ribs, and floating ribs. Here's how you can tell the difference. The true ribs are going to connect from the vertebrae of the spine to the sternum and there's going to be one piece of costal cartilage for each of the true ribs. So we have a true rib here, a true rib here, a true rib here, here, and here for a total of one, two, three, four, five pairs of true ribs.
The false ribs are where the rib connects to a piece of costal cartilage that joins with other costal cartilage here. So we've got one, two, three, four, five false ribs. And finally, we have two pairs of floating ribs. You can see the floating ribs actually don't connect in the front. They start with the vertebrae right here and they just extend out and they sort of just float there.
They don't connect in the front. So one, two pairs of floating ribs. So 12 pairs of ribs total. We've got five true ribs, five false ribs, and two floating ribs in the back there.
Now connecting the skull to the ribs, of course, are the vertebrae of your spine. And we categorize the different vertebrae depending on where they are and what they attach to. And if you know the names of the spinal nerves, these terms will sound very familiar to you. So in the most superior part, we have eight cervical vertebrae. We have 12 thoracic vertebrae, and the thoracic vertebrae are called thoracic vertebrae because they connect to the ribs.
That's why we have 12 of those in that category. So eight cervical vertebrae, 12 thoracic vertebrae. Then we have five lumbar vertebrae down here.
And then we have this bone called the sacrum, which has multiple nerves that extend out of it. And finally, the tailbone, which is called the coccyx. So eight cervical vertebrae, 12 thoracic vertebrae, five lumbar vertebrae, and then the sacrum and the coccyx. Now all the bones that we've talked about so far, the skull, the vertebrae, and the ribs are all about protection.
The skull, of course, protects your brain. The vertebrae protect your spinal cord. Your spinal cord runs down through the middle of all those vertebrae.
And the ribs, of course, protect your heart and your lungs. Also, all the bones that we've learned so far are part of the axial skeleton. The axial skeleton.
is everything kind of down the middle. We've got the skull, the maxilla mandible, the sternum, the ribs, the vertebrae, and the sacrum and coccyx. That's all part of the axial skeleton. Everything else that I draw on the diagram all in blue is going to be part of the appendicular skeleton.
Appendicular, the same as appendage, means things that are sticking out. And so your arms and your legs sort of stick out from the main part of your torso, which is why they get the name appendicular. We'll start with the shoulder and the arms.
These two bones right here are your collarbones or clavicles. You can feel your clavicle if you feel right there on your neck and those will connect from the sternum to your shoulder blades which is called your scapula. Your scapulas are posterior to your ribs or behind your ribs and they sort of slide around if you can feel your scapula you can feel it sliding around if you move your shoulders like this.
And your scapula and your clavicle which combined are known as the pectoral girdle are going to form a joint with this bone the humerus. Your humerus, of course, is also known as your funny bone. So this is your shoulder joint, clavicle, scapula, and the humerus.
If we follow the humerus from the proximal end down to the distal end, it's going to connect at your elbow joint to two bones called the radius and the ulna. Of these two bones in the forearm, the way to tell which is which is to find the one that's on your thumb side. On your thumb side is going to be the radius. And I think of it like this, I take my thumb and I move it in a circle. Well, circles have a radius.
The bone on the pinky side is called the ulna, which is kind of a tiny little word, like your tiny little pinky. Oh, the cute little ulna. The reason I like to use the thumb and the pinky to remember which is which is because these bones actually move across each other whenever you turn your wrist like this. Watch as the radius goes back and forth over the ulna as Mortimer moves his wrist.
Which brings us to the bones in the hand. The wrist bones right here are called the carpals. And you've got a bunch of them. You can see lots of tiny little bones there. those are the carpals you can find those there in your wrist just distal to the wrist are the metacarpals and these are the bones of the hand so your metacarpals are these bones right across here so carpals metacarpals your the bones in your fingers are called phalanges high five yeah we're tight like that and one single phalanges bone is not a phalange it's called a phalanx so one phalanx or a bunch of phalanges so those are the bones of the arm we've got the clavicle the scapular or shoulder blade in the back there.
We've got the humerus. Here we have the radius on the thumb side, the ulna on the pinky side. We have the carpals, the metacarpals, and the phalanges. All right, let's move down to the bones of the leg, and we'll start with what we call the pelvic girdle. The pelvic girdle is made of the pelvis, which we see right here, and that connects directly to the sacrum back in there.
Now on Mortimer, you see all of the white, which is the bone, but you see this yellowish color here as well, and you see it between the two halves of the pelvis. That yellowish color right there is cartilage. So there's actually a piece of cartilage between the two halves of the pelvis, which we call the pubic symphysis. We see this in the spine as well.
There's all of these yellowish discs right there. Those are called the intervertebral discs, or the cartilage discs between each of the vertebrae. And that just makes your spine a little bit more flexible, and this makes your pelvis a little bit more flexible. Now the bones of the leg. We'll start with this, the femur, which is the longest bone of the body.
The proximal end of the femur connects to the pelvis, and the distal end of the femur, this little bone called the patella, or your kneecap. And the patella can actually slide from here down over your knee as you bend it. Mortimer, you're so flexible. Look at that range of motion.
We have two bones in the lower leg. Here we have the tibia, which is gonna be the bigger of the two bones. That's also your shin bone. So if you ever bang your shin on something, you're hitting your tibia right here. And there's not a lot of cushion between your tibia and the skin over your shin.
It's not like the back of your leg where you got your big calf muscle there for cushion. That's why your shin is so vulnerable to painful collisions. So you can feel your tibia. Your fibula though, which is sort of surrounded by muscles on all sides, you can't really feel that one as easily.
But this is the fibula right here. So tibia is the big bone. Fibula is the smaller bone.
Whoa, cool ankle bracelet. Now in the foot itself, we have your heel bone called the calcaneus. Wave with your foot.
The rest of the bones of the foot kind of mirror the bones of the hand. Instead of the carpals, we have the tarsal bone. So the tarsal bones are all here and then down here we have the calcaneus. If we have tarsals then we have metatarsals.
Calcaneus, tarsals, metatarsals. And finally the bones of your toes are also called phalanges. Easy enough to remember.
So go ahead and take a moment, wiggle all of your phalanges. ...and your toes phalanges. Alright, let's go and review all the bones of the leg again.
We have the pelvis here and the pubic symphysis in between the two halves of the pelvis. We've got the femur. We've got the patella or kneecap.
We've got the tibia, that's the bigger bone, the shin bone. We've got the fibula. You can also remember that the fibula is always on the side. I kind of remember it like it's got the word fib in it, like it's lying about who it is.
It's like, yeah, I contribute a lot to the stability of the leg. When really the tibia is doing all the work, the fibula is sort of lying about its usefulness. That's probably not completely true. It probably is really important, but that's how I remember. Tibia versus fibula.
The fibula, it's lying. It's not doing that much. It's a smaller one.
And then we have the calcaneus or the heel bone. We've got the tarsals, the metatarsals, and the phalanges. Alright, now Mortimer is going to provide us with the bones of the skeleton tour.
Let's go. Here we have the skull of course. We've got the frontal bone right there.
We've got the parietal bones on the top there. We've got the occipital bone and of course the temporal bone on the side. We've got the maxilla right there and the mandible down there. Here's a view from the bottom. That's kind of cool looking.
That big hole is where the spinal cord enters up into the brain. Alright, you just chill right there for a second. I'll be right back.
Okay, boss. Here we've got the sternum with the notch right there, and then this protrusion sticking out right there. We've got the costal cartilage, which connects from the sternum to the ribs. And of course, you have five true ribs, five false ribs.
and in the back here we can see the two floating ribs that don't connect to anything. Pity mortem around the back, we've got cervical vertebrae up here, eight of those, 12 thoracic vertebrae that are all connected to one of the ribs, the lumbar vertebrae, we've got the sacrum, and then the coccyx or the tailbone. Back to the front, we've got the clavicle, which connects from the sternum over to the scapula. The scapula is kind of a strange-shaped bone.
It's kind of a V-shape right here, plus it's got this protrusion sticking out right there. That's your shoulder blade. It connects to the humerus. The humerus runs down here, where it connects to the radius and the ulna. Here's the radius on the thumb side.
Here's the ulna on the pinky side. And, of course, we have got the carpals, the metacarpals of the hand, and then the phalanges. Up here we've got the pelvis and the pubic symphysis, which is the cartilage between the two halves of the pelvis. We've got the femur, which runs all the way down here.
Oop, apparently Mortimer's stand is broken. We've got the patella, or the kneecap. We have the tibia, that's the big bone there.
We've got the fibula, the small bone. Down over here we've got the calcaneus, that's the heel bone back there. We've got the tarsals, the metatarsals, and then finally the phalanges there at the bottom. Alright, thanks for the tour, Mortimer. Oops.
Thanks for the tour Mortimer. No problem. Can you put my head back on now? No problem.
You got it. All right. Here's a blank version of our diagram.
Take a moment, pause the video and see if you can identify all of the bones in the diagram. All right. Here we have the skull.
And of course the skull contains the frontal bone, parietal bone, occipital bone, temporal bone, maxilla, and mandible. We've got the vertebrae, which will include eight cervical, 12 thoracic, five lumbar, and then the sacrum and the coccyx. We have the sternum, And we have the costal cartilage branching out of the sternum, which connect to the ribs. We've got five true ribs, five false ribs, and two floating ribs in the back. We have the pectoral girdle, which includes the clavicle, the scapula or shoulder blade, the humerus, the radius on the thumb side, the ulna on the pinky side, the carpals, metacarpals, and phalanges.
And then all of the leg bones, we have the pelvis, the pubic symphysis is a piece of cartilage between the halves of the pelvis, the femur, the kneecap called the patella, We've got the tibia, fibula, calcaneus, tarsals, metatarsals, and the phalanges of the feet. And of course, all these bones down the center are called the axial skeleton, and all the bones of the arms and the legs are called the appendicular skeleton. Mortimer, should we start a band?
What would I do? Well, I could sing. No, I can't sing, really.
Skull is connected to the cervical vertebrae. Cervical vertebrae connected to the thoracic vertebrae. The thoracic vertebrae connected to the ribs. The ribs are connected to the sternum.
The vertebrae are also connected to the... You know, it's hard to do an anatomically correct version of that song.