Hi everybody, welcome back to Miss Angla's biology class. I am Miss Angla and in today's video we are going to do the follow-on lesson from the axial skeleton and we are now moving on to the appendicular skeleton. If you haven't watched the axial skeleton video, I've linked it above now for you to go and have a look at and then you can move on to this video. Now if you're new here, don't forget to give this video a thumbs up and subscribe and turn your notifications on because I post every Tuesday and Thursday for grade 8 to 12 biology. So let's get into the appendicular skeleton and for now we are going to focus specifically on the features and the functions of the appendicular skeleton.
In any test or an exam you would be asked to label the skeleton with these particular bones and you'll also be asked to provide their functions. So we're going to focus first in on the appendicular skeleton and where we actually find it and when I speak about the appendicular skeleton I am referring to the bones that are not within the central column of the body, which means I'm actually referring to the arms, and I am referring to the legs, and finally the pelvis. Everything else, the ribcage, the sternum, the vertebral column, and the skull are all part of the axial skeleton. Now, when we look at the appendicular skeleton, it has four main functions.
The first function is it attaches your lower limbs to your axial skeleton, as we've mentioned now. It transmits the weight from your upper body to your lower body. And actually, your lower body is much stronger than your upper body because of this. It supports and protects all your organs in the pelvic area, which there are a number. If you think about all your urinary system, reproductive, as well as your digestive system is housed in your lower pelvic area.
And lastly, it provides attachment points for many muscles. So we're going to move into the pectoral girdle, which is the upper limb bones that are all in your arm. And as I mentioned earlier, you should be able to label diagrams like this one. And for some instances, you should be able to explain their functions. So we're going to start off with this large wing-like bone that we have at the back of our arms over here.
And that is known as the scapula. In everyday language, we call it the shoulder blade. Please remember, it is life sciences, biology, which means we need to use the correct scientific terms.
We then have sitting above that, and it stretches the full side of our chest on either side, we have a bone called the clavicle, also known as the collarbone. And this bone allows for many attachments of your pectoral muscles and your intercostals, and it allows and assists in movement in the upper chest. Then we move to the largest arm bone, which is this one over here, your upper arm, and that is known as the humerus bone. Sitting below the humerus are two bones in your forearm. Now, either of these bones can be sometimes quite tricky to tell the difference between them because we don't know necessarily which way the hand is positioned.
So when you are identifying these two bones in the forearm or the lower part of your pectoral girdle, look out for where the thumb bone is. So this is the thumb over here. And the bone that is in line with the thumb is always going to be the radius bone. And the other bone on the other side is the ulna. So make sure when you look at a diagram and a test or exam, you find the thumb bone, and then you can find the radius, which then brings me to all of the bones that we find in our hands.
Now, our hands are actually divided into three sections. And so I'm just going to illustrate that now by drawing a line through the areas. The first area of your hand is essentially your wrist.
And it is made up of these bones over here. And those bones are known as the carpals. These are your wrist bones.
And a nice way to remember carpals is that you use your hand to drive a car. Carpals. We often get these bones confused with the ones that are in our feet, and you'll see now why that's the case when we do our leg. We then move on to these longer set of bones that are in between here, slightly longer than our carpals.
And those bones over there, we call those the metacarpals. Now, after the metacarpals, which are the five bones of your palm, we end off with your phalanges, which are all of these guys at the end here. They're also known as your fingers.
It is important to note that phalanges are both your toes as well as your fingers. Moving on to the pelvic girdle. Now, I've divided the pelvic girdle or the lower body into two pieces, and we're going to start off with the actual pelvic bones.
Now, looking at this diagram, you should already know that this bone here sitting in the center is the sacral bone, and it is part of the axial skeleton. So we're going to ignore it for now. But the two bones attached to it, it only looks like two bones, but it's actually made out of three bones that have fused together. And that's why sometimes we're not so sure how to label it.
The first bone that you need to look out for is this large wing-like bone that sticks out on either side, and that is known as the ilium. You've got one on either side. The second bone sits at the bottom here, and this is essentially like your bum bone.
This is the bone that you like sit on, and that is the ischium. The third and final component of your pelvic bones is going to be this bone that meets in the front over here, and that is your pubis or your pubic bone. Now, those three together make your pelvic bone. The third and final thing is not a bone, but rather an important location or region.
And that important location or region is found, and it's a little bit difficult to see in this picture, but it's found in this area here on either side. It's a crevice. In that crevice, you will find your femur bone or your lower leg bone.
And we'll see that in the next diagram now. But in a lot of textbooks, you need to know what this opening or this hole is where it inserts. And the insertion point is called the acetabulum. It is where your femur joins into your pelvic bone. Now, as I mentioned to you, we are going to look at the rest of the leg bone that's now attached to the pelvic bone.
So here is the pelvic bone, which we've just labeled. And this is the acetabulum that I was speaking about where your femur inserts into your pelvic bone. Below that, we have the largest bone in the body, which is your upper... upper leg bone over here, and this is the femur. The femur supports the entire upper body weight.
It is your biggest bone, your densest bone. It has to be because it also has the largest muscles on it, the quads and the hamstrings. Below that, we have a cap-like bone that sits on the outside of your knee, affectionately known as your kneecap, but its correct name is the patella. Now below that, and it's not so clear in this image because the two bones are overlapping each other, but there are actually again two leg bones in the same way that there were two forearm bones.
And the thicker, bigger inner leg bone is the tibia, and the fibula is the smaller outer leg bone. Now a nice way to sort of think about this or remember is like in chicken drumsticks or in their chicken legs. When you're eating a chicken drumstick or a chicken leg, you remember that there's the big major bone in the drumstick, which is the tibia.
And then there's that teeny tiny little thin bone that runs down the side. And that is the fibula in a chicken. Then we're going to move down just like we did in the hands.
We have a section of square like bones that create your ankle down over here. And those are known as your tarsals. Beyond that, you have your slightly longer bones, which form the arch of your foot. And those are called our, and they're over here, those are called our metatarsals.
And finally, right at the bottom of our foot, just like we saw in our hand, right at the bottom over here, you have your phalanges. Again, it is just like the ones that we see in our hands. Now, as always, I like to finish off my lessons with a terminology recap.
You can use any of these words to create flashcards, which makes studying so much easier. Now, we looked at, first of all, the pectoral girdle, which is the upper arm bones, and that was the scapula, clavicle, humerus, radius, and ulna. And then we moved into the hand bones, which were the carpals, the metacarpals, and then the phalanges.
Those together make your pectoral girdle. Then we move down to the pelvic girdle, starting off with the pelvis itself. It's made up of three bones, the ilium, the ischium, and the pubis.
And then we look down into the lower limb, starting off with the femur bone. The femur bone is attached to the pelvic bone via an indentation or a socket called the acetabulum. It's a little space that that bone clicks into and fits into snugly.
Then the lower leg bones are the tibia, the fibula, the patella, which is the kneecap. and then the bones of the feet, the tarsals, the metatarsals, and then the phalanges. Now, if you like this video, don't forget to give it a thumbs up and subscribe, and make sure your notification's on so you get notified the moment I post a new video, and I will see you all again soon. Bye!