 We're going to continue our discussion of the skeletal system, and just a reminder, once again, to divide it up into two main parts, the axial and appendicular skeleton, and our focus today will be on the appendicular and more specifically on the upper limb. But the axial skeletal system is the skull, the thoracic cage, the vertebral column, and if you look at the skeleton, this is really the main core or the main part of the body. So it would consist basically of the sternum, the ribs, the skull, which is missing on this particular skeleton, and then the vertebral column. Now, hanging off of the axial skeleton is the appendages. And you can kind of see the upper limbs and then also the lower limbs. And then there are some girdles that are going to attach those upper and lower limbs basically to the axial skeleton, and that's the pectoral girdle and the pelvic girdle. The pectoral girdle has been in a previous video, but basically consists of two main bones. You've got your clavicle and your scapula, and this is what's going to connect our upper limb, which is our focus today, to basically the thoracic cage. So the upper limb is going to consist of the bone of the arm, which is the humerus, the radius and the ulna, which are the two main bones in the forearm, the bones of the wrist called the carpals, the bones of the hands called the metacarpals, and then the bones of the fingers or the flanges. And so let's start off by talking about the humerus. All right, so if you look at the upper limb as a whole, you can kind of see how the humerus connects really to the rest of the upper limb. Now this particular humerus you'll notice is actually from the left side of the body. I can kind of show it to you right there, so just remember that everything in the epidicular skeleton is duplicated. Now some major features that you should notice on the humerus is the first one is the head of the humerus. And you'll notice that this is at the proximal end of the humerus. And proximal, remember, means it's closer to the point of attachment. So this is the one closest to the scapula. And the importance of the head of the humerus is this is actually one part of that shoulder joint. It's actually the ball part of that ball and socket joint fitting into the depression on the scapula called the glenoid cavity. And so really it's a very shallow depression. And then the head of the humerus fits into that. Moving on down, we've got the greater and lesser tubercle. These are some attachment points for muscles that you'll learn about later on. A rough area on the anterior side, this is called the deltoid tuberosity. It's an attachment point for a muscle you learned about called the deltoid. So that's how it gets its name. And then on the distal side of the humerus, we have several features. One is collectively referred to as a condyle, which actually has two main parts to it. A capitulum on the lateral side, and then a trochlea on the medial side. And there are also two other processes kind of coming off of them. These are called condyles, epicondyles, excuse me. And this would be the medial epicondyle. This is actually the largest and you should be able to easily feel this. It's a major point on either side of, on your elbow. And then you have the lateral epicondyle. Now looking on the posterior side of the humerus, you should notice a large depression called the elecronon. And as you can see the point of your elbow, actually the lecronon fossa. The point of the elbow is called the elecronon and this is actually on the ulna. And you'll notice that these two fit together and actually rotate each other and this is going to create the elbow joint. So that's the humerus. Now in the forearm, we have two main bones. Now assuming that we are standing at anatomical position, you always make that assumption unless otherwise stated, the ulna is going to be the medial bone of this forearm and the radius is going to be the lateral bone. And if we were not standing at anatomical position, you would notice that the radius actually would cross over the ulna. So we're always assuming anatomical position at least partially for that reason. Now looking at just the elecronon, a couple points to note is you've got this large point. This is the point of your elbow. This is called the elecronon. And just a reminder, this is what's fitting into the elecronon fossa of the humerus. Another point that you'll notice is the trochlear notch. Kind of reminds me of some of those videos I've seen of the milking snakes for venom. But this is called the trochlear notch. And what this does is it rotates around the trochlea of the humerus. And keep in mind trochlea actually means pulley. And so the trochlea of the humerus is going to kind of look like a pulley shaped figure. Now the bone of the forearm on the lateral side is the radius. And the radius is very distinguishable by having a flat head. And then there's a process that you can, just down here, this is called the radial tuberosity and actually a major muscle of your arm, the biceps brachii, actually attaches at this point. Looking further down at the hand we've got the carpals. Now there are eight of these and actually they all have individual names. Fortunately for you, you will not have to know all those individual names. Just recognize them as the carpals. Then we've got the metacarpals and these are the bones in your hand. Now aside from recognizing them as the metacarpals, you also need to be able to number them. And the numbering system starts always with the metacarpals associated with the thumb. So the metacarpals associated with the thumb is metacarpal 1, 2, 3, 4 and 5. And then from there these next group of bones are the flanges. And you can of course easily see the different flanges even on your own hand. You'll notice that for each finger there are three flanges and for the thumb there is just two flanges. So for the flanges that are making a joint directly with the metacarpals those are called the proximal flanges. So each digit has proximal flanges associated with it. For the fingers there are some middle flanges and then for the thumb and also the fingers the one that is most distal hence its name is the distal flanges. And these are very, very tiny little bones that you can see now. The other interesting thing about these flanges is technically speaking these are long bones. So you think well they don't look very long to me. Well that's because they do have two distinct ends and then a middle region between them and that's what is considered the long bone. So that's it and next series of videos would deal with the pelvic girdle and then the lower limb.