This example tells us that forensic analyses can use bones to establish a rough age of a skeleton, and then it wants to know what specific structure in the metaphysis might a forensic scientist look at to determine age. So I'll ask you. Alright. If you want to know the age of the skeleton, roughly, you can look at the metaphysis. What are you looking for?
Well, remember, in the metaphysis, that's that widening end of a long bone, and in there, you have the epiphyseal plate or epiphyseal line. In children, that starts out as cartilage because that's where growth is occurring in the long bone, where the long bone is growing longer. And in adults, it gets converted to compact bone. And so by looking at where it is in that stage from cartilage to compact bone, you can give the rough age of a skeleton. So I'm going to write here the epiphyseal plate/line.
Alright. Now the second part here, it wants to know what would you expect this structure to be comprised of at the following ages. Alright. Well, we kind of already said that, but we also here have these x-rays of different hands. We have a child's hand, an adolescent's hand, and an adult's hand, and that's what we want to know.
What do you expect that epiphyseal plate or line to be comprised of as a child, an adolescent, or an adult? Alright. So I'll just give you one second to think of that. What do you think for each one? Well, as I look down at the images, we can see here.
So this is the child's hand right here, and we can look for that epiphyseal plate or epiphyseal line. Here, it's very clear. This is the radius. Right? That's the end of the long bone in the arm there, and you can see this epiphyseal plate right there.
And then the epiphysis is this sort of bone that's sort of sitting on the end there. This is actually one bone. The same thing in these metacarpals here. You have the metacarpals, and then you have what looks like a little space, and then the epiphysis of each one of those bones is just sort of sitting on the end there. Well, that's because that epiphyseal plate is still cartilage, and cartilage doesn't show up as well on an x-ray.
So in a child, that epiphyseal plate is cartilage. Alright. And now what about an adolescent? Well, that's our adolescent there. So in your teenage years, you're growing a lot, but then growing kind of slows down.
So we can see that in this image again. We can see there's still a very clear line separating the diaphysis from the epiphysis in that metaphysis, and that's that epiphyseal plate. So if there's a very clear line that you can see, that means that it's still cartilage. But I'm going to say here that it's thinning. Not that the cartilage is thinning, but just the size of that space is thinning.
The epiphyseal plate is not as big because growth is slowing down. And then finally, we can look at this adult's hand. And, well, if you look for that epiphyseal plate, there's no more space here. There's no more space at the end of the metacarpals there because it has grown together. It is now compact bone.
Alright. For that, remember, the epiphyseal plate starts out as cartilage because that's where the growth of the long bone happens. When you stop growing, it gets converted to compact bone. More practice problems after this. I will see you there.