To wrap up the gross anatomy of bone, and specifically the structure of a long bone, we're now going to talk about nerves and blood supply. So remember, bone is living dynamic tissue, and as such, it contains blood vessels and nerves. But the outside of the bone is also all compact bone, and compact bone is well, it's pretty solid stuff. It's pretty impenetrable. So for blood vessels and nerves to get into the bone, well, it needs a way in.
The way in is through the nutrient foramen. The nutrient foramen is just a small hole, and it's going to be located in the diaphysis of bones, and it's for blood vessels and nerves to go through. Now for the most part, a diaphysis has a single nutrient foramen. Sometimes there's more than one, but usually just one. And I say it's a small hole, but it's macroscopic.
It's big enough blood vessel to supply the blood supply for the entire diaphysis of the bone. And if we look over here, we have a diagram showing a section of diaphysis or a section of that shaft of bone, and part of it's cut away so we can see the medullary cavity and the yellow marrow on the inside. But what we want to look at are these blood vessels and these nerves going around the outside here. And you can see they come up and then they go in this single hole there. That single hole is our nutrient foramen.
Now once inside, those blood vessels can spread out through the medullary cavity, and they can give blood supply to all of the bone and the marrow that's in that shaft of bone. So what goes in? We're going to give specific names. We're going to give it the nutrient artery is going to bring the blood into the medullary cavity or into the bone. The nutrient vein is going to carry the blood out of the bone, and the nerves are also going to pass through the nutrient foramen as well.
Now at the metaphysis and the epiphysis, things are going to be a little different. There isn't a single nutrient foramen. Up where the spongy bone is, you're going to have several smaller foramina. So a foramen is a hole, many small holes we're going to call foramina. So these are located in the metaphysis and also in the epiphysis.
And this is also going to be true for bones that aren't long bones. Anywhere you have that compact bone with spongy bone on the inside instead of that one hole in the shaft, you're going to have many smaller foramina. Okay. With that, like always, we have an example of practice problems to follow. Give them a whirl.