Gordon Johnson: As I understand human evolution, essentially we have an airbag, hard-surface protector system there to keep us safe. I guess an egg carton is a better way to describe it, that the brain sits inside of its own egg carton.
Dr. Erin Bigler: It does.
Gordon Johnson: Then it has several different mechanisms to protect it, is that right?
Dr. Erin Bigler: There are what are called the meninges that cover the brain. And the dura mater, which is the outside of the meninges, is a sinewy-like kind of tissue; it’s leather like. And it sits on the surface of the brain, and it interfaces with the skull – here. So it’s a bit of a boundary between the skull and the much softer brain. But you also have blood vessels. You have major blood vessels that’re coming here on the surface of the meninges. In fact, if you look in the wall of the skull, you can actually see the embedded outline of the vessel. And so the soft bone of the infant skull actually molds around these blood vessels on the surface of the dura as the brain is developing and expands out and pushes into the skull. So that all helps hold the brain in place. You also what’re called the cranial fossa.
Gordon Johnson: What’s a fossa?
Dr. Erin Bigler: A fossa is a cavity, a space. And so you have the posterior cranial fossa back here.
Gordon Johnson: Posterior meaning the back?
Dr. Erin Bigler: Meaning the back.
Gordon Johnson: Cranial meaning the head?
Dr. Erin Bigler: Meaning the head. And this is where the cerebellum sits.
Gordon Johnson: And that’s this separate darker object.
Dr. Erin Bigler: That’s, that’s the separate darker object on the model
Gordon Johnson: OK.
Dr. Erin Bigler: Correct. So, the cerebellum sits there, and then on the top of the cerebellum is another part of the dura matter, part of the meninges. It separates the top of the cerebellum from the bottom of the brain, the occipital area. And then you have this bony area here, which is now the middle cranial foca, and this is where the temporal lobe sits.
Gordon Johnson: Now this would be the temporal lobe essentially this lower part?
Dr. Erin Bigler: That’s correct.
Gordon Johnson: That is kind of behind the eyes.
Dr. Erin Bigler: Yes. It’s right behind, behind the eyes and in back. Yep, you got it. Okay? And then this is the anterior cranial fossa, and frontal area nsits here.
Gordon Johnson: Anterior being the front?
Dr. Erin Bigler: Being the front, yes.
Gordon Johnson: And that would be this part, right?
Dr. Erin Bigler: Where your left hand is pointing, correct. So you have those different fossa, and they help hold the brain in place. So at a normal walking rate, jumping, running, those areas are your friend. At a high-velocity impact they’re your foe, because the soft brain hits these bony ridges or mechanically deforms around them, and that soft tissue then can be injured.