Brain

Students think that the brain is sort of the consistency of a rubber ball. And that's because in the laboratories and teaching specimens we have fixed, formal and fixed brains. However, if you're a trauma surgeon or a neurosurgeon, you realize that the brain is really very, very soft and much more vulnerable than the impression you get looking at the fixed brain. So I would like to show you a 1400 gram brain that has just been removed from an autopsy. And we are fortunate enough to be able to show you what a normal, unfixed,

recently deceased patient's brain would look like. This is the ventral surface of the brain. And what you see are the peel vessels, this nice blush with the clear leptomaninges, and the vessels running in between the arachnoid and the Pia. The cerebral spinal fluid has leaked out through the cisterns, and so that subarachnoid space is no longer visible unless I move the brain. But it's very, very soft. Notice it's totally squishy. It's the consistency. It's much softer than most of the meat you would see in a market.

So if I were to pinch this in either way, I could easily damage this with my thumb. In fact, neurosurgeons, when they are doing surgery, often just evacuate with a vacuum or suck out parts of the brain. This string here has been placed around the basilar artery so it can be suspended in a bucket or formaldehyde in order to denature the protein and harden it. If we didn't, it would sit on the bottom of the bucket and the brain would become deformed as you would see here,

so that it would be compressed in this direction just from the weight of the brain. So that points out one of the purposes of the cerebral spinal fluid is to float the brain inside the calvarium and act as a cushion. The cerebellum is easily seen, the medulla, the pons. Here you can see the arachnoid spanning across the space here at the base of the brain. The optic nerves are very obvious as are the olfactory nerves. Here are our temporal lobes and here is the uncus on either side.

The uncus, remember, is the most mesial part of the temporal lobe. The tentorium that fit in here has been removed, but we can see a slight groove right along here where the tentorium sat. So there is no evidence in this brain of any of the temporal lobe herniating immediately over the edge of the tentorium. It's a beautiful specimen. Unfortunately, this cancer patient died of complications secondary to a cell transplant. Here you can see how soft and pliable the dura is, and we can look down between the hemispheres and see the corpus callosum.

I can also see a bit of the anterior cerebral artery coming over the surface. So this is the inter hemispheric fissure. And if I turn the brain around and we look at the occipital lobe, we can see the top of the cerebellum. And here there is a very small amount of blood that was actually seen on MRI that the patient had before death. If I let the cerebellum hang down a little bit, you can see the superior surface of the cerebellum. Turn it back around. So our very delicate and vulnerable brain with its two vertebral arteries on the medulla,

its basilar artery on the pons, it's branching to the posterior cerebral artery right here where you have the cerebral peduncle. And here we have the inter space here is the inter peduncular cistern. And we can see the two mammillary bodies, the pituitary gland stayed within the body. And here you can see the base of the brain with the optic nerve, the chiasm and the tract. You can see here an impression, a depression just from where I was holding the brain. Just from holding it that small amount of time, the depression from my finger is clearly visible.

Think how vulnerable the brain is, then think how narrow and small the spinal cord is and what a devastating consequence, just a quick subluxation of the vertebra or a herniation of the disc can cause to the delicate spinal cord, which is about the width of one of these gyri. These gyri are nice, there's no big space between them, but neither does it look particularly swollen for a patient of this age.