Diann Godsoe, age 15, of Morenci, Arizona, for her question:
What is the cerebellum?
The cerebellum is a part of the brain ‑ it is the little brain, or the old brain. It acts as a sort of calculating machine for the body. Nerves reach it from the muscles and the senses and the cerebellum is able to coordinate all this information. Other brain centers use this coordinated information when we get ready to take action.
Did you ever wonder how an expert golfer can hit the little ball so accurately? The figuring for this job is done by the cerebellum. The golfer keeps his eye on the ball. He holds the club ready. The cerebellum begins to calculate. It figures distance, direction, and angles. It figures the necessary strength and energy for the muscles to make the swing. And the wonderful cerebellum makes all these calculations in a moment.
Glow your eyes and tip over your head. You can tell, more or less, whether your head is straight up or rolled over to one side. This information comes from the cerebellum. This brain center is in constant contact with the canals within the inner ear which register balance. It is the cerebellum which makes it easy for us to walk upright.
Yes, indeed, the cerebellum is a reliable organizer and our bodies could not function without it. But it is not the reasoning, thoughtful part of the brain. This section is the cerebrum which, in man, is equal in weight to half the total nervous system.
The cerebellum is a smallish section of the human brain, in close contact with the spinal column. The spinal column is a sort of trunk line of nerves gathered in from all parts of the body. It is a sensitive white cord running through a protective tunnel of backbone. It joins the brain centers at the base of the skull.
At this point the nerve tissues become a thickened wad called the medulla oblongata. This is the lowest of the brain centers. It controls our heartbeat, blood pressure and breathing. These actions are done automatically without consulting the cerebrum, or thinking part of the brain.
The cerebellum is above and behind the medulla, protected by the bones at the base of the skull. The brain acts like a central telephone service, the nerves act as telephone wires carrying messages to end from all parts of the body. The sensory nerves carry sense impulses ‑ heat, cold, smell. They also carry motor impulses ‑ orders to move. Sometimes the cerebrum must make decisions on this information ‑ to move or not to move. This information is carried by a nerve fiber into the cerebrum which is in the front and top of the brain. But this motor or sensory nerve also sends a sort of carbon copy of its message to the cerebellum at the base of the brain.
The cerebellum coordinates the messages with all the other facts it has, When the brain orders action, the cerebellum provides a total picture of the action to be taken. This is the information which helps you walk about without consciously thinking how you do it. And it helps you play a ball game, without using a math book to figure all the angle s distances and movements. These brilliant calculations are done in a jiffy by your cerebellum.