Why Head Injuries Are So Dangerous
There's no disputing the fact that a bump on the head is much different than a bump on the knee, and that the bump on the head produces broader implications for long-term health. Depending on what part of the head is injured (and, therefore, the passageways in the brain that are damaged), the injured person can lose the ability to speak or walk or even remember his name. The brain, after all, regulates all body functions. It tells us what to think and what to feel, and it is what makes us human—and unique.
There are six distinct areas of the brain. Each of those areas controls different body functions that can be affected or disabled as the result of a head injury.
This list looks at each of the different parts of the brain in detail and outlines the function of each—which can be affected if that part is accidentally damaged. It will help you understand what's going on if a head injury occurs.
- CNS No, it's not a new bank. The CNS is the central nervous system, and it functions as the go-between that sends messages back and forth from the masses of peripheral nerves in the body to the spinal cord that leads to the brain. Damage here can affect a person's ability to move.
- Brainstem You'll find the brainstem at the uppermost tip of the spinal cord. Connected to the spinal cord by thick nerve fibers, it's the invisible underbelly of the “corporation.” It is divided into three areas: the Medulla is the place where basic life functions such as heartbeat, temperature, and breathing are regulated. Moving up the brainstem, we next come to the Pons: the bridge between the medulla and the “upper echelons” of the brain. It is also the area where reflexes are controlled and instinctively used, and it houses the brain's alarm nerve cells that keep you alert. The third area of the brainstem is the Midbrain, which provides eye muscle control, as well as helping the Pons with its basic job.
- Cerebellum Located behind the brainstem, the cerebellum is the body's center for balance and coordination: every step and every movement is regulated from here. The cerebellum acts as a traffic coordinator of your body's corporation, too. It coordinates your movement and your speech muscles.
- Diencephalon Considered the “outer corridor” of mind power, the diencephalon sits above the brainstem, as a proud, majestic gateway to the emotional and mental depth above. Here, the hypothalamus and the thalamus—the partners in crime— decipher every sensation. These two partners also delegate where memory will be stored.
The thalamus is a beehive of activity through which messages are transported to the place that determines who gets what in the “upper echelons” of power. To illustrate its function, think of this. The words of the poem you're reading sit next to your recipe for veggie burgers in your memory storage tank. The words of the poem are sent to both the emotional core of the brain (where they affect your feelings) and the intellectual center of the brain (where they are deciphered and analyzed). They bounce from emotion to intellect and evoke the deep sigh you produce. In the meantime, the smell of those cooking veggie burgers is sent to the brainstem, which activates your salivary glands in anticipation of lunch. All this and more. The thalamus never stops!
First Aids
Short-term memory enables you to remember things about this morning or the movie you saw at the mall last week. Long-term memory accounts for those deep-seated remembrances of long-ago birthday parties, old friends, and music to which you once danced the night away. It also “locks in” repetitious, rote-learned motor skills, such as how to tie your shoe. The two types of memories are kept in “chemical loops” in different parts of the brain. Because short-term memory is stored in an area that's vulnerable to head injury and it has not yet become ingrained in the brain by repetition, it is usually more affected from an accident.
- Limbic System This region, located between the Diencephalon and the intellectual Cerebrum, packs a big whallop in the human experience. We can experience joy, anger, happiness, fear, and many variations of those. Thanks to this area of the brain, our emotions get dimension and feelings—the color and depth that makes life a celebration. Together with the intellect, the Limbic System deciphers the messages it receives from below and creates emotional responses to them.
- Cerebrum You might call it the CEO, the Man, or the Head Honcho. The cerebrum is the intellectual heart of the very being. Here, the higher functions decode and respond to the various messages coming in from the areas of memory, thought, and even emotion. This part of the brain enables you to understand and organize your thoughts, to perceive the world and its meaning, to communicate, to finish tasks, and to dissect and solve problems. This is where reading, writing, and 'rithmetic create a masterly whole.
The hypothalamus, though no bigger than a pea, is also a whirling dynamo. It controls basic instincts ranging from appetite to sexual arousal and from thirst to sleep. Thanks to its position close to the pituitary gland—the master gland of the body—it also controls the hormonal (chemical) secretions that, as they propel messages through the brain, determine the underlying basis of what we are, how we feel, and what we think, as well as “telling” the pituitary gland which hormones to release for growth, metabolism, sex, lactation, and other “basics.” Because it lies so close to the “upper crust” of the brain, it also helps regulate our emotions, motivations, and moods.
Globe and Lobe
The brain is not only divided into parts, it is also divided into two distinct hemispheres: the right and the left. The two work in tandem to make the whole “greater than its parts.” The left hemisphere, for example, provides the ability to speak in most people. The right hemisphere gives that speech its lilt, color, and dialect. When a head injury occurs in the left hemisphere, the functions that are affected usually occur on the right side. Similarly, an accident in the right hemisphere will create problems in left-sided functions of the body.
Not only are there two hemispheres, but there are four “quarters” or lobes of the brain. Their functions are also at risk if a head injury occurs in their “section.” These are the four “quarters”:
which are responsible for very specific functions.
- Frontal lobes are the most crucial part of the brain in terms of intellect, emotion, organizational and executive skills, and personality.
- Temporal lobes hold the bulk of the memory. They also make sense of “incoming information” and decide where it should go within the brain.
- Parietal lobes control the sense of touch, as well as the ability for reading comprehension and understanding spatial relationships.
- Occipital lobes are responsible for sight.
Knowing where a head injury occurred—in which part of the brain, which hemisphere, and which lobe—can help pinpoint the functions that will be affected.
Excerpted from The Complete Idiot's Guide to First Aid Basics © 1996 by Stephen J. Rosenberg, M.D. and Karla Dougherty. All rights reserved including the right of reproduction in whole or in part in any form. Used by arrangement with Alpha Books, a member of Penguin Group (USA) Inc.
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