Hesperian Health Guides

Examining The Nervous System

Sometimes physical disability results from problems in the muscles, bones, or joints themselves. But often it comes from a problem in, or damage to, the nervous system.

Depending on what part of the nervous system is affected, the disability will have different patterns.

For example, polio affects only certain action nerves at points in the spinal cord (or brain stem). It therefore affects movement. It never affects sensory nerves, so sight, hearing, and feeling stay normal. (See Chapter 7.)

A spinal-cord injury, however, can damage or cut both the sensory and action nerves, so that both movement and feeling are lost. (See Chapter 23.)


a child's body, showing brain and nerves.
The nervous system is the body’s communication system. The ‘central switchboard’ is the brain, from which electrical messages run back and forth, to all parts of the body, through ‘wires’ called nerves.

Sensory nerves bring messages from parts of the body about what the body sees (eyes), hears (ears), smells (nose), and feels (skin).

Action nerves (motor nerves) carry messages to parts of the body, telling muscles to move.
The brain is the main control center of the nervous system.

The ‘trunk line’ of the nerves is the spinal cord. It runs from the brain down the middle of the spine.

Nerves come out from between each back bone and communicate to a part lower down in the body.

Unlike polio and spinal-cord injury, which come from damage to nerves in the spine, cerebral palsy comes from damage to the brain itself. Because any part or parts of the brain may be damaged, any or all parts of the body may be affected: movement, sense of balance, seeing, hearing, speech, and mental ability. (See Chapter 9.)

Therefore, how completely you examine the workings of the nervous system will depend partly on what disability the child appears to have. If it is fairly clear the disability comes from polio, little examination of the nervous system is needed. But sometimes polio and cerebral palsy can be confused. If you have any suspicion that the disability might be caused by brain damage, you will want to do a fairly complete exam of nervous system function. Damage to the brain or nervous system can cause problems in any of these areas:

Methods for testing some of these things are included on the next few pages and on the RECORD SHEETS 2, 3, and 4. Other tests that you will need less often, we include with specific disabilities. Refer to the links listed above.

This page was updated:21 Nov 2019