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11-19. GENERAL

a. Definitions.

(1) A pathway is the series of nervous structures utilized in the transmission of an item of information. An example of a pathway is the reflex arc discussed in Module 11-15c.

(2) The brainstem is continuous with the spinal cord. Together, the brainstem and the spinal cord are sometimes known as the neuraxis.

b. General Categories of Neural Pathways.

(1) Sensory pathways. A sensory pathway is a series of nervous structures used to transmit information from the body to the CNS. Upon arrival in the CNS, these pathways ascend (go up) the neuraxis to the brain.

(2) Motor pathways. A motor pathway is a series of nervous structures used to transmit information from the CNS to the body. The commands for motor action originate in the brain and descend (go down) the neuraxis to the appropriate spinal levels. From this point, the commands pass through the nerves to the effector organs.

c. Controls. The human nervous system has several levels for control. The lowest level is the simple reflex arc (see Module 11-15c). The highest level of control is the conscious level. From the lowest to the highest levels are several progressively higher levels, such as the righting reflex. Thus, the processing of information and the transmission of commands are not haphazard but very carefully monitored and controlled. All information input and all information output are monitored and evaluated.

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