Wilderness and Rescue Medicine 8th Edition

Chapter 6: The Nervous System

The central nervous system is one of the three critical systems and controls all essential life func- tions, both voluntary and involuntary. The brain receives stimuli directly from the eyes, nose, and facial nerves via the cranial nerves in the head, and indirectly from the rest of the body through peripheral nerves and the spinal cord. Impulses traveling from the brain in the other direction control most of the functions of our muscles, glands, and organs. Failure of the brain to ade- quately regulate and control body systems can result in failure of the circulatory and respiratory systems resulting in death. Brain failure is a seri- ous critical system problem requiring immediate and aggressive treatment. Spinal cord failure is less likely to be immediately life threatening but is also an emergency (see the Spine Injury chapter). Structure and Function The soft tissue of the brain and spinal cord are enclosed and protected within the bony structure of the skull and vertebrae of the spine. From the gap between the individual vertebrae, unprotect- ed peripheral nerves branch out from the spinal cord to reach all body tissues. Nerves controlling the most critical functions of the major body sys- tems exit the cord at the base of the skull and the

upper part of the cervical spine . Several serious problems can affect the central nervous system. Brain Failure Because nervous system tissue is exquisitely sensi- tive to oxygen deprivation, any significant prob- lem with oxygenation and perfusion will affect mental status. A subtle change in brain function is often the first indication of a serious condition. This is the peeling of the evolutionary onion as discussed in the General Principles of Physiology and Pathology chapter. Inevitably, the level of con- sciousness will begin to decrease if the perfusion or oxygenation problem persists.

Central Nervous System Brain

General Principles

1

Structure: • Cerebrum

• Cerebellum • Brain stem • Cerebrospinal fluid Function: • Voluntary Action • Involuntary Control Problem: • Brain Failure

*

© 2018 WMA