Human Anatomy and Physiology - N. I. Fedyukovich 2003
Nervous system
Central nervous system
The Central Nervous System (CNS) consists of the Brain AND SPINAL cord, which are composed of gray and White matter. The Gray matter of the brain and Spinal Cord is an aggregation of nerve Cell bodies along with the immediate branches of their processes. The white matter consists of nerve fibers—the processes of Nerve Cells covered by a myelin sheath, which gives these fibers their white color.
Nerve fibers make up the tracts of the brain and spinal cord, connecting various nerve centers with one another. Depending on its role in the body, The Nervous System is conventionally divided into two parts—somatic and autonomic (vegetative).
The somatic nervous system primarily innervates the Organs of the body (the soma), such as skeletal Muscles, Skin, and others. This division of the nervous system connects the body to the external environment through the Sensory Organs and enables movement.
The Autonomic nervous system innervates Internal Organs, Blood Vessels, glands (including Endocrine glands), and smooth Muscle, and regulates metabolic processes in all organs and Tissues.
The autonomic nervous system, in turn, is divided into parasympathetic and sympathetic parts, both of which have central and peripheral divisions.
Last update: 08/08/2026
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