The Peripheral Nervous System

The peripheral nervous system (PNS) is one of the two main parts of the body’s nervous system. The central nervous system (CNS) is comprised of the brain and the spinal cord. The peripheral nervous system acts as a connector to the central nervous system.

The peripheral nervous system branches outside of the central nervous system and is comprised of nerves and neurons that transmit information to and from the brain.

Anatomy of the Peripheral Nervous System

The peripheral nervous system is further divided into two parts called the somatic nervous system and the autonomic nervous system.

Somatic Nervous System

The somatic nervous system is comprised of cranial nerves and spinal nerves. The nerves of the somatic nervous system supply the muscular system and external receptors. It is this part of the body that remains in control to enable movement.

The Somatic Nervous System (SNS) includes all nerves controlling the muscular system and external sensory receptors. External sense organs (including skin) are receptors. The reaction to the stimulus is involuntary, with the CNS being informed but not consciously controlling the response. Examples of reflex arcs include balance, the blinking reflex, and the stretch reflex.

A person’s sense of touch, taste, sight, sound and smell are controlled by the somatic nervous system.

Autonomic Nervous System

The autonomic system controls and regulates the body internally. The autonomic nervous system is comprised of the sympathetic and parasympathetic nervous systems. Cranial nerves make up the parasympathetic nervous system.

The autonomic nervous system conveys impulses to from the sensory organs to the brain. This part of the peripheral nervous system is in control when the body is at rest. It is also the part of the nervous system that regulates internal processes such as increased and decreased heart rates as a response to stimuli, secretion of digestive fluids, and the body’s reaction to stress.

Conditions that can affect the Peripheral Nervous System

Trauma or injury to the spinal cord or brain can affect both the peripheral nervous system and the central nervous system. Disease can also affect the nervous system, and some often present with symptoms affecting the peripheral nervous system. Damage or disease to the central nervous system is often more serious than damage to the peripheral nervous system.

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