Peripheral Nervous System

The nervous system is the controlling system of the body and is composed of nerve cells and organs. It is further classified into the central nervous system and the peripheral nervous system.

The central nervous system comprises the brain and the spinal cord. The peripheral nervous system comprises the network of nerves connected to the brain and the spinal cord.

Table of Contents

• Peripheral Nervous System
• Somatic Nervous System
• Autonomic Nervous System
• Peripheral Nervous System Functions

Nerve fibres are of two types – afferent fibres and efferent fibres. The afferent nerve fibres are responsible for the transmission of impulses from the tissues to the central nervous system while the efferent nerve fibres are responsible for the transmission of impulses from the central nervous system to the concerned tissues or organs.

Let us study the peripheral nervous system, its definition, types, diagram and functions in detail.

Also Read: Central Nervous System

Peripheral Nervous System Definition

“Peripheral nervous system involves the parts of the nervous system outside the brain and the spinal cord.”

The peripheral nervous system has two divisions:

• Somatic Nervous System
• Autonomic Nervous System

The main function of the somatic nervous system is to transfer impulses from CNS to skeletal muscles.

It consists of

• Cranial Nerves
• Spinal Nerves

Cranial nerves are 12 pairs and they emerge from the brain. Some of the examples of cranial nerves are optic, olfactory, etc.

Spinal nerves have their point of emergence as the spinal cord. There are 31 pairs of spinal nerves. They emerge from the spinal cords into dorsal and ventral roots. At the junction of these two roots, the sensory fibres continue into the dorsal root and the motor fibres into the ventral root.

The autonomic nervous system relays impulses from the central nervous system to the involuntary organs and smooth muscles of the body.

It is divided into two parts –

• Sympathetic Nervous System
• Parasympathetic Nervous System

The sympathetic nervous system consists of nerves arising from the spinal cord between the neck and waist region. It prepares the body for violent actions against abnormal conditions and is generally stimulated by adrenaline.

The parasympathetic nervous system is located anterior in the head and neck and posterior in the sacral region. It is mainly involved in the re-establishment of normal conditions when violent action is over.

Following are the important functions of the peripheral nervous system:

1. The peripheral nervous system connects the brain and the spinal cord to the rest of the body and the external environment.
2. It regulates internal homeostasis.
3. It can regulate the strength of muscle contractility.
4. It controls the release of secretions from most exocrine glands.

Also Read: Nervous System

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