The peripheral nervous system includes the nerves and ganglia outside the brain and spinal cord. The PNS includes the peripheral nerves, neuromuscular junctions, cranial nerves, and spinal nerves. This system also carries information to and from the central nervous system. Show
The peripheral nervous system (PNS) is made up of two divisions: the somatic nervous system and the autonomic system. Each part of this system plays a vital role in how information is communicated throughout the body. This article discusses what the peripheral nervous system is, how it works, and the influence that it has on how the body functions, including what happens when there is a problem affecting the PNS. What Is the Peripheral Nervous System?The nervous system is divided into two parts: the central nervous system and the peripheral nervous system. The central nervous system (CNS) includes the brain and spinal cord, while the peripheral nervous system includes all of the nerves that branch out from the brain and spinal cord and extend to other parts of the body, including muscles and organs. The primary role of the PNS is to connect the CNS to the organs, limbs, and skin. The nerves of the PNS extend from the central nervous system to the outermost areas of the body. The peripheral system allows the brain and spinal cord to receive and send information to other areas of the body, which allows us to react to stimuli in our environment. The four primary functions of the PNS are to:
Examples of processes controlled by the peripheral nervous system include dilating or constricting the pupils in response to light, stimulating digestion, activating the sweat response, controlling blood flow, and regulating heart rate. The nerves that make up the peripheral nervous system are actually the axons or bundles of axons from nerve cells or neurons. In some cases, these nerves are very small, but some nerve bundles are so large that they can be seen by the human eye. Structures of the Peripheral Nervous SystemThe peripheral nervous system itself is divided into two parts: the somatic nervous system and the autonomic nervous system. Each of these components plays a critical role in how the peripheral nervous system operates. The Somatic Nervous SystemThe somatic system is the part of the peripheral nervous system responsible for carrying sensory and motor information to and from the central nervous system. The somatic nervous system derives its name from the Greek word soma, which means "body." The somatic system is responsible for transmitting sensory information as well as for controlling voluntary movement. This system contains two major types of neurons:
The Autonomic Nervous SystemThe autonomic system is the part of the peripheral nervous system that's responsible for regulating involuntary body functions, such as blood flow, heartbeat, digestion, and breathing. In other words, it is the autonomic system that controls
aspects of the body that are usually not under voluntary control. This system allows these functions to take place without needing to consciously think about them happening. The autonomic system is further divided into two branches:
RecapThe PNS is made up of two divisions: the somatic nervous system and the autonomic nervous system. The somatic system contains sensory and motor neurons. It sends and receives sensory information and motor signals. The autonomic system is responsible for regulating involuntary body functions. Nerves in the Peripheral Nervous SystemThe PNS is composed of nerves that are responsible for carrying signals between the central nervous system and the parts of the body that lie outside the CNS. This includes information from the senses, organs, and muscles. The axons of these nerve cells are bundled together and can be found throughout the body. Information is received by the dendrites of these cells, the information travels down the axon to the cell body. The message can then be communicated to other cells. The nerves that make up the peripheral nervous system connect with either the spinal cord or brain in order to transmit information to the CNS. PNS NervesThe main nerves that make up the peripheral nervous system include:
Spinal NervesSpinal nerves are responsible for transmitting information from the muscles, organs, and glands to the spinal cord. There are 31 spinal nerves that branch out to different areas of the body from the spinal cord. Cranial NervesThe cranial nerves are responsible for the receptors found in the head and neck area. Instead of connecting with the spinal cord, these nerves travel directly to the brain. There are 12 pairs of cranial nerves that transmit motor and sensory information from areas including the face, mouth, eyes, nose, and ears. RecapThe PNS is made up of cranial nerves that connect directly with the brain and spinal nerves that connect with the spinal cord. Diseases of the Peripheral Nervous System There are a number of diseases and disorders that can affect the peripheral
nervous system. Problems with the sensory and motor neurons in the PNS can result in changes in sensation, muscle weakness, or muscle paralysis. Some of the conditions that can affect the PNS include:
Symptoms of PNS diseases and disorders can include numbness, pain, tingling, burning, sensitivity to touch, and muscle weakness. RecapDisorders, injuries, toxins, and viruses can cause problems with the peripheral nervous system. Such conditions can lead to symptoms related to sensation, muscle strength, and muscle control. Treatment for PNS ConditionsTreatment for peripheral nerve problems depends on the cause and focuses on treating the underlying disorder and offering supportive care. For example, some PNS conditions may be caused by injury while others may be related to underlying health conditions, viruses, toxins, or genetic disorders. In addition to treating conditions that may be causing dysfunction or damage to PNS nerves, treatment may also involve surgery, physical therapy, occupational therapy, speech/language therapy, and respiratory support. A Word From Verywell The peripheral nervous system plays a critical role in motor and sensory function. If you are experiencing symptoms such as muscle weakness, numbness, loss of sensation, or sensitivity, talk to a healthcare provider for further evaluation. Frequently Asked Questions
What is peripheral nervous system and its function?What does the peripheral nervous system do? The nerves of the peripheral nervous system are responsible for relaying information between the body and the brain. This includes involuntary body functions such as breathing, blood flow, and heartbeat as well as sensory information and control of voluntary movement.
What are the four main divisions of the peripheral nervous system?The peripheral nervous system is subdivided into nerves, the autonomic system, and the somatic system. The autonomic nervous system is further subdivided into the parasympathetic and sympathetic nervous systems. The enteric nervous system is an independent subsystem of the peripheral nervous system.
What are the two divisions of the peripheral nervous system describe each?The sensory division of the PNS carries sensory information from the body to the central nervous system. The motor division of the PNS carries nerve impulses from the central nervous system to muscles and glands throughout the body.
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