Theories Psychosocial Psychology What Is the Somatic Nervous System? By Kendra Cherry facebook twitter Kendra Cherry, MS, is an author, educational consultant, and speaker focused on helping students learn about psychology. Learn about our editorial process Kendra Cherry Medically reviewed by Medically reviewed by Huma Sheikh, MD on April 16, 2020 facebook twitter linkedin Huma Sheikh, MD, is a board-certified neurologist, specializing in migraine and stroke, and affiliated with Mount Sinai of New York. Learn about our Review Board Huma Sheikh, MD Updated on April 14, 2021 Print PASIEKA / Brand X Pictures / Getty Images Table of Contents View All Table of Contents What Is the Somatic Nervous System? Somatic vs. Autonomic Nervous Systems Parts of the Somatic Nervous System Reflex Arcs Impact of Damage Preventing Peripheral Neuropathy What Is the Somatic Nervous System? The somatic nervous system plays a vital role in initiating and controlling the movements of your body. The system is responsible for nearly all voluntary muscle movements, as well as for processing sensory information that arrives via external stimuli, including hearing, touch, and sight. How exactly does this complex system work? Let’s start by taking a closer look at the key parts of the somatic nervous system. Somatic vs. Autonomic Nervous Systems The somatic and autonomic nervous systems are both part of the peripheral nervous system, which allows the brain and spinal cord to receive and send information to other areas of the body. However, they have different functions. The autonomic nervous system regulates a variety of involuntary body processes that take place, including heartbeat, blood flow, breathing, body temperature, and emotion response. The primary function of the somatic nervous system is to connect the central nervous system to the body's muscles to control voluntary movements and reflex arcs. For example, imagine that you are out for a jog in the park one brisk winter morning. As you run, you spot a patch of slick ice on the path ahead. Your visual system perceives the icy patch and relays this information to your brain. Your brain then sends signals to engage your muscles to take action. Your somatic system allows you to turn your body and move to a different part of the path, successfully avoiding the icy patch and preventing a possibly dangerous fall on the hard pavement. What You Should Know About the Peripheral Nervous System Parts of the Somatic Nervous System The term somatic is drawn from the Greek word soma, which means "body," which is appropriate considering it is this system that transmits information back and forth between the central nervous system (CNS) and the rest of the body. The somatic nervous system contains two major types of neurons (nerve cells): Sensory neurons, also known as afferent neurons, are responsible for carrying information from the body to the CNS. Motor neurons, also known as efferent neurons, are responsible for carrying information from the brain and spinal cord to muscle fibers throughout the body. The neurons that make up the somatic nervous system project outwards from the CNS and connect directly to the muscles of the body, and carry signals from muscles and sensory organs back to the central nervous system. The body of the neuron is located in the CNS, and the axon (a portion of the neuron that carries nerve impulses away from the cell body) then projects and terminates in the skin, sensory organs, or muscles. How Neurons Transmit Information Throughout the Body Reflex Arcs In addition to controlling voluntary muscle movements, the somatic nervous system is also associated with involuntary movements known as reflexes (or reflex actions), which are controlled by a neural pathway known as a reflex arc. Reflex arcs include sensory nerves that carry signals to the spinal cord, often connect with interneurons there, and then immediately transmit signals down the motor neurons to the muscles that triggered the reflex. During a reflex, muscles move involuntarily without input from the brain. This occurs when a nerve pathway connects directly to the spinal cord. Examples of reflex actions include: Jerking your hand back after accidentally touching a hot pan Involuntary jerking when your doctor taps on your knee You don’t have to think about doing these things. Reflex arcs that impact the organs are called autonomic reflex arcs, while those that affect the muscles are referred to as somatic reflex arcs. Diseases of the Somatic Nervous System Somatic nervous system diseases are those that impact the peripheral nerves that are outside of the brain and spinal cord. Diseases that impact the peripheral nerve fibers of the somatic nervous system can cause what is known as peripheral neuropathy. This leads to nerve damage that causes numbness, weakness, and pain, often in the hands and feet. The causes of damage to the peripheral nerves found in the somatic system can include conditions present from birth as well as acquired conditions. Diabetes is one of the most common causes of peripheral neuropathy, but it may also be caused by autoimmune conditions, infectious diseases, and trauma. Other types of somatic nervous system diseases include: Brachial plexus neuropathies Guillain-Barre syndrome Myasthenia gravis Nerve compression syndromes Trigeminal neuralgia Preventing Peripheral Neuropathy While diseases that impact the somatic nervous system are not always preventable, there are lifestyle changes you can make that may help prevent peripheral neuropathy. Some strategies that may help include: Avoiding alcohol Correcting vitamin deficiencies Eating a healthy diet Getting regular exercise Maintaining a healthy weight Quitting smoking It is also essential to treat chronic health conditions such as diabetes, which may play a role in the onset of peripheral neuropathy. What You Need to Know About the Nervous System Was this page helpful? Thanks for your feedback! Ever wonder what your personality type means? Sign up to find out more in our Healthy Mind newsletter. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Cuevas J. The somatic nervous system. In: Reference Module in Biomedical Sciences. Elsevier; 2015:B9780128012383054000. doi:10.1016/B978-0-12-801238-3.05364-2 Barrett KE, Barman SM, Boitano S et al. Ganong's Review of Medical Physiology 25th Edition. McGraw Hill Professional; 2015. Dorland. Dorland's Illustrated Medical Dictionary E-Book. Elsevier Health Sciences; 2011. Cleveland Clinic. Neuropathy (peripheral neuropathy). Updated December 16, 2019. Akinrodoye MA, Lui F. Neuroanatomy, somatic nervous system. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. Updated April 2, 2020. Cleveland Clinic. Neuropathy (peripheral neuropathy): Prevention. Updated December 16, 2019. Additional Reading Somatic nervous system. Dorland's Illustrated Medical Dictionary. Merck & Co., Inc; 2011. Ganong, W. F. Review of Medical Physiology. New York: McGraw-Hill Publishing; 2015.