The peripheral nervous system is composed of nerves that branch from the brain and spinal cord and then divide repeatedly to supply every part of the body. The nerves transmit information necessary for sensation, muscle stimulation, and the regulation of unconscious functions. Disorders of these nerves may be painful, cause loss of sensation, or lead to paralysis.
This section starts with an overview of peripheral neuropathies, in which one or more peripheral nerves are damaged. Peripheral neuropathies are relatively common and have many causes, including injuries, infection, nutritional deficiencies, and disorders such as diabetes mellitus. Diabetic neuropathy, the most common cause of peripheral nerve damage, is covered next. This is followed by an article on nutritional neuropathies, in which deficiency of essential nutrients in the diet, especially the vitamin B complex, causes the nerve damage.
The next articles cover disorders such as sciatica, carpal tunnel syndrome, and facial palsy, all of which may be caused by compression of a nerve. Rarer disorders that affect peripheral nerves are covered next. Such disorders include myasthenia gravis, in which the immune system affects the body’s ability to transmit impulses from the nerves to muscles, and Guillain–Barré syndrome, which is the result of an abnormal response of the immune system after an infection. The final article covers nervous tics, which are often caused by stress.
For more information on the structure and function of the peripheral nervous system.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.