That part of the nervous system excluding the brain and the spinal cord. It includes the nerves throughout the body that send messages to and from the central nervous system.
The peripheral nervous system is divided into the following sections:
- Sensory nervous system, which sends information to the CNS from internal organs or from external stimuli.
- Motor nervous system, which carries information from the CNS to organs, muscles, and glands.
- Somatic nervous system, which controls skeletal muscle as well as external sensory organs.
- Autonomic nervous system, which controls involuntary muscles, such as smooth and cardiac muscle. This includes:
- sympathetic — controls activities that increase energy expenditures, and
- parasympathetic — controls activities that conserve energy expenditures.
About.com.biology. Nervous system. Internet. Accessed on 12 November 2011.