Peripheral nervous system

The peripheral nervous system (PNS) is one of two components that make up the nervous system of bilateral animals, with the other part being the central nervous system (CNS). The PNS consists of the nerves and ganglia outside the brain and spinal cord.[1] The main function of the PNS is to connect the CNS to the limbs and organs, essentially serving as a relay between the brain and spinal cord and the rest of the body.[2] Unlike the CNS, the PNS is not protected by the vertebral column and skull, or by the blood–brain barrier, which leaves it exposed to toxins and mechanical injuries.[3]

Peripheral nervous system
The human nervous system. Sky blue is PNS; yellow is CNS.
Identifiers
Acronym(s)PNS
MeSHD017933
TA98A14.2.00.001
TA26129
FMA9093
Anatomical terms of neuroanatomy

The peripheral nervous system is divided into the somatic nervous system and the autonomic nervous system. In the somatic nervous system, the cranial nerves are part of the PNS with the exception of the optic nerve (cranial nerve II), along with the retina. The second cranial nerve is not a true peripheral nerve but a tract of the diencephalon.[4] Cranial nerve ganglia originated in the CNS. However, the remaining ten cranial nerve axons extend beyond the brain and are therefore considered part of the PNS.[5] The autonomic nervous system exerts involuntary control over smooth muscle and glands.[6] The connection between CNS and organs allows the system to be in two different functional states: sympathetic and parasympathetic.


Share this article:

This article uses material from the Wikipedia article Peripheral nervous system, and is written by contributors. Text is available under a CC BY-SA 4.0 International License; additional terms may apply. Images, videos and audio are available under their respective licenses.