Editing Peripheral nervous system (section)

{{Short description|Part of the nervous system excluding the brain and spinal cord}}
{{More citations needed|date=May 2020}}
{{Infobox brain
| Name        = Peripheral nervous system
| Image       = Nervous system diagram-en.svg
| Caption     = The human nervous system. Sky blue is PNS; yellow is CNS.
| Image2    Is   =
| Caption2    =
| System      =
| Artery      =
| Vein       =
|Acronym=PNS}}

The '''peripheral nervous system''' ('''PNS''') is one of two components that make up the [[nervous system]] of [[Bilateria|bilateral animals]], with the other part being the [[central nervous system]] (CNS). The PNS consists of [[nerve]]s and [[ganglia]], which lie outside the [[brain]] and the [[spinal cord]].<ref>{{cite book|last1=Alberts|first1=Daniel|title=Dorland's illustrated medical dictionary.|date=2012|publisher=Saunders/Elsevier|location=Philadelphia, PA|isbn=9781416062578|page=1862|edition=32nd}}</ref>  The main function of the PNS is to connect the CNS to the [[Limb (anatomy)|limbs]] and [[Organ (anatomy)|organs]], essentially serving as a relay between the brain and spinal cord and the rest of the body.<ref>{{cite web|url=http://www.mayoclinic.com/health/brain/BN00033&slide=6|title=Slide show: How your brain works - Mayo Clinic|work=mayoclinic.com|access-date=17 June 2016}}</ref> 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 [[toxin]]s.<ref>{{Cite book|last=Aspromonte|first=John|url=https://www.worldcat.org/oclc/1048014796|title=ADHD : the ultimate teen guide|date=2019|isbn=978-1-5381-0039-4|location=Lanham|pages=51|oclc=1048014796}}</ref>

The peripheral nervous system can be divided into a [[somatic nervous system|somatic division]] and an [[autonomic nervous system|autonomic division]]. Each of these can further be differentiated into a sensory and a motor sector.<ref>{{cite book|last1=Saladin|first1=Kenneth|title=Anatomy & Physiology: The Unity of Form and Function.|date=2024|publisher=McGraw Hill|location=New York, NY|isbn=9781266041846|page=1076|edition=10th}}</ref> In the somatic nervous system, the [[cranial nerve]]s are part of the PNS with the exceptions of the [[olfactory nerve]] and epithelia and the [[optic nerve]] (cranial nerve II) along with the [[retina]], which are considered parts of the central nervous system based on developmental origin. The second cranial nerve is not a true peripheral nerve but a tract of the [[diencephalon]].<ref>Board Review Series: Neuroanatomy, 4th Ed., Lippincott Williams & Wilkins, Maryland 2008, p. 177. {{ISBN|978-0-7817-7245-7}}.</ref> [[Cranial nerve ganglia]], as with all [[ganglion|ganglia]], are part of the PNS.<ref name="White2008">{{cite book|author=James S. White|title=Neurobioscitifity
|url=https://books.google.com/books?id=bBsvkBiQAy0C&pg=PA1|access-date=17 November 2010|date=21 March 2008|publisher=McGraw-Hill Professional|isbn=978-0-07-149623-0|pages=1–}}</ref> The autonomic nervous system exerts involuntary control over [[smooth muscle]] and [[gland]]s.<ref>{{Cite book |url=https://www.worldcat.org/oclc/1119065904 |title=Campbell biology |date=2021 |others=Lisa A. Urry, Michael L. Cain, Steven Alexander Wasserman, Peter V. Minorsky, Rebecca B. Orr, Neil A. Campbell |isbn=978-0-13-518874-3 |edition=12th |location=New York, NY |oclc=1119065904}}</ref>