View source for Sciatic nerve

{{short description|Large nerve in humans and other animals}}
{{Infobox nerve
| Name        = Sciatic nerve
| Latin       = nervus ischiadicus
| Image       = sciatic nerve2.jpg
| Caption     = Right [[gluteal region]], showing the formation of the sciatic nerve
| Image2      =
| Caption2    =
| Innervates  = [[Lateral rotator group]] (except [[Piriformis muscle|piriformis]] and [[Quadratus femoris muscle|quadratus femoris]]) and the [[posterior compartment of thigh]]
| BranchFrom  = [[Lumbar plexus|Lumbar]] and [[sacral plexus]] ([[Lumbar spinal nerve 4|L4]]-[[Sacral spinal nerve 3|S3]])
| BranchTo    = [[Tibial nerve|Tibial]] and [[common fibular nerve]]
| Pronunciation = {{IPAc-en|s|aɪ|ˈ|æ|t|ɪ|k}}
}}
The '''sciatic nerve''', also called the '''ischiadic nerve''', is a large [[nerve]] in humans and other vertebrate animals. It is the largest branch of the [[sacral plexus]] and runs alongside the hip joint and down the [[lower limb]]. It is the longest and widest single nerve in the [[human body]], going from the top of the leg to the foot on the posterior aspect. The sciatic nerve has no cutaneous branches for the thigh. This nerve provides the connection to the nervous system for the skin of the lateral leg and the whole foot, the muscles of the back of the thigh, and those of the leg and foot. It is derived from [[Spinal nerve|spinal nerves]] [[Lumbar spinal nerve 4|L4]] to [[Sacral spinal nerve 3|S3]]. It contains [[Axon|fibres]] from both the anterior and posterior divisions of the [[lumbosacral plexus]].

==Structure==
In humans, the sciatic nerve is formed from the L4 to S3 segments of the sacral plexus, a collection of nerve fibres that emerge from the [[Sacrum|sacral]] part of the [[spinal cord]]. The lumbosacral trunk from the L4 and L5 roots descends between the sacral promontory and ala, and the S1 to S3 roots emerge from the ventral sacral foramina. These nerve roots unite to form a single nerve in front of the [[piriformis muscle]]. The nerve passes beneath the piriformis and through the [[greater sciatic foramen]], exiting the pelvis. <ref name="GRAYS20052">{{cite book |last=Drake |first=Richard L. |title=Gray's anatomy for students |author2=Vogl, Wayne |author3=Tibbitts, Adam W.M. Mitchell |author4=illustrations by Richard |author5=Richardson, Paul |publisher=Elsevier/Churchill Livingstone |year=2005 |isbn=978-0-8089-2306-0 |location=Philadelphia}}</ref>{{rp|422–4}} From here, it travels down the posterior thigh to the [[popliteal fossa]]. The nerve travels in the [[Posterior compartment of thigh|posterior compartment of the thigh]] behind (superficial to) the [[adductor magnus muscle]] and is itself in front of (deep to) the long head of the [[biceps femoris muscle]]. At the popliteal fossa, the nerve divides into its two branches: <ref name="GRAYS20052">{{cite book |last=Drake |first=Richard L. |title=Gray's anatomy for students |author2=Vogl, Wayne |author3=Tibbitts, Adam W.M. Mitchell |author4=illustrations by Richard |author5=Richardson, Paul |publisher=Elsevier/Churchill Livingstone |year=2005 |isbn=978-0-8089-2306-0 |location=Philadelphia}}</ref>{{rp|532}}
* The [[tibial nerve]], which travels down the [[posterior compartment of the leg]] into the foot
* The [[common fibular nerve]] (also called the [[common peroneal nerve]]), which travels down the [[anterior compartment of leg|anterior]] and [[lateral compartment of leg|lateral compartments of the leg]] into the foot

The sciatic nerve is the largest nerve in the human body.<ref name=GRAYS2005 />{{rp|422–4}}<ref>{{Cite web |others=Medically Reviewed by Tyler Wheeler |title=What Is Sciatica? |url=https://www.webmd.com/back-pain/what-is-sciatica |access-date=12 May 2022 |website=WebMD}}</ref><ref>{{Cite book |last1=Winn |first1=Richard |last2=Youmans|first2=Julian |title=Youmans & Winn neurological surgery |publisher=Elsevier |year=2017 |isbn=9780323287821}}</ref>
[[File:3D still showing Sciatica nerve.jpg|thumb|260x260px|3D still showing Sciatica.]]
[[File:Tibial nerve and common peroneal nerve.jpg|thumb|right|350px|Tibial and [[common fibular nerve]] (aka common peroneal nerve)]]

===Development===
{{Expert needed|biology|section
| ex2 = anatomy
| date = February 2023
| reason = Adequate information with reliable citations is not available
}}{{expand section|date=March 2014|small=no}}

==Function==
The sciatic nerve supplies sensation to the [[skin]] of the [[foot]], as well as the entire lower leg (except for its inner side). Sensation to skin to the sole of the foot is provided by the [[tibial nerve]], and the lower leg and upper surface of the foot via the [[common fibular nerve]].<ref name=GRAYS2005>{{cite book|last=Drake|first=Richard L.|title=Gray's anatomy for students|year=2005|publisher=Elsevier/Churchill Livingstone|location=Philadelphia|isbn=978-0-8089-2306-0|author2=Vogl, Wayne |author3=Tibbitts, Adam W.M. Mitchell  |author4=illustrations by Richard |author5= Richardson, Paul }}</ref>{{rp|422–4}}

The sciatic nerve also innervates muscles. In particular:<ref name=GRAYS2005 />{{rp|422–4}} 
* Via the [[tibial nerve]], the muscles in the [[posterior compartment of the leg]] and sole of the foot (plantar aspect).{{efn|Namely the [[flexor hallicus longus]], [[flexor digitorum longus]], [[tibialis posterior]] and [[popliteus]] of the deep part of the compartment, and the [[gastrocnemius]], [[soleus]] and [[plantaris]] of the superficial part of the compartment. }} 
* Via the [[common fibular nerve]], the muscles in the [[anterior compartment of the leg|anterior]] and [[lateral compartment of the leg|lateral compartments]] of the leg.{{efn|Namely the [[tibialis anterior muscle|tibialis anterior]], [[extensor hallucis longus muscle|extensor hallucis longus]], [[extensor digitorum longus muscle|extensor digitorum longus]], and [[fibularis tertius]] (peroneus tertius) of the anterior compartment, and the [[Fibularis longus]] and [[Fibularis brevis|brevis]] of the lateral compartment.}}

==Clinical significance==

===Sciatica===
{{Main|Sciatica}}
Pain caused by compression or irritation of the sciatic nerve by a problem in the lower back is called [[sciatica]].  Common causes of sciatica include the following lower back and hip conditions:  [[spinal disc herniation]], [[degenerative disc disease]], [[lumbar spinal stenosis]], [[spondylolisthesis]], and [[piriformis syndrome]].<ref>{{cite web|url=http://www.webmd.com/back-pain/tc/sciatica-topic-overview|title=Sciatica - Topic Overview|date=21 July 2010|publisher=WebMD|access-date=23 April 2012}}</ref>  Other acute causes of sciatica include [[cough]]ing, muscular [[hypertension]], and [[sneezing]].<ref>{{cite web|url=http://www.medicalbug.com/what-is-sciatica-what-causes-sciatica/|title=What is sciatica: What causes sciatica?|date=11 April 2012|publisher=MedicalBug|access-date=23 April 2012}}</ref>

===Injury===
A sciatic nerve injury occurs between 0.5% and 2.0% of the time during a [[Hip replacement|hip]] replacement. <ref name="Stiehl2">{{cite journal |vauthors=Stiehl JB, Stewart WA |year=1998 |title=Late sciatic nerve entrapment following pelvic plate reconstruction in total hip arthroplasty |journal=J Arthroplasty |volume=13 |issue=5 |pages=586–8 |doi=10.1016/s0883-5403(98)90060-2 |pmid=9726326}}</ref> Sciatic nerve palsy is a complication of total hip arthroplasty with an incidence of 0.2% to 2.8% of the time, or with an incidence of 1.7% to 7.6% following revision. <ref>{{cite journal |author=Alessandro Bistolfi |display-authors=etal |year=2011 |title=Operative Management of Sciatic Nerve Palsy due to Impingement on the Metal Cage after Total Hip Revision: Case Report |journal=Case Rep Med |volume=2011 |pages=1–3 |doi=10.1155/2011/830296 |pmc=3163138 |pmid=21876701 |doi-access=free}}</ref> Following the procedure, in rare cases, a screw, broken piece of trochanteric wire, fragment of [[methyl methacrylate]] bone cement, or Burch-Schneider antiprofusio cage can impinge on the nerve; this can cause sciatic nerve [[palsy]], which may resolve after the fragment is removed and the nerve is freed. The nerve can be surrounded by oxidised, regenerated cellulose to prevent further scarring. Sciatic nerve palsy can also result from severe [[spinal stenosis]] following the procedure, which can be addressed by [[spinal decompression]] surgery.<ref name="Stiehl2">{{cite journal |vauthors=Stiehl JB, Stewart WA |year=1998 |title=Late sciatic nerve entrapment following pelvic plate reconstruction in total hip arthroplasty |journal=J Arthroplasty |volume=13 |issue=5 |pages=586–8 |doi=10.1016/s0883-5403(98)90060-2 |pmid=9726326}}</ref><ref>{{cite journal |vauthors=Abitbol JJ, Gendron D, Laurin CA, Beaulieu MA |year=1990 |title=Gluteal nerve damage following total hip arthroplasty. A prospective analysis |journal=J Arthroplasty |volume=5 |issue=4 |pages=319–22 |doi=10.1016/s0883-5403(08)80090-3 |pmid=2290087}}is cited by Stiehl and Stewart for the 0.5-2.0% figure.</ref> It is unclear if [[inversion therapy]] is able to decompress the sacral vertebrae; it may only work on the lumbar aspects of the sciatic nerves.
 
A sciatic nerve injury may also occur from improperly performed injections into the buttock, and may result in sensory loss.<ref name="Andrews">{{cite book |author1=James, William D. |author2=Berger, Timothy G. |title=Andrews' Diseases of the Skin: clinical Dermatology |publisher=Saunders Elsevier |year=2006 |isbn=978-0-7216-2921-6 |display-authors=etal}}</ref>{{rp|66}}

===Other disease===
Bernese periacetabular [[osteotomy]] resulted in major nerve deficits in the sciatic or femoral nerves in 2.1% of 1760 patients, of whom approximately half experienced complete recovery within a mean of 5.5 months.<ref>{{cite journal |vauthors=Sierra RJ, Beaule P, Zaltz I, Millis MB, Clohisy JC, Trousdale RT |title=Prevention of nerve injury after periacetabular osteotomy |journal=Clin. Orthop. Relat. Res. |volume=470 |issue=8 |pages=2209–19 |year=2012 |pmid=22684336 |pmc=3392380 |doi=10.1007/s11999-012-2409-1}}</ref>

Sciatic nerve exploration can be done by [[endoscopy]] in a [[minimally invasive]] procedure to assess lesions of the nerve.<ref>{{cite journal |vauthors=Mobbs RJ, Teo C |year=2004 |title=Endoscopic-assisted sciatic nerve exploration |journal=Minim Invasive Neurosurg |volume=47 |issue=3 |pages=178–80 |doi=10.1055/s-2004-818488 |pmid=15343436 |s2cid=260241055}}</ref> Endoscopic treatment for sciatic nerve entrapment has been investigated in [[deep gluteal syndrome]]. Patients were treated with sciatic nerve decompression by [[Segmental resection|resection]] of fibrovascular scar bands, [[piriformis]] tendon release, [[obturator internus]], or [[quadratus femoris]], or by [[hamstring]] tendon scarring. <ref>{{cite journal |vauthors=Martin HD, Shears SA, Johnson JC, Smathers AM, Palmer IJ |year=2011 |title=The endoscopic treatment of sciatic nerve entrapment/deep gluteal syndrome |url=http://www.arthroscopyjournal.org/article/S0749806310006870/pdf |journal=Arthroscopy |volume=27 |issue=2 |pages=172–81 |doi=10.1016/j.arthro.2010.07.008 |pmid=21071168 |doi-access=free}}</ref>

=== Anaesthetic ===
Signals from the sciatic nerve and its branches can be blocked, in order to interrupt the transmission of [[Pain signal|pain signals]] from the innervation area, by performing a [[Local anesthetic nerve block|regional nerve blockade]] called a [[sciatic nerve block]].

==Society and culture==
According to [[Jewish law]], the sciatic nerve ([[Hebrew]]: [[Gid hanasheh]]) may not be eaten by Jews to commemorate [[Jacob]]'s  injury in his struggle with an [[angel]].<ref>{{cite web|last=Goldberger|first=Moshe|title=1: Not to Eat the Gid HaNasheh|url=http://www.torah.org/learning/mitzvah/firstprohibition.html|work=The First Prohibitions|access-date=10 March 2014}}</ref>

==Additional images==
<gallery>
 File:Sciatic nerve1.jpg|Sciatic nerve.
 File:Gray344.png|Structures surrounding left hip-joint.
 File:Gray832.png|Nerves of the right lower extremity. Posterior view.
 File:Slide4i.JPG|Sciatic nerve.
 File:Slide8z.JPG|Sciatic nerve.
 File:Slide4hh.JPG|Sciatic nerve.
</gallery>

==See also==
{{Anatomy-terms}}
* [[Lesser sciatic notch]]
* [[Greater sciatic notch]]
* [[Lumbosacral plexus]]
* [[Sacral plexus]]
* [[Tibial nerve]]
* [[Common peroneal nerve]]
* [[Peripheral nervous system]]
* [[Sciatica]]
* [[Spinal disc herniation]]
* [[Piriformis syndrome]]
* [[Deep gluteal syndrome]]

==Notes==
{{notelist}}

==References==
{{Gray's}}
{{Reflist|30em}}

==External links==
* {{DukeOrtho|Sciatic_nerve}}
* {{MedlinePlusImage|19503}}
* {{NormanAnatomy|pelvis}} ({{NormanAnatomyFig|pelvicnerves}})
* {{NormanAnatomy|glutealregion}} ({{NormanAnatomyFig|glutealner}})
* [http://www.norcc.org/wiki/Sciatica Sciatica and the Sciatic Nerve]

{{Use dmy dates|date=February 2021}}
{{Lumbosacral plexus}}
{{Portal bar|Anatomy}}
{{Authority control}}

[[Category:Nerves of the lower limb and lower torso]]