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==Overview==
==Overview==
The '''sural nerve''' ''(L4-S1)'' is a [[cutaneous]] [[Sensory neuron|sensory]] [[nerve]] of the posterolateral [[calf]] with [[cutaneous]] [[innervation]] to the distal one-third of the lower leg.<ref>{{cite book |last1=Moore |first1=Keith |title=Clinically Oriented Anatomy |date=August 2017 |publisher=Lippincot Williams and Wilkins |location=Philidelphia, PA |isbn=9781496347213}}</ref> Formation of the ''sural nerve'' is the result of either [[anastomosis]] of the [[medial sural cutaneous nerve]] and the [[sural communicating branch of the common peroneal nerve|sural communicating nerve]], or it may be found as a continuation of the [[lateral sural cutaneous nerve]] Steele et al, Type 4,6,8 ([https://www.sciencedirect.com/science/article/abs/pii/S0940960221000686?via%3Dihub Figure 1]) traveling parallel to the medial sural cutaneous nerve.
The '''sural nerve''' ''(L4-S1)'' is a [[cutaneous]] [[Sensory neuron|sensory]] [[nerve]] of the posterolateral [[calf]] with [[cutaneous]] [[innervation]] to the distal one-third of the lower leg.<ref>{{cite book |last1=Moore |first1=Keith |title=Clinically Oriented Anatomy |date=August 2017 |publisher=Lippincot Williams and Wilkins |location=Philidelphia, PA |isbn=978-1-4963-4721-3}}{{pn}}</ref> Formation of the ''sural nerve'' is the result of either [[anastomosis]] of the [[medial sural cutaneous nerve]] and the [[sural communicating branch of the common peroneal nerve|sural communicating nerve]], or it may be found as a continuation of the [[lateral sural cutaneous nerve]]<ref name="Steele Coker Freed et al 2021">{{cite journal |last1=Steele |first1=Robert |last2=Coker |first2=Charles |last3=Freed |first3=Blair |last4=Wright |first4=Barth |last5=Brauer |first5=Philip |title=Anatomy of the sural nerve complex: Unaccounted anatomic variations and morphometric data |journal=Annals of Anatomy |date=November 2021 |volume=238 |pages=151742 |doi=10.1016/j.aanat.2021.151742 |pmid=33932499 }}</ref> traveling parallel to the medial sural cutaneous nerve.


The nerves contributing to the formation of the sural nerve ''([[medial sural cutaneous nerve]], [[lateral sural cutaneous nerve]], [[sural communicating branch of the common peroneal nerve|sural communicating nerve]])'' are deemed the ''[[sural nerve complex]]'' by some anatomists and surgeons. Eight formations of the ''[[sural nerve complex]]'' have been described in cadaveric studies.<ref>{{cite journal| vauthors= Robert Steele DO MS et al. |title=Anatomy of the sural nerve complex: Unaccounted anatomic variations and morphometric data |journal=[[Annals of Anatomy]] |volume=238 |issue=151742 |doi=10.1016/j.aanat.2021.151742 |pmid=33932499}}</ref><ref name=":0">{{Citation|last=Rea|first=Paul|title=Chapter 3 - Lower Limb Nerve Supply|date=2015-01-01|url=https://www.sciencedirect.com/science/article/pii/B9780128030622000036|work=Essential Clinically Applied Anatomy of the Peripheral Nervous System in the Limbs|pages=101–177|editor-last=Rea|editor-first=Paul|publisher=Academic Press|language=en|doi=10.1016/b978-0-12-803062-2.00003-6|isbn=978-0-12-803062-2|access-date=2021-03-02}}</ref><ref>{{cite journal |last1=Ortiguela |first1=ME |title=Anatomy of the sural nerve complex |journal=[[Journal of Hand Surgery (American Volume)|J Hand Surg Am]] |date=November 1987 |volume=12 |issue=6 |page=1119 |doi=10.1016/s0363-5023(87)80129-6 |url=https://pubmed.ncbi.nlm.nih.gov/3693848/}}</ref><ref>{{cite journal |last1=Ramakrishnan |first1=Piravin |title=Anatomical variations of the formation and course of the sural nerve: A systematic review and meta-analysis |journal=[[Annals of Anatomy]] |date=November 2015 |volume=202 |page=36 |doi=10.1016/j.aanat.2015.08.002}}</ref>
The nerves contributing to the formation of the sural nerve ''([[medial sural cutaneous nerve]], [[lateral sural cutaneous nerve]], [[sural communicating branch of the common peroneal nerve|sural communicating nerve]])'' are deemed the ''[[sural nerve complex]]'' by some anatomists and surgeons. Eight formations of the ''[[sural nerve complex]]'' have been described in cadaveric studies.<ref name="Steele Coker Freed et al 2021"/><ref name=":0">{{cite journal |doi=10.1016/b978-0-12-803062-2.00003-6 }}</ref><ref>{{cite journal |last1=Ortigiiela |first1=Maria E. |last2=Wood |first2=Michael B. |last3=Cahill |first3=Donald R. |title=Anatomy of the sural nerve complex |journal=The Journal of Hand Surgery |date=November 1987 |volume=12 |issue=6 |pages=1119–1123 |doi=10.1016/s0363-5023(87)80129-6 |pmid=3693848 }}</ref><ref>{{cite journal |last1=Ramakrishnan |first1=Piravin |title=Anatomical variations of the formation and course of the sural nerve: A systematic review and meta-analysis |journal=[[Annals of Anatomy]] |date=November 2015 |volume=202 |page=36 |doi=10.1016/j.aanat.2015.08.002}}</ref>


===Function===
===Function===
The '''sural nerve''' provides [[cutaneous]] [[innervation]] to the [[skin]] of the posterior to posterolateral [[leg]]. This [[nerve]] is part of the [[sciatic nerve]] [[sensorium]]. It only provides autonomic and sensory nerve fibers to the skin. These fibers originate from [[perikaryon]] located in the [[spinal ganglia]].<ref>https://www.frontiersin.org/articles/10.3389/fneur.2019.00970, Cutaneous innervation review, Frontiers in Medicine</ref> When testing for deficits understand that often multiple nerves (lateral calcaneal nerve, sural nerve, and lateral dorsal cutaneous nerves of the foot) provide a complicated marriage of converging sensorium around the lower extremity.
The '''sural nerve''' provides [[cutaneous]] [[innervation]] to the [[skin]] of the posterior to posterolateral [[leg]]. This [[nerve]] is part of the [[sciatic nerve]] [[sensorium]]. It only provides autonomic and sensory nerve fibers to the skin. These fibers originate from [[perikaryon]] located in the [[spinal ganglia]].<ref>{{cite journal |last1=Glatte |first1=Patrick |last2=Buchmann |first2=Sylvia J. |last3=Hijazi |first3=Mido Max |last4=Illigens |first4=Ben Min-Woo |last5=Siepmann |first5=Timo |title=Architecture of the Cutaneous Autonomic Nervous System |journal=Frontiers in Neurology |date=10 September 2019 |volume=10 |pages=970 |doi=10.3389/fneur.2019.00970 }}</ref> When testing for deficits understand that often multiple nerves (lateral calcaneal nerve, sural nerve, and lateral dorsal cutaneous nerves of the foot) provide a complicated marriage of converging sensorium around the lower extremity.


===Anatomy===
===Anatomy===
Grossly, the course of this nerve leads it from its highly varied anastomotic formation<ref>{{cite book |last1=Tubbs |first1=Shane |title=Bergmans's Comprehensive Encyclopedia of Human Anatomic Variation |date=May 2016 |publisher=John Wiley & Sons |isbn=9781118430354 |page=1113|url=https://www.wiley.com/en-us/Bergman%27s+Comprehensive+Encyclopedia+of+Human+Anatomic+Variation-p-9781118430354}}</ref> to its more predictable terminal course down the remaining posterior leg. The anastomosis forming the sural nerve typically occurs in the deep fascia above or within the surrounding space above the gastrocnemius muscle. Once formed, the sural nerve then pierces out of a fascial crura and travels from its posterior midline position wrapping laterally around the lateral malleolus; once around the lateral malleolus the name of the nerve changes to the lateral dorsal cutaneous nerve. Eight variations of sural nerve origin have been described with categorical subtyping.<ref>[https://www.sciencedirect.com/science/article/abs/pii/S0940960221000686?via%3Dihub],As shown in Figure 1. of Steele et al. "Anatomy of the sural nerve complex: Unaccounted anatomic variations and morphometric data" DOI:10.1016/j.aanat.2021.151742]</ref>
Grossly, the course of this nerve leads it from its highly varied anastomotic formation<ref>{{cite book |last1=Tubbs |first1=Shane |title=Bergmans's Comprehensive Encyclopedia of Human Anatomic Variation |date=May 2016 |publisher=John Wiley & Sons |isbn=978-1-118-43035-4 |page=1113 }}</ref> to its more predictable terminal course down the remaining posterior leg. The anastomosis forming the sural nerve typically occurs in the deep fascia above or within the surrounding space above the gastrocnemius muscle. Once formed, the sural nerve then pierces out of a fascial crura and travels from its posterior midline position wrapping laterally around the lateral malleolus; once around the lateral malleolus the name of the nerve changes to the lateral dorsal cutaneous nerve. Eight variations of sural nerve origin have been described with categorical subtyping.<ref name="Steele Coker Freed et al 2021"/>


====Morphometrics====
====Morphometrics====
The pathway of the sural nerve ''(once formed)'' is consistent as it travels superficially in the posterior leg over the distal part of the gastrocnemius over the beginning of the [[achilles tendon]] and then travels parallel to the achilles with the [[small saphenous vein]] to send of [[lateral calcaneal branches]] while the remaining nerve passes under the [[lateral malleolus]] and finally finding its ''terminal name'' as the sural nerve becomes the [[lateral dorsal cutaneous nerve]].
The pathway of the sural nerve ''(once formed)'' is consistent as it travels superficially in the posterior leg over the distal part of the gastrocnemius over the beginning of the [[achilles tendon]] and then travels parallel to the achilles with the [[small saphenous vein]] to send of [[lateral calcaneal branches]] while the remaining nerve passes under the [[lateral malleolus]] and finally finding its ''terminal name'' as the sural nerve becomes the [[lateral dorsal cutaneous nerve]].


The formation patterns of the sural nerve complex is much more complicated than very common anastomotic scenario of the sural communicating branch joining the medial sural cutaneous nerve to become the sural nerve. Although these types of sural nerve complex (type 1 and 2) are the highest prevalence (by one study ([https://www.sciencedirect.com/science/article/abs/pii/S0940960221000686?via%3Dihub Steele et al. Figure 1 and Table 1]),was 75.95%). There are multiple other contributing nerves that range in size and union location. There are examples of this in ([https://www.sciencedirect.com/science/article/abs/pii/S0940960221000686?via%3Dihub Steele et al. Figure 3 and Table 2 & 3] Anatomists limit the name of the sural nerve from its origins after an anastomosis of the SCB (type 1) and medial sural cutaneous nerve or we name it for when it penetrates out of the deep fascia of the posterior sura .<ref>https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4392956/ Study of Sural Nerve Complex in Human Cadavers, Seema(2013)</ref>
The formation patterns of the sural nerve complex is much more complicated than very common anastomotic scenario of the sural communicating branch joining the medial sural cutaneous nerve to become the sural nerve. Although these types of sural nerve complex (type 1 and 2) are the highest prevalence.<ref name="Steele Coker Freed et al 2021"/> There are multiple other contributing nerves that range in size and union location.<ref name="Steele Coker Freed et al 2021"/> Anatomists limit the name of the sural nerve from its origins after an anastomosis of the SCB (type 1) and medial sural cutaneous nerve or we name it for when it penetrates out of the deep fascia of the posterior sura.<ref>{{cite journal |last1=Seema |first1=S. R. |title=Study of Sural Nerve Complex in Human Cadavers |journal=ISRN Anatomy |date=16 December 2013 |volume=2013 |pages=827276 |doi=10.5402/2013/827276 |pmc=4392956 }}</ref>


==Clinical significance==
==Clinical significance==
The sural nerve has a purely sensory function, and so its removal results in only a relatively minor consequential deficit. Due to its large size and significant length it has had a significant contribution in medicine twofold; the sural nerve is the most frequently accessed donor nerve site for peripheral nerve grafting and serves as the primary diagnostic site for nerve conduction studies for understanding of peripheral nerve pathologies.<ref>https://pubmed.ncbi.nlm.nih.gov/16045849/</ref><ref>https://pubmed.ncbi.nlm.nih.gov/20191047/</ref> It is frequently a site of iatrogenic nerve injury during percutaneous repair of the Achilles tendon or surgical interventions on the lower extremity. <ref>https://pubmed.ncbi.nlm.nih.gov/32553425</ref>
The sural nerve has a purely sensory function, and so its removal results in only a relatively minor consequential deficit. Due to its large size and significant length it has had a significant contribution in medicine twofold; the sural nerve is the most frequently accessed donor nerve site for peripheral nerve grafting and serves as the primary diagnostic site for nerve conduction studies for understanding of peripheral nerve pathologies.<ref>{{cite journal |last1=Ikiz |first1=Z Asli Aktan |last2=Uçerler |first2=Hülya |last3=Bilge |first3=Okan |title=The Anatomic Features of the Sural Nerve With an Emphasis on its Clinical Importance |journal=Foot & Ankle International |date=July 2005 |volume=26 |issue=7 |pages=560–567 |doi=10.1177/107110070502600712 |pmid=16045849 }}</ref><ref>{{cite journal |last1=Pyun |first1=Sung-Bom |last2=Kang |first2=Seok |last3=Kwon |first3=Hee-Kyu |title=Anatomical and Electrophysiological Myotomes Corresponding to the Flexor Carpi Ulnaris Muscle |journal=Journal of Korean Medical Science |date=2010 |volume=25 |issue=3 |pages=454 |doi=10.3346/jkms.2010.25.3.454 |pmid=20191047 }}</ref> It is frequently a site of iatrogenic nerve injury during percutaneous repair of the Achilles tendon or surgical interventions on the lower extremity.<ref>{{cite journal |last1=McGee |first1=Roddy |last2=Watson |first2=Troy |last3=Eudy |first3=Adam |last4=Brady |first4=Candice |last5=Vanier |first5=Cheryl |last6=LeCavalier |first6=Daniel |last7=Hoang |first7=Victor |title=Anatomic relationship of the sural nerve when performing Achilles tendon repair using the percutaneous Achilles repair system, a cadaveric study |journal=Foot and Ankle Surgery |date=June 2021 |volume=27 |issue=4 |pages=427–431 |doi=10.1016/j.fas.2020.05.011 |pmid=32553425 }}</ref>


The sural nerve is also a source for iatrogenic injuries during orthopedic interventions of the lower ankle and extremity. For this reason, and due to its large size and significant length it has had a significant contribution in medicine in the form of [[nerve biopsy]] and diagnostics of peripheral nerve diseases. Sural [[peripheral neuropathy|mononeuropathy]] is uncommon, however If affected, it can be due to diabetes, peripheral neuropathies, or trauma. <ref name="Stickler">Stickler DE, Morley KN, Massey EW. Sural neuropathy: etiologies and predisposing factors. Muscle Nerve. 4:482-484, 2006.</ref> Sometimes [[inflammation|inflammatory]] or [[vasculitis|vasculitic]] diseases will selectively involve the sural nerve. In addition, the sural nerve will be involved in any kind of generalized [[peripheral neuropathy|peripheral sensory or sensorimotor neuropathy]]. Sensory changes from sural neuropathy are variable but usually occur in the posterolateral aspect of the leg and the dorsolateral foot. These can sometimes be painful with [[paresthesia]]s and [[dysesthesia]]s.<ref>Yuebing L, Lederman RJ. Sural mononeuropathy: A report of 36 cases. Muscle Nerve 49:443-445, 2014.</ref> [[nerve conduction study|Nerve conduction studies]] can be used to delineate sural nerve lesions.<ref>Kimura J. Electrodiagnosis in Diseases of Nerve and Muscle: Principles and Practice. 1983 Philadelphia, FA Davis, p 502.</ref> Treatment will depend on the cause of the neuropathy. Occasionally biopsy of the nerve is performed for diagnostic purposes. For example, ganglions are usually resected. Traumatic neuropathy is usually treated non-surgically.<ref name="Stickler" /><ref>{{Cite journal|last=Mcleod|first=J. G.|date=2000-10-01|title=Sural nerve biopsy|journal=Journal of Neurology, Neurosurgery & Psychiatry|language=en|volume=69|issue=4|pages=431|doi=10.1136/jnnp.69.4.431|issn=0022-3050|pmid=10990498|pmc=1737139|doi-access=free}}</ref> It is often the donor nerve when a [[nerve allograft]] is performed.<ref>{{Citation|last1=Piedra Buena|first1=Ignacio T.|title=Sural Nerve Graft|date=2020|url=http://www.ncbi.nlm.nih.gov/books/NBK557715/|work=StatPearls|place=Treasure Island (FL)|publisher=StatPearls Publishing|pmid=32491647|access-date=2021-01-07|last2=Fichman|first2=Matias}}</ref>
The sural nerve is also a source for iatrogenic injuries during orthopedic interventions of the lower ankle and extremity. For this reason, and due to its large size and significant length it has had a significant contribution in medicine in the form of [[nerve biopsy]] and diagnostics of peripheral nerve diseases. Sural [[peripheral neuropathy|mononeuropathy]] is uncommon, however If affected, it can be due to diabetes, peripheral neuropathies, or trauma. <ref name="Stickler">{{cite journal |last1=Stickler |first1=D. E. |last2=Morley |first2=K. N. |last3=Massey |first3=E. W. |title=Sural neuropathy: Etiologies and predisposing factors |journal=Muscle & Nerve |date=October 2006 |volume=34 |issue=4 |pages=482–484 |doi=10.1002/mus.20580 |pmid=16691605 }}</ref> Sometimes [[inflammation|inflammatory]] or [[vasculitis|vasculitic]] diseases will selectively involve the sural nerve. In addition, the sural nerve will be involved in any kind of generalized [[peripheral neuropathy|peripheral sensory or sensorimotor neuropathy]]. Sensory changes from sural neuropathy are variable but usually occur in the posterolateral aspect of the leg and the dorsolateral foot. These can sometimes be painful with [[paresthesia]]s and [[dysesthesia]]s.<ref>{{cite journal |last1=Yuebing |first1=Li |last2=Lederman |first2=Richard J. |title=Sural mononeuropathy: A report of 36 cases: Short Reports |journal=Muscle & Nerve |date=March 2014 |volume=49 |issue=3 |pages=443–445 |doi=10.1002/mus.24107 |pmid=24531991 }}</ref> [[nerve conduction study|Nerve conduction studies]] can be used to delineate sural nerve lesions.<ref>Kimura J. Electrodiagnosis in Diseases of Nerve and Muscle: Principles and Practice. 1983 Philadelphia, FA Davis, p 502.</ref> Treatment will depend on the cause of the neuropathy. Occasionally biopsy of the nerve is performed for diagnostic purposes. For example, ganglions are usually resected. Traumatic neuropathy is usually treated non-surgically.<ref name="Stickler" /><ref>{{cite journal |last1=Mcleod |first1=J G |title=Sural nerve biopsy |journal=Journal of Neurology, Neurosurgery & Psychiatry |date=1 October 2000 |volume=69 |issue=4 |pages=431–431 |doi=10.1136/jnnp.69.4.431 |pmid=10990498 |pmc=1737139 |doi-access=free }}</ref> It is often the donor nerve when a [[nerve allograft]] is performed.<ref>{{cite book |last1=Piedra Buena |first1=Ignacio T. |last2=Fichman |first2=Matias |chapter=Sural Nerve Graft |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK557715/ |pmid=32491647 |title=StatPearls |date=2022 |publisher=StatPearls Publishing }}</ref>


===Sural nerve block===
===Sural nerve block===


A sural [[nerve block]] can be used for quick anesthetization to the foot and lower leg. Because this technique requires few injections to reach adequate [[anesthesia]], a smaller volume of anesthetic is needed.<ref>{{cite journal |doi=10.1016/j.emc.2004.12.012 |pmid=15829393 |title=Local Anesthetics and Peripheral Nerve Blocks in the Emergency Department |journal=Emergency Medicine Clinics of North America |volume=23 |issue=2 |pages=477–502 |year=2005 |last1=Crystal |first1=Chad S. |last2=Blankenship |first2=Robert B. }}</ref> The sural nerve is rather superficial, which makes it more accessible to surgeons. Therefore, it is relatively easier than other procedures. Also, due to its superficial properties, the sural nerve is easily blocked at multiple levels at or above the ankle. In one study, regional anesthesia of the foot and ankle, when performed by surgeons, was completely successful 95% of the time.<ref>{{cite journal |doi=10.1177/107110079201300510 |pmid=1624194 |title=Regional Anesthesia for Foot and Ankle Surgery |journal=Foot & Ankle International |volume=13 |issue=5 |pages=282–8 |year=1992 |last1=Myerson |first1=M. S. |last2=Ruland |first2=C. M. |last3=Allon |first3=S. M. |s2cid=43439010 }}</ref> Sural nerve block is not advised if a patient is allergic to the anesthetic solution, has infected tissue at the injection site, has severe bleeding disorder, or has preexisting neurological damage.<ref>{{EMedicine|article|83199|Sural Nerve Block}}</ref>
A sural [[nerve block]] can be used for quick anesthetization to the foot and lower leg. Because this technique requires few injections to reach adequate [[anesthesia]], a smaller volume of anesthetic is needed.<ref>{{cite journal |doi=10.1016/j.emc.2004.12.012 |pmid=15829393 |title=Local Anesthetics and Peripheral Nerve Blocks in the Emergency Department |journal=Emergency Medicine Clinics of North America |volume=23 |issue=2 |pages=477–502 |year=2005 |last1=Crystal |first1=Chad S. |last2=Blankenship |first2=Robert B. }}</ref> The sural nerve is rather superficial, which makes it more accessible to surgeons. Therefore, it is relatively easier than other procedures. Also, due to its superficial properties, the sural nerve is easily blocked at multiple levels at or above the ankle. In one study, regional anesthesia of the foot and ankle, when performed by surgeons, was completely successful 95% of the time.<ref>{{cite journal |last1=Myerson |first1=Mark S. |last2=Ruland |first2=Charles M. |last3=Allon |first3=Steven M. |title=Regional Anesthesia for Foot and Ankle Surgery |journal=Foot & Ankle |date=June 1992 |volume=13 |issue=5 |pages=282–288 |doi=10.1177/107110079201300510 |pmid=1624194 |s2cid=43439010 }}</ref> Sural nerve block is not advised if a patient is allergic to the anesthetic solution, has infected tissue at the injection site, has severe bleeding disorder, or has preexisting neurological damage.<ref>{{EMedicine|article|83199|Sural Nerve Block}}</ref>


==Additional images==
==Additional images==

Revision as of 16:19, 9 April 2022

sural nerve
Area of innervation by the sural nerve
Details
FromMedial sural cutaneous nerve, communicating branch with the common fibular nerve (S1, S2)
InnervatesSupplies sensation to the skin of the lateral foot and lateral lower ankle.
Identifiers
Latinnervus suralis
MeSHD013497
TA98A14.2.07.062
TA26586
FMA44688
Anatomical terms of neuroanatomy

Overview

The sural nerve (L4-S1) is a cutaneous sensory nerve of the posterolateral calf with cutaneous innervation to the distal one-third of the lower leg.[1] Formation of the sural nerve is the result of either anastomosis of the medial sural cutaneous nerve and the sural communicating nerve, or it may be found as a continuation of the lateral sural cutaneous nerve[2] traveling parallel to the medial sural cutaneous nerve.

The nerves contributing to the formation of the sural nerve (medial sural cutaneous nerve, lateral sural cutaneous nerve, sural communicating nerve) are deemed the sural nerve complex by some anatomists and surgeons. Eight formations of the sural nerve complex have been described in cadaveric studies.[2][3][4][5]

Function

The sural nerve provides cutaneous innervation to the skin of the posterior to posterolateral leg. This nerve is part of the sciatic nerve sensorium. It only provides autonomic and sensory nerve fibers to the skin. These fibers originate from perikaryon located in the spinal ganglia.[6] When testing for deficits understand that often multiple nerves (lateral calcaneal nerve, sural nerve, and lateral dorsal cutaneous nerves of the foot) provide a complicated marriage of converging sensorium around the lower extremity.

Anatomy

Grossly, the course of this nerve leads it from its highly varied anastomotic formation[7] to its more predictable terminal course down the remaining posterior leg. The anastomosis forming the sural nerve typically occurs in the deep fascia above or within the surrounding space above the gastrocnemius muscle. Once formed, the sural nerve then pierces out of a fascial crura and travels from its posterior midline position wrapping laterally around the lateral malleolus; once around the lateral malleolus the name of the nerve changes to the lateral dorsal cutaneous nerve. Eight variations of sural nerve origin have been described with categorical subtyping.[2]

Morphometrics

The pathway of the sural nerve (once formed) is consistent as it travels superficially in the posterior leg over the distal part of the gastrocnemius over the beginning of the achilles tendon and then travels parallel to the achilles with the small saphenous vein to send of lateral calcaneal branches while the remaining nerve passes under the lateral malleolus and finally finding its terminal name as the sural nerve becomes the lateral dorsal cutaneous nerve.

The formation patterns of the sural nerve complex is much more complicated than very common anastomotic scenario of the sural communicating branch joining the medial sural cutaneous nerve to become the sural nerve. Although these types of sural nerve complex (type 1 and 2) are the highest prevalence.[2] There are multiple other contributing nerves that range in size and union location.[2] Anatomists limit the name of the sural nerve from its origins after an anastomosis of the SCB (type 1) and medial sural cutaneous nerve or we name it for when it penetrates out of the deep fascia of the posterior sura.[8]

Clinical significance

The sural nerve has a purely sensory function, and so its removal results in only a relatively minor consequential deficit. Due to its large size and significant length it has had a significant contribution in medicine twofold; the sural nerve is the most frequently accessed donor nerve site for peripheral nerve grafting and serves as the primary diagnostic site for nerve conduction studies for understanding of peripheral nerve pathologies.[9][10] It is frequently a site of iatrogenic nerve injury during percutaneous repair of the Achilles tendon or surgical interventions on the lower extremity.[11]

The sural nerve is also a source for iatrogenic injuries during orthopedic interventions of the lower ankle and extremity. For this reason, and due to its large size and significant length it has had a significant contribution in medicine in the form of nerve biopsy and diagnostics of peripheral nerve diseases. Sural mononeuropathy is uncommon, however If affected, it can be due to diabetes, peripheral neuropathies, or trauma. [12] Sometimes inflammatory or vasculitic diseases will selectively involve the sural nerve. In addition, the sural nerve will be involved in any kind of generalized peripheral sensory or sensorimotor neuropathy. Sensory changes from sural neuropathy are variable but usually occur in the posterolateral aspect of the leg and the dorsolateral foot. These can sometimes be painful with paresthesias and dysesthesias.[13] Nerve conduction studies can be used to delineate sural nerve lesions.[14] Treatment will depend on the cause of the neuropathy. Occasionally biopsy of the nerve is performed for diagnostic purposes. For example, ganglions are usually resected. Traumatic neuropathy is usually treated non-surgically.[12][15] It is often the donor nerve when a nerve allograft is performed.[16]

Sural nerve block

A sural nerve block can be used for quick anesthetization to the foot and lower leg. Because this technique requires few injections to reach adequate anesthesia, a smaller volume of anesthetic is needed.[17] The sural nerve is rather superficial, which makes it more accessible to surgeons. Therefore, it is relatively easier than other procedures. Also, due to its superficial properties, the sural nerve is easily blocked at multiple levels at or above the ankle. In one study, regional anesthesia of the foot and ankle, when performed by surgeons, was completely successful 95% of the time.[18] Sural nerve block is not advised if a patient is allergic to the anesthetic solution, has infected tissue at the injection site, has severe bleeding disorder, or has preexisting neurological damage.[19]

Additional images

  • Areas of skin sensation supplied by nerves in the leg.
    Areas of skin sensation supplied by nerves in the leg.
  • Areas of skin supplied by nerves of the leg - the sural nerve supplies the lateral ankle.
    Areas of skin supplied by nerves of the leg - the sural nerve supplies the lateral ankle.
  • Deep nerves of the front of the leg.
    Deep nerves of the front of the leg.
  • Course of nerves at the bottom of the foot.
    Course of nerves at the bottom of the foot.

References

Public domain This article incorporates text in the public domain from page 963 of the 20th edition of Gray's Anatomy (1918)

  1. ^ Moore, Keith (August 2017). Clinically Oriented Anatomy. Philidelphia, PA: Lippincot Williams and Wilkins. ISBN 978-1-4963-4721-3.[page needed]
  2. ^ a b c d e Steele, Robert; Coker, Charles; Freed, Blair; Wright, Barth; Brauer, Philip (November 2021). "Anatomy of the sural nerve complex: Unaccounted anatomic variations and morphometric data". Annals of Anatomy. 238: 151742. doi:10.1016/j.aanat.2021.151742. PMID 33932499.
  3. ^ . doi:10.1016/b978-0-12-803062-2.00003-6. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  4. ^ Ortigiiela, Maria E.; Wood, Michael B.; Cahill, Donald R. (November 1987). "Anatomy of the sural nerve complex". The Journal of Hand Surgery. 12 (6): 1119–1123. doi:10.1016/s0363-5023(87)80129-6. PMID 3693848.
  5. ^ Ramakrishnan, Piravin (November 2015). "Anatomical variations of the formation and course of the sural nerve: A systematic review and meta-analysis". Annals of Anatomy. 202: 36. doi:10.1016/j.aanat.2015.08.002.
  6. ^ Glatte, Patrick; Buchmann, Sylvia J.; Hijazi, Mido Max; Illigens, Ben Min-Woo; Siepmann, Timo (10 September 2019). "Architecture of the Cutaneous Autonomic Nervous System". Frontiers in Neurology. 10: 970. doi:10.3389/fneur.2019.00970.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  7. ^ Tubbs, Shane (May 2016). Bergmans's Comprehensive Encyclopedia of Human Anatomic Variation. John Wiley & Sons. p. 1113. ISBN 978-1-118-43035-4.
  8. ^ Seema, S. R. (16 December 2013). "Study of Sural Nerve Complex in Human Cadavers". ISRN Anatomy. 2013: 827276. doi:10.5402/2013/827276. PMC 4392956.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  9. ^ Ikiz, Z Asli Aktan; Uçerler, Hülya; Bilge, Okan (July 2005). "The Anatomic Features of the Sural Nerve With an Emphasis on its Clinical Importance". Foot & Ankle International. 26 (7): 560–567. doi:10.1177/107110070502600712. PMID 16045849.
  10. ^ Pyun, Sung-Bom; Kang, Seok; Kwon, Hee-Kyu (2010). "Anatomical and Electrophysiological Myotomes Corresponding to the Flexor Carpi Ulnaris Muscle". Journal of Korean Medical Science. 25 (3): 454. doi:10.3346/jkms.2010.25.3.454. PMID 20191047.
  11. ^ McGee, Roddy; Watson, Troy; Eudy, Adam; Brady, Candice; Vanier, Cheryl; LeCavalier, Daniel; Hoang, Victor (June 2021). "Anatomic relationship of the sural nerve when performing Achilles tendon repair using the percutaneous Achilles repair system, a cadaveric study". Foot and Ankle Surgery. 27 (4): 427–431. doi:10.1016/j.fas.2020.05.011. PMID 32553425.
  12. ^ a b Stickler, D. E.; Morley, K. N.; Massey, E. W. (October 2006). "Sural neuropathy: Etiologies and predisposing factors". Muscle & Nerve. 34 (4): 482–484. doi:10.1002/mus.20580. PMID 16691605.
  13. ^ Yuebing, Li; Lederman, Richard J. (March 2014). "Sural mononeuropathy: A report of 36 cases: Short Reports". Muscle & Nerve. 49 (3): 443–445. doi:10.1002/mus.24107. PMID 24531991.
  14. ^ Kimura J. Electrodiagnosis in Diseases of Nerve and Muscle: Principles and Practice. 1983 Philadelphia, FA Davis, p 502.
  15. ^ Mcleod, J G (1 October 2000). "Sural nerve biopsy". Journal of Neurology, Neurosurgery & Psychiatry. 69 (4): 431–431. doi:10.1136/jnnp.69.4.431. PMC 1737139. PMID 10990498.
  16. ^ Piedra Buena, Ignacio T.; Fichman, Matias (2022). "Sural Nerve Graft". StatPearls. StatPearls Publishing. PMID 32491647.
  17. ^ Crystal, Chad S.; Blankenship, Robert B. (2005). "Local Anesthetics and Peripheral Nerve Blocks in the Emergency Department". Emergency Medicine Clinics of North America. 23 (2): 477–502. doi:10.1016/j.emc.2004.12.012. PMID 15829393.
  18. ^ Myerson, Mark S.; Ruland, Charles M.; Allon, Steven M. (June 1992). "Regional Anesthesia for Foot and Ankle Surgery". Foot & Ankle. 13 (5): 282–288. doi:10.1177/107110079201300510. PMID 1624194. S2CID 43439010.
  19. ^ Sural Nerve Block at eMedicine
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