Sural nerve

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sural nerve
RobertSteele SuralNerve GraysMODified.png
Dissection of popliteal space to show the formation of a type 1 sural nerve
Sural nerve formation.jpg
Cartoon version adapted from Steele et al. depicting type 1 sural nerve
Details
FromUnion of Medial sural cutaneous nerve + sural communicating nerve
ToSural nerve forms after piercing out of deep fascia or after an anastomosis, terminates as lateral dorsal cutaneous nerve
InnervatesSupplies cutaneous sensation to the skin of the posterolateral leg and lateral ankle.
Identifiers
Latin nervus suralis
MeSH D013497
TA98 A14.2.07.062
TA2 6586
FMA 44688
Anatomical terms of neuroanatomy

The sural nerve(L4-S1) is generally considered a pure cutaneous nerve of the posterolateral leg to the lateral ankle. The sural nerve originates from a combination of either the sural communicating branch and medial sural cutaneous nerve, or the lateral sural cutaneous nerve. This group of nerves is termed the sural nerve complex. There are eight documented variations of the sural nerve complex. Once formed the sural nerve takes its course midline posterior to posterolateral around the lateral malleolus. The sural nerve terminates as the lateral dorsal cutaneous nerve.

Contents

Anatomy

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 sural nerve specifically innervates cutaneous sensorium over the posterolateral leg and lower lateral ankle via lateral calcaneal branches.

Innervation

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 of the posterolateral leg and ankle. These fibers originate from perikaryon located in the spinal ganglia and travel via the lumbosacral plexus via nerve roots L4-S1. [3] 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.

Anatomic Course

Grossly, the course of this nerve leads it from its highly varied anastomotic formation [4] 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]

Anatomic Formation

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] [5] [6] [7]

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 and highly varied as documented by anatomists. [2] [8] The most common formation is the anastomotic scenario described above; the sural communicating branch joins the medial sural cutaneous nerve to become the sural nerve. Type 1 and 2 sural nerve complex formation prevalence is estimated up to greater than 70%, Although the remaining types (3-8) provide difficulty in making consistent clinical approximation of this nerve in the random population.

The sural nerve then travels out of deep fascia to the subcutaneous posterior sura. Although, these types of sural nerve complex (type 1 and 2) are of the highest prevalence [2] there are multiple scenarios which other contributing nerves that range in morphology of formation, sural nerve size, and location of the sural nerve union. [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. [9]

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. [10] [11] It is frequently a site of iatrogenic nerve injury during percutaneous repair of the Achilles tendon or surgical interventions on the lower extremity. [12]

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. [13] 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. [14] Nerve conduction studies can be used to delineate sural nerve lesions. [15] 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. [13] [16] It is often the donor nerve when a nerve allograft is performed. [17]

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. [18] 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. [19] 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. [20]

Additional images

Related Research Articles

<span class="mw-page-title-main">Human leg</span> Lower extremity or limb of the human body (foot, lower leg, thigh and hip)

The human leg is the entire lower limb of the human body, including the foot, thigh or sometimes even the hip or buttock region. The major bones of the leg are the femur, tibia, and adjacent fibula. The thigh is between the hip and knee, while the calf (rear) and shin (front) are between the knee and foot.

<span class="mw-page-title-main">Radial nerve</span> Nerve in the human body that supplies the posterior portion of the upper limb

The radial nerve is a nerve in the human body that supplies the posterior portion of the upper limb. It innervates the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compartment of the forearm and the associated joints and overlying skin.

<span class="mw-page-title-main">Soleus muscle</span> Powerful muscle in the back part of the lower leg

In humans and some other mammals, the soleus is a powerful muscle in the back part of the lower leg. It runs from just below the knee to the heel, and is involved in standing and walking. It is closely connected to the gastrocnemius muscle and some anatomists consider them to be a single muscle, the triceps surae. Its name is derived from the Latin word "solea", meaning "sandal".

The posterior tibial artery of the lower limb is an artery that carries blood to the posterior compartment of the leg and plantar surface of the foot. It branches from the popliteal artery via the tibial-fibular trunk.

<span class="mw-page-title-main">Tibial nerve</span> Branch of the sciatic nerve

The tibial nerve is a branch of the sciatic nerve. The tibial nerve passes through the popliteal fossa to pass below the arch of soleus.

<span class="mw-page-title-main">Tarsal tunnel syndrome</span> Medical condition

Tarsal tunnel syndrome (TTS) is a nerve entrapment syndrome causing a painful foot condition in which the tibial nerve is compressed as it travels through the tarsal tunnel. This tunnel is found along the inner leg behind the medial malleolus. The posterior tibial artery, tibial nerve, and tendons of the tibialis posterior, flexor digitorum longus, and flexor hallucis longus muscles travel in a bundle through the tarsal tunnel. Inside the tunnel, the nerve splits into three segments. One nerve (calcaneal) continues to the heel, the other two continue on to the bottom of the foot. The tarsal tunnel is delineated by bone on the inside and the flexor retinaculum on the outside.

<span class="mw-page-title-main">Plantaris muscle</span> One of the superficial muscles of the superficial posterior compartment of the leg,

The plantaris is one of the superficial muscles of the superficial posterior compartment of the leg, one of the fascial compartments of the leg.

The common fibular nerve is a nerve in the lower leg that provides sensation over the posterolateral part of the leg and the knee joint. It divides at the knee into two terminal branches: the superficial fibular nerve and deep fibular nerve, which innervate the muscles of the lateral and anterior compartments of the leg respectively. When the common fibular nerve is damaged or compressed, foot drop can ensue.

<span class="mw-page-title-main">Superficial fibular nerve</span> Nerve in the human leg and foot

The superficial fibular nerve is a mixed nerve that provides motor innervation to the fibularis longus and fibularis brevis muscles, and sensory innervation to skin over the antero-lateral aspect of the leg along with the greater part of the dorsum of the foot.

<span class="mw-page-title-main">Deep fibular nerve</span>

The deep fibular nerve begins at the bifurcation of the common fibular nerve between the fibula and upper part of the fibularis longus, passes infero-medially, deep to the extensor digitorum longus, to the anterior surface of the interosseous membrane, and comes into relation with the anterior tibial artery above the middle of the leg; it then descends with the artery to the front of the ankle-joint, where it divides into a lateral and a medial terminal branch.

<span class="mw-page-title-main">Sole (foot)</span> Bottom part of foot

The sole is the bottom of the foot.

The saphenous nerve is the largest cutaneous branch of the femoral nerve. It is derived from the lumbar plexus (L3-L4). It is a strictly sensory nerve, and has no motor function. It commences in the proximal (upper) thigh and travels along the adductor canal. Upon exiting the adductor canal, the saphenous nerve terminates by splitting into two terminal branches: the sartorial nerve, and the infrapatellar nerve. The saphenous nerve is responsible for providing sensory innervation to the skin of the anteromedial leg.

<span class="mw-page-title-main">Malleolus</span> Ankle bone protrusion

A malleolus is the bony prominence on each side of the human ankle.

<span class="mw-page-title-main">Tarsal tunnel</span> Canal in the ankle area

The tarsal tunnel is a passage found along the inner leg underneath the medial malleolus of the ankle.

<span class="mw-page-title-main">Superior cluneal nerves</span>

The superior cluneal nerves are pure sensory nerves that innervate the skin of the upper part of the buttocks. They are the terminal ends of the L1-L3 spinal nerve dorsal rami lateral branches. They are one of three different types of cluneal nerves. They travel inferiorly through multiple layers of muscles, then traverse osteofibrous tunnels between the thoracolumbar fascia and iliac crest.

<span class="mw-page-title-main">Lateral sural cutaneous nerve</span> Sensory nerve of the leg that supplies part of the posterolateral side of the leg

The lateral sural cutaneous nerve of the lumbosacral plexus supplies the skin on the posterior and lateral surfaces of the leg. The lateral sural cutaneous nerve originates from the common fibular nerve(L4-S2) and is the terminal branch of the common fibular nerve.

<span class="mw-page-title-main">Medial sural cutaneous nerve</span> Sensory nerve of the leg that supplies part of the medial side of the leg

The medial sural cutaneous nerve(L4-S3) is a sensory nerve of the leg. It supplies cutaneous innervation the posteromedial leg.

<span class="mw-page-title-main">Lateral dorsal cutaneous nerve</span>

The lateral dorsal cutaneous nerve is a cutaneous branch of the foot.

<span class="mw-page-title-main">Sural communicating branch of common peroneal nerve</span> Communicating nerve transferring nerve fascicles to the medial sural cutaneous nerve

The sural communicating nerve(SCN) is a separate and independent nerve from both the medial and lateral sural cutaneous nerves, often arising from a common trunk of the common fibular nerve The primary purpose of the sural communicating branch is to provide the structural path for transferring tibial nerve fascicular components to the sural nerve.

The sural nerve complex are the contributing nerves that form the sural nerve. There are eight documented anatomic variations of the sural nerve complex.

References

PD-icon.svgThis 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. Philadelphia, PA: Lippincot Williams and Wilkins. ISBN   978-1-4963-4721-3.[ page needed ]
  2. 1 2 3 4 5 6 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. ↑ 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 . PMC   6746903 . PMID   31551921.
  4. ↑ Tubbs, Shane (May 2016). Bergmans's Comprehensive Encyclopedia of Human Anatomic Variation. John Wiley & Sons. p. 1113. ISBN   978-1-118-43035-4.
  5. ↑ Rea, Paul (2015). "Lower Limb Nerve Supply". Essential Clinically Applied Anatomy of the Peripheral Nervous System in the Limbs. pp. 101–177. doi:10.1016/b978-0-12-803062-2.00003-6. ISBN   978-0-12-803062-2.
  6. ↑ 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.
  7. ↑ 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: 36–44. doi:10.1016/j.aanat.2015.08.002. PMID   26342158.
  8. ↑ 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: 36–44. doi:10.1016/j.aanat.2015.08.002. PMID   26342158. Background and information section reviews the many anatomy papers that demonstrate extreme variability in the formation of the sural nerve
  9. ↑ 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 . PMID   25938105.
  10. ↑ 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. S2CID   11029085.
  11. ↑ 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): 454–457. doi:10.3346/jkms.2010.25.3.454. PMC   2826750 . PMID   20191047.
  12. ↑ 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. S2CID   219902087.
  13. 1 2 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. S2CID   25070694.
  14. ↑ 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. S2CID   2184884.
  15. ↑ Kimura J. Electrodiagnosis in Diseases of Nerve and Muscle: Principles and Practice. 1983 Philadelphia, FA Davis, p 502.
  16. ↑ Mcleod, J G (1 October 2000). "Sural nerve biopsy". Journal of Neurology, Neurosurgery & Psychiatry. 69 (4): 431. doi: 10.1136/jnnp.69.4.431 . PMC   1737139 . PMID   10990498.
  17. ↑ Piedra Buena, Ignacio T.; Fichman, Matias (2022). "Sural Nerve Graft". StatPearls. StatPearls Publishing. PMID   32491647.
  18. ↑ 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.
  19. ↑ 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.
  20. ↑ Sural Nerve Block at eMedicine

Referenced papers:

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