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The sural nerve complex are the contributing nerves that form the sural nerve. There are eight documented anatomic variations of the sural nerve complex.
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The sural nerve complex are the contributing nerves that form the sural nerve. There are eight documented anatomic variations of the sural nerve complex.
In 1987, an orthopedic surgeon named Dr. Ortiguela of the Mayo Clinic conducted a cadaveric study in which the posterior leg was exposed. She was studying the nerve fascicle contribution of each of the nerves that contribute to the final formation of the sural nerve to find better nerve donors. She originated the term sural nerve complex to fully encompass all contributions to the terminally named sural nerve (and later lateral dorsal cutaneous nerve). Further research would go on to use the sural nerve complex terminology to discuss the lateral sural cutaneous nerve, the medial sural cutaneous nerve, the sural communicating nerve and sural nerve proper. [1]
Recent cadaveric research shows that there are potentially six to eight variations of the sural nerve complex.
Ramakrishnan et al. reviewed 39 cadaveric studies (limbs n= 3974) and concluded that there were 6 common classifications of the contributing nerves in the origins of the sural nerve. [2] Later cadaveric research in which 208 limbs were dissected demonstrated two variations that were unaccounted for and directly align with what previous sural nerve anatomists had uncovered in both case reports and direct research. These two variations (type 7 and 8 according to Steele et al.) demonstrate a parallel course for the medial sural cutaneous nerve and the sural nerve.
Most common formations are type 1 and 3 according to Ramakrishnan et al., Steele et al. found the same prevalence of sural nerve complex formation. The following image is of type 1-8 sural nerve formation and is a replica of what both Ramakrishan and Steele found in their work. Ramakrishnan successfully defined (types 1-6) with the largest difference being the addition of type 7 and 8 sural nerve complex by Steele. These two formations were robustly vetted due to their prevalence in the sample (in a high power study) that directly correlates with both historical and previous case literature describing formations of these SNC types. [3]
| Sural Nerve complex | |
|---|---|
 Sural nerve complex consists of the lateral sural cutaneous nerve (small black dash), media sural cutaneous nerve (large black dash), sural communicating branch/neve (large yellow dash). These together contribute eight variations in which the sural nerve may form. | |
 Cartoon version adapted from Steele et al. depicting type 1 sural nerve with contribution of medial sural cutaneous nerve and sural communicating branch | |
| Anatomical terms of neuroanatomy |
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.
The axillary nerve or the circumflex nerve is a nerve of the human body, that originates from the brachial plexus at the level of the axilla (armpit) and carries nerve fibers from C5 and C6. The axillary nerve travels through the quadrangular space with the posterior circumflex humeral artery and vein to innervate the deltoid and teres minor.
The triceps, or triceps brachii, is a large muscle on the back of the upper limb of many vertebrates. It consists of three parts: the medial, lateral, and long head. It is the muscle principally responsible for extension of the elbow joint.
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.
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.
The intercostal nerves are part of the somatic nervous system, and arise from the anterior rami of the thoracic spinal nerves from T1 to T11. The intercostal nerves are distributed chiefly to the thoracic pleura and abdominal peritoneum, and differ from the anterior rami of the other spinal nerves in that each pursues an independent course without plexus formation.
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.
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.
The posterior cutaneous nerve of the thigh is a sensory nerve of the thigh. It is a branch of the sacral plexus. It supplies the skin of the posterior surface of the thigh, leg, buttock, and also the perineum.
The obturator nerve in human anatomy arises from the ventral divisions of the second, third, and fourth lumbar nerves in the lumbar plexus; the branch from the third is the largest, while that from the second is often very small.
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.
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.
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.
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.
The medial sural cutaneous nerve(L4-S3) is a sensory nerve of the leg. It supplies cutaneous innervation the posteromedial leg.
Cutaneous innervation of the lower limbs is the nerve supply to areas of the skin of the lower limbs which are supplied by specific cutaneous nerves.
Cutaneous innervation of the upper limbs is the nerve supply to areas of the skin of the upper limbs which are supplied by specific cutaneous nerves.
The lateral dorsal cutaneous nerve is the continuation/terminal sensory branch of the sural nerve, and is ultimately derived from the 1st sacral nerve (S1). It passes distally along the lateral part of the dorsum of foot. It gives rise to the lateral dorsal digital nerve of the 5th toe, and sometimes also the medial dorsal digital nerve of the 5th toe as well as the lateral dorsal digital nerve of the 4th toe.
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.
Dorsal digital nerves of foot are branches of the intermediate dorsal cutaneous nerve, medial dorsal cutaneous nerve, sural nerve and deep fibular nerve.
This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)
Referenced papers:
