The relative contributions of the medial sural and peroneal communicating nerves to the sural nerve

The medial sural cutaneous nerve (MSCN) and peroneal communicating nerve (PCN) conjoin in the calf area to form the sural nerve (SN). In previous anatomic studies, there was unresolved debate as to the main contributor to the sural nerve, and the relative contributions of MSCN and PCN had not been studied. The purpose of this study is to determine their relative neurophysiologic contributions to the SN by nerve conduction study (NCS). A total of 47 healthy subjects (25 males and 22 females, mean age 29.6 +/- 10.4 yrs, range 20-59 yrs) participated in the study. This study employed the orthodromic nerve conduction technique: stimulation at the ankle and recording at the mid calf (SN); specifically, we preformed stimulation at the mid calf (MSCN, PCN) and recording at 14 cm proximal to the middle of the popliteal fossa (MSCN) and fibular head (PCN). The onset and peak latencies (ms) were SN 2.3 +/- 0.2 and 3.0 +/- 0.2; MSCN 2.1 +/- 0.2 and 2.8 +/- 0.2; and PCN 2.1 +/- 0.2 and 2.8 +/- 0.2. The peak-to-peak amplitudes (microV) and areas (nVsec) of the SN, MSCN, and PCN were 9.7 +/- 3.9, 7.0 +/- 4.7, and 5.0 +/- 3.2; and 7.2 +/- 2.9, 5.7 +/- 3.4, and 4.0 +/- 2.4, respectively. The side-to-side difference was not statistically significant. The main contributor to the SN was found to be the MSCN. The relative contribution ratio of the MSCN to the PCN was 1.37:1 by amplitude and 1.42:1 by area. However, in 32.9% of the subjects, the contribution of the PCN was greater than that of the MSCN.     

带腓肠外侧皮神经及其营养血管筋膜皮瓣的应用解剖

目的 为带腓肠外侧皮神经及其营养血管筋膜皮瓣的临床应用提供解剖学基础.方法 在32例成人下肢标本上,对腓肠外侧皮神经及其营养血管进行解剖观测.结果 腓肠外侧皮神经在腓骨头平面上方 7.1±2.4cm处起于腓总神经,分布于小腿后外侧上半或上2/3的皮肤.其营养动脉主要为:腓肠外侧皮动脉:起自腘动脉,在腓骨头平面上方5.0±1.5cm处浅出,外径为0.9±0.3mm;肌间隔筋膜皮支:起自胫后动脉和腓动脉,分别在腓骨头平面下方9.2±3.8cm和15.8±3.8cm处浅出,外径为0.7±0.3mm和0.9±0.4mm.该营养动脉除在腓肠外侧皮神经周围或其内呈链式吻合外,还发出筋膜皮支与邻位的皮动脉连接.静脉血可沿伴行静脉或小隐静脉及其属支回流至深静脉.结论 以腓肠外侧皮神经及其营养血管为蒂,可设计成顺行或逆行转位筋膜皮瓣,修复邻近部位的软组织缺损.     

Anatomic study of the superficial sural artery and its implication in the neurocutaneous vascularized sural nerve free flap

Combined extended nerve and soft tissue defects of the upper extremity require nerve reconstruction and adequate soft tissue coverage. This study focuses on the reliability of the free vascularized sural nerve graft combined with a fasciocutaneous posterior calf flap within this indication. An anatomical study was performed on 26 cadaveric lower extremities that had been Thiel fixated and color silicone injected. Dissection of the fasciocutaneous posterior calf flap involved the medial sural nerve and superficial sural artery (SSA) with its septocutaneous perforators, extended laterally to include the lateral cutaneous branch of the sural nerve and continued to the popliteal origin of the vascular pedicle and the nerves. The vessel and nerves diameter were measured with an eyepiece reticle at 4.5× magnification. Length and diameter of the nerves and vessels were carefully assessed and reported in the dissection book. A total of 26 flaps were dissected. The SSA originated from the medial sural artery (13 cases), the popliteal artery (12 cases), or the lateral sural artery (one case). The average size of the SSA was 1.4 ± 0.4 mm. The mean pedicle length before the artery joined the sural nerve was 4.5 ± 1.9 cm. A comitant vein was present in 21 cases with an average diameter of 2.0 ± 0.8 mm, in 5 cases a separate vein needed to be dissected with an average diameter of 3.5 ± 0.4 mm. The mean medial vascularized sural nerve length was 21.2 ± 8.9 cm. Because of inclusion of the vascularized part of the lateral branch of the sural nerve (mean length of 16.7 ± 4.8 cm), a total of 35.0 ± 9.6 cm mean length of vascularized nerve could be gained from each extremity. The free vascularized sural nerve graft combined with a fasciocutaneous posterior calf flap pedicled on the SSA offers a reliable solution for complex tissue and nerve defect. Clin. Anat. 26:903–910, 2013. © 2012 Wiley Periodicals, Inc.     

Surgical anatomy of the sural and superficial fibular nerves with an emphasis on the approach to the lateral malleolus

The aim of this study was to investigate the risk and to analyse the significance of laceration of the sural and superficial fibular nerves during the surgical approach to the lateral malleolus. The sural and the superficial fibular nerves, and their branches were dissected under ×3 magnifying lenses in 68 embalmed leg‐ankle‐foot specimens. The specimens were measured, drawn and photographed. In 35% of specimens the superficial fibular nerve branched before piercing the crural fascia, and in all these specimens the medial dorsal cutaneous nerve of the foot was located in the anterior compartment while the intermediate dorsal cutaneous nerve of the foot was located in the lateral compartment. In 35% of specimens the intermediate dorsal cutaneous nerve of the foot was absent or did not innervate any toe. The deep part of the superficial fibular nerve was in contact with the intermuscular septum. Its superficial part was parallel with the lateral malleolus when the nerve pierced the fascia more proximally and oblique to the lateral malleolus when the nerve pierced the fascia distally. In one case the intermediate dorsal cutaneous nerve of the foot was in danger of laceration during a subcutaneous incision to the lateral malleolus. In 7 cases (10%) the sural nerve overlapped or was tangent to the tip of the malleolus. Malleolar nerve branches were identified in 76% of the cases (in 28% from both sources). The sural nerve supplies the lateral 5 dorsal digital nerves in 40% of cases. Our study indicates that during the approach to the lateral malleolus there is a high risk of laceration of malleolar branches from both the sural and the superficial fibular nerves. There is less risk of damage to the main trunk of these nerves, but the 10% chance of laceration of sural nerve at the tip of the malleolus is significant. As the sural nerve supplies the superficial innervation to the lateral half of the foot and toes in 40% of cases, the risk of its laceration is even more important than indicated by the common anatomical teaching.     

The bilateral anatomical variation of the sural nerve and a review of relevant literature

The sural nerve is a sensory nerve, usually formed in the distal part of the leg by the union of the lateral sural cutaneous nerve or the communicating fibular branch with the medial sural cutaneous nerve. The aim of this paper is to present a case of a variant formation of the sural nerve and a review of the literature related to this case. During the dissection of an adult male cadaver, the medial sural cutaneous nerve and communicating fibular branch, after respectively deriving from the tibial and common fibular nerve, were noticed to continue their course without any formation of a unique nerve trunk on the posterior side of both lower limbs. A transverse communicating branch, connecting these two nerves, was present in both legs. As the sural nerve is of significant diagnostic and therapeutic importance, detailed knowledge of the sural nerve’s anatomy and its contributing nerves is also of great importance.     

外踝术中腓肠神经和腓浅神经的应用解剖

目的　探讨外踝术中腓肠神经和腓浅神经损伤的风险 ,并分析损伤后感觉缺失情况。方法　在解剖显微镜下对 5 0侧常规防腐固定成年尸体的腓肠神经和腓浅神经及其分支作解剖 ,观测和绘图。结果　 2 4 % (12侧 )的腓浅神经或足背中间皮神经浅出点在外踝前缘水平 ,10 % (5侧 )的腓肠神经横切过外踝尖 ,78% (39侧 )的标本可识别来自这两条神经的踝支 (其中 2 8%同时具有两个来源 ) ,腓肠神经管理 38% (19侧 )标本的足及足趾的外侧半。结论　外踝术中很容易损伤来自腓肠神经和腓浅神经的踝支 (可能性为 78% ) ,损伤神经主干的风险较小 ,但有 2 4 %的可能损伤在外踝前缘浅出的腓浅神经或足背中间皮神经 ,10 %的可能损伤外踝尖处的腓肠神经 ,而且损伤后感觉缺失范围差异很大 ,腓肠神经具有比解剖学以往描述的更重要的意义     

Anatomical and clinical study of the common fibular nerve. Part 1: Anatomical study

The aims of this research were: (1) to minimize injury to the common fibular nerve by a detailed anatomical study of the nerve and its branches and (2) clinically to establish a protocol for preoperative and postoperative assessment of patients undergoing surgery on the proximal third of the leg. Thus the incidence of fibular nerve palsy would definitely be negligible. The first part of the research consisted of an anatomical study of the common fibular nerve and its branches, paying particular attention to the motor nerve branches innervating different muscles of the leg. Dissections were done on 20 unselected lower limbs of cadavers, of unknown gender, age and dominant side, to study the anatomy of the common fibular nerve and its branches and the neighboring structures, such as the tibia, the fibula and the muscles of the leg. It was found that 76.7% of all motor nerve branches were located in the proximal third of the leg, 19.5% in the middle third and 3.8% in the distal third. The free courses of the motor nerve branches were 48.5% in the proximal third, 44.4% in the middle third and 7.1% in the distal third. Within a distance of 6 cm from the fibular head we found 51.1% of the motor nerve branches and from 6 to 11 cm there were only 25.5%. Hence there were danger zones of high and low risk for injury to the common fibular nerve and its branches. Results obtained are evaluated and discussed with regard to safer surgical approaches and insertion of Steinmann pins in the proximal third of the leg.     

Distribution patterns of the cutaneous nerves on the dorsum of the foot and their clinical significance

The aim of this study was to clarify the distribution patterns of the cutaneous nerves on the dorsum of the foot. This study investigated 130 feet of 77 cadavers. The distribution patterns of the sural (SN) and deep fibular nerves (DFN) were classified into five and four types, respectively. In Type A, the SN was only distributed to the lateral side of the fifth toe. In Type B, the nerve was distributed to the medial side of the fourth toe and both sides of the fifth toe. In Type C, the nerve was mainly distributed to the lateral side of the fifth toe. In Type D, the nerve was distributed to the lateral side of the third toe and both sides of the fourth and fifth toes. In Type E, no SN was found. In Type α, the DFN was simultaneously distributed to the lateral side of the first toe and the medial side of the second toe. In Type β, the nerve was distributed like in Type α and additionally to the medial side of the first toe. In Type γ, the nerve was distributed like in Type α and additionally to the lateral side of the second toe and the medial side of the third toe. In Type δ, no DFN was found. The results of this study will help physicians to reduce the incidence of iatrogenic nerve injury and improve the quality of diagnoses of relevant nerves in this body region. Clin. Anat. 33:592–597, 2020. © 2019 Wiley Periodicals, Inc.     

Anatomical variations of the human sural nerve and its role in clinical and surgical procedures

The sural nerve is the most commonly nerve used in nerve transplantation, and so the aim of this study was to determine the variations of the sural nerve in the back of the leg, its relations to the calcaneal tendon and lateral malleolus, and determine the patterns of its distribution on the dorsum of the foot. Twenty‐four Egyptian legs and feet were dissected. The results showed that the sural communicating nerve connected with the sural nerve in 87.5%. The predominant site of union between these two nerves was in the lower one‐third of the leg and ankle region (62%). There was only one right leg that the sural nerve passed through the gastrocnemius. The small saphenous vein passed along the medial side of the sural nerve in 100%. The sural nerve crossed the lateral border of the calcaneal tendon in 50%. The distance between the sural nerve and insertion of calcaneal tendon was 16 + 7 mm in 91.7%. There were four types of pattern of innervation of the toes by the sural nerve. The predominant pattern was type I (45.8%), where the lateral side of the little toe was supplied by the sural nerve alone. The second pattern was type IV (29.2%), where the lateral 2 ½ toes were supplied by the sural nerve alone. These findings are important for sural nerve biopsy and grafts, surgical repair of the calcaneal tendon, and regional anesthesia of the foot. Clin. Anat. 24:237–245, 2010. © 2010 Wiley‐Liss, Inc.     

Variations in sural nerve formation pattern and distribution on the dorsum of the foot

The sural nerve, a cutaneous nerve, is clinically important because it is frequently for nerve conduction testing, biopsy, and harvesting for nerve grafts. This nerve exhibits a wide variety of variation in formation, distribution on the dorsum of the foot, and so on, depending on the population observed. In this study, we examined the variation in the sural nerve in 110 Korean cadavers. Of these cadavers, 86.1% of the sural nerves corresponded to type A, where tibial and peroneal components were united to form the sural nerve. These two components most frequently united (65.9%) in the third quarter of the calf, and when the union position was expressed as a ratio to calf length, it corresponded to 0.408 in men and 0.346 in women, with a statistically significant difference. Due to this sexual dimorphism in addition to shorter calf length in females, the length of the sural nerve was shorter in females (male average length: 14.5 ± 4.8 cm; female average length: 11.4 ± 2.9 cm). In terms of distribution of the lateral dorsal cutaneous nerve, the distal continuation of the sural nerve on the dorsum of the foot, it showed variation in association with the superficial peroneal nerve. The innervation of the sural nerve extended most frequently up to the lateral two and a half toes, solely or in conjunction with the superficial peroneal nerve. Obtaining further information regarding sural nerve variation will be useful for various clinical procedures and interpretation of sural nerve conduction results. Clin. Anat. 30:525–532, 2017. © 2017 Wiley Periodicals, Inc.     

Sural-tibial nerve communications in humans

We investigated the occurrence of a communication between the sural and tibial nerves in 49 legs of 28 Japanese cadavers. In front of the calcanean tendon, we found the communication in 7 legs (14.3%) or in 5 cadavers (18.9%). The sural nerve gave rise to a number of medial and lateral branches, including the lateral calcanean branch at the lateral side of the ankle. The communicating branch with the tibial nerve arose from the first medial branch and pierced the deep fascia of the leg. In 4 cases, the U-shaped communication was formed between the sural and tibial nerves, and in 3 cases, the Y-shaped communication. Electrophysiologi-cal evidence of an anomalous motor function of the sural nerve has been reported recently. We consider that the U-shaped communication between the sural and tibial nerves gives a morphological basis to the motor function of the sural nerve.     

Anatomic variation of the spinal origins of lateral and medial pectoral nerves

Lateral and medial pectoral nerves are distributed to the pectoralis major and minor muscles. The purpose of this study was to identify the spinal origins of lateral and medial pectoral nerves and to evaluate the participating amounts of each spinal nerve composing both pectoral nerves. Two types of spinal origins appeared in lateral pectoral nerves. The first type was composed of nerve fibers from C5, C6, and C7 with a frequency of 50.0% and the second type was composed of nerve fibers from C6 and C7 at a frequency of 50.0%. Regarding the average participating diameter to the lateral pectoral nerve, C7 was the thickest with a value of 1.60 +/- 0.35 mm (mean +/- SD), next was C6 at 0.83 +/- 0.18 mm, and C5 was the third at 0.42 +/- 0.24 mm. Three types of spinal origin appeared in the medial pectoral nerve. The first type was comprised of nerve fibers from C8 and T1 in 73.3% of cases. The second type was comprised of C8 only in 23.4% of cases, and the third type was comprised of T1 only in 3.3% of cases. The average participating diameter was 0.71 +/- 0.22 mm from C8 and 0.52 +/- 0.17 mm from T1. These results show that the spinal origins of the both pectoral nerves were various. Participating amounts of the lateral pectoral nerve appeared sequentially in the order of C7, C6, and C5. In the medial pectoral nerve, C8 participated more amounts than T1.     

The surgical anatomy of the sural nerve: An ultrasound study

The aim of this study was (a) to examine the anatomy of the sural nerve (SN) in a sample of 30 patients and (b) to analyze the incidence of different origins of the SN, and the distance of the SN from planned arthroscopic portals. An ultrasound (USG) examination of the SN was performed bilaterally on thirty healthy patients with no history of surgery or trauma of the lower limb. The SNs were classified into six main types of pattern, with an additional category for new and unclassified types. Each of Types 1 and 3 had two subdivisions. The distances from the superior border of the calcaneal tuberosity to the three simulated arthroscopy portal sites (Z1, Z1.5, Z2) to the SN were measured. A total of 30 patients (n = 60 limbs) with an average age of 27 ± 7.5 years were examined and the SN was visualized in all cases. The most common origin was Type 3A, accounting for 30% of limbs. Type 2 was the second most common seen in 18.3%. The distances of the SN from arthroscopic portal placement sites above the lateral malleolus were 2.07 ± 0.39 cm at the Z1 portal, 2.15 ± 0.38 cm at Z1.5, and 2.28 ± 0.33 cm at Z2. The variability in the anatomy of the SN warrants the use of USG to locate it accurately, thus preventing iatrogenic injury when portals are placed for arthroscopy, improving proper administration of anesthesia, and helping to localize the nerve for graft harvesting. Clin. Anat. 31:450–455, 2018. © 2017 Wiley Periodicals, Inc.     

The anatomical relationship between the sural nerve and small saphenous vein: An ultrasound study of healthy participants

Procedures involving the small saphenous vein (SSV) can result in sural nerve (SN) damage due to the proximity of the two structures. The relationship between the SN and SSV has previously been described in cadaveric studies with limited scope on surface landmarks. This study investigates the relationship between the SN and SSV in vivo through ultrasound. Transverse/short‐axis ultrasound scans of 128 legs (64 healthy participants) were taken by a single observer using a GE Logiq e ultrasound system with a 5–13 Hz linear transducer (GE Logiq 12L‐RS). The SN was identified and traced from the lateral malleolus to the popliteal fossa noting its course and proximity to the SSV. The distance between the SN and SSV was measured at points representing the distal 50% and 25% of the total leg length (the distance between the medial tibial condyle and the inferior edge of the medial malleolus). The SN and SSV were visualized in all participants regardless of BMI and atypical anatomical relationship were noted in 20.3%. The SN pierced the fascia in the distal 25.9% ± 5.3% of the total leg length. The distance between the SN and SSV was 4.06 ± 1.8 mm and 3.4 ± 1.4 mm in the distal 50% and 25% points of the total leg length, respectively. There was no significant effect of sex or body side. The SSV is a viable option for multiple vein harvest. Ultrasound visualization can be a beneficial tool for delineating variations of the SN in relation to SSV prior to surgery. Clin. Anat. 32:277–281, 2019. © 2018 Wiley Periodicals, Inc.     

Origin and make up of the human sural nerve

Abstract The dissection of 37 cadavers has shown that in only a third of cases, the sural nerve comes from the communication between the medial cutaneous nerve, derived from the tibial nerve, and the communicating branch of the lateral cutaneous nerve of the leg which comes from the lateral popliteal nerve. The communication is most often at the junction between the proximal two-thirds and distal third of the leg, on average 2 mm below the transverse crease of the popliteal fossa. The medial cutaneous nerve was absent in only one case. On the other hand, in 11 cases the lateral cutaneous nerve or its communicating branch was missing. In 12 cases without any anastomoses, the route of the sural nerve was followed by the medial cutaneous nerve of the leg in 9 cases and by the lateral cutaneous nerve in 3 cases. The majority of branches to the proximal half of the calf came from the lateral cutaneous nerve. In the lower part of the leg, the sural nerve and/or the medial cutaneous nerve gave numerous branches to the Achilles’ tendon and to the integuments of the lateral aspect of the heel and lateral malleolus.     

腓总神经与腓骨颈的关系及其小腿各肌支的解剖学研究

目的明确腓总神经与腓骨颈的关系以及小腿各肌支的解剖学特征。方法取成人下肢标本40例,在肉眼及放大镜下解剖,观察腓总神经与腓骨颈的关系以及腓总神经各肌支的数目及走行,以腓骨头最突出点为测量起点,测量腓总神经绕腓骨颈处至腓骨头最突出点的距离;测量各肌支的发出点、入肌点的高度,并作统计学分析。结果腓总神经绕腓骨颈处至腓骨头最突出点的距离,左、右侧分别为(1.64±0.36)cm和(1.58±0.34)cm。各肌支的数目不等,其中胫骨前肌支数目最多,腓骨短肌支和跗长伸肌支的数目较少。40例标本中,腓总神经均穿行于腓骨颈部骨一筋膜管。结论腓总神经在绕腓骨颈处均穿行于骨一筋膜管。提示:这可能是导致腓总神经卡压综合征的主要原因之一;不同肌肉的神经肌支数目差别较大,与其所支配肌肉的结构、功能有关。     

Formation and distribution of the sural nerve based on nerve fascicle and nerve fiber analyses

The formation and distribution of the sural nerve are presented on the basis of an investigation of 31 legs of Japanese cadavers using nerve fascicle and fiber analyses. Nerve fibers constituting the medial sural cutaneous nerve were designated as 'T', whereas those constituting the peroneal communicating branch were designated as 'F'. In 74.2% of cases (23/31), the T and F fibers joined each other in the leg, whereas in 9.7% of cases (3/31) they descended separately. In 16.1% of cases (5/31), the sural nerve was formed of only the T fibers. The sural nerve gave off lateral calcaneal branches and medial and lateral branches at the ankle. The lateral calcaneal branches always contained T fibers. The medial branches consisted of only T fibers, whereas most of the lateral branches consisted of only F fibers (71.0%; 22/31). In addition to the T and F fibers, P fibers, which derived from the superficial and deep peroneal nerves, formed the dorsal digital nerves. The P fibers were entirely supplied to the medial four and one-half toes. However, they were gradually replaced by the T and F fibers in the lateral direction. The 10th proper dorsal digital nerve consisted of T fibers only (38.7%; 12/31), of F fibers only (19.4%; 6/31) or of both T and F fibers (38.7%; 12/31). These findings suggest that the T fibers are essential nerve components for the skin and deep structures of the ankle and heel rather than the skin of the lateral side of the fifth toe. The designation of the medial sural cutaneous nerve should be avoided and only the T fibers are appropriate components for naming as the sural nerve.     

Anatomic basis of vascularised nerve grafts: the blood supply of peripheral nerves

The present study was carried out on 30 cadavers (5 fresh, 20 preserved adult and 5 fresh stillborn) following injection of red latex through the subclavian and common iliac arteries. The blood supply to the peripheral nerves was studied in general, together with the vascular pedicles to the ulnar, saphenous, sural, deep and superficial peroneal nerves, and the superficial branch of the radial nerve. The nutrient arteries supplying the peripheral nerves came from either the adjacent axial artery or the fasciocutaneous or muscular arteries. They formed anastomotic channels in the epineurium and penetrated it to form a continuous longitudinal artery. Based on the presence of absence of dominant arterial pedicles, five patterns of blood-supply to the nerves could be identified. I: no dominant arterial pedicle; II: only one dominant artery (e.g. artery with a diameter more than 0.8 mm and accompanying the nerve for most of its length); III: only one dominant vessel that divided into ascending and descending branches to supply the nerve; IV: multiple dominant pedicles; V: multiple dominant arterial pedicles forming a continuous artery that accompanied the nerve. The arterial pedicles to the ulnar, saphenous and deep peroneal nerves and the superficial branch of the radial n. had mean diameters of over 0.8 mm, thus being suitable for microvascular anastomosis. Those to the sural nerve were not present in two thirds of the dissected cadavers. In 10% of the cadavers the superficial peroneal nerve had an arterial pedicle that accompanied the nerve for less than two cm with a mean diameter less than 0.8 mm. The ulnar nerve could be very suitable as a donor vascularized nerve graft as it had a dominant vascular pedicle in all the cases studied; however, its use should be restricted to C8 and T1 root damage of the brachial plexus. The superficial branch of the radial n. might be suitable for vascularized nerve grafting, but this is difficult in practice since the radial artery is a major limb artery. The saphenous nerve had a dominant arterial pedicles in all the cadavers dissected and could be the most suitable as a donor vascularized nerve graft, unlike the sural nerve which did not have a dominant arterial pedicle in two-thirds of the specimens. The deep and superficial peroneal nerves may also be unsuitable since the former is accompanied by a major limb vessel while the latter had a dominant vascular pedicle that accompanied the nerve for only a short distance in 10% of the dissected cadavers.