Anatomic variations of the musculotendinous junction of the soleus muscle and its clinical implications

The soleus muscle, like the gastrocnemius, is a powerful plantarflexor muscle in the lower limb. The soleus muscle joins the aponeurosis of the gastrocnemius muscle to form the calcaneal (Achilles) tendon. While the basic anatomy of the soleus muscle has been previously described, no study has addressed the anatomical variations of its distal attachment. We found considerable anatomic variation in the distance between this musculotendinous junction and the most proximal point of the proximal edge. This distal measuring point was defined as the most proximal point of the proximal edge of the posterior surface of the calcaneal tuberosity. Eighty human cadaver specimens were preserved according to Thiel's method; we examined one limb from each cadaver, studying 80 lower extremities in total. Following careful dissection of the lower limb, we measured the distance between the distal point of attachment of the soleus muscle fibers (the musculotendinous junction) and the designated measuring point. Our findings were divided into three groups: Group 1 (10 cases, 12.5%), where the distance between the musculotendinous junction and the designated point on the calcaneal tuberosity was between 0 and 1 inches; Group 2 (56 cases, 70%), where the distance was between 1 and 3 inches; and Group 3 (14 cases, 17.5%), where the distance was greater than 3 inches. Detailed knowledge of the anatomic variations of the soleus muscle at its insertion point onto the calcaneal tendon has clinical implications in calcaneal tendon repair following rupture and in the planning of reconstructive surgery using soleus muscle flaps.     

Clinical anatomy of the calcaneal tuberosity.

The aim of the study was a qualitative anatomical analysis of the macroscopic features of the surface of the calcaneal tuberosity, of the architecture of its cancellous bone and histological structure of the whole region. Dry human bones and pathological dissection material 24-36 h post mortem were used in the study. On the tuberosity, the variability of its surface relief and the two borders between the superior, middle and inferior facets were studied. More frequent medial declination of the inferior line, corresponding to the distal circumference of the Achilles tendon attachment, was found. Two systems of expressive condensation of cancellous bone just below the surface of the calcaneal tuberosity were described. In the histological part of the study, the distribution and different thickness of the fibrous cartilage layer covering the attachment region of Achilles tendon, the bottom of retro-calcaneal bursa and the whole surface of the calcaneal tuberosity were described. The functional and clinical relevance of results obtained are evaluated from the point of view of disciplines dealing with the pathology and surgery of the heel region. The relationships of official anatomical terms and a wide spectrum of clinical synonyms designating this region are discussed.     

无滑膜肌腱滑膜化的组织工程学研究

我们将兔趾腱鞘内滑膜组织进行体外培养,经原代培养和传代培养,制成滑膜细胞悬液,再把兔腱鞘外无滑膜肌腱段放入滑膜细胞悬液中混全培养。经光镜、扫描电镜和免疫组织化学检测。结果显示,滑膜细胞爬行并覆盖了无滑膜肌腱段的表面,使无滑膜肌腱形成了有滑膜肌腱。     

Structure of the Achilles tendon at the insertion on the calcaneal tuberosity

Findings on the twisting structure and insertional location of the AT on the calcaneal tuberosity are inconsistent. Therefore, to obtain a better understanding of the mechanisms underlying insertional Achilles tendinopathy, clarification of the anatomy of the twisting structure and location of the AT insertion onto the calcaneal tuberosity is important. The purpose of this study was to reveal the twisted structure of the AT and the location of its insertion onto the calcaneal tuberosity using Japanese cadavers. The study was conducted using 132 legs from 74 cadavers (mean age at death, 78.3 ± 11.1 years; 87 sides from men, 45 from women). Only soleus (Sol) attached to the deep layer of the calcaneal tuberosity was classified as least twist (Type I), both the lateral head of the gastrocnemius (LG) and Sol attached to the deep layer of the calcaneal tuberosity were classified as moderate twist (Type II), and only LG attached to the deep layer of the calcaneal tuberosity was classified as extreme twist (Type III). The Achilles tendon insertion onto the calcaneal tuberosity was classified as a superior, middle or inferior facet. Twist structure was Type I (least) in 31 legs (24%), Type II (moderate) in 87 legs (67%), and Type III (extreme) in 12 legs (9%). A comparison between males and females revealed that among men, 20 legs (24%) were Type I, 57 legs (67%) Type II, and eight legs (9%) Type III. Among women, 11 legs (24%) were Type I, 30 legs (67%) Type II, and four legs (9%) Type III. No significant differences were apparent between sexes. The fascicles of the Achilles tendon attach mainly in the middle facet. Anterior fibers of the Achilles tendon, where insertional Achilles tendinopathy is most likely, are Sol in Type I, LG and Sol in Type II, and LG only in Type III. This suggests the possibility that a different strain is produced in the anterior fibers of the Achilles tendon (calcaneal side) where insertional Achilles tendinopathy is most likely to occur in each type. We look forward to elucidating the mechanisms generating insertional Achilles tendinopathy in future biomedical studies based on the present results.     

The plantaris tendon and a potential role in mid-portion Achilles tendinopathy: an observational anatomical study

The source of pain and the background to the pain mechanisms associated with mid-portion Achilles tendinopathy have not yet been clarified. Intratendinous degenerative changes are most often addressed when present. However, it is questionable if degeneration of the tendon itself is the main cause of pain. Pain is often most prominent on the medial side, 2-7cm from the insertion onto the calcaneus. The medial location of the pain has been explained to be caused by enhanced stress on the calcaneal tendon due to hyperpronation. However, on this medial side the plantaris tendon is also located. It has been postulated that the plantaris tendon might play a role in these medially located symptoms. To our knowledge, the exact anatomy and relationship between the plantaris- and calcaneal tendon at the level of complaints have not been anatomically assessed. This was the purpose of our study. One-hundred and seven lower extremities were dissected. After opening the superficial fascia and paratendon, the plantaris tendon was bluntly released from the calcaneal tendon moving distally. The incidence of the plantaris tendon, its course, site of insertion and possible connections were documented. When with manual force the plantaris tendon could not be released, it was defined as a 'connection' with the calcaneal tendon. In all specimens a plantaris tendon was identified. Nine different sites of insertion were found, mostly medial and fan-shaped onto the calcaneus. In 11 specimens (10%) firm connections were found at the level of the calcaneal tendon mid-portion. Clinical and histological studies are needed to confirm the role of the plantaris tendon in mid-portion Achilles tendinopathy.     

跟骨关节内骨折合并腓骨肌腱脱位的多层螺旋CT诊断

目的：探讨多层螺旋CT(multi-slice computed tomography,MSCT)诊断跟骨关节内骨折合并腓骨肌腱脱位的临床价值。方法：选择新乐市中医医院2013年1月至2015年6月收治的跟骨关节内骨折患者142例,共154足,对所有患者进行MSCT扫描,并进行附带肌腱的容积再现(virtual reality, VR)和多平面重组(multiple planar reconstruction,MPR),测量足跟骨结节外侧突后缘至载距突内侧面的距离、载距突后缘的跟骨宽度。结果：128只足不存在腓骨肌腱脱位(未脱位组),轴位及冠状位MPR及VR图显示腓骨肌腱位于腓骨肌腱沟内;26只足存在腓骨肌腱脱位(脱位组),MSCT显示腓骨肌腱从腓骨肌腱沟内脱出,并向外侧移位。脱位组跟骨结节外侧突后缘至载距突内侧面的距离、载距突后缘的跟骨宽度均大于未脱位组[(5.08±0.61) vs.(4.78±0.59) cm;(4.18±0.47) vs.(3.83±0.50) cm;P<0.05]。脱位组均行骨折切开复位、钢板内固定治疗,未对腓骨肌腱脱位进行处理。术后对15只足随访12个月,其中3只足腓骨肌腱复位,另外12只仍处于脱位状态。结论：MSCT可多角度观察腓骨肌腱和腓骨肌腱沟的位置,准确判断跟骨关节内骨折是否合并腓骨肌腱脱位,对于腓骨肌腱脱位的临床诊断和治疗具有重要意义。     

Evidence for an elongated Achilles tendon in Australopithecus

Modern humans have the longest Achilles tendon (AT) of all the living primates. It has been proposed that this anatomy increases locomotor efficiency and that its elongation may have played a crucial role in the origin and early evolution of the genus Homo. Unfortunately, determining the length of the AT in extinct hominins has been difficult as tendons do not fossilize. Several methods have been proposed for estimating the length of the AT from calcaneal morphology, but the results have been inconclusive. This study tested the relationship between the area of the superior calcaneal facet and AT length in extant primates. The superior facet is instructive because it anchors the retrocalcaneal bursa, a soft tissue structure which helps to reduce friction between the AT and the calcaneus. Calcanei from 145 extant anthropoid primates from 12 genera were photographed in posterior view and the relative superior facet size quantified. AT lengths were obtained from published sources. The relative area of the superior facet is predictive of AT length in primates (R² = 0.83; p < .001) and differs significantly between the great apes and humans (p < 0.001). When applied to fossil Australopithecus calcanei, our results suggest that australopiths possessed a longer, more human-like, AT than previously thought. These findings have important implications for the locomotor capabilities of Australopithecus, including their capacity for endurance running and climbing.     

Tendon impingement of the extensor digiti minimi: clinical cases series and cadaveric study

The authors describe two unique clinical cases of closed extensor digiti minimi (EDM) tendon injuries after hyperflexion of the wrist with full finger flexion and one case of chronic tenosynovitis around the EDM tendon. All three cases were thought to be related to the bifurcation of the EDM tendon and synovial septum. Subsequently, variations in EDM tendons were investigated in 49 cadaveric hands with a focus on patterns of tendon bifurcation and their relationships with the surrounding synovial sheath. The EDM tendon was found to be bifurcated in 74% (n = 36) of hands and all of these hands contained a synovial septum. In 9 (25%) hands, the EDM tendon bifurcated proximal to the retinaculum, in 15 (42%), it bifurcated distal to the retinaculum, and in the other 12 hands (33%), the tendon bifurcated at the retinacular level. In 6 of the 15 hands with an infraretinacular bifurcation, the tendon was found to impinge on the synovial septum during passive flexion of the wrist with full finger flexion, and the mean distance between the synovial septum and the bifurcation point in these specimens was 0.6 cm (range, 0.4-0.7 cm), which was differed significantly from hands not showing impingement (P = 0.01). This study shows that distal bifurcation of the EDM tendon may lead to tendon impingement on the septum and suggests that this is a potential etiology of chronic tenosynovitis of the fifth compartment and of acute closed tendon injuries.     

Development of the human Achilles tendon enthesis organ

The attachment of the Achilles tendon is part of an ‘enthesis organ’ that reduces stress concentration at the hard–soft tissue interface. The organ also includes opposing sesamoid and periosteal fibrocartilages, a bursa and Kager's fat pad. In addition, the deep crural and plantar fasciae contribute to Achilles stress dissipation and could also be regarded as components. Here we describe the sequence in which these various tissues differentiate. Serial sections of feet from spontaneously aborted foetuses (crown rump lengths 22–322 mm) were examined. All slides formed part of an existing collection of histologically sectioned embryological material, obtained under Spanish law and housed in the Universidad Complutense, Madrid. From the earliest stages, it was evident that the Achilles tendon and plantar fascia had a mutual attachment to the calcaneal perichondrium. The first components of the enthesis organ to appear (in the 45‐mm foetus) were the retrocalcaneal bursa and the crural fascia. The former developed by cavitation within the mesenchyme that later gave rise to Kager's fat pad. The tip of the putative fat pad protruded into the developing bursa in the 110‐mm foetus and fully differentiated adipocytes were apparent in the 17‐mm foetus. All three fibrocartilages were first recognisable in the 332‐mm foetus – at which time adipogenesis had commenced in the heel fat pad. The sequence in which the various elements became apparent suggests that bursal formation and the appearance of the crural fascia may be necessary to facilitate the foot movements that subsequently lead to fibrocartilage differentiation. The later commencement of adipogenesis in the heel than in Kager's pad probably reflects the non‐weight environment in utero. The direct continuity between plantar fascia and Achilles tendon that is characteristic of the adult reflects the initial attachment of both structures to the calcaneal perichondrium rather than to the skeletal anlagen itself.     

Biomechanical evaluation of reconstruction plates with locking,nonlocking, and hybrid screws configurations in calcaneal fracture: a finite element model study

Calcaneal fractures are the most common fractures of the tarsal bones. The stability of fixation is an important factor for successful reconstruction of calcaneal fractures. The purpose of this study was to analyze the biomechanical influence of plate fixation with different combinations of locking and nonlocking screws during early weight-bearing phase. A three-dimensional FE foot model was established using ANSYS software, which comprised bones, cartilages, plantar fascia, and soft tissue. Calcaneal plate was fixed with whole locking (WLS), whole nonlocking (WNS), and hybrid screw configurations for FE analysis. The WNS generated a 6.1° and 2.2° Bohler angle decrease compared with the intact model and WLS (WNS: 18.9; WLS: 21.1; intact: 25.0°). Some hybrid screw configurations (Bohler angle: 21.5° and 21.2°) generated stability similar to WLS. The FE results showed that the fragments at the posterior facet and the posterior tuberosity sustained more stress. This study recommends that the hybrid screw configuration with at least four locking screws, two at the posterior facet fragment and two at the posterior tuberosity fragment, is the optimal choice for the fixation of Sanders type IIB calcaneal fractures.     

载距突解剖形态学分型及特征分析

目的 基于CT三维重建的载距突,探讨其解剖形态学分型及特征,为螺钉植入治疗跟骨骨折提供解剖学支持。 方法 2019年3月~2020年3月,经纳入标准排除后,最终共收集336例来自西南医科大学附属中医医院的成年人跟骨CT三维重建图像,依据载距突冠状位轴线与跟骨轴线的夹角（β）进行分型,研究参数：β、载距突内侧中点与后距关节面内侧中点的距离（AB）,载距突内侧中点与后距关节面外侧中点的距离（AC）,载距突内侧中点冠状位轴线与跟骨最外侧交点的距离（AD）,载距突内侧中点与跟骨结节内侧突中点的距离（AE）,载距突内侧中点与跟骨结节中点的距离（AF）,载距突内侧中点与跟骨结节外侧突中点的距离（AG）,根据分型和男女、左右分别对测量结果进行统计学分析。 结果 根据 β,我们将载距突分为3型：Ⅰ型（β<70°,68例,20.24%）、Ⅱ型（70°≤β<80°,153例,45.54%）、Ⅲ型（80°≤β<90°,115例,34.23%）。其中Ⅲ型与其他型别在 β、AB、AF上具有差异（P<0.05）,Ⅲ型和Ⅰ型在AE上具有差异（P<0.05）。此外,男性和女性的载距突在AB、AC、AD、AE、AF、AG上均具有差异（P<0.05）,左右两侧的载距突在 β、AB上具有差异（P<0.05）。 结论 载距突可以分为3型,以Ⅱ型为主,内固定治疗跟骨骨折时,螺钉植入角度可以尽量在70°~ 80°,其解剖形态学分型对螺钉植入有一定的临床指导意义。     

The conjoint junction of the triceps surae: implications for gastrocnemius tendon lengthening

Forty embalmed cadaver lower limbs were dissected to identify the morphology of the conjoint junction of the tendons of gastrocnemius and soleus and the location of the gastrocnemius tendon relative to bony landmarks. Five patterns of conjoint junction morphology were found: transverse (25%), oblique passing distally and medially (45%), oblique passing distally and laterally (5%) and arcuate as an inverted U (17.5%) and a U-shape (7.5%). Left-right asymmetry of the junction was observed in 31.6% of 19 paired cadaver legs. On the medial side of the calf the gastrocnemius tendon could be located between 38 and 46% of the proportion of the distance between the upper border of the calcaneus and the fibular head. Corresponding values for the midline and lateral side of the calf were 45-58% and 48-51%. The location of the gastrocnemius tendon relative to bony landmarks may help to guide incision planning for open or endoscopic division of the tendon.     

The accumulation of inflammatory cells in synovial sheath and epitenon during adhesion formation in healing rat flexor tendons.

The accumulation of inflammatory cells in synovial tissue was studied using indirect immunofluorescence assays on cell cultures and frozen tissue sections of healing rat digital flexor tendons. Flexor tendons were collected from rats 3, 7 and 14 days after crush injury. Tendon sheath and epithenon cells were isolated by sequential enzymic digestion and cultured for 2 days. Subpopulations of synovial and inflammatory cells were identified with MoAbs against cell surface glycoproteins present on B lymphocytes (CD45), T lymphocytes (CD2, CD4, CD8), macrophages (CD14) and endothelial cells. A phagocytosis assay was also used to identify macrophages. We report a substantial increase in the number of T lymphocytes (mainly helper/inducer) and phagocytotic cells with monocyte/macrophage surface markers in tendon sheath and epitenon 3 days after crush injury. The infiltration of inflammatory cells into synovial sheath and epitenon preceded an increase in fibronectin production by tendon cells which was seen 7 days after injury. To study the interaction between T lymphocytes and synovial cells in vitro, we established synovial fibroblast-like type B cell cultures and used stimulated and non-stimulated T lymphocytes in cell binding assays. We observed increased adhesiveness between unstimulated synovial cells and synovial cells previously cultured with activated and non-activated T lymphocytes. ELISA inhibition studies have shown an increase in fibronectin production by synovial fibroblasts co-cultured with stimulated CD4+ T lymphocytes. We suggest that the presence of inflammatory cells in synovial sheath and epitenon during tendon healing induces synovial fibroblasts and epitenon cells to increase their production of fibronectin, which provides a scaffold for subsequent adhesion formation.     

The “safe zone” in medial percutaneous calcaneal pin placement

Percutaneous pin insertion into the medial calcaneus places a number of structures at risk. Evidence suggests that the greatest risk is to the medial calcaneal nerve (MCN). The medial calcaneal region of 24 cadavers was dissected to determine the major structures at risk. By using four palpable anatomical landmarks, the inferior tip of the medial malleolus (point A), the posterior superior portion of the calcaneal tuberosity (point B), the navicular tuberosity (point C), and the medial process of the calcaneal tuberosity (point D), we attempted to define the safe zone taking into account all possible variables in our dissections including ankle position, side, gender, and possible anatomical variations of the MCN. The commonest arrangement of the MCN was two MCNs that arose independently, one arising before the bifurcation of the tibial nerve and the other arising from the medial plantar nerve. A zone could be defined posterior to 75% of the distance along the lines AB, CD, AD, and CB which would avoid most structures. The posterior branches of the MCN, however, would still be at risk and placing the pin too far posteriorly risks an avulsion fracture. This is the first study to employ four palpable anatomical landmarks to identify a zone to minimize damage to neurovascular structures. It may not be possible, however, to avoid injury of the MCN and consequent sensory loss to the sole of the foot. foot. Clin. Anat. 22:523–529, 2009. © 2009 Wiley‐Liss, Inc.     

Blood supply of the flexor digital tendon in the hand and its clinical significance

Summary An anatomical study on the blood sources and vascularity of the flexor digital tendon was conducted in the upper extremities of fresh cadavers by means of arterial injection and meticulous dissection of the transparent tendon under the microscope. According to whether or not synovial membrane surrounded the tendon, the flexor digital tendon can be divided into 2 regions: non-synovial and synovial. The major intrinsic blood supply of the digital tendon was in the form of longitudinal vascular bundles, while the transverse anastomotic branches were short and sparse. The non-synovial region of the tendon was covered by paratenon and the vascular distribution of this region was uniform. In the synovial sheath, the blood vessels distributed only on the dorsal side, while the volar side was devoid of vessels. The profundus and superficialis tendons had an avascular zone at the proximal interphalangeal and metacarpophalangeal joints respectively. It was considered that the difference of the vascular architecture might be related to the mechanical force to which the tendon was subjected. The nutrition of tendon was discussed and the selection of tendon graft at operation was suggested.

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Vascularisation des tendons fléchisseurs des doigts au niveau de la main : signification clinique

Résumé Une étude anatomique des pédicules et de la vascularisation des tendons fléchisseurs des doigts a été réalisée sur cadavres frais, au moyen d'injections artérielles d'encre de chine, et d'une dissection méticuleuse sous microscope du tendon diaphanisé. Selon que la membrane synoviale entoure ou non le tendon, ce dernier peut être divisé en deux parties: partie non synoviale et partie synoviale. La vascularisation intrinsèque du tendon fléchisseur digital est essentiellement constituée par des éléments vasculaires longitudinaux, tandis que les anastomoses transversales sont courtes et éparses. La partie non synoviale du tendon est enveloppée par le paratendon et la distribution vasculaire dans cette région est uniforme; dans la gaine synoviale les vaisseaux sanguins se distribuent seulement du côté dorsal, tandis que le côté palmaire est dépourvu de vaisseaux. Les tendons fléchisseurs superficiels et profonds présentent une zone avasculaire au niveau des articulations interphalangienne et métacarpophalangienne. On peut penser que la différence d'architecture vasculaire peut être en relation avec les forces mécaniques auxquelles le tendon est soumis. Le mode de nutrition du tendon est discuté et le choix d'une greffe tendineuse en per-opératoire est suggéré.

     

The influence of aging on the insertion of the Achilles tendon: A magnetic resonance study

The aim of this study was to examine the variations of the Achilles tendon (AT) insertion point into the calcaneal bone (CB) in relation to age and sex using magnetic resonance imaging (MRI). A total of 202 foot and ankle MRIs were reviewed and patients were allocated into three age groups: (I) <18, (II) 18-65, and (III) >65 years. All measurements were obtained on a mid-sagittal scan. The mean measurement values were used to assess the relationships among the AT insertion point, sex, and age. Our main findings revealed that (1) the distance between the most inferior point of the CB and the most inferior part of the AT insertion into the CB increases with age, (2) the height of the AT insertion into the posterior aspect of the CB decreases with age, and (3) the length of the AT insertion into the posterior aspect of the CB decreases with age. The terminal insertion point of the AT on the CB in younger subjects was more distal, whereas in older individuals it was more proximal. These results could help in developing novel strategies for the treatment and prophylaxis of AT injuries in particular patient age groups. Anatomical data about the AT insertion are crucial for developing a computer model of the AT and for biomechanical considerations regarding this tendon. Clin. Anat. 33:545–551, 2020. © 2019 Wiley Periodicals, Inc.     

异体跟腱骨移植修复髌韧带近止点断裂

目的探讨髌韧带近止点断裂的治疗方法和疗效。方法 9例髌韧带近止点断裂患者,受伤至手术时间1~6周。患者均有明确外伤史,3例为闭合性损伤,6例为开放性损伤,均采用异体跟腱骨重建髌韧带。结果 9例患者均得到随访,平均随访时间2年。术前膝关节Lysholm评分平均为67.3分﹙63.5~71.1分﹚,术后1年膝关节Lysholm评分平均为86.2分﹙83.1~89.3分﹚,行检验﹙<0.05﹚。结论采用异体跟腱骨修复髌韧带近止点断裂,允许早期功能锻炼,可获得良好的疗效,是理想的治疗方法。     

Development and ageing of phenotypically distinct fibrocartilages associated with the rat Achilles tendon

Summary We describe by routine histology and by immunohistochemistry three phenotypically and developmentally distinct fibrocartilages associated with the Achilles tendon of the rat. All the fibrocartilages develop after birth and show significant age-related changes in the composition of their extracellular matrix. Attachment-zone fibrocartilage occurs at the insertion of the tendon on the calcaneus. It derives from the cartilage rudiment of the calcaneus and from the region where the tendon merges with the perichondrium. The extracellular matrix contain type II collagen and chondroitin sulphate. Compressive tendon fibrocartilage occurs in the deep part of the tendon where it presses against the calcaneus, and is derived by metaplasia of tendon cells. The cells label strongly for the intermediate filament vimentin, and the extracellular matrix contains chondroitin and keratan sulphates, but type II collagen only in very old animals (>2 years). Calcaneal fibrocartilage covered the posterior surface of the calcaneus where it was in contact with the Achilles tendon. It labelled intensely for type II collagen and contained chondroitin and keratan sulphates. The cells were rich in vimentin. This fibrocartilage was derived from the calcaneal perichondrium.     

跟外侧动脉的显微外科解剖

目的探讨跟外侧动脉的起始、行程、分支和分布等情况,为临床实践提供解剖学资料。方法在12侧经股动脉灌注红色乳胶溶液的成人下肢标本上,对跟外侧动脉进行显微外科解剖,观察其出现率并测量其起始位置、起始处及穿深筋膜处的口径。以外踝尖为基点,对外踝尖上6 cm范围内每2 cm间隔内跟外侧动脉分支的蒂长和口径进行测量并作统计学分析。另取小腿动脉血管造影标本5例,进一步观察跟外侧动脉行程及其与跟腱表面皮瓣血供的关系。结果跟外侧动脉于外踝尖上4.9～9.4(6.56±1.30)]cm处源自腓动脉,起始处口径为1.0～3.3(1.78±0.60)mm,穿深筋膜处口径为0.44～2.0(0.81±0.40)mm。其全程呈"L"型,垂直段共有2～5(2.50±0.80)支分支。在外踝尖上0.00～2.00、2.01～4.00、4.01～6.00 cm间隔内,分支的蒂长和口径分别是:(0.81±0.31)、(1.68±0.55)、(1.59±0.41)cm和(0.80±0.31)、(0.80±0.11)、(0.85±0.23)mm。垂直段分支分支纵、橫穿行,纵者吻合成链状与腓肠神经及小隐静脉伴行,参与腓肠神经营养血管皮瓣供血系统的组成,橫行者越过跟腱浅面与来自胫后动脉的分支吻合,供养跟腱区皮瓣;水平段分支3～5支,分布于足外侧面后侧约1/3皮肤软组织。结论跟外侧动脉是腓动脉的直接延续,尸体标本和活体标本中跟外侧动脉出现率分别为100%和80%;跟外侧动脉既参与腓肠神经营养血管皮瓣供血系统的组成,又营养跟腱表面的皮瓣。