Comprehensive Summary of Anastomoses between the Median and Ulnar Nerves in the Forearm and Hand
前臂和手正中神經和尺神經之間吻合術的全面總結

Jennifer L. Smith $^{1}$ Saaid A. Siddiqui $^{1}$ Nabil A. Ebraheim $^{1}$
詹妮弗·史密斯 $^{1}$ （Jennifer L. Smith）薩伊德 A. 西迪基 $^{1}$ （Saaid A. Siddiqui）納比爾 A. 埃布拉海姆（Nabil A. Ebraheim $^{1}$ ）

^{1}

Department of Orthopaedic Surgery, The University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, United States

^{1}

托萊多大學醫學與生命科學學院骨科外科，美國俄亥俄州托萊多

Abstract 抽象

Address for correspondence Jennifer L. Smith, MSE, Department of Orthopaedic Surgery, The University of Toledo College of Medicine and Life Sciences, 3000 Arlington Avenue, Toledo, OH 43614, United States (e-mail: Jennifer.Smith9@rockets.utoledo.edu).
通信位址 Jennifer L. Smith，MSE，托萊多大學醫學與生命科學學院骨科外科，3000 Arlington Avenue， Toledo， OH 43614， United States（電子郵件：Jennifer.Smith9@rockets.utoledo.edu）。

J Hand Microsurg 2019;11:1-5
J Hand Microsurg 2019 年;11:1-5

Abstract 抽象

Keywords - median-ulnar anastomosis - Martin-Gruber - Marinacci - Riche-Cannieu - Berrettini
關鍵詞 - 正中尺骨吻合術 - Martin-Gruber - Marinacci - Riche-Cannieu - Berrettini

Four main presentations of median-ulnar anastomosis exist. Those manifesting in the forearm include Martin-Gruber and Marinacci, while those found in the hand are referred to as Riche-Cannieu and Berrettini. Martin-Gruber anastomosis involves branching of the median nerve proximally to ulnar nerve distally. Marinacci anastomosis, the rarest of all the presentations, is often termed reverse Martin-Gruber, with the ulnar nerve stemming proximally to meet the median nerve distally in the forearm. Riche-Cannieu anastomosis occurs as an interconnection between the recurrent branch of the median nerve and the deep branch of the ulnar nerve in the hand. Berrettini anastomosis is the most frequently encountered of the anomalies and is described as a neural connection between common digital nerves of the ulnar and median nerves. Due to altered innervation patterns, musculoskeletal disorders of the forearm and hand may present with misleading symptoms. Additionally, existence of an anastomosis may require an alteration of surgical methods or be a source of iatrogenic injury. Consequently, knowledge of these anastomoses is crucial to clinical practice. Therefore, the objective of this review is to concisely present the most relevant information regarding median and ulnar anastomoses in the forearm and hand.
正中尺骨吻合術有 4 種主要表現。出現在前臂上的包括 Martin-Gruber 和 Marinacci，而在手上發現的被稱為 Riche-Cannieu 和 Berrettini。Martin-Gruber 吻合術涉及正中神經向近端分支到遠端尺神經。Marinacci 吻合術是所有表現中最罕見的，通常被稱為反向 Martin-Gruber，尺神經向近端莖起，與前臂遠端的正中神經相遇。Riche-Cannieu 吻合術是正中神經的返支和手尺神經深支之間的互連。Berrettini 吻合術是最常見的異常，被描述為尺總指神經和正中神經之間的神經連接。由於神經支配模式的改變，前臂和手部的肌肉骨骼疾病可能會出現誤導性的癥狀。此外，吻合口的存在可能需要改變手術方法或成為醫源性損傷的來源。因此，了解這些吻合口對臨床實踐至關重要。因此，本綜述的目的是簡明扼要地介紹有關前臂和手正中和尺骨吻合術的最相關信息。

Introduction 介紹

A variety of anomalous interconnections exist between the median and ulnar nerves in the forearm and hand. The four major classifications of anastomoses include Martin-Gruber anastomosis (MGA), Marinacci anastomosis (MA), RicheCannieu anastomosis (RCA), and Berrettini anastomosis (BA), with the former two occurring in the forearm and the latter two arising in the hand. While generally considered atypical, the presence of these anatomical variations may impact the presentation of musculoskeletal disorders and surgical outcomes, as well as mandate alteration of surgical approaches.

^{1 - 7}

Therefore, knowledge and recognition of these median-ulnar anastomoses by surgeons is clinically significant. The aim of this review is to concisely summarize current literature, to provide clinicians with an easily referenced and comprehensive resource.
前臂和手的正中神經和尺神經之間存在各種異常的互連。吻合的四種主要分類包括 Martin-Gruber 吻合術（MGA）、Marinacci 吻合術（MA）、RicheCannieu 吻合術（RCA）和 Berrettini 吻合術（BA），前兩者發生在前臂，后兩者出現在手部。雖然通常被認為是非典型的，但這些解剖學變異的存在可能會影響肌肉骨骼疾病的表現和手術結果，並需要改變手術方法。

^{1 - 7}

因此，外科醫生對這些正中尺骨吻合術的了解和識別具有臨床意義。本綜述的目的是簡明扼要地總結當前的文獻，為臨床醫生提供易於參考和全面的資源。

received 收到

February 10, 2018  2月10， 2018
accepted after revision  修訂後接受
August 10, 2018  八月 10， 2018
published online  在線發佈
October 29, 2018  十月 29， 2018

Martin-Gruber Anastomosis
Martin-Gruber 吻合術

Located in the forearm, MGA has a prevalence of

19.5 %

as estimated by the meta-analysis of 41 studies (

n = 6, 409

upper limbs) conducted by Roy et al.

^{7}

Caetano et

{al}^{8}

observed a prevalence as high as

27 %

using an anatomical dissection method, demonstrating the degree of variation that may be possible. In the same study, Roy et al further showed that MGA is more commonly unilateral and on the right side, in agreement with other studies.

^{9 - 11}

MGA is considered to follow an autosomal dominant pattern of inheritance

^{12, 13}

and has been linked to Trisomy 21 with bilateral presentation.

^{14}

Structurally, MGA is characterized as the proximal extension of the median nerve or its branches to the ulnar nerve distally, as seen in - Fig. 1. While there are several subtypes detailed throughout the literature, in the
MGA 位於前臂，根據 Roy 等人對 41 項研究（

n = 6, 409

上肢）的薈萃分析估計，

^{7}

{al}^{8}

MGA 的患病率與

27 %

19.5 %

使用解剖解剖方法一樣高，證明瞭可能的變異程度。在同一項研究中，Roy 等人進一步表明，MGA 更常見於單側和右側，與其他研究一致。

^{9 - 11}

MGA 被認為遵循常染色體顯性遺傳模式

^{12, 13}

，並且與雙側表現的 21 三體有關。

^{14}

在結構上，MGA 的特徵是正中神經或其分支向遠端尺神經的近端延伸，如圖 1 所示。雖然文獻中詳細介紹了幾種亞型，但在

DOI https://doi.org/
10.1055/s-0038-1672335. 10.1055/s-0038-1672335。

ISSN 0974-3227. 國際標準書號 0974-3227。

Fig. 1 Martin-Gruber anastomosis (MGA). MGA involves the median nerve stemming proximally to join the ulnar nerve distally. It is most commonly unilateral and on the right side. (Found in first paragraph under section titled “Martin-Gruber Anastomosis”).
圖 1 Martin-Gruber 吻合術（MGA）。MGA 涉及向近端莖起的正中神經，向遠端加入尺神經。它最常見的是單側和右側。（可在標題為“Martin-Gruber 吻合症”一節下的第一段中找到）。
majority of cases, the connecting branch is between the anterior interosseous nerve of the median nerve and the ulnar nerve, running an oblique course superficial to the flexor digitorum superficialis or flexor digitorum profundus and connecting posterior to the ulnar artery.

^{7, 9, 15 - 18}

Thirty-three percent of specimens with MGA present demonstrated this organization (type I) in Cavalheiro et al. Other possible arrangements described in the same study included double anastomosis between the anterior interosseous nerve and ulnar nerve (type II, 7.4%); anastomosis between the median and ulnar nerves (type III, 14.8%); anastomosis between branches of the median nerve and ulnar nerve heading toward the flexor digitorum profundus muscle of the fingers (type IV, 18.5%); intramuscular anastomosis (type V,

18.5 %

); and anastomosis between a branch of the median nerve to the flexor digitorum superficialis muscle and the ulnar nerve (type VI, 7.4%).

^{19}

While MGA is most frequently associated with the ulnar artery, it is important to note that it has also been related to the anterior ulnar recurrent artery. Awareness of this variation during open reduction and internal fixation of a radius/ulnar shaft fracture may be significant in minimizing iatrogenic damage.

^{7, 15}

大多數情況下，連接分支位於正中神經的骨間前神經和尺神經之間，沿淺屈肌或趾深屈肌淺表的斜行路線，並連接到尺動脈的後部。

^{7, 9, 15 - 18}

在 Cavalheiro 等人中，33% 的 MGA 標本證明瞭這種組織（I 型）。同一研究中描述的其他可能安排包括骨前神經和尺神經之間的雙吻合術（II 型，7.4%）;正中神經和尺神經之間的吻合（III 型，14.8%）;正中神經和尺神經分支之間的吻合口朝向手指趾深屈肌（IV 型，18.5%）;肌內吻合術（V 型）;

18.5 %

以及正中神經分支與趾淺屈肌和尺神經（VI 型，7.4%）之間的吻合。

^{19}

雖然 MGA 最常與尺動脈相關，但重要的是要注意它也與尺前返動脈有關。在橈骨/尺骨幹骨折的切開複位和內固定過程中意識到這種變化可能對減少醫源性損傷具有重要意義。

^{7, 15}

While there is some evidence of afferents, MGA nerve fibers are most often of an efferent nature,

^{15, 20, 21}

providing innervation primarily to the first dorsal interosseous muscle.

^{7.22}

Hypothenar muscles are also commonly supplied, followed by thenar muscles.

^{7}

雖然有一些傳入神經的證據，但 MGA 神經纖維通常具有傳出性質，

^{15, 20, 21}

主要為第一背側骨間肌提供神經支配。

^{7.22}

通常提供下魚際肌，其次是魚際肌。

^{7}

The clinical implications of MGA are far-reaching. Riechers et

{al}^{2}

cite this anastomosis as the main factor causing or inducing complications during surgical procedures. In addition to cases involving the anterior ulnar recurrent artery, iatrogenic damage is possible in the management of ulnar artery reconstruction, wrist drop, and ulnar nerve transposition.

^{7, 23, 24}

Complication of diagnosis of carpal tunnel syndrome, cubital tunnel syndrome, peripheral lesions, and neuropathies may also result in the presence of MGA. For example, in the case of carpal tunnel syndrome, there may be partial or total sparing of thenar muscles, as well as unusual findings in evoked muscle potentials.

^{5, 23, 25, 26}

Conversely, a patient may present with symptoms of carpal tunnel syndrome, but show negative findings with regard to Tinel and Phalen tests, due to ulnar nerve compression at the elbow.

^{8}

The intramuscular MGA subtype mentioned previously, found in

5 %

of total limbs

(n = 100)

in the study
MGA 的臨床意義是深遠的。Riechers 等

{al}^{2}

人認為這種吻合是外科手術過程中引起或誘發併發症的主要因素。除了涉及尺前返動脈的病例外，在尺動脈重建、腕下垂和尺神經轉位的治療中也可能出現醫源性損傷。

^{7, 23, 24}

腕管綜合征、肘管綜合征、外周病變和神經病變的診斷併發症也可能導致 MGA 的存在。例如，在腕管綜合征的情況下，魚際肌可能部分或全部保留，以及誘發電位的異常發現。

^{5, 23, 25, 26}

相反，患者可能出現腕管綜合征的癥狀，但由於肘部尺神經受壓，在 Tinel 和 Phalen 試驗中表現出陰性結果。

^{8}

前面提到的肌內 MGA 亞型，在研究

(n = 100)

的總肢體中

5 %

發現
by Caetano et al,

^{8, 19}

is clinically relevant in and of itself. This branch penetrates the flexor digitorum profundus muscle, potentially serving as a location of nerve compression.

^{15, 27, 28}

作者 Caetano 等人，

^{8, 19}

本身就具有臨床意義。該分支穿透趾深屈肌，可能作為神經壓迫部位。

^{15, 27, 28}

Marinacci Anastomosis Marinacci 吻合器

Also found exclusively in the forearm, MA is the rarest of the median-ulnar anastomoses, estimated at

0.7 %

(

n = 1, 884

) via the meta-analysis by Roy et al. However, MeenakshiSundaram et al

^{1}

reported its incidence to be as high as

4 %

(

n = 200

) in an electrophysiological study, suggesting that this type of anastomosis might be underreported. Consequently, there is little data on this variation.
MA 也只發現於前臂，是最罕見的正中尺骨吻合口，通過 Roy 等人的薈萃分析估計為

0.7 %

（

n = 1, 884

）。然而，MeenakshiSundaram 等人

^{1}

在一項電生理學研究中報告其發生率高達

4 %

（

n = 200

），這表明這種類型的吻合術可能被低估了。因此，關於這種變化的數據很少。

MA is also known as reverse MGA, with the ulnar nerve branching proximally to join the median nerve distally, - Fig. 2. Like MGA, MA is mainly comprised of motor fibers, with few accounts of afferents only.

^{29}

Presence of MA should be suspected if ulnar nerve stimulation at the elbow yields compound muscle action potentials (CMAPs) with larger amplitudes than with stimulation at the wrist.

^{1}

Knowledge of this possible finding can prevent interpretation of changes over the median nerve as neuropraxia.

^{1}

MA 也被稱為反向 MGA，尺神經向近端分支，與遠端的正中神經相連，- 圖 2。與 MGA 一樣，MA 主要由運動纖維組成，很少有僅介紹傳入神經的情況。

^{29}

如果肘部尺神經刺激產生的複合肌肉動作電位（CMAP）的振幅大於手腕刺激，則應懷疑存在 MA。

^{1}

瞭解這一可能的發現可以防止將正中神經的變化解釋為神經失用症。

^{1}

Median nerve injuries at the elbow may not result in clinically significant effects on the thenar muscles, such as the abductor pollicis brevis.

^{1}

For instance, in a patient case reported in Felippe et

a l,^{30, 31}

no disruption of innervation to the hand muscles was experienced despite trauma to the median nerve in the forearm and accompanying denervation of flexor muscles in the forearm. Alternatively, ulnar nerve
肘部正中神經損傷可能不會對魚際肌肉（如拇短展肌）產生臨床意義的影響。

^{1}

例如，在 Felippe et

a l,^{30, 31}

報導的一例患者病例中，儘管前臂正中神經受到創傷，並伴有前臂屈肌去神經支配，但手部肌肉神經支配未中斷。或者，尺神經

Fig. 2 Marinacci anastomosis (MA). MA is often referred to as reverse Martin-Gruber anastomosis, as the ulnar nerve is branching in the distal direction to unite with the median nerve. It is the rarest of the four types of anastomoses. (Found in second paragraph of section titled “Marinacci Anastomosis”).
圖 2 Marinacci 吻合術（MA）。MA 通常被稱為反向 Martin-Gruber 吻合術，因為尺神經向遠端分支以與正中神經結合。它是四種吻合口中最稀有的。（見標題為“Marinacci 吻合症”部分的第二段）。
injuries at the elbow may be accompanied by denervation changes over median-innervated thenar muscles.

^{1}

肘部損傷可能伴有正中支配魚際肌的去神經支配變化。

^{1}

Riche-Cannieu Anastomosis
Riche-Cannieu 吻合術

RCA occurs in the hand, with a pooled prevalence of

55.5 %

(

n = 501

^{7}

Similar to MA, incidence of RCA may also be underestimated. Some studies have reported rates as great as 70 to

80 %

, which the authors emphasized could potentially be higher with finer techniques.

^{32, 33}

This belief is supported by the findings in another study by Caetano et al,

^{34}

in which the presence of RCA was recorded in

100 %

of dissected fresh cadaver hands

(n = 80)

, with the use of careful, high magnification (10-16

\times

) technique. It may therefore be feasible to consider RCA as a normal anatomical neural connection.

^{7, 34}

Further, race might factor into observed prevalence.

^{33, 35}

For example, in a study by Kimura et

{al}^{33}

, African-Americans presented with RCA significantly less frequently than other racial groups, and no significant difference was found between Hispanics and Caucasians.

^{7}

This pattern supports the notion that, like MGA, RCA is inherited in an autosomal dominant manner.

^{36}

RCA 發生在手上，總體患病率為

55.5 %

（

n = 501

）。

^{7}

與 MA 類似，RCA 的發病率也可能被低估。一些研究報告了高達 70 到

80 %

的比率，作者強調，使用更精細的技術可能會更高。

^{32, 33}

Caetano 等人在另一項研究中的發現支援了這一信念，

^{34}

其中 RCA 的存在記錄

100 %

在解剖的新鮮屍體手中

(n = 80)

，使用小心的高放大倍率（10-16

\times

）技術。因此，將 RCA 視為正常的解剖神經連接可能是可行的。

^{7, 34}

此外，種族可能會影響觀察到的患病率。

^{33, 35}

例如，在 Kimura 等

{al}^{33}

人的一項研究中，非裔美國人出現 RCA 的頻率明顯低於其他種族群體，並且西班牙裔和高加索人之間沒有發現顯著差異。

^{7}

這種模式支持這樣一種觀點，即與 MGA 一樣，RCA 以常染色體顯性方式遺傳。

^{36}

RCA exists as an interconnection between the recurrent branch of the median nerve and the deep branch of the ulnar nerve, illustrated in - Fig. 3. Both motor and sensory fibers may be involved, with three possible presentations: a hand that is entirely supplied by the ulnar nerve

^{37}

; a hand with motor fibers solely from the ulnar nerve

^{38, 39}

; or, a hand with normally median-innervated muscles partially supplied by the ulnar nerve.

^{40}

With regard to the third scenario, Ahadi et al found that the abductor pollicis brevis is most often supplied,
RCA 作為正中神經的復發支和尺神經深支之間的互連存在，如圖 3 所示。運動和感覺纖維都可能受累，有三種可能的表現：一隻完全由尺神經供應的手

^{37}

;一隻手的運動纖維僅來自尺神經

^{38, 39}

;或者，一隻手的肌肉正常由尺神經支配，部分由尺神經供應。

^{40}

關於第三種情況，Ahadi 等人發現拇短外展肌最常被供應，

Fig. 3 Riche-Cannieu anastomosis (RCA). RCA arises as an interconnection between the recurrent branch of the median nerve and the deep branch of the ulnar nerve. Three possible presentations exist: a hand may be completely supplied by the ulnar nerve; a hand with all motor innervation via the ulnar nerve; or, a hand with normally median-innervated muscles partially supplied by the ulnar nerve. (Found in second paragraph of section titled “Riche-Cannieu Anastomosis”).
圖 3 Riche-Cannieu 吻合術（RCA）。RCA 作為正中神經的返支和尺神經深支之間的互連而出現。存在三種可能的表現：一隻手可能完全由尺神經供應;一隻通過尺神經進行所有運動神經支配的手;或者，一隻手的肌肉正常由尺神經支配，部分由尺神經供應。（見標題為“Riche-Cannieu 吻合症”一節的第二段）。
followed by the opponens pollicis. Therefore, weakness of abduction and opposition of the thumb may not accurately predict compromise of the median nerve in patients with RCA.

^{35}

其次是 opponens pollicis。因此，外展無力和拇指對立可能無法準確預測 RCA 患者正中神經的損害。

^{35}

Due to the nature of this anastomosis, neglect of RCA in patients with complete median nerve injury can lead to error in interpretation of 60.8 to

82.6 %

of complete median injury cases.

^{35, 41}

Likewise, lack of recognition of RCA may lead to misdiagnosis of severe carpal tunnel syndrome and, consequently, inappropriate surgical intervention.

^{42}

Electrodiagnosis of polyneuropathies or focal mononeuropathies other than median mononeuropathies, as seen in diabetes mellitus or certain autoimmune disease, may also be clouded by the presence of RCA.

^{42}

由於這種吻合的性質，在完全正中神經損傷患者中忽視 RCA 會導致 60.8 到

82.6 %

完全正中損傷病例的解釋錯誤。

^{35, 41}

同樣，缺乏對 RCA 的認識可能會導致嚴重腕管綜合征的誤診，從而導致不適當的手術干預。

^{42}

在糖尿病或某些自身免疫性疾病中見到的多發性神經病或局灶性單神經病（中位單神經病除外）的電診斷也可能因 RCA 的存在而變得模糊。

^{42}

Berrettini Anastomosis Berrettini 吻合術

The fourth and final type of anastomosis, BA, also occurs in the hand. Roy et

{al}^{7}

estimated a pooled prevalence of

60.9 %

(

n = 1, 768

), making it the most common of the anomalies. Because its incidence has been found to be greater than

80 %

in several other studies, there is general acceptance of BA as a normal anatomical structure.

^{4}

第四種也是最後一種吻合術 BA 也發生在手部。Roy et

{al}^{7}

估計了

60.9 %

（

n = 1, 768

）的匯總患病率，使其成為最常見的異常。由於發現其發生率高於

80 %

其他幾項研究，因此普遍接受 BA 作為一種正常的解剖結構。

^{4}

BA is described as a neural connection between common digital nerves of the ulnar and median nerves, - Fig. 4. Reports have demonstrated that the connecting branch most commonly originates from the fourth common digital nerve, joining distally with the third common digital nerve.

^{7}

BA 被描述為尺側總指神經和正中神經之間的神經連接，- 圖 4。報告表明，連接分支最常見於第四指總神經，在遠端與第三指總神經相連。

^{7}

Fig. 4 Berrettini anastomosis (BA). BA is described as a neural connection between common digital nerves of the ulnar and median nerves. It is purely sensory and is most often bilateral, arising proximal to the distal edge of the transverse carpal ligament and following an oblique course. (Found in second paragraph of section titled “Berrettini Anastomosis”).
圖 4 Berrettini 吻合術（BA）。BA 被描述為尺總指神經和正中神經之間的神經連接。它純粹是感覺性的，通常是雙側的，起源於腕橫韌帶遠端邊緣，呈斜向。（見標題為“Berrettini 吻合症”部分的第二段）。

Comprehensive Summary of Anastomoses between the Median and Ulnar Nerves in the Forearm and Hand 前臂和手正中神經和尺神經之間吻合術的全面總結

Abstract 抽象

Abstract 抽象

Introduction 介紹

received 收到

Martin-Gruber AnastomosisMartin-Gruber 吻合術

Marinacci Anastomosis Marinacci 吻合器

Riche-Cannieu AnastomosisRiche-Cannieu 吻合術

Berrettini Anastomosis Berrettini 吻合術

Comprehensive Summary of Anastomoses between the Median and Ulnar Nerves in the Forearm and Hand
前臂和手正中神經和尺神經之間吻合術的全面總結

Martin-Gruber Anastomosis
Martin-Gruber 吻合術

Riche-Cannieu Anastomosis
Riche-Cannieu 吻合術