Riché-Cannieu Anastomosis: Structure, Function, and Clinical Significance / Anastomose de Riché-Cannieu: estrutura, função e significância clínica

Abstract Objective To define the anatomy pattern and the incidence of Riché-Cannieu anastomosis, that is, median and ulnar communication in the palmar aspect of the hand. Materials Methods A total of 80 anatomical dissections were performed on 60 hands of 30 cadavers from 1979 to 1982, and on 20 hands from 2012 to 2015. All of these procedures were performed at the Department of Anatomy of our institution. The incidence of Riché-Cannieu anastomosis and the innervation of the thenar muscles were studied. Results Riché-Cannieu anastomosis was identified in every dissected hand (100%). The extramuscular Riché-Cannieu anastomosis was recorded in 57 hands, and the intramuscular, in 19 hands. The association of extra- and intramuscular Riché-Cannieu anastomoses occurred in four hands. The ulnar component always originated from the deep branch. The anastomotic branch arising from the median nerve originated from the motor thenar branch (recurrent branch) of the median nerve in most of the observations. The median-ulnar double innervation only to the deep head of the flexor pollicis brevis was identified in 29 of 80 hands. The double innervation only of the superficial head of the flexor pollicis brevis was found in 13 hands. In 12 hands, the deep head of the flexor pollicis brevis was absent. The double innervation of the superficial and deep heads of the flexor pollicis brevis occurred in 14 hands. The oblique head of the adductor pollicis received double innervation in 12 hands. The deep head of the flexor pollicis brevis and the oblique head of adductor pollicis were doubly-innervated in nine hands. The transverse head of the adductor pollicis received double innervation in two hands. Double innervation of the deep head of the flexor pollicis brevis and the transverse head of the adductor pollicis were found in one hand. Conclusion According to the present study, Riché-Cannieu anastomosis should be considered a normal anatomical neural connection, not an anatomical variation. Knowledge of this anastomosis is essential because the presence of such neural communication may result in confusing clinical, surgical, and electromyographic findings in cases of median or ulnar damage or entrapment.

Resumo Objetivo Definir a anatomia e a incidência da anastomose de Riché-Cannieu, ou seja, a comunicação entre os nervos medianos e ulnar na palma da mão. Materiais e Métodos Foram dissecadas 60 mãos de 30 cadáveres frescos de adultos, entre 1979 a 1982, e 20 mãos entre 2011 e 2015, num total de 80 mãos, no Departamento de Anatomia da nossa instituição. A incidência da anastomose de Riché-Cannieu e a inervação dos músculos da região do tênar foram estudadas. Resultados A anastomose de Riché-Cannieu foi identificada em todas as mãos dissecadas (100%). A anastomose de Riché-Cannieu extramuscular foi registrada em 57 mãos, e a intramuscular, em 19, e a associação das anastomoses extra e intramuscular, em 4 mãos. O componente ulnar da anastomose de Riché-Cannieu foi sempre do seu ramo profundo. O ramo anastomótico oriundo do nervo originava-se do ramo recorrente do nervo mediano na maioria das observações. A dupla inervação mediano-ulnar apenas da cabeça profunda do músculo flexor curto do polegar foi identificada em 29 de 80 mãos. Observou-se dupla inervação apenas da cabeça superficial do músculo flexor curto do polegar em 13 mãos. Foi observada dupla inervação das cabeças superficial e profunda do flexor curto do polegar em 14 mãos. A cabeça oblíqua do adutor do polegar recebeu inervação dupla em 12 mãos. A cabeça profunda do músculo flexor curto do polegar e a cabeça oblíqua do adutor do polegar foram inervadas duplamente em nove mãos. A cabeça transversa do adutor do polegar recebeu inervação dupla em duas mãos. A inervação dupla da cabeça profunda do flexor curto do polegar e da cabeça transversa do adutor do polegar foi observada em uma mão. Conclusão De acordo com o presente estudo, a anastomose de Riché-Cannieu deve ser considerada uma conexão nervosa normal, e não uma variação anatômica. O conhecimento dessa anastomose é essencial, pois a presença dessa comunicação neural pode resultar em achados clínicos, cirúrgicos e eletromiográficos confusos em casos de lesões ou síndromes compressivas dos nervos mediano ou ulnar.

Palmar cutaneous branch of median nerve: an anatomical study / Rama cutánea palmar del nervio mediano: un estudio anatómico

The purpose of this study was to determine the origin, frequency and anatomical variations of the palmar cutaneous branch of the median nerve (PCBMN) and its clinical implications in surgical procedures such as decompression of the carpal tunnel and volar approach to the wrist. Dissection of 30 forearms from 18 adult male specimens (9 bilateral, 7 right limbs and 5 left limbs) were performed using 2.5X magnification loupe in order to better understand the PCBMN. Origin, number, length, positioning, anatomical relations and variations were recorded and analyzed. The PCBMN was identified in all dissected forearms, being the most distal branch of the median nerve in all forearms. The average origin was 4.8 cm (ranging 3.8 to 6.5 cm) proximal to the wrist flexion crease. Anatomical variations of the PCBMN are not rare and could endanger the nerve during surgical approach for the volar wrist and proximal palm. We did not find the PCBMN positioned ulnar to the fourth metacarpal axis as well as radial to the flexor carpi radialis tendon.

El objetivo de este estudio fue determinar el origen, la frecuencia y las variaciones anatómicas de la rama cutánea palmar del nervio mediano (RCPNM) y sus implicaciones clínicas en procedimientos quirúrgicos como la descompresión del túnel carpiano y el abordaje palmar de la muñeca. Se realizó la disección de 30 antebrazos de 18 especímenes adultos de sexo masculino (9 bilaterales, 7 miembros derechos y 5 miembros izquierdos) utilizando una lupa de aumento de 2,5X para comprender mejor la RCPNM. Origen, número, longitud, posicionamiento, relaciones anatómicas y variaciones fueron registradas y analizadas. El RCPNM fue identificado en todos los antebrazos disecados, siendo la rama más distal del nervio mediano en todos los antebrazos. El origen promedio fue de 4,8 cm (rango de 3,8 a 6,5 cm) proximal al pliegue de flexión de la muñeca. Las variaciones anatómicas de la RCPNM no son raras y podrían poner en peligro el nervio durante el abordaje quirúrgico de la cara volar y palmar proximal de la muñeca. No encontramos el RCPNM posicionado a nivel ulnar del cuarto metacarpiano, así como radial al tendón del músculo flexor radial del carpo.

Anastomosis between the deep branch of ulnar nerve and a branch of the median nerve (Cannieu-Riché anastomosis) and thenar muscles innervation: anatomical study and clinical implications / Anastomosis entre el ramo profundo del nervio ulnar y un ramo del nervio mediano (anastomosis de Cannieu-Riché) e inervación de la eminencia tenar: estudio anatómico e implicaciones clínicas

SUMMARY: The aim of this paper was to report the incidences of the anastomosis between deep branch of ulnar nerve and a branch of the median nerve commonly named Cannieu-Riché anastomosis (CRA) and thenar muscles innervation. The anatomical dissection of 80 limbs from 40 fresh adult cadavers were performed in the Department of Anatomy at the Medical School of the Catholic University of São Paulo. The incidence of CRA and thenar muscle innervation were studied. The CRA was found in all of the dissected hands (100 %). The abdutor pollicis brevis and the opponens pollicis muscle are innervated exclusively by median nerve in all dissected hands. The superficial head of flexor pollicis brevis was innervated by the median nerve in of 56 the hands (70 %), in 24 (30 %) it had double innervation (median nerve and deep branch of ulnar nerve). The deep head of flexor pollicis brevis were absent in 11 hands (14 %), in 52 hands (65 %), a double innervation was observed. In 14 (17.5 %) exclusively by deep branch of ulnar nerve and in 3 hands (3.6 %) exclusively by a branch of median nerve. The oblique head of adductor pollicis muscle was innervated only by deep branch of ulnar nerve in 66 hands (82 %) of dissected hands, 14 (17.5 %) had a double innervation. The transverse head of adductor pollicis was innervated exclusively by deep branch of ulnar nerve in 77 hands (96.4 %), and in 3 (3.6 %) had a double innervation. According to our study the pattern of innervation was more frequent in relation to the flexor pollicis brevis muscle and should be considered as a normal pattern, in that the superficial head receives innervation of branches of median nerve, and the deep head receives innervation of deep branch of ulnar nerve and branches of median nerve (dual innervation). The abductor pollicis brevis and opponens pollicis received innervation exclusively by median nerve. Both the oblique and transverse head of adductor pollicis exclusively by ulnar nerve. The RCA was found in all of the dissected hands (100 %).

RESUMEN: El objetivo de este trabajo fue informar la anastomosis entre el ramo profundo del nervio ulnar y un ramo del nervio mediano (Anastomosis de Cannieu-Riché) y de la inervación de los músculos de la eminencia tenar. Se realizó la disección anatómica de 80 miembros de 40 cadáveres adultos frescos en el Departamento de Anatomía de la Facultad de Medicina de la Universidad Católica de São Paulo, Brasil. Se estudió la incidencia de formación de la ACR y la inervación de los músculos tenares. La ACR se encontró en todas las manos disecadas (100 %). El músculo abductor corto del pulgar y el músculo oponente del pulgar recibían inervación exclusivamente por el nervio mediano en todas las manos disecadas. La cabeza superficial del músculo flexor corto del pulgar estaba inervada por el nervio mediano (70 %), en 24 casos, (30 %) presentó inervación doble (nervio mediano y ramo profundo del nervio ulnar). La cabeza profunda del músculo flexor corto del pulgar estuvo ausente en 11 manos (14 %), mientras que en 52 manos (65 %) se produjo una doble inervación. En 14 casos (17,5 %) se vio inervado exclusivamente por el ramo profundo del nervio ulnar y en 3 manos (3,6 %) exclusivamente por un ramo del nervio mediano. La cabeza oblicua del músculo aductor del pulgar estaba inervada sólo por el ramo profundo del nervio ulnar en 66 manos (82 %), en 14 casos (17,5 %) tenía una doble inervación. La cabeza transversa del músculo aductor del pulgar estaba inervada exclusivamente por el ramo profundo del nervio ulnar en 77 manos (96,4 %), en 3 manos (3,6 %) presentó una doble inervación. De acuerdo con nuestro estudio, el patrón de inervación más frecuente en relación al músculo flexor corto del pulgar debe ser considerado como un patrón normal, en el que la cabeza superficial recibe inervación de ramos del nervio mediano y la cabeza profunda recibe inervación del ramo profundo de nervio ulnar y ramos del nervio mediano (inervación dual). El músculo abductor corto del pulgar y el músculo oponente del pulgar recibieron inervación exclusivamente por el nervio mediano. Tanto la cabeza oblicua como transversa del músculo aductor del pulgar están inervadas exclusivamente por el nervio ulnar. La ACR se encontró en todas las manos disecadas (100 %).