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 %).

Anatomical variations of pronator teres muscle: predispositional role for nerve entrapment.

OBJECTIVE: To assess the anatomical variations of the pronator teres muscle (PTM) and its implication in the compression of the median nerve, which passes through the humeral and ulnar heads of the PTM. METHODS: For the present study, 100 upper limbs from human cadavers from the anatomy laboratory were dissected. Forty-six specimens were male and four, female, whose aged ranged from 28 to 77 years; 27 were white and 23, non-white. A pilot study consisting of six hands from three fresh cadaver dissections was conducted to familiarize the authors with the local anatomy; these were not included in the present study. RESULTS: The humeral and ulnar heads of PTM were present in 86 limbs. In 72 out of the 86 limbs, the median nerve was positioned between the two heads of the PTM; in 11, it passed through the muscle belly of ulnar head of the PTM, and in three, posteriorly to both heads of the PTM. When both heads were present, the median nerve was not observed as passing through the muscle belly of the humeral head of PTM. In 14 out of the 100 dissected limbs, the ulnar head of the PTM was not observed; in this situation, the median nerve was positioned posteriorly to the humeral head in 11 limbs, and passed through the humeral head in three. In 17 limbs, the ulnar head of PTM was little developed, with a fibrous band originating from the ulnar coronoid process, associated with a distal muscle component near the union with the humeral head. In four limbs, the ulnar head of the MPR was represented by a fibrous band. In both limbs of one cadaver, a fibrous band was observed between the supinator muscle and the humeral head of the PTM, passing over median nerve. CONCLUSION: The results suggest that these anatomical variations in relationship median nerve and PTM are potential factors for median nerve compression, as they narrow the space through which the median nerve passes.

OBJETIVO: Analisar as variações anatômicas do músculo pronador redondo (MPR) e suas implicações na compressão do nervo mediano, que passa entre as cabeças umeral e ulnar do MPR. MÉTODO: Foram dissecados 100 membros superiores de cadáveres adultos pertencentes ao laboratório de anatomia; 46 cadáveres eram do sexo masculino e quatro do feminino. A idade variou entre 28 e 77 anos; 27 eram da etnia branca e 23, não branca. Um estudo piloto que incluiu três cadáveres frescos foi feito, para familiarização dos autores com a anatomia regional. Esses não foram incluídos no estudo. RESULTADOS: Em 86 membros, observou-se a presença das cabeças umeral e ulnar do MPR. Em 72 dos 86 membros, o nervo mediano estava posicionado entre as cabeças umeral e ulnar do MPR; em 11, esse encontrava-se através da massa muscular da cabeça ulnar do MPR e em três, o nervo mediano estava posicionado posteriormente às duas cabeças do MPR. Nos casos em que as duas cabeças do músculo estavam presentes, não se observou o nervo mediano passando através da massa muscular da cabeça umeral do MPR. Em 14 dos 100 membros dissecados, a cabeça ulnar do MPR não estava presente. Nessa situação, o nervo mediano posicionava-se posteriormente à cabeça umeral em 11 membros e através da cabeça umeral em três membros. Em 17 membros, a cabeça ulnar estava muito pouco desenvolvida, com conformação fibrosa em sua origem no processo coronoide da ulna, associada a um componente muscular distal, próximo a sua união com a cabeça umeral. Em quatro membros, a cabeça ulnar do MPR estava representada apenas por uma banda fibrosa. Nos dois membros de um cadáver, observou-se uma expansão fibrosa que saía do músculo supinador para a cabeça umeral do MPR, passando como uma cinta sobre o nervo mediano. CONCLUSÕES: Esses resultados sugerem que as variações anatômicas na relação nervo mediano e MPR representam fatores potenciais para compressão nervosa, por estreitar o espaço no qual passa o nervo mediano.

Anatomical variations of pronator teres muscle: predispositional role for nerve entrapment / Variações anatômicas do músculo pronador redondo e sua importância nas síndromes compressivas

ABSTRACT OBJECTIVE: To assess the anatomical variations of the pronator teres muscle (PTM) and its implication in the compression of the median nerve, which passes through the humeral and ulnar heads of the PTM. METHODS: For the present study, 100 upper limbs from human cadavers from the anatomy laboratory were dissected. Forty-six specimens were male and four, female, whose aged ranged from 28 to 77 years; 27 were white and 23, non-white. A pilot study consisting of six hands from three fresh cadaver dissections was conducted to familiarize the authors with the local anatomy; these were not included in the present study. RESULTS: The humeral and ulnar heads of PTM were present in 86 limbs. In 72 out of the 86 limbs, the median nerve was positioned between the two heads of the PTM; in 11, it passed through the muscle belly of ulnar head of the PTM, and in three, posteriorly to both heads of the PTM. When both heads were present, the median nerve was not observed as passing through the muscle belly of the humeral head of PTM. In 14 out of the 100 dissected limbs, the ulnar head of the PTM was not observed; in this situation, the median nerve was positioned posteriorly to the humeral head in 11 limbs, and passed through the humeral head in three. In 17 limbs, the ulnar head of PTM was little developed, with a fibrous band originating from the ulnar coronoid process, associated with a distal muscle component near the union with the humeral head. In four limbs, the ulnar head of the MPR was represented by a fibrous band. In both limbs of one cadaver, a fibrous band was observed between the supinator muscle and the humeral head of the PTM, passing over median nerve. CONCLUSION: The results suggest that these anatomical variations in relationship median nerve and PTM are potential factors for median nerve compression, as they narrow the space through which the median nerve passes.

RESUMO OBJETIVO: Analisar as variações anatômicas do músculo pronador redondo (MPR) e suas implicações na compressão do nervo mediano, que passa entre as cabeças umeral e ulnar do MPR. MÉTODO: Foram dissecados 100 membros superiores de cadáveres adultos pertencentes ao laboratório de anatomia; 46 cadáveres eram do sexo masculino e quatro do feminino. A idade variou entre 28 e 77 anos; 27 eram da etnia branca e 23, não branca. Um estudo piloto que incluiu três cadáveres frescos foi feito, para familiarização dos autores com a anatomia regional. Esses não foram incluídos no estudo. RESULTADOS: Em 86 membros, observou-se a presença das cabeças umeral e ulnar do MPR. Em 72 dos 86 membros, o nervo mediano estava posicionado entre as cabeças umeral e ulnar do MPR; em 11, esse encontrava-se através da massa muscular da cabeça ulnar do MPR e em três, o nervo mediano estava posicionado posteriormente às duas cabeças do MPR. Nos casos em que as duas cabeças do músculo estavam presentes, não se observou o nervo mediano passando através da massa muscular da cabeça umeral do MPR. Em 14 dos 100 membros dissecados, a cabeça ulnar do MPR não estava presente. Nessa situação, o nervo mediano posicionava-se posteriormente à cabeça umeral em 11 membros e através da cabeça umeral em três membros. Em 17 membros, a cabeça ulnar estava muito pouco desenvolvida, com conformação fibrosa em sua origem no processo coronoide da ulna, associada a um componente muscular distal, próximo a sua união com a cabeça umeral. Em quatro membros, a cabeça ulnar do MPR estava representada apenas por uma banda fibrosa. Nos dois membros de um cadáver, observou-se uma expansão fibrosa que saía do músculo supinador para a cabeça umeral do MPR, passando como uma cinta sobre o nervo mediano. CONCLUSÕES: Esses resultados sugerem que as variações anatômicas na relação nervo mediano e MPR representam fatores potenciais para compressão nervosa, por estreitar o espaço no qual passa o nervo mediano.

Flexor Pollicis Brevis Muscle. Anatomical Study and Clinical Implications.

INTRODUCTION: This paper reports anatomical study of nature, incidence, innervation and clinical implications of Flexor Pollicis Brevis muscle (FPB). MATERIAL AND METHODS: The anatomical dissection of 60 limbs from 30 cadavers were performed in the Department of Anatomy of Medical School of Catholic University of São Paulo. RESULTS: The superficial head of FPB has been innervated by the median nerve in 70% and in 30% it had double innervation. The deep head of FPB were absent in 14%, in 65%, occurred a double innervation. In 17.5% by deep branch of ulnar nerve and in 3.6% by recurrent branch of median nerve. CONCLUSION: The pattern of innervation more frequent in relationship to the flexor pollicis brevis muscle and should be considered as a normal pattern is that superficial head receives innervation of branches of median nerve and the deep head receives innervation of ulnar and median nerve.