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. 2017 Dec 6;53(1):75-81.
doi: 10.1016/j.rboe.2017.11.014. eCollection 2018 Jan-Feb.

Bicipital aponeurosis. Anatomical study and clinical implications

Edie Benedito Caetano  1 , Luiz Angelo Vieira  1 , Tyago Araújo Almeida  1 , Luis Andres Montero Gonzales  1 , José Eduardo de Bona  1 , Thais Mayor Simonatto  1
Affiliations

Bicipital aponeurosis. Anatomical study and clinical implications

Edie Benedito Caetano et al. Rev Bras Ortop. .

Abstract
in English, Portuguese

Objective: The aim of this study was to analyze the anatomic variations of the bicipital aponeurosis (BA) (lacertus fibrosus) and its implications for the compression of the median nerve, which is positioned medially to the brachial artery, passing under the bicipital aponeurosis.

Methods: Sixty upper limbs of 30 cadavers were dissected, 26 of which were male and four, female; of the total, 15 had been previously preserved in formalin and glycerine and 15 were dissected fresh in the Laboratory of Anatomy.

Results: In 55 limbs, short and long heads of the biceps muscle contributed to the formation of the BA, and the most significant contribution was always from the short head. In three limbs, only the short head contributed to the formation of the BA. In two limbs, the BA was absent. The length of the bicipital aponeurosis from its origin to its insertion ranged from 4.5 to 6.2 cm and its width, from 0.5 to 2.6 cm. In 42 limbs, the BA was thickened; of these, in 27 it was resting directly on the median nerve, and in 17 a high insertion of the humeral head of the pronator teres muscle was found, and the muscle was interposed between the BA and the median nerve.

Conclusion: These results suggest that a thickened BA may be a potential factor for nerve compression, by narrowing the space through which the median nerve passes.

Objetivo: Analisar as variações anatômicas da aponeurose bicipital (lacertus fibrosus) e suas implicações na compressão do nervo mediano, que passa sob a aponeurose bicipital (AB) e se posiciona medialmente à artéria braquial.

Método: Foram dissecados 60 membros superiores de 30 cadáveres adultos, 26 do sexo masculino e quatro do feminino; 15 haviam sido previamente preservados em formol e glicerina e 15 foram dissecados a fresco no Laboratório de Anatomia.

Resultados: Em 55 membros, a AB recebia contribuição das cabeças curta e longa do musculo bíceps braquial, a contribuição mais significativa foi sempre da cabeça curta. Em três membros recebia contribuição exclusiva da cabeça curta. Em dois membros, a AB estava ausente. O comprimento da AB desde sua origem até sua inserção variou entre 4,5 e 6,2 cm e sua largura entre 0,5 e 2,6 cm. Em 42 membros, a AB apresentava-se espessada, em 27 apoiava-se diretamente sobre o nervo mediano e em 17 havia inserção alta da cabeça umeral do músculo pronador redondo, de forma que o músculo ficava interposto entre a AB e o nervo mediano.

Conclusão: Esses resultados sugerem que a AB espessada pode ser um dos fatores potenciais da compressão nervosa, por estreitar o espaço no qual passa o nervo mediano.

Keywords: Cadaver; Musculoskeletal abnormalities; Nerve compression syndrome.

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Figures

Fig. 1
Fig. 1
(A) In 55 limbs, the BA (a) received contribution from the short (b) and long (c) heads; the most significant contribution was always from the short head. Median nerve (d). (B) In three limbs, one bilateral, it was observed that the short (b) and long (c) heads were completely separated; the short head continued with the BA (a) and the long head, with the bicipital tendon (d).
Fig. 2
Fig. 2
(A) In most cases the BA (a) had a rectangular anatomical conformation. Short head (b), long head (c), median nerve (d). (B) At other times, the BA had a trapezoidal conformation (a). The median nerve (b) is positioned medially to the brachial artery (c) and the biceps brachii muscle (d).
Fig. 3
Fig. 3
In 44 limbs, the BA (a) was thickened; in 27, it was resting directly on the median nerve (b).
Fig. 4
Fig. 4
In 17 limbs, there was a high insertion of the humeral head of the pronator teres muscle (c) so that the muscle was interposed between the BA (a) and the median nerve (b).
Fig. 5
Fig. 5
(A) In one limb with hypertrophied musculature, the thick BA (a) caused an indentation on the median nerve (b). (B) In 14 limbs, the BA (a) was very narrow and of little thickness.
Fig. 6
Fig. 6
In two limbs, the AB was not present. (A) AB was replaced by a fibromuscular component (b) that originated in the biceps brachii (a) and extended distally to be inserted into the flexor digitorum superficialis (c). (B) The AB (a) originated in the brachialis muscle (b). Biceps (c). Median nerve (d).
Fig. 7
Fig. 7
In five limbs, the presence of an accessory head (a) of the biceps brachii muscle (b) was observed. (A) Short head (b). Long head (c). (B) Accessory head (a) Long head (b).
Fig. 8
Fig. 8
In three limbs, the presence of accessory aponeurosis (a) of the brachial muscle (b) located close to the BA (c) was identified. Biceps brachii (d).
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