Clarification of the Distribution Pattern of the Twig(s) of Radial Nerve Innervating Brachial Muscle in Human

Research Article

Austin J Musculoskelet Disord. 2015;2(1): 1014.

Clarification of the Distribution Pattern of the Twig(s) of Radial Nerve Innervating Brachial Muscle in Human

Jun Yan1*, Kazuki Masu1, Karen Tokunaga2, Yoshie Nagasawa3 and Jiro Hitomi1

1Department of Biokinetics, Exercise and Leisure Sciences, University of Kwa Zulu-Natal, South Africa

2Department of Sport, Rehabilitation and Dental Sciences, Tshwane University of Technology, South Africa

*Corresponding author: Jun Yan, Department of Anatomy, Iwate Medical University, 2-1-1, Nishi-Tokuta, Yahaba-cho, Shiwa-Gun, Iwate, 028-3694, Japan

Received: January 01, 2015; Accepted: February 24, 2015; Published: February 24, 2015

Abstract

To clarify the distributional pattern of the radial nerve branches innervating the lateral lower part of the brachial muscle, 76 Japanese cadavers (152 sides) were examined, and the number and patterns of the branches were recorded and classified. The results showed that (1), the mean lengths from the lateral epicondyle to the point where the radial nerve pierces through the lateral intermuscular septum were 97.4 mm (range, 70-140 mm) and 96.7 mm (range, 65-126 mm) on the left and right sides, respectively (2), the mean lengths between the lateral epicondyle and the points of the first twig branching from the radial nerve were 64.7 mm (range, 25-130 mm) and 68.9 mm (range, 40-120 mm) on the left and right sides, respectively (3) ,the mean lengths of the branches were 16.6 mm (range, 3-37 mm) and 15.4 mm (range, from 3-80 mm) on the left and right sides, respectively, and (4) the distribution pattern on the brachialis muscle could be divided into 4 types. These data will be useful for clinical practice and helpful for medical students to understand double innervation of muscles.

Keywords: Brachial muscle; Musculocutaneous nerve; Radial nerve; Double innervation; Human

Introduction

In general, the brachial muscle is innervated by the musculocutaneous nerve, as the muscle originates from the ventral myogenic region [1,2]. However, it is also consented that a fine branch from the radial nerve innervates the lateral lower part of the muscle [2-7]. In these twigs, motor fibers also exist [8-13], and these fibers have been shown to belong to the ventral component of the brachial plexus, as demonstrated using the fiber analysis method [14]. Recently, the distribution patterns of the twigs innervating the muscle were indicated and divided into three types however, the number of cases in this previous report was very small [10]. We think, however, as a basic date of human anatomy a certain number of the cases is necessary and reality of the twig(s) can be grasped by the observation of significance number of cases. Moreover, the current distribution pattern of the twig(s) was simple, and it is impossible to explain the variety of the twig(s). Therefore it is necessary to clarify the twig(s) of radial nerve innervating brachial muscle. With this in mind, the purpose of the present observation was to clarify the distribution pattern of the twig(s) of the brachial muscle and to compare the results with those of previous studies.

Materials and Methods

Seventy-six Japanese cadavers (152 sides; age: 60-102 years) were used for this investigation. The cadavers were fixed with 15% formalin through the radial artery and were preserved in 50% alcohol for six months. The cadavers were handled in compliance with the ethical guidelines of Iwate Medical University. During the gross anatomy course at the School of Medicine (2013 and 2014 terms) in Iwate Medical University, the superficial tissues in the brachial and elbow joint region were removed, and the radial nerve and lateral cutaneous nerve of the forearm were dissected (Figure 2). The lengths from the lateral epicondyle to the point where the radial nerve pierces through the lateral intermuscular septum, between the lateral epicondyle and the points of the first twig branching from the radial nerve, and of the twig(s) were examined using a digital caliper (SHINWA, JAPAN). The number and branching patterns of the twig(s) were identified by photography (EOS X3, CANON, JAPAN) and were sketched. A surgical microscope (OME, Olympus, Japan) was used for examination of cases in which fine vessels existed on the side of the twig(s).

Results

Lengths of the twig(s)

  1. As shown in Figure 1, the mean lengths from the lateral epicondyle to the point where the radial nerve pierces through the lateral intermuscular septum (OA) were 97.4 mm (range, 70-140 mm) and 96.7 mm (range, 65-126 mm) on the left and rights sides, respectively.
  2. The mean lengths between the lateral epicondyle and the points of the first twig branching from the radial nerve (Figure 1 OB) were 64.7 mm (range, 25-130 mm) and 68.9 mm (range, 40-120 mm) on the left and right sides, respectively.
  3. The mean lengths of the main twig were 16.6 mm (range, 3-40 mm) and 15.4 mm (range, 3-80 mm) on the left and right sides, respectively.

Citation: Yan J, Masu K, Tokunaga K, Nagasawa Y and Hitomi J. Clarification of the Distribution Pattern of the Twig(s) of Radial Nerve Innervating Brachial Muscle in Human. Austin J Musculoskelet Disord. 2015;2(1): 1014. ISSN:2381-8948