Background

The coracobrachialis muscle, along with the brachialis and biceps brachii muscles, belong to the anterior group of the brachial region. It is characterized by high level of morphological variabilities, with a common variation being the coracobrachialis longus (CBL) muscle. The CBL may be recognized as a distal part of the coracobrachialis muscle, originating from the anteromedial surface of the humerus, however, the two muscles are distinct from each other, and the distal attachment of the CBL is longer and located closer to the elbow joint. The CBL muscle may also be inserted on to various structures. The aim of the present study was to determine the frequency of the CBL muscle among a studied population, and to prepare a classification based on its morphological features.

Material and Methods

Classical anatomical dissection was performed on 100 upper limbs from fifty human cadavers (30 female and 20 male) fixed in 10% formalin solution.

Results

The coracobrachialis muscle was found in all individuals, and the CBL muscle was present in 11%, i.e. 11 upper limbs: four women, and seven men; five left and six right. Significantly, in all cadavers in which the coracobrachialis longus was found, its presence was unilateral (five left and six right). A new classification of the CBL can be proposed based on its insertion: Type I characterized by a distal attachment located on the medial epicondyle (73% of all cases of the CBL) and Type II by an insertion into the olecranon (27% of all cases of the CBL).

Conclusion

The CBL muscle is morphologically variable. More studies focused on the course of this muscle among various populations are needed. Nevertheless, our findings indicate that the CBL muscle could be classified as a distinct muscle.

中文翻译：

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对长喙肱肌新分类的提议：罕见病例还是新的、独特的肌肉？

背景

喙肱肌，连同肱肌和肱二头肌，属于肱区的前群。它的特点是高度的形态变异，常见的变异是喙肱长肌 (CBL)。CBL 可能被认为是喙肱肌的远端部分，起源于肱骨的前内侧表面，然而，这两种肌肉彼此不同，CBL 的远端附着点更长，位置更靠近肘关节. CBL 肌肉也可以插入到各种结构上。本研究的目的是确定研究人群中 CBL 肌肉的频率，并根据其形态特征准备分类。

材料与方法

对固定在 10% 福尔马林溶液中的 50 具人类尸体（30 名女性和 20 名男性）的 100 条上肢进行经典解剖解剖。

结果

所有个体均发现喙肱肌，11%存在CBL肌，即11条上肢：4名女性，7名男性；左五右六。值得注意的是，在所有发现长喙肱肌的尸体中，它的存在都是单侧的（左五只，右六只）。可以根据其插入情况提出 CBL 的新分类：I 型的特征是位于内侧上髁（所有 CBL 病例的 73%）和 II 型，其特征是插入鹰嘴（所有病例的 27%） CBL 的案例）。

结论

CBL 肌肉在形态上是可变的。需要更多关于这种肌肉在不同人群中的运动过程的研究。尽管如此，我们的研究结果表明 CBL 肌肉可以归类为不同的肌肉。