Background

The subscapularis muscle originates from the medial two-thirds and from the lower two-thirds of the groove on the subscapular fossa of the scapula and inserts into the lesser tubercle of the humerus. Our initial hypothesis is that it shows little morphological variation. The aim of this study is to demonstrate and classify the morphological variability of the subscapularis muscle.

Methods

Classical anatomical dissection was performed on 64 upper limbs (44 females, 20 males, 30 left and 34 right, fixed in 10% formalin). The mean age “at death” of the cadavers was 75.6 years (range 48–95), and the group comprised equal numbers of female and male adults (Central European population). Upon dissection, the following morphological features were assessed: the number of tendons of the SM, the type of insertion of each tendon of the SM, morphometric measurements of the SM.

Results

Four types of morphology (based on number of tendons) were observed in the cadavers. Type I was characterized by a single band. This was the most common type, occurring in 43.7% of all cases. Type II was characterized by a double tendon (superior and inferior); it occurred in 9.4%. Type III had three tendons (superior, middle, and inferior). It was the rarest type (7.8% of cases). Type IV, called “multiband”, was the second most common (39.1%) and was divided into five subtypes.

Conclusions

The subscapularis muscle is highly morphologically variable. Knowledge of particular types of insertion is essential for both clinicians (for example orthopedists, physiotherapists) and anatomists.

中文翻译：

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肩胛下肌腱：建议的分类系统

背景

肩胛下肌起源于肩胛骨肩胛下窝的内侧三分之二和下三分之二的凹槽，并插入肱骨小结节。我们最初的假设是它的形态变化很小。本研究的目的是展示和分类肩胛下肌的形态变异性。

方法

对 64 条上肢（女性 44 条，男性 20 条，左侧 30 条，右侧 34 条，固定在 10% 福尔马林中）进行了经典解剖解剖。尸体“死亡时”的平均年龄为 75.6 岁（范围 48-95），该组包括同等数量的女性和男性成年人（中欧人口）。解剖后，评估了以下形态特征：SM 的肌腱数量、每个 SM 肌腱的插入类型、SM 的形态测量测量。

结果

在尸体中观察到四种类型的形态（基于肌腱数量）。I 型的特点是单条带。这是最常见的类型，占所有病例的 43.7%。II型的特点是双肌腱（上和下）；它发生在 9.4%。III型有三个肌腱（上、中、下）。这是最罕见的类型（占病例的 7.8%）。IV型，称为“多波段”，是第二常见的（39.1%），分为五个亚型。

结论

肩胛下肌在形态上是高度可变的。了解特定类型的插入对于临床医生（例如骨科医生、物理治疗师）和解剖学家来说都是必不可少的。