Multiple bilateral anatomical variations of the tendons of the forearm and wrist: a case report based on a cadaver study

Introduction Anatomical variations of muscle and tendons are commonly encountered. These variations may consist of absence of a muscle, supernumerary muscles, deviations from the normal course, or an unusual origin or insertion. Accessory muscles or muscle slips and tendons are anatomical variations representing additional distinct muscles that are encountered along with the normal complement of muscles. Accessory muscles are typically asymptomatic and encountered as incidental findings although they have been implicated as a potential source of clinical symptoms [1]. Historically, the majority of data regarding accessory musculature has been based on serendipitous findings during surgical interventions and anatomical dissections. However, with the upcoming modern cross-section imaging techniques such as ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) anatomical variations are more regularly encountered and can be identified noninvasively [1]. Anatomical variations in the tendons of the wrist have been described for more than a century [2]. Reports of more than one variation in the forearm of one specimen are however quite rare. During routine human cadaver dissection at the Department of Anatomy, Embryology and Physiology of the University of Amsterdam, we found not just a single, but a multiplicity of anatomical variations. In this article we describe these three muscles and tendon variations found on this one cadaver forearm and we will discuss their clinical and educational relevance.