Anatomical Study of the Digastric Muscle: Variations in the Anterior Belly

The digastric muscle is formed by two muscle bellies: one anterior and one posterior, joined by an intermediate tendon. It is localized in the anterior cervical region. The anterior belly divides the region between the hyoid bone and the mandible into two: laterally the submandibular triangle, and medially the submental triangle. The anatomical variations described in the literature relate to the anterior belly and consist of differences in shape and muscle attachment. This cross-sectional cohort study had the objective of describing anatomical variations in the anterior belly of the digastric muscle. The neck regions of 10 cadavers of male adults were dissected in the Department of Morphology, between June 2004 and June 2006. The digastric muscles that presented anatomical variations were photographed using a Sony Cyber-shot DSC-T1 camera, with a Carl Zeiss Vario-Tessar lens and their bellies were measured using a universal pachymeter. Anatomical variations in the anterior bellies of the digastric muscle were observed in four individuals. Cases 1 and 4 presented a unilateral right variation, with an anomalous anterior belly. Cases 2 and 3 presented bilateral variation, with the presence of two supernumerary bellies. The anatomical variations observed on this study related only to the anterior belly, as previously described by other authors. It is important to consider the occurrence of these variations in the digastric muscle when differentiating between cervical masses and during surgical procedures on the anterior region of the neck