Anatomical variations in the digastric muscle.

The aim of this study was to investigate anatomical variations in the digastric muscle. Anatomical dissections of the head and neck region were performed in 15 cadavers at the Anatomy Department during a gross anatomy course. Three cadaver heads revealed anatomical variations in the anterior belly of the digastric muscle. The positional relationships among the accessory muscle bundles, the anterior belly of the digastric muscle, and the mylohyoid muscle were examined. Innervating branches from the mylohyoid nerve were also investigated. The remaining 12 cadaver heads without accessory muscle bundles were used for comparison. Of the three heads with accessory muscle bundles, one head (male) had two muscle bundles of the unilateral type, one head (male) had symmetrical muscle bundles of the crossover type, and one head (female) had a mix of unilateral and crossover types. The likely explanation for these and various other anomalies reported in the literature is the complex morphogenesis of the first branchial arch. Therefore, clinicians should be aware of these anatomical variations of the submental region when performing surgical procedures involving the head and neck and when using computed tomography and magnetic resonance imaging for interpretation or differential diagnosis of neck masses.