Unilateral duplication of the anterior digastric muscle belly: a case report with implications for surgeries of the submental region.

Anterior belly of the digastric muscle (ABDM) variations have been reported to occur in as few as 2.7% to as many as 69.6% of individuals. Therefore, it is important to understand the anatomical diversity of ABDM variants, particularly with regard to head and neck surgery. The report documents a unilateral duplication of the ABDM with an oblique belly which crosses the midline. Measurements of muscle length, width, orientation and inferior surface area are documented. ABDM variants may cause confusion during surgeries, including submental lipectomy, rhytidectomy, surgical alteration of the cervicomental angle via partial resection of the ABDM, muscle transfer for reanimation of the mouth and submental artery flap procedures. Therefore, knowledge of this particular variant may aid in surgical planning as well as prevent confusion and disorientation during operations in the submental region.