Cross-over type of supernumerary digastric muscle

A cross-over type asymmetric anomaly of the anterior belly of the right digastric muscle was observed during a cadaveric dissection of the submental region. Three irregularly-shaped supernumerary muscle bundles were found between the anterior bellies of the digastric muscles. Although the anomalies of the digastric muscles are often observed, this complicated pattern has not been previously reported. Our findings and previous reports illustrate the morphogenetic complexity of the anterior belly of the digastric muscle, and their potential importance in confounding clinical evaluation or complicating surgical procedures in the submental region.