Cross-over type of supernumerary digastric muscle.

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