Anatomical Variations of the Anterior Belly of the Digastric Muscle

Abstract

A routine dissection of the digastric muscle reflected that it originated by two muscle bellies namely. the anterior and posterior belly which are connected by an intermediate tendon (IT). These bellies originated from the mastoid process of the temporal bone and the digastric fossa of the mandible respectively. The digastric muscle serves as an important surgical landmark in surgical interventions involving the submental area however, accessory bellies may interfere with surgical intervention in this area. Therefore, this study aimed to document the occurrence of the anatomical variations in the anterior belly of the digastric muscle (ABDM) in a selected number of cadaveric samples. Ten bilateral adult cadaveric head and neck specimens (n = 20) were macro-dissected in order to document the morphology of the digastric muscle. The accessory bellies in the ABDM was observed in 60 % of the specimens. Unilateral and bilateral variations were observed in 20 % and 30 % of the specimens, respectively. These accessory bellies originated in the digastric fossa, ABDM, IT and hyoid bone, and inserted into the mylohyoid raphe, mylohyoid muscle and hyoid bone. In addition, an anomalous main ABDM was observed in 10 % of the specimens inserting through a transverse tendon into the hyoid bone. Variations in the digastric muscle are common especially the accessory bellies, therefore, a comprehensive understanding of these anatomical variations could be of clinical importance to the surgeons during head and neck radiological diagnosis and surgical interventions.