mylohyoid insertion at the mid-belly of a combined geniohyoid via a fibrous pseudo-hyoid: an observation with implications for submental flap surgery

The mylohyoid is a triangular, sheet-like muscle that typically attaches at the mylohyoid line of the mandible, the body of the hyoid, and a median raphe, which stretches from the mandibular symphysis anteriorly to the hyoid bone posteriorly. Few cases have ever documented anatomical variation of the mylohyoid outside of the common mylohyoid boutonnière. Dissection of the suprahyoid musculature of an 88-year-old Caucasian male revealed mylohyoid musculature that did not insert at the hyoid, but rather inserted firmly at the mid-belly of the geniohyoid musculature at a tough fibrous ‘pseudo-hyoid.’ This case report is the first to ever document a mylohyoid inserting firmly to the geniohyoid musculature midway between the chin and hyoid. The case described herein lends support to the exclusion of musculature from the submental artery flap. Inclusion of a mylohyoid, as described in this report, in the submental artery flap may lead to surgical confusion and unintentional damage to the mylohyoid and geniohyoid musculature as well as surrounding structures.