Unusual anatomical variants of infrahyoid muscles - a case report

Anatomical anomalies of neck muscles are rarely observed, and usually comprise variations of digastric and omohyoid muscles. Neck muscle abnormalities are sometimes correlated with embryological development and are observed in individuals with aneuploidies such as Edwards' syndrome (18-trisomy) or Down's syndrome (21-trisomy). Some infrahyoid muscles are important landmarks during surgery, and therefore the anatomical variations of these muscles are related to a higher risk of surgical complications. Below, we present a rare case of infrahyoid muscle anomalies found during routine dissection of a male cadaver. Redundant muscle bellies of sternohyoid muscle (sternohyoid azygos muscle), the presence of levator glandulae thyroideae and also one hypoplastic superior belly of the omohyoid muscle were observed. The presence of muscle fibres within the found structures was confirmed using Masson's trichrome staining method.