Dual innervations of mylohyoid muscle: a case report

Mylohyoid and anterior belly of the digastric muscles are supplied by a branch from the inferior alveolar nerve called the mylohyoid branch. Here we present an unusual finding in a 60-year-old male cadaver in which the mylohyoid muscle is supplied by a branch from hypoglossal nerve in addition to its usual nerve supply. Hypoglossal nerve after giving superior root of the ansa cervicalis and muscular branches to thyrohyoid and geniohyoid muscles gave another branch to supply the mylohyoid muscle. Any variation in the formation and/or branching pattern of ansa cervicalis or hypoglossal nerve can cause confusion and may complicate the procedures involving this nerve such as skull base surgery, neck dissection, and anterior cervical spinal approach. Developmentally mylohyoid muscle is from the mesoderm of the first arch, therefore, must be innervated by the mandibular nerve. Hence, we report this uncommon variation based on embryology and the clinical implications.