[Neurovascular infrahyoid myofascial flap. Anatomic-topographic study of innervation and vascular supply].

Fifteen cadavers were examined bilaterally for the topography of the superior thyroid artery and vein an lower cervical ansa as an axial bundle of vessels and nerves for the infrahyoid myofascial flap. Using injections of methylene blue, the vascular territories of the superior thyroid artery were demonstrated. The superior thyroid artery and vein could be found in all cases. This artery was derived in 47% of cases from the external carotid artery, in 30% from the bifurcation and in 23% from the common carotid artery. In 43% of cases the vein flowed to the facial vein and in 37% to the internal jugular vein. In the remaining 20%, several segmental veins were found that flowed separately to the jugular vein. In case of a far caudally situated vascular bundle the radius of rotation was limited in a cranial direction. The voluntary innervation of the muscles of the infrahyoid myofascial flap was derived from the lower cervical ansa. The upper radix of the ansa was found 1 cm in latero-cranial direction to the greater horn of the hyoid bone, where it separated from the hypoglossal nerve. Present findings show that the superior thyroid artery supplies the infrahyoid musculature in its whole extension from the hyoid bone to the sternum. It is therefore possible to develop a myofascial flap of 3.5 cm x 11.5 cm in size, which can be predicted at an upper vascular and neural bundle. Depending on the radius of rotation, defects of the floor of mouth, tongue and oro- and hypopharynx can be covered sufficiently with this neurovascular myofascial flap.