[TA] the longitudinal groove in the midline of the anterior aspect of the medulla oblongata; it is the medullary equivalent of the anterior median fissure of the spinal cord and ends at the foramen cecum posterius; its caudal part is obliterated by the decussation of the pyramids. SYN: fissura mediana anterior medullae oblongatae [TA], anteromedian groove (1).