[TA] (1) the grooves between the anal columns; SYN: Morgagni sinus (1). (2) pockets or crypts in the columnar zone of the anal canal between the anocutaneous line and the anorectal line; the sinuses give the mucosa a scalloped appearance. SYN: sinus anales [TA], anal crypts, Morgagni crypts, rectal sinuses.
