anal sinuses anal sinuses the anal sinuses (rectal sinuses) are furrows in the anal canal, that separate the anal columns from one another. the anal sinuses end below in small valve-like folds, termed anal valves. anal sinusescoronal section of rectum and anal canalthe interior of the anal canal and lower part of the rectum, showing the anal columns and the anal valves between their lower ends (the columns were more numerous in the specimen than usual)detailsidentifierslatinsinus analesta98a05.7.05.006ta23013fma76584anatomical terminology