The (Neuro)anatomy of the Lacrimal System and the Biological Aspects of crying

All terrestrial animals, amphibians, reptiles, birds and mammals produce tears to keep the surface of their eyes in wet condition. The formation of the lacrimal apparatus was one of the changes that took place during the evolution of fishes into amphibians, which were the first vertebrates living outside the water. Fishes, whose eyes are bathed by the fluid medium in which they live, do not possess a lacrimal apparatus. In antique science it was believed that tears came from the heart (Egyptians, about 1500 B.C.), the brain (Hippocrates, 5^th, 4^th centuries B.C.), or glands at the puncta lacrimalis (Galen, 2nd century A.D.). However, after Stensen (1662/1992) described the tear ducts and the main lacrimal gland in 1662 it was accepted that tears originated there.