The lacrimal apparatus is a system responsible for the production and drainage of tears. It includes the lacrimal glands, which produce tears, and the lacrimal ducts, which transport them to the surface of the eye. Tears help to keep the eye moist, provide nutrients, and protect against infections. When tears are produced, they spread across the eye's surface and eventually drain into the puncta, small openings located in the inner corners of the eyelids. From there, tears travel through the lacrimal canals into the nasolacrimal duct, which leads to the nasal cavity, explaining why crying can cause a runny nose.