A tear duct, also known as a lacrimal duct, is a small tube that carries tears from the eye to the nasal cavity. Tears are produced by the lacrimal glands and help keep the eyes moist, wash away debris, and provide protection against infections. When we blink, tears spread across the surface of the eye and eventually drain through the tear ducts. The tear ducts begin at the inner corners of the eyelids and lead to the nasolacrimal sac, which then connects to the nasal cavity. This connection is why our noses can run when we cry, as excess tears drain into the nose.