The Lacrimal System

The eyes are moisturized by a constant flow of tears produced by the lacrimal gland, which lies above each eye under the upper eyelid. These tears lubricate the cornea of the eye, preventing injury and ulceration. The tears are collected by the superior and inferior puncta, two small holes in the upper and lower eyelid. The canaliculi, or small canals, direct the tears to the lacrimal sac. The lacrimal sac lies just medial to the eye within the nasal cavity. The tears then flow within the nasolacrimal duct which is a thin tube that empties out underneath the inferior turbinate via Hasner’s valve.