Description
The lacrimal apparatus is a system of structures that produces tears (i.e. the lacrimal glands and accessory lacrimal glands) and additionally provides a drainage pathway for the tears, draining the fluid into the nasal cavity (i.e. the lacrimal canaliculi, lacrimal sac, and nasolacrimal duct).
Each tear drop consists of about 7μl of fluid. The tear is distributed over the cornea (1-2μl) and along the upper and lower margins of the eyelids. Some of the tear fluid is lost to evaporation or absorption into the conjunctiva, however, the majority is drained via the nasolacrimal drainage system. Tears collect at the medial angle of the eye (medial canthus) and two puncta in the region drain it into the superior and inferior lacrimal canaliculi. The canaliculi transport the tears to the lacrimal sac, and then onto the nasolacrimal duct which directs the tears to the inferior meatus of the nasal cavity.
Related parts of the anatomy
