Lacrimal canaliculi

The lacrimal canaliculi (also lacrimal ducts, singular: lacrimal canaliculus, Latin: canaliculus lacrimalis) are small channels between the puncta lacrimalia and the lacrimal sac that participate in the tear-drainage system of the lacrimal apparatus.

Structure of the lacrimal canaliculi

Each lacrimal canaliculus opens with punctum lacrimalis, an opening on the margin of each lower eyelid in the medial corner of the eye, where the drainage of tears begins. There are two lacrimal canaliculi - superior and inferior. Both drain into the lacrimal sac.

The superior lacrimal canaliculus ascends at first, bends at an acute angle, then passes medially and downward to the lacrimal sac.

The inferior lacrimal canaliculus is larger and longer than the superior duct, it descends at first, then passes almost horizontally to reach the lacrimal sac.

Each duct has a slight enlargement at its bend - the ampulla of the lacrimal canaliculus. The lacrimal canaliculi can be up to 1 cm long.

Both lacrimal canaliculi are positioned behind the medial palpebral ligament and are surrounded by the lacrimal part fibers of the orbicularis oculi muscle.