The lacrimal sac or lachrymal sac is the upper dilated end of the

nasolacrimal duct The nasolacrimal duct (also called the tear duct) carries tears from the lacrimal sac of the eye into the nasal cavity. The duct begins in the eye socket between the maxillary and lacrimal bones, from where it passes downwards and backwards. ...

, and is lodged in a deep groove formed by the lacrimal bone and frontal process of the maxilla. It connects the lacrimal canaliculi, which drain tears from the eye's surface, and the

, which conveys this fluid into the nasal cavity. Lacrimal sac occlusion leads to dacryocystitis.

Structure

It is oval in form and measures from 12 to 15 mm. in length; its upper end is closed and rounded; its lower is continued into the nasolacrimal duct. Its superficial surface is covered by a fibrous expansion derived from the medial palpebral ligament, and its deep surface is crossed by the lacrimal part of the orbicularis oculi, which is attached to the crest on the lacrimal bone.

Histology

Like the nasolacrimal duct, the sac is lined by stratified columnar epithelium with mucus-secreting goblet cells, with surrounding connective tissue. The lacrimal sac also drains the eye of debris and microbes.

Function

It serves as a reservoir for overflow of tears, in which the lacrimal sac pumps inward and outward driven by the orbicularis muscle during blinking.

Imaging

The lacrimal sac can be imaged by ''dacrocystography'', in which radiocontrast is injected, followed by X-ray imaging.

Additional images

File:Gray192.png, Medial wall of left orbit. File:Gray379.png, Left orbicularis oculi, seen from behind. File:Gray896.png, The

lacrimal apparatus The lacrimal apparatus is the physiological system containing the Orbit (anatomy), orbital structures for tears, tear production and drainage.Cassin, B. and Solomon, S. ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing Co ...

. Right side. (Lacrimal sac visible at upper right.) File:Gray894.png, The tarsi and their ligaments. Right eye; front view. (Lacrimal sac visible at middle right.)

References