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Lacrimal sac
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The lacrimal sac refers to the closed, dilated upper portion of the nasolacrimal ductwhich drains lacrimal fluid ( tears) into the nasal cavity. It measures approximately 12 mm in length and lies within the lacrimal fossa on the anteromedial wall of the orbit.
More specifically, the lacrimal sac is positioned between the anterior lacrimal crest, which is formed by the frontal process of the maxilla, and the posterior lacrimal crest, which forms part of the lacrimal bone. It is bounded anteriorly by the medial palpebral ligament and posteriorly by the lacrimal portion of the orbicularis oculi muscle.
The lacrimal sac is one of several components of the lacrimal apparatus, which is responsible for the production and drainage of tears. The apparatus includes the lacrimal gland which produces tears, the lacrimal canaliculi that channel tears from the conjunctival sac into the lacrimal sac by capillary action, and the nasolacrimal duct which carries tears from the lacrimal sac into the nasal cavity.
The lacrimal sac has a fibroelastic wall and is lined internally by pseudostratified ciliated epithelium similar to the one found in the nasal cavity.
| Terminology |
English: Lacrimal sac Synonyms: Fold of Hasner, Hasner's valve, valve of Hasner, lachrymal sac Latin: Saccus lacrimalis |
| Definition | Dilated superior part of the nasolacrimal duct |
| Function | Collection and drainage of lacrimal fluid (tears) |
Learn more about the lacrimal sac in the following study unit:
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