Structure
The lacrimal sac forms the closed upper end of the nasolacrimal duct. The common lacrimal canaliculus, which drain tears from the medial angle of the eye, opens into the upper end of the lacrimal sac on its lateral side.
Related parts of the anatomy
Key Features & Anatomical Relations
The lacrimal sac is located within a fossa of the lacrimal bone, a bone forming the anterior part of the medial wall of the orbit.
Function
The lacrimal sac aids in draining tears from the medial angle of the eye. 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 (Standring, 2016). 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.
References
Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series: Elsevier Limited.
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Lacrimal Sac
Congenital dacryocystocele is a rare anomaly accompanied by swelling of the lacrimal sac that is present at birth and resulting from obstruction of the lacrimal system either above or below the lacrimal sac.
