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. T ...

, and is lodged in a deep groove formed by the

lacrimal bone The lacrimal bone is a small and fragile bone of the facial skeleton; it is roughly the size of the little fingernail. It is situated at the front part of the medial wall of the orbit. It has two surfaces and four borders. Several bony landmarks of ...

and

frontal process of the maxilla The frontal process of maxilla is a strong plate, which projects upward, medialward, and backward from the maxilla, forming part of the lateral boundary of the nose. Its ''lateral surface'' is smooth, continuous with the anterior surface of the b ...

. 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 The medial palpebral ligament (medial canthal tendon) is a ligament of the face. It attaches to the frontal process of the maxilla, the lacrimal groove, and the tarsus of each eyelid. It has a superficial (anterior) and a deep (posterior) layer ...

, 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 Goblet cells are simple columnar epithelial cells that secrete gel-forming mucins, like mucin 5AC. The goblet cells mainly use the merocrine method of secretion, secreting vesicles into a duct, but may use apocrine methods, budding off their sec ...

, 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 Radiocontrast agents are substances used to enhance the visibility of internal structures in X-ray-based imaging techniques such as computed tomography (contrast CT), projectional radiography, and fluoroscopy. Radiocontrast agents are typically i ...

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. 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