Lacrimal apparatus

The Lacrimal apparatus is the physiological system containing the orbital structures for tear production and drainage. It consists of the Lacrimal gland, which secretes the tears, and its excretory ducts, which convey the fluid to the surface of the human eye; the Lacrimal canaliculi, the Lacrimal sac, and the Nasolacrimal duct, by which the fluid is conveyed into the cavity of the nose; and the innervation to these structures.

Structure

The lacrimal apparatus is made up of a secretory system, which produces tears, and an excretory system, which drains the tears. The main components of the secretory system are the Lacrimal gland and accessory lacrimal glands, and the excretory system includes the Lacrimal canaliculi, Lacrimal sac, and the Nasolacrimal duct.

Secretory system

The Lacrimal gland is primarily responsible for producing emotional or reflexive tears. As tears are produced, some fluid evaporates between blinks, and some is drained through the lacrimal punctum. The rest of the tears flow over the eye and down the cheeks.

Excretory system

The excretory system starts at the Lacrimal punctum, located on the upper and lower eyelids. These tiny openings suck in tears through capillary action and drain into the Lacrimal canaliculi, then into the Lacrimal sac, and finally down the Nasolacrimal duct and into the nose.

Function

The lacrimal apparatus produces, distributes, and removes tears, a fluid which is essential for the anterior surface of the eye. Tears provide the cornea and conjunctiva with necessary hydration and nutrients, wash away foreign bodies, and also contain enzymes that help to fight bacterial infection.

Clinical significance

Dysfunction of the lacrimal apparatus can lead to dryness of the eyes, excessive tearing, or infection of the lacrimal sac (Dacryocystitis). Treatment can involve artificial tears, medication, or surgery, depending on the specific condition and its severity.

See also

• Dry eye syndrome
• Dacryocystitis
• Epiphora
• Keratoconjunctivitis sicca

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  Gray's Anatomy illustration of the lacrimal apparatus