Lacrimal gland

At a glance

English

Lacrimal gland

Latin (TA2)

Glandula lacrimalis

System

Eye

Region

Head

Side

Paired, left and right

About the lacrimal gland

The lacrimal gland sits in the lacrimal fossa, a shallow hollow on the underside of the orbital part of the frontal bone, just inside the upper lateral rim of the orbit. It is about the size and shape of an almond. The tendon of levator palpebrae superioris sweeps through it from front to back and divides it into two parts: a larger orbital lobe above, tucked against the bone, and a smaller palpebral lobe below, which lies in the outer part of the upper eyelid and can be seen through the conjunctiva when the lid is turned out.

Tears leave the gland through about a dozen fine excretory ducts. Those from the orbital lobe pass through the palpebral lobe, joining its own ducts, and all open into the superior conjunctival fornix at the upper outer part of the eye. Blinking spreads the fluid across the cornea and conjunctiva towards the medial angle, where it enters the puncta and drains through the canaliculi, lacrimal sac and nasolacrimal duct into the nose. Because the palpebral ducts pass through the lower lobe, removing that lobe can cut off drainage from the whole gland.

Microscopically it is a compound tubuloacinar gland. Lobules divided by connective tissue contain grape-like acini of serous cells, wrapped in contractile myoepithelial cells, which release a watery secretion containing salts, lysozyme, lactoferrin and antibodies. This keeps the corneal surface smooth for clear vision and protects it against infection.

Secretion is driven mainly by parasympathetic fibres. They start in the facial nerve, travel in the greater petrosal nerve and the pterygoid (Vidian) nerve to the pterygopalatine ganglion, and then reach the gland through the zygomatic and lacrimal nerves. A facial nerve lesion above this branch may therefore leave the eye dry. Reduced tear output with age, drugs or autoimmune disease such as Sjögren syndrome causes dry eye, assessed with a Schirmer paper strip, and inflammation of the gland is dacryoadenitis.

Function and supply

Function

Secretes the aqueous part of the tear film, which moistens, cleans, nourishes and protects the cornea and conjunctiva.

Nerve supply

Secretomotor parasympathetic fibres from the facial nerve via the pterygopalatine ganglion, zygomatic and lacrimal nerves; sympathetic fibres from the superior cervical ganglion; sensory fibres in the lacrimal nerve of the ophthalmic division.

Blood supply

The lacrimal artery from the ophthalmic artery; venous drainage to the superior ophthalmic vein.