Lacrimal Gland

• It is a serous gland.
• Situated chiefly in the lacrimal fossa on the anterolateral part of the roof of the bony orbit.
• It is J-shaped.
• It is indented by the tendon of levator palpebrae superioris.

Parts

Lacrimal Ducts

• About 12 ducts pierce the conjunctiva of the upper lid.
• They open into the conjunctival sac near the superior fornix.
• Most ducts of the orbital part pass through the palpebral part.

Accessory Lacrimal Glands

• Small accessory lacrimal glands are found in the conjunctival fornices.
• They are also called Krause’s glands.
• After removal of the palpebral part of the lacrimal gland, the conjunctiva and cornea are moistened by accessory lacrimal glands, if present.

Nerve and Arterial Supply

Lacrimal gland is supplied by:

• Lacrimal branch of ophthalmic artery.
• Lacrimal nerve.

Lacrimal Nerve

• Sensory fibres.
• Secretomotor fibres.

Nerve Supply of Lacrimal Gland

Functions of Lacrimal Gland

• Lacrimal glands secrete about 1 ml of lacrimal fluid per day.
• Most of it evaporates.
• The rest is drained into the lacrimal sac.

Functions of Lacrimal Fluid

1. Keeps the cornea moist, which is essential for its transparency.
2. Nourishes the cornea.
3. Flushes the conjunctival sac.
4. Prevents infection by the action of its lysozymes.
5. Provides a medium for expression with shedding of tears during:
   • Grief.
   • Sorrow.
   • Extreme emotional happiness.

Conjunctival Sac

• Conjunctiva lining the deep surfaces of the eyelids is called palpebral conjunctiva.
• Conjunctiva lining the front of the eyeball is called bulbar conjunctiva.
• The potential space between palpebral and bulbar parts is the conjunctival sac.
• The lines along which the palpebral conjunctiva of the upper and lower eyelids is reflected onto the eyeball are called:
  • Superior conjunctival fornix.
  • Inferior conjunctival fornix.

Lacrimal Puncta

• Lacrimal puncta are small openings on the lid margin.
• They are situated at the tip of the lacrimal papillae.
• Lacrimal papilla is a small conical projection at the medial end of the free margin of the eyelids.

Lacrimal Canaliculi

• There is one canaliculus in each eyelid.
• Each is about 10 mm long.
• Each canaliculus begins at the lacrimal punctum.
• It has two parts:

• There is an ampulla (dilated part) in each canaliculus.
• Canaliculi open into the lacrimal sac.

Lacrimal Sac

• It is a membranous sac.
• About 12 mm long and 5 mm wide.
• Lies in the lacrimal groove behind the medial palpebral ligament.
• Its upper end is blind.
• Its lower end is continuous with the nasolacrimal duct.

Relations of Lacrimal Sac

Nasolacrimal Duct

• It is a membranous passage.
• About 18 mm long.
• Begins at the lower end of the lacrimal sac.
• Runs:

• Downwards.
• Backwards.
• Laterally.

• Opens into the inferior meatus of the nose.
• A fold of mucous membrane called the valve of Hasner forms an imperfect valve at the lower end of the duct.

Factors Helping Drainage of Tears

1. Capillary action of lacrimal canaliculi.
2. Blinking of eyelids, which spreads the tears in the conjunctival sac.
3. Drying of tears.
4. Inward direction of puncta during blinking.
5. Contraction of the lacrimal part of orbicularis oculi pulls the lacrimal fascia and dilates the lacrimal sac.

Lacrimal Gland

The source describes the gland as J-shaped.

Lacrimal Canaliculi

• Each canaliculus is about 10 mm long.
• Vertical part → 2 mm long.
• Horizontal part → 8 mm long.

Lacrimal Sac

About 12 mm long and 5 mm wide.

Nasolacrimal Duct

About 18 mm long.

Lacrimal Fluid

Lacrimal glands secrete about 1 ml of lacrimal fluid per day.

Lacrimal Gland

• Situated chiefly in the lacrimal fossa on the anterolateral part of the roof of the bony orbit.
• Indented by the tendon of levator palpebrae superioris.

Lacrimal Sac

Anteriorly:

• Medial palpebral ligament.
• Orbicularis oculi.

Medially:

• Lacrimal groove separates it from the nose.

Laterally:

• Lacrimal fascia.
• Lacrimal part of orbicularis oculi.

Nasolacrimal Duct

• Begins at the lower end of the lacrimal sac.
• Runs downwards, backwards and laterally.
• Opens into the inferior meatus of the nose.