What is the lacrimal apparatus and what does it do?

The lacrimal apparatus is a group of structures that produce and drain tears. It includes the lacrimal gland, ducts, conjunctival sac, puncta, canaliculi, sac, and nasolacrimal duct. Its main functions are to moisten the eye, flush debris, and provide antibacterial protection.

What are the parts of the lacrimal gland?

The lacrimal gland has two main parts: the orbital part, which is almond-shaped and located in the lacrimal fossa of the orbit, and the palpebral part, which is smaller and in the upper eyelid beneath the levator palpebrae superioris muscle. Together, they secrete tears through about 12 ducts into the conjunctival sac.

How do tears drain from the eye?

Tears drain through a pathway starting at the lacrimal puncta on the eyelids, then into the lacrimal canaliculi, which lead to the lacrimal sac. From there, they flow down the nasolacrimal duct into the inferior nasal meatus. Factors like blinking and muscle contractions help move tears along this route.

What nerves supply the lacrimal gland?

The lacrimal gland receives nerve supply from three sources: parasympathetic nerves stimulate tear secretion via the pterygopalatine ganglion, sympathetic nerves control blood vessel constriction, and sensory nerves provide sensation through the lacrimal nerve from the trigeminal nerve.

What is epiphora and what causes it?

Epiphora is an overflow of tears, often due to hypersecretion from emotions or spicy food, obstruction in drainage pathways like the puncta or nasolacrimal duct, or ectropion where the eyelid turns outward from aging or facial palsy.

Why doesn't removal of the lacrimal gland cause dry eye?

Removing the lacrimal gland does not cause dry eye because accessory lacrimal glands (Krause) continue to secrete tears. These small glands are located under the palpebral conjunctiva and provide enough moisture to prevent dryness.

How does Bell's palsy affect tear production?

In Bell's palsy, facial nerve paralysis reduces lacrimal secretion, leading to dry eye. This occurs because the parasympathetic nerve supply to the lacrimal gland is disrupted. Patients often require artificial tears to maintain eye moisture.

Lacrimal Apparatus – Tear Production & Drainage

❓ Frequently Asked Questions