Lacrimal gland

The lacrimal gland is a serous tubuloacinar exocrine gland responsible for the production of tears.

Location

• The lacrimal gland is located in the lacrimal fossa of the frontal bone in the superolateral part of the orbit. It is divided by the aponeurosis of the levator palpebrae superioris into a larger orbital and a smaller palpebral part.

Functions

• About 8 to 12 excretory ducts drain the tears from the lacrimal gland into the superior lateral part of the superior conjunctival fornix. The tears lubricate the cornea and conjunctiva, provide nutrients and oxygen to the cornea, contain antibacterial substances such as lysozyme, and wash away debris.

Blood Supply

• Lacrimal artery (branch of the ophthalmic artery)

Venous Drainage

• Drains into the superior ophthalmic vein

Nerve Supply

1. Sensory

• Lacrimal nerve (branch of ophthalmic division of trigeminal nerve, CN V1)

2. Secretomotor (Parasympathetic)

• Parasympathetic innervation arises from the facial nerve (CN VII) via the greater petrosal nerve. The latter joins with the deep petrosal nerve to form the nerve of pterygoid canal. The parasympathetic neurons travel via the following nerves to reach the lacrimal nerve and eventually innervate the lacrimal gland:

• Pathway: Greater petrosal nerve → nerve of pterygoid canal → pterygopalatine ganglion (synapse) → zygomatic nerve (V2) → communicating branch to lacrimal nerve (V1) → lacrimal gland

3. Sympathetic

• Fibres from the superior cervical ganglion via the deep petrosal nerve

Clinical correlates

• Sjögren Syndrome: Autoimmune destruction of lacrimal and salivary glands leading to severe dry eyes and dry mouth.

• Facial Nerve Lesions: May reduce parasympathetic stimulation and impair tear secretion.