Adnexa · 21 of 24
What is the lacrimal gland?
The lacrimal gland sits in a shallow fossa in the upper outer corner of the orbit, tucked behind the rim under the outer third of the upper lid. It makes the watery layer of the tear film, the layer that washes, nourishes and smooths the cornea, and it pours it through a dozen ducts into the upper outer fornix, from where blinking spreads it across the eye and the lids sweep it to the nose.
- Position
- The lacrimal fossa of the frontal bone, superotemporal orbit
- Parts
- An orbital lobe above and a palpebral lobe below, split by the levator aponeurosis
- Nerve
- Parasympathetic secretomotor fibres from the facial nerve, via the pterygopalatine ganglion
- Makes
- The aqueous layer of the tear film, and reflex tears
The tear film
The tear film is three layers on the cornea. A mucin layer from the conjunctival goblet cells wets the surface; the aqueous layer from the lacrimal gland and the small accessory glands in the fornices gives the volume; and an oil layer from the meibomian glands in the lids floats on top and slows evaporation. Dry eye is a failure of any of them, and most dry eye is not too little water but too little oil: meibomian gland dysfunction, with tears that evaporate between blinks.
The lacrimal gland is also responsible for reflex tearing, the flood of tears from a corneal foreign body, a bright light or emotion. A watery eye is more often a drainage problem than an over-production problem.
What goes wrong
Dacryoadenitis is an inflamed gland: a tender swelling of the outer upper lid that gives it an S-shaped curve, viral in the young, and in adults sometimes the first sign of sarcoidosis, Sjögren syndrome or IgG4 disease. Sjögren syndrome dries the gland out along with the mouth. The gland is a site of lymphoma and of the rare pleomorphic adenoma, a slowly growing painless mass that pushes the eye down and in. A gland that is prolapsed, visible under the lateral upper lid when it is lifted, is a normal variant.
Examine it
Dry eye, dacryoadenitis and lymphoma involve it; it sits under the temporal upper lid.
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