The system involved in the production and conduction of tears. It consists of the lacrimal gland and accessory lacrimal glands (glands of Krause and Wolfring); the eyelid margins; and the two puncta lacrimae. Each punctum is a small round or oval aperture situated on a slight elevation at the inner end of the upper and lower lid margin (lacrimal papilla) and forms the entrance to the canaliculi. Each canaliculus consists of a vertical portion of about
The system involved in the production and conduction of tears. It consists of the
lacrimal gland and accessory lacrimal glands (glands of Krause and Wolfring); the
eyelid margins; and the two
puncta lacrimae. Each punctum is a small round or oval aperture situated on a slight elevation at the inner end of the upper and lower lid margin (
lacrimal papilla) and forms the entrance to the
canaliculi. Each canaliculus consists of a vertical portion of about 2 mm long and then bends inward for some 8 mm, the upper one being slightly shorter. The canaliculi pierce the
lacrimal fascia (i.e. the periorbita covering the
lacrimal sac or
tear sac) and unite (forming the
common canaliculus) to enter a small diverticulum of the sac called the
sinus of Maier. The
lacrimal sac is closed above and open below where it is continuous with the
nasolacrimal duct which extends over some 1.5 cm in length to
Hasner's valve (or
Bianchi's valve or
plica lacrimalis) (folds of mucous membrane) at the inferior meatus of the nose. The inferior opening of the duct is called the
ostium lacrimale (Fig. L1).
See dacryocystitis;
epiphora;
lacrimal fistula;
fossa for the lacrimal sac;
Sjögren's syndrome;
tear duct;
dye dilution test;
Jones II test;
valve of Krause.


Fig. L1 Lacrimal apparatus