Lacrimal Passage
1. LACRIMAL PUNCTA
Two small rounded or oval openings — one each on the upper and lower lid.
Located at the junction of the ciliary and lacrimal portions of the lid margin.
Each punctum sits on a slight elevation called the lacrimal papilla.
Distance from inner canthus: Upper punctum: ~8 mm lateral, Lower punctum: ~6.5 mm lateral
When the eyes are closed, the upper punctum lies medial to the lower punctum.
Direction:
Upper punctum: downwards and backwards
Lower punctum: upwards and backwards
Puncta are surrounded by a ring of dense fibrous tissue to keep them patent.
2. LACRIMAL CANALICULI
Connect the puncta to the lacrimal sac.
Each canaliculus is ~0.5 mm in diameter.
2 parts: Vertical (~2 mm) & Horizontal (~8 mm)
Slight dilatation at the junction of the two parts — called the ampulla.
Horizontal portion runs medially toward the inner canthus.
Each canaliculus pierces the lacrimal fascia and commonly joins to form a common canaliculus, which opens into a small diverticulum of the sac called the lacrimal sinus of Maier.
In ~10% of people, canaliculi open into the sac separately.
3. LACRIMAL SAC
Location: Lies in the lacrimal fossa — formed by the lacrimal bone and frontal process of the maxilla.
Bounded by anterior and posterior lacrimal crests.
Lacrimal Fascia:
The sac is enclosed by a fascia derived from the periorbita, which splits at the posterior lacrimal crest.
Dimensions (when distended):
Length: ~15 mm
Breadth: ~5–6 mm
Volume: ~20 cm³
Parts:
Fundus (~3–5 mm)
Body (~10–12 mm)
Neck: narrows to continue with the nasolacrimal duct (NLD)
4. Nasolacrimal Duct (NLD)
Continues from the neck of the lacrimal sac to the inferior meatus of the nose.
Dimensions:
Length: ~18 mm (range: 12–24 mm)
Diameter: ~3 mm
Narrowest at its upper end.
Direction: Downward, backward, and laterally.
External Landmark: Line from inner canthus to the ala of the nose.
Parts:
Intraosseous part (~12 mm) — lies in the nasolacrimal canal
Anterolateral wall: maxilla
Posteromedial wall: lacrimal bone and inferior nasal concha
Intrameatal part (~5 mm) — opens into the inferior meatus, 30–40 mm from the anterior nares.
Valve of Hasner:
Located at the lower end.
Prevents air from entering the sac during nose blowing.
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