Anatomy Review - Nasolacrimal system
HIDEInteractive Transcript
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We are ready to discuss the lesions
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of the orbital appendages.
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By the orbital appendages, we are referring to the lacrimal
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gland and the lacrimal sac, and lacrimal duct.
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The lacrimal gland is the source of the tears that flow across the eye.
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So from the lacrimal gland,
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we have the tears that flow across the eye
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to get to the region of the lacrimal sac and the lacrimal duct.
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We have two components here.
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One is the superior and one is the inferior canaliculi,
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and the canaliculi open into the lacrimal sac by the sinus of Mayer.
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The lacrimal sac is seen near the punctum of the eye and is
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the uppermost portion of the lacrimal duct and sac apparatus.
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From the lacrimal sac, we enter the nasal lacrimal duct
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via the valves of Krause.
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The tears then flow downward through the nasal lacrimal duct
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and come to the inferior turbinate.
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At which point, they exit via the valve of Hasner.
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This is epithelial-lined tissue along the lacrimal duct,
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whereas the lacrimal gland is said to be
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effectively like a salivary gland.
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And so the diseases of the lacrimal gland simulate those of
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the salivary glands, whereas the diseases of the nasal
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lacrimal sac and duct simulate the parotid duct.
David M Yousem, MD, MBA
Professor of Radiology, Vice Chairman and Associate Dean
Johns Hopkins University
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