Applied anatomy: Lacrimal ducts and Tear film Flashcards
Where is the lacrimal gland situated
Laterally and superiorly to orbit
What innervates the lacrimal duct
Parasympathetic (preganglion) from facial nerve
What does the lacrimal duct open into and what happens when we blink
Drains into conjuctivial sac
And when we blink the eye lids spread tears evenly on the surface of the cornea from the conjuctivial sac (maintaining a wet cornea) and then drain through punctae on the medial side of each eye lid
How is tears drain into the nasolacrimal sac
When we blink, contraction pulls lacrimal sac open creates a pressure which pulls tears into the punctae and then further drains into lacrimal sac then nasolacrimal duct
Where is the final drainage of the tears from nasolacrimal duct
Inferior meatus of nasal cavity
What is the function of the tear film
Keeps conrea moist
washes away any particular foreign bodies
has antibodies and lysosomes to kill microbes
smooth outer surface of cornea providing smooth surface for refraction
What is the 3 layers of the tear film
Mucinous layer
Aqueous layer
Oily layer
What layer over lies corneal epithelium
Mucinous layer
What secretes the mucinous layer
Conjuctivia
What secretes the aqueous layer
Lacrimal gland
What secreted the oily layer
Meibomian glands
What is the purpose of the oily layer
Prevents the aqueous layer getting evaporates to quickly
Where is meibomian glands situated
inside tarsal plate
What is the purpose of blinking
Spread tear film across the apex of the cornea
How does the tear film break up
Overtime the aqueous layer begins to evaporate meaning the oily layer becomes really close to muccinous layer
