Unit 3 Flashcards
Orbicularis oculi muscle vs. Levator palpebrae superioris muscle
OOM- closes upper and lower eyelids and facilitates movement of tears to the tear drainage system
LPSM- opens upper eyelid
Palperbral conjunctiva vs. Bulbar conjunctiva
PC- mucous membrane lining the inner surface of the eyelids
BC- mucous membrane covering the whole sclera
Functions of the ciliary body
-accommodation
-Produces aqueous humour
-Anchors the zonules that hold the lens in place
Function of canal of schlemm
Collects and drains aqueous humour from the anterior chamber into the veinous system
How does iris control pupil size
Sphincter pupillae- circular muscle that contracts pupil
Dilator pupillae- Radial muscle that dilates pupil
Composition and structure of lens
Three layers:
-capsule (outer)
-cortex (body)
-nucleus (inner)
65% water and 35% protein
How a lens changes as it ages
Fibres form under the capsule and push the older lens fibres centrally and they become harder and less flexible
Layers of cornea
-Epithelium
-Bowmans layer
-Stroma
-descemet’s membrane
-endothelium
Two functions of the corneal endothelium
-Allows nutrients to pass from the aqueous to the anterior corneal cells
-Pumps fluid out of the stromal layer to keep the cornea clear
Thickest corneal layer
Stroma
Zonules
Muscles that pull on lens
The sclera is composed of what tissue
Collagen
Function of the choroid
Supplies the retina with oxygen via blood
Components of the vitreous humour
Mostly water but also has collagen fibres and Hyaluronin gel (?)
Function of the vitreous humour
Allows light rays to pass through to the retina
What is cloquet’s canal
It is a remnant structure from foetal development. It runs through the vitreous body from the optic nerve disc to the lens
Layers of the retina
-bruch’s membrane
-Retinal pigment epithelium
-Rods and cones
-External limiting membrane
-Outer nuclear layer
-outer plexiform layer
– Inner nuclear layer
– Inner plexiform layer
-Ganglion cell layer
-Nerve fibre layer
-Internal limiting membrane
Accessory glands of tear production
-Krause
-wolfring
Valves in the lacrimal sac
Valve of Rosemuller at the start
valve of Hasner at the end
Layers of the tear film and where they’re made
Mucin- adheres tear layer to cornea
-Produced by goblet cells in the conjunctiva
Aqueous- Contains nutrients and immune cells
-Produced by lacrimal and accessory glands
Lipid- prevents evaporation
-produced by meibomian gland

Protective accessory structures
-eyebrows
-eyelashes
Accessory structures for eyelid movement
-ocularis oculari (closes both lids)
-levator palpebrae superioris (opens upper lid)
-palpebral conjunctiva (lines eyelid)
-cornea
-bulbar conjunctiva (covers eyeball)
Lacrimal system
Parasympathetic
-production of tears
-lacrimal gland
-accessory glands (Krause and wolfring)
-movement of tears
-drainage of tears
-valve of rosemuller
-valve of hasner
Structures in lacrimal system
-lacrimal gland (accessory glands Krause and wolfring)
-superior and inferior punctum
-superior and inferior canaliculus
-lacrimal sac
-lacrimal duct (valves of rosemuller and hasner)
