Eye Anatomy Flashcards
What are the layers of the eyelid? (superficial to deep)
Skin/subcutaneous tissue Orbicularis oculi Tarsal plates Levator apparatus Conjunctiva
What are the sweat glands in the eyelids called?
Ciliary glands of Moll
What are the sebaceous glands in the eyelids called?
Glands of Zeis
What are the muscles that open the eyelids?
Levator palpebrae
Muller’s muscle
What muscle closes the eyelid?
Orbicularis orbis
What are the 3 parts of the orbicularis oculi muscle?
Palpebral
Lacrimal
Orbital
What are the attachments of orbicularis oculi?
Origin
- medial margin
- medial palpebral ligament
- lacrimal bone
Insertion
- skin around margin of orbit
- superior tarsal plate
- inferior tarsal plate
What is the action of the palpebral part of the orbicularis oculi?
Gently closes the eyelids
What is the action of the lacrimal part of the orbicularis oculi?
Involved in the drainage of tears
What is the action of the orbital part of the orbicularis oculi?
Tightly closes the eyelids
What are the tarsal plates?
Dense connective tissue that acts as scaffolding of the eyelid
What glands are found in the tarsal plates?
Meibomian glands
What is the function of Meibomian?
Prevents evaporation of tear film
Prevents eyelids sticking together
What is an external stye?
Infection of a hair follicle
What is an internal stye?
Infection of a Meibomian gland
What is a chalazion?
Painless granuloma of the Meibomian glands
What muscles are found in the levator apparatus?
Levator palpebrae superioris
Superior tarsal muscle
What is the superior tarsal muscle also known as?
Muller’s muscle
What are the attachements of levator palpebrae superioris?
Origin
- lesser wing of sphenoid
Insertion
- upper eyelid
- superior tarsal plate
What is the action of levator palpebrae superioris?
Opens the eye lid
What is the innervation of levator palpebrae superioris?
CNIII - oculomotor
What is the innervation of the orbicularis orbis?
CNVII - facial (temporal + zygomatic branches)
What are the attachments of the superior tarsal muscle?
Origin
- underside of levator palpebrae superioris
Insertion
- superior tarsal plate
What is the action of the superior tarsal muscle?
Opens eyelid
What is the innervation of the superior tarsal muscle?
Sympathetic fibres from the superior cervical ganglion
What is the deepest part of the eyelid?
Palpebral conjunctiva
What is the reflection of the palpebral conjunctiva on the eyeball called?
Bulbar conjunctiva
What are the lacrimal glands?
Serous exocrine glands that secrete lacrimal fluid onto the surface of the conjunctiva and cornea
What is the function of lacrimal fluid?
Clean, nourish + lubricate eyes
Excess = tears
Where is lacrimal fluid produced?
Lacrimal gland
Where are lacrimal glands located?
Superolateral aspect of orbit - in the lacrimal fossa
Where does the lacrimal gland drain into?
Superior conjunctival fornix - spreads fluid over eyes by blinking
What is the lacrimal apparatus?
System responsible for drainage of lacrimal fluid from the orbit
Where does lacrimal fluid drain from eye?
Medial aspect of eye - via superior + inferior punctum -> canaliculi -> lacrimal sac
Where is the lacrimal sac located?
Groove formed by the lacrimal bone and frontal process of the maxilla
Where does the lacrimal sac drain?
Via nasolacrimal duct into the inferior meatus of nasal cavity
What is the valve connecting the lacrimal duct to the inferior meatus called?
Valve of Hasner
What are the main layers of the eyeball?
Fibrous layer
Vascular layer
Inner layer
What makes up the fibrous layer?
Sclera + cornea
What is the function of the fibrous layer?
Provide shape to eye
Support deeper structures
Where does the sclera lie?
Most of the eye
What is the function of the sclera?
Point of attachment to the extraocular muscles
Where does the cornea le?
Centrally at the front of the eye
What makes the cornea clear?
Water pump
What makes up the vascular layer?
Choroid
Ciliary body
Iris
What is the iris?
Circular structure - coloured part
Hole in the centre = pupil
What is the ciliary body?
Ciliary muscle + ciliary processes
What is the function of the ciliary muscle?
Control shape of lens
Produce aqueous humour
What is the choroid?
Layer of connective tissue + blood vessels
What makes up the inner layer?
Retina
What are the layers of the retina?
Pigmented layer
Neural layer
What is the pigmented layer?
Outer layer - single layer of cells
Supports the choroid in absorbing light
What is the neural layer?
Inner layer - consists of photoreceptor cells
Found posteriorly + laterally
What is found at the centre of the retina?
Macula
What is found in the macula?
Fovea
What is the fovea?
Area of high concentration light detecting cells - area responsible for high visual acuity
What is the optic disc?
Area the optic nerve enters the retina
Where does the retina start?
Ora serrata
Where does the lens lie?
Between the vitreous humour and the pupil
Where does the anterior chamber lie?
Between the cornea + iris
Where does the posterior chamber lie?
Between iris and ciliary processes
What fills the posterior and anterior chambers?
Aqueous humour
How is aqueous humour drained?
Via trabecular meshwork (in the iridocorneal angle) -> schlem’s canal -> venous system
