Vision Anatomy (2) Flashcards
Accessory structures mean:
What surrounds the eye
What do eyebrows do?
Prevent sweat from getting into the eye and shade the eyes from sunlight
Another word for eyelid
Palpebrae
What are the eyelids separated by?
Palpebral fissure
What is a medial and lateral commissure (canthus) and canthi)?
The medial and lateral angels of the palpebral fissure
What is a sty?
A painful inflammation of the sebaceous glands at the base of the eyelashes
Where do eyelashes project from?
The free margin
What do eyelashes do?
The follicles of each eyelash hairs are richly innervated by nerve endings (hair follicle receptors) and anything that touches the lashes (puff of air) triggers reflex blinking
What do tarsal glands do?
These sebaceous glands produce an oily secretion that lubricates the eyelid
Prevents the eyelids from sticking together
Tarsal glands are embedded in the…
tarsal plates
Tarsal gland’s ducts open at the…
eyelid edge posterior to the eyelashes
What is a chalazion?
A small, firm bump that forms on the eyelid when an oil gland becomes blocked (large)
The eyelids are thin, skin-covered folds supported internally by connective tissue called…
Tarsal plates
What muscle does the tarsal plate anchor?
Orbicularis oculi
What does the orbicularis oculi do?
Squeezes the eyes shut
What eye muscles are part of the oculomotor nerve?
Inferior rectus, superior rectus, medial rectus, and inferior oblique
What eye muscle is part of the trochlear nerve?
Superior oblique
What eye muscle is part of abducens?
Lateral rectus
What is the palpebral conjunctiva?
It lines the eyelids
What is the bulbar conjunctiva?
It folds over back over the anterior surface of the eyeball
Covers only the white part of the eye
What is the conjunctiva?
A transparent mucous membrane
What is conjunctivitis?
Inflammation of the conjunctiva, results in red and irritated eyes
What is conjunctivitis caused by?
Bacteria or viruses, they are highly contagious: pinkeye
Where is the lacrimal gland?
Lies in the orbit above the lateral end of the eye and is visible through the conjunctiva when the lid is everted (inside out)
What does the lacrimal gland do?
Continuously releases a dilute saline solution (tears) into the superior part of the conjunctival sac through several small excretory ducts
Step 1 path of tears:
The LACRIMAL GLAND produces and secretes tears (lacrimal secretions)
Step 2 path of tears:
Tears enter the conjunctional sac via the EXCRETORY DUCTS OF THE LACRIMAL GLAND
Step 3 path of tears:
Tears flow down and across the eyeball
Step 4 path of tears:
Tears enter the LACRIMAL CANALICULI at openings called LACRIMAL PUNCTA
Step 5 path of tears:
Tears drain into the LACRIMAL SAC
Step 6 path of tears:
From the lacrimal sac, tears empty via the NASOLACRIMAL DUCT into the inferior meatus of the nasal cavity
What are the 6 eye muscles?
Superior rectus, inferior rectus, lateral rectus, medial rectus, inferior oblique and superior oblique
What are the 2 parts of fibrous tunic?
Sclera and cornea
What is the fibrous layer?
The outermost coat of the eyeball
What is the sclera?
Forms the posterior portion and bulk of the fibrous layer (of the eyeball)
What does the sclera do?
Protects and shapes the eyeball,
and provides a sturdy anchoring site for the extrinsic eye muscles
Posteriorly, the sclera is pierced by which nerve?
Optic (II)
What is continuous with the dura mater of the brain?
The sclera
Where is the cornea?
The anterior sixth of the fibrous layer and bulges anteriorly from its junction with the sclera
What does the cornea do?
Forms a window that lets light enter the eye
and is a major part of the light-bending apparatus of the eye
What cells protect the cornea from abrasion? (the external sheet?)
Stratified squamous epithelium
What cells compose the deep corneal endothelium? (inner layer)
Simple squamous epithelium
The cornea does not have a…
blood supply
The cornea is well supplied with…
nerve endings, most of which are pain receptors
The wall of the eyeball is composed of what 3 layers?
Fibrous, vascular and inner layers
What is the vascular tunic (uvea) layer?
Forms the middle coat of the eyeball
What are the 3 parts of the vascular tunic?
Choroid, ciliary body and iris
What does the choroid do?
As light enters the pupil, it absorbs excess light which prevents it from scattering and reflecting within the eye
The choroid’s blood vessels…
nourish all eye layers
The choroid forms…
the posterior 5/6 of the vascular layer
The choroid has a posterior opening where the…
optic nerve leaves the eye
