The Eyes Flashcards
Limbus
junction of the sclera and cornea
Tapetum lucidum
the specialized reflective area of the choroid
Pupil
the central opening of the iris that lets light into the eye
Palpebral conjunctiva
clear membrane that lines the inner surface of the eyelid
Bulbar conjunctiva
the reflection of the palpebral conjunctiva onto the eyeball
Conjunctival sac
space between the palpebral conjunctiva and the eyeball
Zonular fibers
attach lens to the ciliary body; holds the lens in position and allow its shape to change due to actions of ciliary muscles
Blind spot
area of the retina where the axons from the ganglion neurons leave the eye as the optic nerve. Has no rods or cones.
Cilia
eyelashes; hairs coming out of the eyelids
Lateral/medial canthus
the point where eyelids meet; the lateral and medial angles are the areas near the canthi
Lacrimal caruncle
the triangular prominence in the medial angle
Lacrimal gland
pink gland at the dorsolateral aspect of the eyeball, secretes tears
Lacrimal puncta
openings into lacrimal canals on upper and lower eyelids near the medial canthus
What are the three tunics of the eyeball?
- Fibrous tunic
- Vascular tunic (uvea)
- Nervous tunic (retina)
What structures are a part of the FIBROUS TUNIC?
divided into the sclera and cornea
Limbus (junction of the sclera and cornea)
What structures are a part of the VASCULAR TUNIC?
choroid, ciliary body, and iris
blood vessels and smooth muscle
tapetum lucidum
ciliary process
zonular fibers
What structures are a part of the NERVOUS TUNIC?
retina*
photoreceptors
bipolar neurons
ganglion neurons
optic disc
lens
What structures comprise the ANTERIOR uvea? What are their features?
Iris
-two layers of muscles reacting to light to
increase or decrease size of pupil
-regulates amount of light entering eye
-has double layered cuboidal epithelium that -
contains melanin
Ciliary body
-thickest portion of the vascular tunic between
choroid and iris
-supports the lens through zonular fibers
-major site for production of aqueous humor
-consists of ciliary muscle and ciliary process
What structures comprise the POSTERIOR uvea? What are their features?
Choroid
- thin, dark, highly vascular membrane deep
to the sclera
- supplies retina and serves to absorb light not
reflected out of eye
What are the boundaries of the anterior chamber, posterior chamber and vitreous chamber? What type of fluid is found in each?
Anterior chamber - space between the cornea and iris.
Fluid type: aqueous humor
Posterior chamber - space between iris and lens.
Fluid type: aqueous humor
Vitreous chamber - larger space lying between the lens and retina.
Fluid type: vitreous humor
What is the primary site of production of the aqueous humor?
Aqueous humor is produced by the ciliary body/processes; flows from the posterior chamber through the pupil into the anterior chamber.
What cranial nerves innervate the eye?
CN 2, 3, 4, 6.
What are the extrinsic muscles of the eye and their function?
- Dorsal rectus - moves eyeball dorsally
- Lateral rectus - moves eyeball laterally
- Ventral rectus - moves eyeball ventrally
- Medial rectus - moves eyeball medially
- Ventral oblique - rotates the bottom of the
eye medially - Dorsal oblique - rotates the top of the eye medially
What are the intrinsic muscles of the eye and their function?
- Pupillary sphincter
- Pupillary dilator
- Ciliary muscles
all deal with the size of the pupil and lens shape.
What are the shape of pupils in cats, dogs, and cattle?
Cats - vertical/elliptic
Dogs - round
Cattle - horizontal
What is the function of the tarsal (Meibomian glands)?
Function to secrete waxy substance that helps to form a dam for excessive tear secretion.
What is the nictitating membrane’s features & function?
Nictitating membrane is the third eyelid.
- Functions to provide protection and to distribute the tear film.
- The fold of conjunctiva, reinforced by t-shaped cartilage, located between the eyelids’ medial angle and the eyeball.
What is the function of the Gland of the Nictitating Membrane?
Contribute to tear formation.
