Canine Vision Flashcards
The organ of vision consists of?
- eyeball (bulbus oculi)
- adnexa
The adnexa includes what structures?
- eyelids
- ocular muscles
- lacrimal apparatus
In dogs, the bony process lateral to the orbit are separated and joined together by?
the orbital ligament
In cats, the bony processes lateral to the orbit are what?
very close or fused
What are the bony processes lateral to the orbit?
- zygomatic process of frontal bone
- frontal process of zygomatic bone
The straight line passing through both poles of the eyeball is known as?
optic axis
The line equidistant from the poles of the eyeball is known as?
equator
What tunic of the eyeball gives form to and protects the eyeball?
external fibrous tunic
What tunic of the eyeball contains blood vessels and smooth muscle, nutrition of the eyeball and the regulation of the shape of the lens and size of the pupil?
middle vascular tunic
What tunic of the eyeball is responsible for translation of visual stimuli into nerve impulses?
internal nervous tunic
The external fibrous tunic includes what structures of the eye?
- cornea
- sclera
What is the outermost transparent layer of the eye that helps focus light and protect the eye, and forms about one quarter of the fibrous tunic?
cornea
What is the white, fibrous tissue that covers the outside of the eye, extending from the cornea to the optic nerve?
sclera
What is the border between the cornea and sclera?
limbus
The cornea’s nerves are responsible for what?
- sensation of touch, pain, and temperature
- reflexes (trigger blink reflex and tear production)
- help with wound healing
The middle vascular tunic is also known as?
uvea
The middle vascular tunic (uvea) consists of what structures?
- iris
- ciliary body
- choroid
What is responsible for adjusting the size of the pupil, and divides the space between the lens and cornea into anterior and posterior chambers that communicate through the pupil?
iris
The anterior and posterior chambers are filled with what?
aqueous humor
The iris contains how many layers of smooth muscles?
two
The sphincter of the pupil causes what?
miosis via GVE parasympathetic (constriction)
The dilator of the pupil causes what?
mydriasis via GVE sympathetic (dilation)
Miosis via GVE parasympathetic occurs by what nerve?
oculomotor nerve CN III
What structure of the middle vascular tunic suspends the lens and regulates its curvature?
ciliary body
What structure is a raised ring with ridges converging toward the lens in the center?
ciliary body
Smooth ciliary muscles do the accommodation, which is what?
the ability of the eye to focus on near or distant objects by changing the shape of the lens
What structure of the middle vascular tunic provides the blood supply?
choroid
What is the light reflecting area of the eye?
tapetum lucidum
What is the area of the internal nervous tunic where the axons of the fourth layer concentrate to leave the eye?
optic disk
What is the area of the internal nervous tunic that contains light sensitive receptor cells?
retina
The retina in dogs is mostly composed of rods or cones?
rods (95%)
What is the eye chamber between the cornea and iris, filled with aqueous humor?
anterior chamber
What is the eye chamber between the iris and ciliary body-lens, filled with aqueous humor?
posterior chamber
What is the eye chamber between ciliary body and retina, filled with vitreous humor?
vitreous chamber
What has a role in the maintenance of intraocular pressure and is produced by the cells of the ciliary processes?
aqueous humor
What is the disease of the eye in which the pressure within the ye, called intraocular pressure, is increased?
glaucoma
What is the soft, transparent tissue that sits posterior to the iris and helps focus incoming light onto the retina?
lens
What connects the zygomatic process of the frontal bone with the frontal process of the zygomatic bone?
orbital ligament
What muscle is located dorsal in the orbit, attaches within the superior eyelid structure, and is resposible to elevate the superior eyelid?
levator palpebrae superioris muscle
What nerve innervates the levator palpebrae superioris muscle?
oculomotor nerve CN III
What is the mucosa that covers th posterior surface of the eyelids?
palpebral conjunctiva
What glands are located posterior to the orbicularis oculi muscle and produce an oily substance (meibum), which coats the tearm film to prevent the evaporation of tears and from spilling onto the face?
tarsal glands (meibomian glands)
What muscle forms the main muscular structure of the eyelids and closes the aperture between the eyelid or palpebral fissure?
orbicularis oculi muscle
What nerve innervates the orbicularis oculi muscle?
facial nerve CN VII
The third eyelid is also called?
nictitanting membrane
What covers the surface of the sclera?
bulbar conjunctiva
What is the blind sac between the palpebral and bulbar conjunctiva?
fornix (superior)
What covers the deep surface of the eyelids?
palpebral conjuctiva
What is the fascia that encapsules the extrinsic muscles that move the eye, periorbital adipose tissue, vessels, and nerves?
periorbita (orbital fascia)
What is the parasympathetic ganglion where preganglionic fibers from facial nerve CN VII synapse?
pterygopalatine ganglion
What are the extrinsic muscles of the eye?
- dorsal rectus muscle
- ventral rectus muscle
- medial rectus muscle
- lateral rectus muscle
- retractor bulbi muscle
- dorsal oblique muscle
- ventral oblique muscle
The dorsal, ventral , and medial rectus muscles is innervated by what nerve?
oculomotor nerve CN III
The lateral rectus muscle is innervated by what nerve?
abducens nerve CN VI
The dorsal oblique muscle is innervated by what nerve?
trochlear nerve CN IV
The ventral oblique muscle is innervated by what nerve?
oculomotor nerve CN III
What muscle has fibers located around the optic nerve, and is reponsible for retracting the eyeball into the orbit as result of a reflex?
retractor bulbi muscle
The retractor bulbi muscle is innervated by what nerve?
abducens nerve CN VI
