Exam 4: Sense organ of vision CN II,III,IV,VI (34) Flashcards
The organ of vision consists of (2)
Eyeball (bulbus oculi)
Adnexa
bulbus oculi is the term for
eye ball
what 3 things make up the Adnexa
- Eyelids
- Ocular muscles
- Lacrimal apparatus
Are housed in the orbit, where the eyeball is embedded in generous quantities of _____
fat
In cats:
The bony processes lateral to the orbit are __________
Are very close or fused.
T/F the orbits in carnivores are very big
true
identify 1-3
dog or cat
1: zygomatic process of frontal bone
2: Orbital ligament
3: Frontal process of zygomatic bone
CAT
what are the blue arrows referencing
blind area
identify 1-3
dog or cat
1: zygomatic process of frontal bone
2: Orbital ligament
3: Frontal process of zygomatic bone
DOG
Dogs
The bony processes lateral to the orbit
are separated and joined together by
the __________
orbital ligament
what type of vision is represented by 1 and 2
- monocular vision
- Binocular vision
visual axis of eye in _______ position
central
T/F the orbital ligament is strong in dogs BUT thin/nonexistent in cats
true
what does it mean to have “binocular vision”
both eyes are participating in viewing
define Optic axis
straight line passing through both pole
a line equidistant from the poles is referred to as
Equator
Eyeball (bulbus oculi) has ___ thin tunics
3
what are the three thin tunics of the eyeball (bulbus oculi)
External fibrous tunic
Middle vascular tunic
Internal nervous tunic
what tunic of the eyeball does this action:
Gives form to and protects the eyeball
External fibrous tunic
what tunic of the eyeball does this action:
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 does this action:
Translation of visual stimuli into nerve impulses
Internal nervous tunic:
what 2 things make up the External fibrous tunic
Cornea
Sclera
T/F the Sclera is ALWAYS white
TRUE
Outermost transparent layer of the eye that helps focus light and protect the eye.
Forms about one quarter of
the fibrous tunic
Cornea
White, fibrous tissue that covers the outside of
the eye, extending from the cornea to the
optic nerve
Sclera
identify 1-4
1.Sclera
2. Limbus
3. Cornea
4. optic nerve
Border between the cornea and sclera
Limbus
identify A, C
The cornea is the most densely
innervated tissue
what nerve mainly innervates it
CN V1 (ophthalmic n. branch of the trigeminal)
The cornea’s nerves are responsible for many functions, including what 3 main things
Sensation
Reflexes
Wound Healing
T/F Sclara is very sensitive to things like cold, pain, etc
true
what function of the cornea is this:
Trigger the blink reflex and tear production
Reflexes
what are some sensations the cornea feels
Touch, pain & temperature
Middle vascular tunic also known as the
uvea
identify A-C
what are the 3 parts of the Middle vascular tunic
Iris, Ciliary body, Choroid
Adjusts the size of the pupil. Divides the space between the lens and cornea into anterior and posterior chambers that communicate through the pupil.
Both are filled with aqueous humor
Iris
The iris divides the space between the _____ and ______ into anterior and posterior chambers
lens and cornea
what is the colored portion of the eye called
iris
the iris contains how many layers of smooth muscle
2; sphincter and dilator
(open and close pupil)
what is uveitis
inflammation of the middle part of the eye (uvea)
what is the “hole” in the iris
the pupil
what eye color is most common is dogs
brown
Cat or dog
cat
cat or dog
dog
what are the smooth muscle of the iris controlled by
ANS
what is the term for constricting the pupil
Miosis
what is the term for pupils dilating
Mydriasis
is Miosis GVE Parasympathetic or Sympathetic
GVE Parasympathetic
is Mydriasis GVE Parasympathetic or Sympathetic
GVE Sympathetic
what CN is involved in Miosis
GVE Parasympathetic: Via oculomotor n. (cn III)
At night or when an animal is scared does miosis or mydriasis occur
mydriasis
Do big cats (tiger, lion, etc) have the same miosis as a DSH or like a dog
Like dogs
explain why Paralytic Mydriasis is BAD
probably means they’re dead or significant head trauma
the stronger muscle is the dilator
suspends the lens, regulates
its curvature
Ciliary body
___________ is a raised ring with ridges converging toward the lens in the center
Ciliary body
Smooth ciliary muscle do the accommodation the ability of the eye to focus on near or distant objects by changing the shape of the _____
lens
in order from top to bottom label 1-3
smooth ciliary muscle
ciliary processes
zonular fibers (tendons that suspend the lens)
what view is this
Dorsal(horizontal) section of the head at the level of the orbits
identify 1-3
- Ciliary body
- Iris
- Cornea
T/F when you contract the ciliary body the diameter increases
false; smaller
Smooth ciliary muscle do the ___________ the ability of the eye to focus on near or distant objects by changing the shape of the lens
accommodation
The reflex of accommodation, or focusing on near objects, occurs by a concerted action of the ___________
ciliary muscle on the zonule fibers which hold the lens in place
The reflex of accommodation, or focusing on near objects performed by the ciliary muscle can get fatigued
yes or no
YES
Ciliary muscles are a ring of smooth muscle that, upon contraction, relaxes the tension on the zonular fibers and allows the lens to become more spherical
this is due to what CN?
Parasympathetic innervation
from CN III (oculomotor n.)
blood supply of the Middle vascular tunic
Choroid (normally black)
Dense network of blood vessels embedded in heavily pigmented connective tissue
Choroid
Light-reflecting area that aids with seeing at night is known as the
Tapetum lucidum (green/blue)
why do humans have red eyes in photos
Choroid
do humans have a tapetum lucidum
NO
identify 1-3
- Choroid
- tapetum lucidum
- Optic disc
Internal nervous tunic has light-sensitive receptor cells and is known as the
Retina (photoreceptors)
The area where the axons of
the fourth layer concentrate
to leave the eye
Optic disc (“blind spot”)
T/F the optic disc has receptors
FALSE
the retina in dogs 95% _____
rods–> cant see red, purple green
what is the arrow pointing to
optic disc
why is the optic disc white
congregation of axons
identify 1-4
- tapetum nigrum
- tapetum lucidum
- Optic disc
- Optic nerve
what are the Eyes chambers
anterior, posterior, vitrerous
which eye chamber is this:
between the cornea and iris, filled with aqueous humor
Anterior
which eye chamber is this:
between iris and ciliary body-lens, filled with aqueous humor
Posterior
which eye chamber is this:
between ciliary body and retina, filled with vitreous humor
Vitreous
what eye chamber is the main area of receptors
Posterior chamber
which of the eye chambers is filled with aqueous humor vs. vitreous humor
what is significant about the iridocorneal angle
drains aqueous humor fluid
what is significant about the ciliary
processes
muscles
produce humor filtered from the blood
Role in the maintenance of intraocular pressure.
Produced by cells of the ciliary processes
The aqueous humor
disease of the eye in which the pressure within the eye, called intraocular pressure (IOP), is increased
Glaucoma
Soft, transparent tissue that
sits posterior to the iris. It helps focus incoming light
onto the retina
Lens
what causes the pressure associated with glaucoma
aqueous humor is NOT getting drained
whats this dogs problem
cataracts
identify 1-3
Lens
Ciliary body
vitreous humor
