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Exam 3: Orbit and Contents
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The eyeball consists of how many layers of tissue?
3
What is included in the outer fibrous layer of the eyeball?
opaque sclera
transparent cornea
Where is the opaque sclera of the eyeball?
posterior 5/6's
Where is the transparent cornea of the eyeball?
anterior 1/6
What part of the eye is the sclera?
white part
What is the middle layer of the eye known as?
middle vascular layer
What does the middle vascular layer of the eye include?
choroid
ciliary body
iris
The sclera is continous with what?
cornea in outer layer
What is the inner layer of the eye?
retina
What is contained in the retina?
sensory receptors for light
What are sensory receptors?
rods and cones
What does light pass through before it strikes the retina?
numerous refractive media
What are refractive media?
cornea
aqueous humor in anterior/posterior chambers
lens
vitreous humor
Is the aqueous humor continuously produced and absorbed?
yes
What does the lens do?
focuses light onto macula
What causes glaucoma?
disruption in balance in prduction and absorption of aqueous humor
excess aqueous humor
The lens is suspended by what?
tiny ligaments attached to ciliary muscle
Contraction and relaxation of the ciliary muscle results in:
accommodation of lens
What is accommodation?
changing shape of lens
What is accommodation essential for?
focusing light rays comming from differnet distance onto the retina
What nerve supplies the ciliary muscle?
parasympathetic motor fibers in CN III
How many smooth muscles does the iris contain?
2
What do the smooth muscle of the iris do?
regulate size of pupil
Where is the optic nerve attached to the eyeball?
posterior side of eyeball in position of blind spot of retina
Does the blind spot contain rods or cones?
no
What is included in the blind spot?
central artery of retina
What surrounds the optic nerve?
all three layers of meninges
What does increase in intracranial pressure do?
affect central artery of retina
Where is the central artery of the retina?
within the optic nerve
An increase in intracranial pressure due to closed-head injury can be detected how?
visualiing changes in blind spot and arteries supplying retina
Where is the highest concentration of cones?
the macula
Where is the sharpest vision?
macula
what is the optic disc?
where optic nerve enters eye
Where does the optic nerve enter the eye?
through fovea centralis
How many extraocular muscles are there?
6
Where do extraocular muscles insert?
into eyeballs
Contraction of extraocular muscles causes what?
eyeballs to move in various directions to track objects in visual field
What is elevating the eye?
looking up
What is abducting the eye?
turns eye outward
What is adducting the eye?
turns eye inward
What holds the superior oblique in place?
trochlea
Which muscle lies on top of superior rectus?
levator palpebrae superioris muscle
The superior part of the levator palpebrae superioris muscle consists of what type of muscle fibers?
skeletal muscle fibers
What is the inferior part of the levator palpebrae superioris known as?
superior tarsal muscle
The inferior part of the levator palpebrae superioris muscle consists of what type of muscle fibers?
smooth muscle fibers
Patients with oculomotor nerve palsy are unable to:
elevate upper eyelid voluntarily
Why are patients with oculomotor nerve palsy unable to elevate upper eyelid voluntarily?
levator palpebrae superiorir is paralyzed
What doesa lesion of the cervical sympathetic chain ganglia cause?
ptosis
What is ptosis?
drooping of upper eyelid
What is ptosis a sign of?
cervical sympathetic trunk injury
Horner's syndrome:
cervical sympathetic trunk injury
loss of sympathetic innervation to head and neck region
ptosis (drooping of upper eyelid)
What supplies blood to the contents of the orbit?
ophthalmic artery and its branches
The ophthalmic artery is the first branch of which artery?
internal carotid artery in cranial cavity
What is the sole blood supply of the retina?
central artery of the retina
The central artery of the retina is a branch of what?
ophthalmic artery
Where is the central artery of the retina?
in the optic nerve
The contents of the orbit are drained by:
ophthalmic veins
Ophthalmic veins have connections with which veins?
facial vein
cavernous sinus
What is the only blood supply to the retina?
central artey and vein of retina
What is found in the anterior chamber of the eye?
aqueous humor
What is found in the posterior chamber of the eye?
aqueous humor
When is aqueous humor produced?
24/7
Where is aqueous humor produced?
by cells in eye in posterior chamber
How does aqueous humor reach the anterior chamber from the posterior chamber?
through the pupil
Where is aqueous humor reabsorbed?
venous sinuses
If aqueus pressure is high, this causes:
gluacoma
What is the path of light through the eye?
light-cornea (bends)-pupil-lens (bends)-macula (focus)
What type of muscle fibers does the levator papilbrae superioris have?
skeletal and smooth
Sympathetic neurons of the levator papilbrae superioris are found where?
within carotid plexus
Author
brau2308
ID
160991
Card Set
Exam 3: Orbit and Contents
Description
review of 7/3 lecture on orbit and contents for exam 3
Updated
7/4/2012, 9:01:31 PM
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