Chapter 19: Special Senses Part II (Vision) SYDNEY Flashcards
superficial anatomy of the eye
-superior & inferior palpebrae
-medial & lateral palpebral comissures
-pupil
-iris
what are the palpebrae?
eyelids
provide a superficial covering over its anterior exposed surface
conjunctiva
where are the eyelids united at?
medial and lateral palpebral commissures
parts of the conjunctivial sac
-specialized bursa
-bulbar & palpebral conjuctivia
-covers sclera
parts of the lacrimal apparatus
-lacrimal gland
-lacrimal ducts
-lacrimal canaliculi
-nasolacrimal ducts
located within the superolateral depression of each orbit
lacrimal gland
drains lacrimal fluid into a rounded lacrimal sac
lacrimal canaliculi
what is lacrimal fluid
commonly known as tears
receives the lacrimal fluid from the lacrimal sac
nasolacrimal duct
3 layers of the eyeball
-fibrous layer
-vascular layer
-inner layer (retina)
parts of the fibrous layer
-sclera
-cornea
part of the outer layer that is called the “white” of the eye
sclera
forms the anterior surface of the fibrous tunic
cornea
features of the sclera
-covers 5/6 of eyeball
-opaque, white (irregular fibers)
-attachment for muscles
-has blood vessels
features of the cornea
-convex anterior to iris/pupil
-transparent
-completely avascular
meaning of the cornea being completely avascular
nourishment from ringing capillaries, aqueous humor and tears
parts of the vascular layer
-choroid
-ciliary body
-iris
-pupil
most extensive and posterior region of the vascular tunic & lines most of sclera
choroid
located anterior to the choroid
ciliary body
features of the ciliary body
-attaches the lens
-controls lens focus
-ciliary processes secrete aqueous humor
what type of muscles does the iris have?
involuntary muscles
two groups of smooth muscle layers
-sphincter pupillae
-dilator pupillae
what is the sphincter pupillae controlled by?
-under the control of parasympathetic division of the ANS
-constricts the pupil
what is the dilator pupillae controlled by?
controlled by the sympathetic division of the ANS to dilate the pupil
center of the iris is a black hole called
pupil
parts of inner layer of retina
-optic part
-non-visual part
-optic disc
-macula lutea
-fovea centralis
what is the optic part of the retina sensitive to
sensitive to light
2 layers of the retina
-neural layer
-pigmented layer
parts of the neural layer
-light receptors
-rods
-cones
function of pigmented layer
limits light scattering
function of the rods
dim light
function of the cones
-bright light
-color
what is the non-visual part of the inner layer retina
anterior extension of pigmented layer
axons extend from the ganglionic cells into and through the _____
optic disc
features of the optic disc
-vessels/optic nerve entry
-no photoreceptors
yellowish region of the neural layer
macula lutea
within the macula lutea is a pit called the _____
fovea centralis
feature of the macula lutea
high cone density
feature of the fovea centralis
highest visual acuity
clinical significance of red eye
-capillary lamina of choroid
-supplies rods & cones of retina
-highest perfusion rate in body
clinical significance of retinal detachment
-neural and pigmented layers not firmly attached
-neural layer can separate and drop
contents of the eyeball
-aqueous humor
-vitreous humor
what is the aqueous humor?
fluid in the anterior cavity
function of aqueous humor
a filtrate of plasma that resembles CSF and is produced by the epithelium covering the ciliary body
features of the aqueous humor
-absorbed by scleral venous sinus
-nourishes cornea
-intraocular pressure
what does the intraocular pressure do?
provide balance
posterior cavity is occupied by the transparent, gelatinous ______
vitreous humor
features of the vitreous humor
-fluid enclosed in vitreous
-posterior chamber (4/5 of eyeball)
-jelly-like
-supports retina & lens
clinical significance of glaucoma
reduction of rate of aqueous humor outflow to scleral venous sinus
features of glaucoma
-results in pressure buildup in both chambers
-compression of the retina
-blindness
appearance of lens
-transparent, biconvex
-enclosed by the capsule of lens
attaches to the lens capsule at its periphery, where they transmit tension that enables the lens to change shape
suspensory ligament
links to ciliary processes
suspensory ligament
tension in the suspensory ligaments varies according to the contraction and relaxation of the ______
ciliary muscles
what happens when the ciliary muscles relax?
-the ciliary body moves away from the lens (far vision), so the tension on the suspensory ligaments increases
-flattened lens
-default position of lens
what happens when the ciliary muscles contract?
-the ciliary body moves near the lens (near vision) and lens becomes relaxed
-more round
process of making the lens more spherical to view close-up objects
accommodation
what is the accommodation controlled by
parasympathetic division of the ANS
what happens during presbyopia?
-lens beomes harder/ flatter with age
-reduced focusing power
area of opacity
cataracts
combined surgeries of cataracts
-remove opacities
-insert new lens
what do the extra-ocular muscles of the eye do?
move superior eyelids and eyeball
