Lecture Outline #19: Special Senses: Eye Flashcards
the eye
extension of the brain, diencephalon is pushed out
fibrous tunic
sclera & cornea
sclera
dense CT - white of the eye
attachment site for muscles of the eye
elastic/mechanical support for globe
cornea
modified sclera - 1/6th of globe
avascular, translucent bulge @ anterior surface, gets nutrients through humor and air in the environment
bends light to focus on retina
optical axis
straight line from center of pupil to back
vascular tunic
choroid, ciliary body (m. & sus ligs), iris
choroid
inner posterior surface of globe
vascular - nourish the retina
black pigmentation absorbs stray light
ciliary body
CN III
ciliary m. - smooth m. of radial and circular fibers, contraction reduces tension of sus ligs, doesn’t pull on sus ligs
suspensory lig - zonular fibers, an/post to lens, attach through ciliary m. to sclera
ora serrata
junction of choroid and cil body
where choroid and retina merge @ non-photic aspect of retina
iris
smooth m - circular & radial m.s (antagonists
- pupillary constrictor m. (sphincter) parasym stimulation - pupil contraction
- pupillary dilator m.s (radial) sym stimulation - pupil dilation
regulates amount of light that passes to retina
separates ant cavity into ant/post chambers
anterior cavity
filled with aqueous humor (~CSF) - helps control intra-ocular pressure, produced by the ciliary process, returned to blood supply via Canal of Schlemm (venous drainage to dural sinuses) by going through pupil.
- anterior chamber - ant to iris
- posterior chamber - post to iris, ant to lens
posterior cavity
filled with vitreous humor - gel-like fluid that assist sclera in maintaining shape of globe
posterior to lens
sus lig
barrier btw. ant/pot cavities
composed of two fused membranes
lens is sandwiched/suspended btw. layers
glaucoma
circulation of aqueous humor is blocked so it stays btw iris & cornea, increased pressure - damage to nerve, compresses BVs and pushes on retina
cloudy/gray-green eye, assoc. with high blood pressure
neural tunic - matter
retina
gray matter - deep, rods and cones
white matter - superficial, vasculature/ganglia
retina - posterior pigmented layer
dark pigmentation absorbs stray light
supports anterior neural layer
integration center
retina - anterior neural layer
contain 9 layers of cells
around 130 mill photoreceptors
houses neurons, neuroglia, ganglia, BVs, rods, cones
photoreceptors
not chemoreceptors
rods - gray-scale, dim light, around 125 mill per
cones - color vision, around 6 mill per, take lots of energy to activate, absence of one type = color blindness