Lecture 1/18 Flashcards
what kind of suture is in embryologic nucleus of the lens?
Y suture
how is the Y suture different on the anterior vs. posterior surface
anterior surface: Y is erect
posterior surface: Y is inverted
in what way do the lenticular fibers in the adult nucleus come together?
in a star pattern (stellate suture)
what does the zonules attach?
the zonules attach the surface of the ciliary body to the capsule of the lens
what are the zonular fibers made up of?
non-collagenous and made of a protein with significant components of glycoprotein
what is the canal of petit?
a potential space between the posterior zonular surface and anterior vitreous
what is the canal of hannover?
potential space in between the zonules
where do the zonules attach on the ciliary body?
most attach to pars plicata (and a few attach to pars plana)
where do the zonules attach on the lens
1.5 mm anterior to equator
1.0 mm posterior to equator
(and a few attach right at equator)
where do principal zonular fibers attach?
from ciliary body to capsule of lens
what are the principal zonular fibers involved with?
in accommodation when C.B. is relaxed and principal fibers pull on lens to flatten them out
tension of zonules does what to the lens
puts it in the unaccommodated state
what are the 2 groups of principal fibers?
- orbiculocapsular
- ciliocapsular
where are the orbiculocapsular principal fibers located?
going from posterior portion of CB (pars plana) to both anterior and posterior to the euator of the lens
where are the ciliocapsular principal fibers located?
from valleys/ridges on ciliary processes to posterior equator and at the equator
what is the purpose of association (or auxiliary) zonular fibers?
structural
list 3 types of association zonular fibers
- orbiculociliary
- interciliary
- circular
orbiculociliary association zonular fibers run from:
from pars plana to pars plicata
interciliary association zonular fibers run from:
from one ciliary process to another
circular association zonular fibers run from:
zonule to zonule in circular pattern (looks like spider web)
the anterior border of the anterior chamber =
posterior cornea
posterior boundary of anterior chamber =
anterior iris and anterior surface of lens in pupil
anterior chamber depth is about:
3.5 mm (average)
anterior chamber depth in myopes vs. hyperopes
myopes: deeper anterior chamber (longer eyes)
hyperopes: have shallower anterior chamber (shorter eye)
anterior chamber depth changes with age
as you age, anterior chamber depth gets shallower
where is the filtration angle located?
at the junction of the ciliary root of the iris and the sclera
the filtration angle is located about ____ from the limbus
1.5 mm posterior to the limbus
what is in the filtration angle?
trabecular meshwork
filration angle varies from ___ to ____ degrees
20 to 45 degrees
20 degree filtration angle is a ____ chamber than 45 degree
20 for more shallow chamber
the triangular trabecular meshwork’s apex faces:
apex pointed towards cornea
the triangular trabecular meshwork’s base faces:
base against scleral spur and anterior surface of CB
list 3 components of the trabecular meshwork:
- uveal meshwork
- corneoscleral meshwork
- juxtacanicular tissue
what component of the trabecular meshwork is most internal?
uveal meshwork
what component of the trabecular meshwork has the largest openings and the smallest fibers
uveal meshwork
where does the uveal meshwork run?
runs from the end of Descemet’s down to the CB
composition of the uveal meshwork is:
fibers have collagen core and are covered with endothelium
composition of corneaoscleral meshwork
composed of concentric sheets that have the holes punched in them (called trabecular sheets)
what is the largest component of the trabecular meshwork?
corneoscleral meshwork
a function of corneoscleral meshwork
has smaller holes and openings for the aqueous to pass through
what is the thin layer between the canal of SChlemm and corneoscleral meshwork?
juxtacanicular tissue
composition of the juxtacanicular tissue:
it is a sheet of connective tissue (a membrane) with no holes/openings in it
where is the canal of scheme located?
external to the trabecular meshwork (between sclera and trabecular meshwork)
purpose of the canal of Schlemm
to collect aqueous
canal of scheme is lined with _____
endothelium
the cross section of the canal of scheme is oval. where is the long axis?
the long axis is parallel with the surface of the sclera
with gonioscopy, what does Descemet’s appear as?
a glistening white line on the “horizon” (called Schwalbe’s line)
what is the only way you can see iris processes?
(also called pectinate fiends) seen with gonioscopy only
list the 2 types of accessory channels of the canal of scheme
- external collector channels
2. large external canals (squeal veins of Ascher)
route of the canal of schlemm - external collector channels
deep scleral plexus -> intrascleral plexus -> surface of sclera (episcleral veins)
route of the canal of schlemm- large external canals (aqueal veins of ascher)
from sclera directly to episcleral vein
what % of the aqueous drainage is through the trabecular meshwork/ canal of schlemm system?
90 % of the flow/drainage of aqueous
where is the remaining 10% of the aqueous drained?
absorption of aqueous into the stroma of the iris and ciliary body -> choroid -> vortex vein
the aqueous supplies nutrients to:
structures in anterior chamber without blood vascular system (the cornea and lens)
other functions of the aqueous humor
- to take away metabolic wastes
- to maintain IOP
- an optical component
what is important about aqueous humor and IOP
- IOP keeps the anterior chamber in its position and form
- IOP is a balance between production and drainage
where is production of aqueous humor?
from ciliary processes of ciliary body
aqueous humor is a derivative of: ___
blood plasma
