Lecture 17.2 Uveal Tract Part I

parasympathetic innervation via __

iris sphincter

sympathetic innervation via __

iris dilator

parasympathetic innervation corresponds to constriction or dilation

constriction

sympathetic innervation corresponds to constriction or dilation

dilation

In bright light there is activation of _ nerve

parasympathetic

In dim light there is activation of _ nerve

sympathetic

in bright light —> pupillary _

constriction

in dim light —> pupillary _

dilation

define direct light reflex

Shining light to an eye causes pupillary constriction same eye

define consensual light reflx

Shining light to one eye causes pupillary constriction of other eye

Afferent pathway of Light reflux is mediated by _ and subserved by _

photoreceptors, four neurons

four neurons that subserve the afferent pathway of Light reflux 

first (sensory) neurons

second (interneuron) neurons

third (pre ganglionic) neurons

fourth (post ganglionic) neurons

first (sensory) neurons of pupillary light reflex connects each retinal with

pretectal nuclei

axons originating from nasal retinal is _ in optic chiasm

crossed

axons originating from nasal retina terminates in _

contralateral pretectal nucleus

axons originating from temporal retinal is _ in optic chiasm

uncrossed

axons originating from temporal retina terminates in

ipsilateral pretectal nucleus

second (interneuron) connects each _ to both _

pretectal nucleus, Edinger-Westphal nuclei

third (pre ganglion) neuron connects _ with _

Edinger-Westphal nuclei, ciliary ganglion

third (pre ganglion) neuron connects Edinger-Westphal nuclei with ciliary ganglion via _ nerve along with _ nerve

oculomotor, parasympathetic

third (pre ganglionic) neuron connects to which cranial nerve

CN III, oculomotor

fourth (post ganglionic) neuron extends from _ to _

ciliary ganglion as short ciliary nerve, sphincter pupillae

which neuron is the interneuron

second

which neuron is the sensory neuron

first

efferent  presynaptic parasympathetic nerve begins at _ in _

oculomoter nucleus (Edinger-Westphal nucleus (EWN)) in midbrain

axons of Edinger-Westphal nucleus (EWN) in efferent pathway extends to which nerve

oculomotor nerve (CN III)

preganglionic parasympathetic axons leaves from where

the dorsomedial aspects of brain stem

preganglionic parasympathetic axons terminate by synapsing inside where

the ciliary ganglion

after terminating at the ciliary ganglion, the preganglionic parasympathetic axons enter the orbit via what

superior orbital fissure

Axons from ciliary ganglion extends as _ via _ to innervate the __.

post synaptic fiber, short ciliary nerve, sphincter pupillae.

how does RAPD occur

due to an asymmetric lesion in the afferent light reflex pathway

what happens to the pretectal ucleus if there is a compression at optic nerve or chiasm

it receives or weaker or no signal when light is shined into affected eye

RAPD: what happens normally when light is shine to one eye

constriction of both eyes

normally when light is shine to one eye, it causes __ of __ of both iris

dual activation, parasympathetic innervation

RAPD: what happens normally when light is shined to the diseased eye

both eyes dilate instead of constrict

RAPD: why does both eyes dilate instead of constrict when light is shine to diseased eye?

due to deactivation of parasympathetic nerve as a result of reduced perception of light

three neurons involved in efferent pathway

first (central) neurons, second (pre ganglionic) neuron, third (post ganglionic) neuron

which neuron is pre ganglionic in the efferent pathway

second

which neuron is post ganglionic in the efferent pathway

third

the efferent pathway involves __ nerve to __ muscle

sympathetic, dilator

the first (central) neuron of the efferent pathway extends from ______ to terminate in ____

posterior hypothalamus, ciliospinal center of Budge (C8-T2)

what is the range for the ciliospinal center of Budge

C8 to T2

the second (pre ganglionic) axons extends from ____ to _____

ciliospinal centre, superior cervical ganglion

the third (post ganglionic) neuron extends from _____ to enter _____ and joins _____

cervical ganglion, cavernous sinus, ophthalmic division of trigeminal nerve.

from ciliary ganglion, the third (post ganglionic) neurons innervates _____ muscle via _____ and ____ nerve

dilator, nasociliary, long ciliary

arterial supply for iris/uveal tract

short and long posterior ciliary arteries, anterior ciliary arteries

origin of short posterior ciliary arteries

15-20 arteries

where can we find short posterior ciliary arteries

around optic nerve

entry of short posterior ciliary arteries

encircle optic nerve

anastomosis (opening) of short posterior ciliary arteries

circle of zinn

pathway for short posterior ciliary arteries

they travel in suprachoroidal space

supply of short posterior ciliary arteries

branch to choroid of uvea and a little to ciliary body

entry of long posterior ciliary arteries

lateral and medial arteries to short ciliary ring

pathway of long posterior ciliary arteries

between sclera and choroid to anterior globe

branching of long posterior ciliary arteries

enter ciliary body and branch superiorly and inferiorly

anastomosis (opening) of long posterior ciliary arteries

with each other and anterior ciliary arteries

formation of long posterior ciliary arteries

create major arterial circle of iris

entry of anterior ciliary arteries

seven anterior ciliary arteries

the seven anterior ciliary arteries in anterior ciliary arteries are derived from ______ of the ______

muscular branches, ophthalmic artery

arteries of ____ only give rise to one anterior ciliary arteries

lateral rectus muscle

anterior ciliary arteries reach ____ to form ____ and give branches

episclera, plexus

the anterior ciliary arteries pierce ____ near the ____ to enter the ____

sclera, limbus uveal tissue

anastomosis of anterior ciliary arteries and what does it form

with long posterior ciliary arteries to form major arterial circle of iris

branching of anterior ciliary arteries from _____ enter ____ and anastomoses with each other to form _____

major arterial circle, iris, minor arterial circle

branches from major arterial circle enter from where and anastomoses with each other to form minor arterial circle

iris

branches from major arterial circle enter from iris and anastomoses with each other to form __

minor arterial circle

The root of the iris the major arterial circle is formed by ____ and ___

anterior and long posterior ciliary arteries

the major arterial circle gives off small _____ branches that converges towards the ___

radial, pupillary margin of iris

the major arterial circle is contained as ____ within _____ of the ____ tissue

radial coils, tube-like formations, stromal

At the level of the collarette of iris, the ______ anastomose with each other and form the _____ of iris.

radial arteries, minor arterial circle

when pupil is constricted, the blood flow from _____ of the iris in the direction of the _____

major circle, iris arterioles

when pupil is constricted, where does the blood go

pupillary region

since dilation of pupil where the iris vessels are tortuous (twisted up together), where does blood flow tend towards

the ciliary processes

when pupil is dilated, the physical bunching of iris is closer to where

the root of iris region

venous drainage of iris: small veins from the pupillary margin form __

minor venous circle

from the minor venous circle, the larger veins empty blood into __

vorticose/vortex veins

from the vorticose/vortex veins, which vein does the blood of iris drain into

jugular vein

there are no ____ junctions in iris

tight

in the iris, the tight junctions are found on __

vascular endothelial cells

Iris capillaries are _____ type

non-fenestrated impermeable

Trauma can cause ______ leading to cells or blood in the ____.

rupture of the arterial circle, anterior chamber

where is the ciliary body anatomically

middle part of the uveal tract between the iris and the choroid

dimensions of ciliary body

5-6 mm wide ring

the ciliary body ring runs along the ______ of the globe with a _____ in cross-section

inner wall, triangular shape

two anatomical zones of the ciliary body

pars plicata and pars plana

how much does the pars plicata take up in ciliary body

the anterior 1/3

how much does the pars plana take up in ciliary body

posterior 2/3

how many processes are there in pars plicata

70-80

describe physical structure of ciliary processes

Delicate finger-like protrusion with major and minor processes

layers of ciliary processes (6)

Network of Capillaries (venules, arterioles)

Stroma

Doubled layers epithelium: Pigmented epithelium and Non-pigmented epithelium

Internal limiting membrane

types of capillaries in ciliary processes

fenestrated

which epithelium layer is more brown in ciliary processes

pigmented epithelium

how is ciliary processes oriented

radially oriented

the folded membrane arrangement of epithelium in ciliary processes provides a _____ for ____ and ___.

large surface area, absorption, secretion

layers of ciliary body from outwards to inwards

supraciliary lamina

stroma

pigmented epithelium

non-pigmented epithelium

internal limiting membrane

name the tissue of supraciliary lamina, the layers they are arranged in

loose connective tissue arranged in ribbonlike layers

supraciliary lamina is attached to __

sclera

stroma in ciliary body contains what muscle

ciliary muscle

which structure contributes to main thickness of ciliary body

stroma