3. The Afferent Pathway
Optic tract
Nasal Fibers decussate in optic chiasm
Travels centrally along the optic nerve
Ganglion cells
Rods and cones AND
Melanopsin Retinal Ganglion cells
4. The Afferent Pathway(contd.)
The Accessory motar nuclei of
EW nucleus
New relay fibers partially cross
over
Pretectal Nucleus
Midbrain from Lateral side of
Superior colliculus
5. The Efferent Pathway
Located inferiorly as it enters the
orbit
Passes laterally to petroclinod
ligament and dorsum sellae
Lie on the superficial dorsomedial
aspect as it leave the brain stem
The axons of the EW nucleus extend
into the III n.
8. Pathway of Convergence Reflex
Fibers form Medial Rectus m.
via III n.
Mesencephalic n. of V n.
Convergence Center in Tectal
or Pre Tectal Region
EW Nucleus
Efferent fibers travel along III
n.
Relay in Accessory Ganglion
Sphincter Pupillae
9. Pathway of Accommodation Reflex
Retina
Via Optic nerve,
Chaisma Optic Tract
Lateral Geniculate
Body
Striate Cortex
From the Para
Striate Cortex
Via
Occipitomesencephalic
Tract and Pontine center
EW Nucleus
Via III n. to
Sphincter Pupillae
Editor's Notes
Melanopsin Retinal Ganglion cells act via the input received from the rods and cones but also a direct transduction of light invokes a light reflex.
Fibers pass into the midbrain from the lateral side of superior colliculus
Reach the Pretectal nucleus where they terminate.
New relay fibers partially cross the posterior commisurae ,go ventrally from the aqueduct
They reach the Accessory motar nuclei of EW nucleus on both Ipsilateral and contra lateral side
From the inferior division of the III n. by the way of its branch to Inf Oblique m .
A short and a thick nerve trunk reaches the ciliary ganglion.
Myelinated PG PS terminate in synapses with ganglionic neurons.
The PG fibers innervate the sphincter pupillae.through the short ciliary
Affeerent fibers from MR via III n.
To Mesencephalic nuclei of 5th n
To convergence center in Tectal or Pre Tectal region
From convergence center to EW nucleus
Efferent fibers travel along the III n.
Relay in accessory ganglion
Reaches the sphincter pupillae
From Retina to Para striate cortex
Via ON,chiasma,OT, LGB,optic radiation and Striate cortex
Relay the impulses from para striate cortex to EW nucleus of both sides
Via the occipito mesencephalic tract and the pontine center
Efferent fibers travel along the III n.
Relay in accessory ganglion
Reaches the sphincter pupillae
