Visual pathway

Question 1

Pathway of light entering eye, 1st, 2nd, 3rd order neurons

Answer 1

Retinal receptors activated - bipolar, horizontal and amacrine cells - ganglion cells - optic disc - pierce sclera - optic nerve

Question 2

Pathway of optic nerve

Answer 2

Decussate in optic disc partly - optic tract - lateral geniculate body

Question 3

4th order neuron

Answer 3

lateral geniculate body - geniculostriate neurons - ipsilateral striate cortex

Question 4

Decussation in optic chiasma

Answer 4

fibers from temporal half of retina ipsilaterally in optic tract
fibers from nasal half of retina decussate to contralateral optic tract

Question 5

Pupillary light reflex

Answer 5

collaterals from optic tract -
terminate in pretectal area -
cross in posterior commissure -
axons to Edinger-Westphal nucleus -
preganglionic fibers of oculomotor nerve to ciliary ggl -
postganglionic fibers short ciliary to sphincter pupillae muscle

Question 6

Superior colliculus as subcortical reflex center

Answer 6

LGB,visual cortex, spinal cord - superior colliculus - tectospinal tract - anterior funiculus - moves head parallel with moving objects crossing visual field

Question 7

Convergence reflex

Answer 7

Retina - optic tract - pretectal nucleus - oculomotor nerve - medial rectus muscle

Question 8

Corneal reflex/ Blinking reflex

Answer 8

nasociliary branch - ophthalmic nerve - trigeminal ganglion - spinal trigeminal nucleus - (medial longitudinal fasciculus) - facial nucleus -> motor respons - orbiculari oculi

Question 9

Visual pathway lesions

Answer 9

1. Total blindness in ipsilateral eye: optic nerve lesion
2. Bitemporal heteronyomous hemianopsia: middle of optic chiasma
3. Ipsilateral nasal hemianopsia: one side of chiasma
4. Contralateral homonymous hemianopsia: optic tract
5. Contralateral lower quadrantic anopsia: upper radiations
6. Contralateral upper quadrantic anopsia: lower radiation
7. Contralateral homonymous hemianopsia with macular sparing: all radiations

Question 10

Accommodation reflex

Answer 10

Retina - optic tract - pretectal nucleus - Edinger-Westphal nucleus - ciliary ganglion - ciliary muscle + sphincter pupillae