CN II: Optic Nerve.

Question 1

Optic Nerve

Answer 1

• contains axons from retinal ganglion cells in the epithelia of the eye
• these axons come together within the eye to exit at the optic disc at the posterior aspect of the eye.

Question 2

optic chiasm

Answer 2

• The optic nerves run along the basal surface of the brain until they come together at the optic chiasm.
• at the optic chiasm, the axons from the nasal hemiretina of each eye cross to the other side of the brain…this allows the information the right visual field to all be sent to the left side of the brain, and information from the left visual field to all be sent to the right side of the brain.

Question 3

Papilledema

Answer 3

• swelling of the optic disc due to an increase in intracranial pressure.
• Because the optic nerve is surrounded by the meningeal layers of the brain, and is therefore continuous with the brain, an increase in intracranial pressure will cause a distortion of the optic disc in the retina; this interferes with vision and may produce blindness if it occurs for an extended period of time.

Question 4

How might an increase in intracranial pressure arise?

Answer 4

produced by pathology such as a tumor, hydrocephalus, or by injury

Question 5

optic tract

Answer 5

-caudal to the optic chiasm, the novel combination of axons is referred to as the

Question 6

lateral geniculate nucleus

Answer 6

Most of these axons from the optic tract briefly continue in a caudal direction entering the brain and ending in the lateral geniculate nucleus of the thalamus

Question 7

Where do thalamic LateralGeniculateNucleus neurons convey information?

Answer 7

to V-1 (primary visual cortex) via the optic radiations, which terminate in the caudo-medial portions of the occipital lobe.

Question 8

Axons from the optic tract that don’t terminate in the caudomedial portions of the occipital lobe. terminate where?

Answer 8

most of the remaining axons in the optic tract terminate in the ipsilateral superior colliculus and play a role in the unconscious detection of stimuli, shifts in attention, and guidance of movements.