CN II Optic Nerve

Authors

Affiliations

Nathaniel Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

• Type: Sensory
• Function: vision (color, acuity, peripheral vision, pupillary light reflex)
• Dysfunction:
  • Blindness
  • Myopia (nearsightedness)
  • Presbyopia (farsightedness, the person needs reading glasses)

flowchart TD
  A[Retina] -- Vision --> B[Optic Canal]
  B --> C[\Optic Chiasm/]
  C --> D[Lateral Geniculate nucleus of the Thalamus]
  C --> E[Extrageniculate pathways]
  
  D --> F[Optic Radiation]
  E --> F

  F --> G[Visual Cortex]
  G --> H{Vision}

Overview

CN II Optic Nerve is the only cranial nerve that is used to transmit information about vision to the brain. CN II is considered part of the CNS since it is myelinated using oligodendrocytes

Pathway

Optic tract

• Left optic tract:
  • Fibers: Left temporal (lateral) retina
  • Fibers: Right nasal (medial) retina
• Right optic tract
  • Fibers: right temporal retina
  • Fibers: Left nasal retina
• Optic tract -> Lateral geniculate nucleus (relay system in thalamus) -> Optic radiation
  • Upper optic radiation: Fibers from Superior Retinal Quadrants (inferior visual field) -> visual cortex
  • Lower Optic Radiation: Fibers from Inferior retinal quadrants (superior visual field) -> Visual cortex

1. Retinal photoreceptors
2. Retinal bipolar neurons
3. (Synapse) Retinal ganglion cells
4. Optic nerve (Optic canal)
5. (Decussate) Optic chiasm
6. Optic tract
7. (Synapse) Lateral geniculate nucleus in Thalamus ->
8. Optic radiations -> Occipital cortex

Pupillary light reflex

The optic n. is involved in the afferent aspect of the pupillary light reflex.

Dysfunction

• Multiple sclerosis

Multiple sclerosis

The optic nerve can be damaged in multiple scerosis since it is myelinated by oligodendrocytes.