CN II Optic Nerve

Authors

Affiliations

Nate 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

Figure 1: Optic Nerve and Tract¹

Left optic nerve²

Schematic of optic nerves and optic tract²

Nerves of the Orbit²

Figure 2: Segregation of Visual Field information at the Optic Chiasm¹

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

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.

References

1.

Betts JG, Blaker W. Anatomy and Physiology. 2nd ed. OpenStax; 2022. https://openstax.org/details/books/anatomy-and-physiology-2e/?Book%20details

2.

Gray H. Anatomy of the Human Body. 20th ed. (Lewis WH, ed.). Lea & Febiger; 1918. https://www.bartleby.com/107/