Overview
Role
- Special sensory (sight).
Optic Nerve Palsy
Abnormalities
- Loss of visual acuity
- Visual field loss
- Loss of light reflexes
- Loss of accommodation
Causes of Optic Nerve Palsy
- Intraorbital - trauma, ischaemia, aneurysm, tumour, optic neuritis, optic nerve hypoplasia
- Optic chiasm - pituitary tumour, craniopharyngioma, pituitary apoplexy
- Optic tract - ischaemia, trauma, tumour, MS
Special Sensory Pathway
Cortical Centre
Primary visual cortex (occipital lobe)
Primary visual cortex (occipital lobe)
Upper Pathway
Optic radiations
(parietal / occipital lobes)
Optic radiations
(parietal / occipital lobes)
Nucleus
Lateral geniculate nucleus (thalamus)
Lateral geniculate nucleus (thalamus)
Lower Pathway
Optic tract
Optic tract
Partial Decussation
Of nasal / temporal visual field
Optic chiasm
Of nasal / temporal visual field
Optic chiasm
Foramen
Optic canal
Optic canal
Bipolar Cells
Retina
Retina
Light Receptors
Rods / cones of retina
Rods / cones of retina
Overview
The optic nerve is encased in meninges, making it the only cranial nerve that is part of the central nervous system. As a result peripheral neuropathies such as Guillain-barré do not affect the optic nerve.
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