Lecture 31- Optic Nerve Part I

A bundle of more than one million retinal ganglion cell (RGC) axons that transmit visual signals from the retina to the brain.

Optic Nerve

Segments of the Optic Nerve

Intraocular, prelaminar, laminar, retrolaminar, intraorbital, intracanalicular, and intracranial

Shortest segment of the optic nerve, located within the eye

Intraocular Segment

Part of the optic nerve containing glial tissue that provides support to RGC axons

Prelaminar Region

Sieve-like structure that allows the RGC axons to exit the eye and become myelinated

Lamina Cribrosa

Longest segment of the optic nerve, allowing for eye movement without stretching

Intraorbital Segment

Condition in which the intraorbital segment is stretched taut, causing the eyeball to protrude from the orbit

Proptosis

Point where the optic nerves from both eyes meet and partially cross paths

Optic Chiasm

Protective meningeal layers covering the optic nerve

Dura mater, arachnoid, and pia mater

Blood supply to the optic nerve’s intraocular segment

Posterior ciliary arteries

Area on the retina where there are no photoreceptors, corresponding to the optic nerve head

Physiologic Blind Spot

Measurement for assessing the health of the optic nerve; typically ranges from 0.1 to 0.8

Cup to Disc Ratio

Process by which the optic nerve converts visual signals into neural impulses

Signal Transduction

Ocular reflexes triggered by visual stimulation

Light reflex and accommodative reflex

Biological processes that cycle daily, influenced by changes in light intensity

Circadian Rhythms

Neurons in the retina that collect visual information and transmit it to the brain.

Retinal Ganglion Cells (RGCs)

Process of transporting materials down the axon from the cell body to the terminal

Anterograde Transport

Transport of materials from the axon terminal back to the cell body

Retrograde Transport

Primary excitatory neurotransmitter used by bipolar cells and RGCs in the retina

Glutamate

Supporting cells in the retina that help regulate the retinal environment and remove excess glutamate

Retinal Müller Cells

Area of the optic disc surrounded by the cup and formed by RGC axons

Neuroretinal Rim

Glial cells that provide structural support and maintain the blood-brain barrier in the optic nerve

Astrocytes

A thickened internal limiting membrane over the optic cup

Central Meniscus of Kuhnt

Peripheral retinal barrier composed of retinal Müller cells and ONH astrocytes

ILM of Elschnig

Glial tissue named after Kuhnt that has significance in optic nerve structure.

Intermediary Tissue of Kuhnt

Separates the choroid from the optic nerve

Border Tissue of Jacoby

Scleral collagenous tissue involved in the structure of the optic nerve

Border Tissue of Elschnig

Study of RGCs and their synaptic and action potential activities

Axon Physiology

Arrangement of RGC axons in the optic nerve to facilitate information transmission

Axon Bundles Organization

RGC axons that bypass the fovea to enter the optic disc superiorly and inferiorly

Temporal Macular Fibers

Axonal fibers carrying information from the macula into the temporal half of the optic disc.

Papillomacular Bundle

Crossing of nasal retinal fibers at the optic chiasm during optic nerve organization

Nasal Fibers Decussation

Optic nerve damage can negatively affect the light reflex, triggered by visual stimuli

Light Reflex Impact

Reflex that adjusts the eye's focus for near and distant vision, influenced by optic nerve function.

Accommodative Reflex

Process through which visual information is relayed from the retina to the brain via the optic nerve

Visual Signal Transmission