A report on Optic nerve

The left optic nerve and the optic tracts.
A fundus photograph showing the back of the retina. The white circle is the beginning of the optical nerve.
MRI scan of human eye showing optic nerve.
The ophthalmic artery derived from internal carotid artery and its branches. (optic nerve is yellow)
Superficial dissection of brain-stem. Lateral view.
Dissection of brain-stem. Lateral view.
Scheme showing central connections of the optic nerves and optic tracts.
Nerves of the orbit. Seen from above.
Nerves of the orbit, and the ciliary ganglion. Side view.
The terminal portion of the optic nerve and its entrance into the eyeball, in horizontal section.
Structures of the eye labeled
This image shows another labeled view of the structures of the eye
Optic nerve.Deep dissection.Inferior view.
Optic nerve.Deep dissection.Inferior view.
Optic nerve
Optic nerve
Human brain dura mater (reflections)
Optic nerve
Optic nerve
Optic nerve
Cerebrum.Inferior view.Deep dissection
Cerebral peduncle, optic chasm, cerebral aqueduct. Inferior view. Deep dissection.

Paired cranial nerve that transmits visual information from the retina to the brain.

- Optic nerve
The left optic nerve and the optic tracts.

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Right human eye cross-sectional view; eyes vary significantly among animals.

Retina

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Innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs.

Innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs.

Right human eye cross-sectional view; eyes vary significantly among animals.
Section of retina
Rods, cones and nerve layers in the retina. The front (anterior) of the eye is on the left. Light (from the left) passes through several transparent nerve layers to reach the rods and cones (far right). A chemical change in the rods and cones send a signal back to the nerves. The signal goes first to the bipolar and horizontal cells (yellow layer), then to the amacrine cells and ganglion cells (purple layer), then to the optic nerve fibres. The signals are processed in these layers. First, the signals start as raw outputs of points in the rod and cone cells. Then the nerve layers identify simple shapes, such as bright points surrounded by dark points, edges, and movement. (Based on a drawing by Ramón y Cajal, 1911.)
Illustration of the distribution of cone cells in the fovea of an individual with normal colour vision (left), and a colourblind (protanopic) retina. Note that the center of the fovea holds very few blue-sensitive cones.
Distribution of rods and cones along a line passing through the fovea and the blind spot of a human eye
Time-Domain OCT of the macular area of a retina at 800 nm, axial resolution 3 µm
Spectral-Domain OCT macula cross-section scan.
macula histology (OCT)
Fundus photograph showing the blood vessels in a normal human retina. Veins are darker and slightly wider than corresponding arteries. The optic disc is at right, and the macula lutea is near the centre.
On-centres and off-centres of the retina
frameless
frameless
The structures of the eye labeled
Another view of the eye and the structures of the eye labeled
Illustration of image as 'seen' by the retina independent of optic nerve and striate cortex processing.

The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then processes that image within the retina and sends nerve impulses along the optic nerve to the visual cortex to create visual perception.

Diagram showing cross-section of retinal layers. The area labeled "Ganglionic layer" contains retinal ganglion cells

Retinal ganglion cell

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Type of neuron located near the inner surface (the ganglion cell layer) of the retina of the eye.

Type of neuron located near the inner surface (the ganglion cell layer) of the retina of the eye.

Diagram showing cross-section of retinal layers. The area labeled "Ganglionic layer" contains retinal ganglion cells
Diagram showing cross-section of retinal layers. The area labeled "Ganglionic layer" contains retinal ganglion cells
A false-color image of a flat-mounted rat retina viewed through a fluorescence microscope at 50x magnification. The optic nerve was injected with a fluorophore, causing retinal ganglion cells to fluoresce.

These axons form the optic nerve, optic chiasm, and optic tract.

The visual system includes the eyes, the connecting pathways through to the visual cortex and other parts of the brain (human system shown).

Visual system

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The visual system includes the eyes, the connecting pathways through to the visual cortex and other parts of the brain (human system shown).
This diagram linearly (unless otherwise mentioned) tracks the projections of all known structures that allow for vision to their relevant endpoints in the human brain. Click to enlarge the image.
Representation of optic pathways from each of the 4 quadrants of view for both eyes simultaneously.
The human eye (horizontal section)
The image projected onto the retina is inverted due to the optics of the eye.
S. Ramón y Cajal, Structure of the Mammalian Retina, 1900
Information flow from the eyes (top), crossing at the optic chiasma, joining left and right eye information in the optic tract, and layering left and right visual stimuli in the lateral geniculate nucleus. V1 in red at bottom of image.
(1543 image from Andreas Vesalius' Fabrica)
Six layers in the LGN
Scheme of the optic tract with image being decomposed on the way, up to simple cortical cells (simplified).
Visual cortex:
V1; V2; V3; V4; V5 (also called MT)
Visual cortex is active even during resting state fMRI.
Intraparietal sulcus (red)
Visual pathway lesions 
From top to bottom: 1. Complete loss of vision Right eye 2. Bitemporal hemianopia 3. Homonymous hemianopsia 4. Quadrantanopia 5&6 Quadrantanopia with macular sparing

The visual system comprises the sensory organ (the eye) and parts of the central nervous system (the retina containing photoreceptor cells, the optic nerve, the optic tract and the visual cortex) which gives organisms the sense of sight (the ability to detect and process visible light) as well as enabling the formation of several non-image photo response functions.

Functional parts of the rods and cones, which are two of the three types of photosensitive cells in the retina

Photoreceptor cell

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Specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction.

Specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction.

Functional parts of the rods and cones, which are two of the three types of photosensitive cells in the retina
Normalized human photoreceptor absorbances for different wavelengths of light
Illustration of the distribution of cone cells in the fovea of an individual with normal color vision (left), and a color blind (protanopic) retina. Note that the center of the fovea holds very few blue-sensitive cones.
Distribution of rods and cones along a line passing through the fovea and the blind spot of a human eye
The absorption of light leads to an isomeric change in the retinal molecule.
3D medical illustration of the rod and cone structure of photoreceptors.

The axons of ganglion cells form the two optic nerves.

Brain viewed from below; the front of the brain is above. Visual pathway with optic chiasm (X shape) is shown in red (image from Andreas Vesalius' Fabrica, 1543).

Optic chiasm

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Brain viewed from below; the front of the brain is above. Visual pathway with optic chiasm (X shape) is shown in red (image from Andreas Vesalius' Fabrica, 1543).
Transformations of the visual field toward the visual map on the primary visual cortex.
Scheme showing central connections of the optic nerves and optic tracts.
Brain seen from below, with the optic chiasm seen in yellow in the centre.
Brain and brainstem seen from below
Left hemisphere of the brain seen in a cadaveric specimen from the side, with the optic chiasm labelled.
Cerebrum, inferior view, deep dissection.
Guidance of axon crossing and non-crossing during development.

The optic chiasm, or optic chiasma (Greek: χίασμα, "crossing", from the Greek χιάζω, "to mark with an X", after the Greek letter "Chi"), is the part of the brain where the optic nerves cross.

Ophthalmoscopy photograph showing the optic disc as a bright area on the right where blood vessels converge.

Optic disc

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Point of exit for ganglion cell axons leaving the eye.

Point of exit for ganglion cell axons leaving the eye.

Ophthalmoscopy photograph showing the optic disc as a bright area on the right where blood vessels converge.
Ophthalmoscopy photograph showing the optic disc as a bright area on the right where blood vessels converge.
Schematic diagram of the human eye, with the optical disc, or blind spot, at the bottom.
Optic disc cross-sections imaged by an SD-OCT.
Blood flow in the optic disc revealed by holographic laser Doppler imaging.
Local direction of blood flow with respect to the optical axis revealed by the Doppler spectrum asymmetry in out-of-plane retinal vessels by holographic laser Doppler imaging.
Three dimensional image of a healthy optic disc in a 24-year-old female.
alt=High detail picture of optic disc.|Optic disc showing microvasculature.
Tilted optic disc in left eye of a 20-year-old male.
Optic disc edema and haemorrhage

The ganglion cell axons form the optic nerve after they leave the eye.

Left View of the human brain from below, showing origins of cranial nerves. Right Juxtaposed skull base with foramina in which many nerves exit the skull.

Cranial nerves

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Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), of which there are conventionally considered twelve pairs.

Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), of which there are conventionally considered twelve pairs.

Left View of the human brain from below, showing origins of cranial nerves. Right Juxtaposed skull base with foramina in which many nerves exit the skull.
The oculomotor (III), troclear (IV) and abducens (VI) nerves supply the muscle of the eye. Damage will affect the movement of the eye in various ways, shown here.
The facial nerve (VII) supplies the muscles of facial expression. Damage to the nerve causes a lack of muscle tone on the affected side, as can be seen on the right side of the face here.
A damaged glossopharyngeal nerve (IX) may cause the uvula to deviate to the affected side.
The cranial nerves in the horse.
Ventral view of a sheep's brain. The exits of the various cranial nerves are marked with red.

The terminal nerves (0), olfactory nerves (I) and optic nerves (II) emerge from the cerebrum, and the remaining ten pairs arise from the brainstem, which is the lower part of the brain.

Schematic diagram showing the central nervous system in yellow, peripheral in orange

Central nervous system

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Part of the nervous system consisting primarily of the brain and spinal cord.

Part of the nervous system consisting primarily of the brain and spinal cord.

Schematic diagram showing the central nervous system in yellow, peripheral in orange
Dissection of a human brain with labels showing the clear division between white and gray matter.
Diagram of the columns and of the course of the fibers in the spinal cord. Sensory synapses occur in the dorsal spinal cord (above in this image), and motor nerves leave through the ventral (as well as lateral) horns of the spinal cord as seen below in the image.
Different ways in which the CNS can be activated without engaging the cortex, and making us aware of the actions. The above example shows the process in which the pupil dilates during dim light, activating neurons in the spinal cord. The second example shows the constriction of the pupil as a result of the activation of the Eddinger-Westphal nucleus (a cerebral ganglion).
A map over the different structures of the nervous systems in the body, showing the CNS, PNS, autonomic nervous system, and enteric nervous system.
Schematic image showing the locations of a few tracts of the spinal cord.
Reflexes may also occur without engaging more than one neuron of the CNS as in the below example of a short reflex.
Diagram depicting the main subdivisions of the embryonic vertebrate brain, later forming forebrain, midbrain and hindbrain.
Development of the neural tube

In vertebrates, the CNS also includes the retina and the optic nerve (cranial nerve II), as well as the olfactory nerves and olfactory epithelium.

Schematic diagram of the human eye, with the fovea at the bottom. It shows a horizontal section through the right eye.

Fovea centralis

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Small, central pit composed of closely packed cones in the eye.

Small, central pit composed of closely packed cones in the eye.

Schematic diagram of the human eye, with the fovea at the bottom. It shows a horizontal section through the right eye.
Time-domain OCT of the macular area of a retina at 800 nm, axial resolution 3 µm
Spectral-domain OCT macula cross-section scan
Macula histology (OCT)
Diagram showing the relative acuity of the left human eye (horizontal section) in degrees from the fovea
Photograph of the retina of the human eye, with overlay diagrams showing the positions and sizes of the macula, fovea, and optic disc
Illustration of the distribution of cone cells in the fovea of an individual with normal color vision (left), and a color blind (protanopic) retina. Note that the center of the fovea holds very few blue-sensitive cones.
Distribution of rods and cones along a line passing through the fovea and the blind spot of a human eye
Illustration showing main structures of the eye including the fovea
Structures of the eye labeled
This image shows another labeled view of the structures of the eye
Schematic diagram of the macula lutea of the retina, showing perifovea, parafovea, fovea, and clinical macula
A fundus photograph showing the macula as a spot to the left. The optic disc is the area on the right where blood vessels converge. The grey, more diffuse spot in the centre is a shadow artifact.

Approximately half the nerve fibers in the optic nerve carry information from the fovea, while the remaining half carry information from the rest of the retina.

The left optic nerve and the optic tracts.

Optic tract

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Part of the visual system in the brain.

Part of the visual system in the brain.

The left optic nerve and the optic tracts.
Diagram of hippocampus
Schematic diagram of the primate lateral geniculate nucleus.
Superficial dissection of brain-stem. Ventral view.
Coronal section of brain through intermediate mass of third ventricle.
Hind- and mid-brains; postero-lateral view.
Scheme showing central connections of the optic nerves and optic tracts.
Base of brain.
Section of brain showing upper surface of temporal lobe.
Dissection showing the course of the cerebrospinal fibers.
Human brainstem anterior view
Optic tract and optic nerve
Optic tract
Cerebrum. Deep dissection. Inferior dissection.
Cerebral peduncle, optic chasm, cerebral aqueduct. Inferior view. Deep dissection.
Cerebral peduncle, optic chasm, cerebral aqueduct. Inferior view. Deep dissection.
Cerebrum.Inferior view.Deep dissection.
Cerebrum.Inferior view.Deep dissection.
Cerebrum.Inferior view.Deep dissection.
Cerebrum. Inferior view.Deep dissection
Cerebrum. Inferior view.Deep dissection

It is a continuation of the optic nerve that relays information from the optic chiasm to the ipsilateral lateral geniculate nucleus (LGN), pretectal nuclei, and superior colliculus.