Introduction
The visual pathway is a part of the brain, because all its components originate there, including the optic nerve. The visual pathway begins at the retina, whose ganglion cells are the starting point, and ends in the visual cortex in the cerebrum. Its complex structure enables us to see.
Anatomy of the visual path
The structure of the human visual path is very complex. It begins at the rear pole of each eye and ends in the cerebral cortex of the cerebrum. The first nerve cells belonging to the visual path are already found in the retina.
The ganglion cells of the retina unite to form the optic nerve and exit the orbit. The optic nerve consists of two different parts of fiber bundles. When we look at the retina, it can be divided into a lateral (outer) and medial or nasal (inner, towards the nose) part.
Accordingly, the following results when the beginning of the visual path is schematically viewed from above: In the right eye, the lateral part of the retina is located on the right and the nasal part on the left, whereas in the left eye it is exactly the opposite. Understanding this fact is essential for understanding the further course of the visual path. At first, the fiber bundles of the nerve cells of the retina of the respective eye attach themselves to each other, partly crossing each other, only to reunite a little later in another combination.
The branching point is called the optic chiasma. Here, only the fibers that represent the respective nasal retinal sections cross. After crossing, the fibers of the corresponding sides of the retina run along each side of the optic tract.
The right optic tractus now carries the fibers of the right half of the retina, the left tractus carries those of the left half. In other words: The uncrossed fibers of the right eye and the crossed fibers of the left eye are now united in the right optic tractus. These retinal sections correspond to the left halves of the visual field. The uncrossed fibers of the left eye and the crossed fibers of the right eye unite in the left tractus opticus, which corresponds to the right halves of the visual field.
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