Optic chiasm

The optic chiasm ( from the Greek χίασμα, chiasm, " crossing ", from the Greek letter Chi, and the Latinized form of the Greek οπτικό ( ν ), optiko (s), " the vision concerning " ), and the optic nerve (s) crossing, is the term for an anatomical intersection of the optic nerves from the right and left eye. In the optic chiasm, the nerve fibers cross each of the nose upward situated sensory cells of the retina to the opposite cerebral hemisphere. This nose- forward sensory cells located only perceive light, which of temporal upward reaches the retinas due to the imaging properties of the eye. This gives the right hemisphere only visual impressions of the left halves of the field for processing and vice versa. The degree of crossing fibers is different for each of vertebrates.

Status within the visual pathway

Visual information that is out of the retina ( retina) was added, leaving the eye through the blind spot as optic nerve.

The degree of cross-over within the chiasm, which follows Hereupon, is different in the animal kingdom. In humans and primates cross about half of all nerve fibers, which allows an optimal binocular (spatial ) vision. When predators cruising about 75 % of the fibers in ungulates 90%. In birds, cross almost all fibers, only when owls there are only 60-70%. In amphibians cross usually 100 % of the fibers.

Like any sensory information, apart from the smell, is also the first optical via the thalamus - precisely the dorsal aspect of the lateral geniculate body - passed before it reaches the cerebral cortex, in this case the visual cortex.

Topography

The optic chiasm is located in front of the pituitary gland (pituitary gland ), which is why, for example, tumors of the pituitary gland can lead to vision problems such as the optic chiasm syndrome.