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The optic tract 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. [14] The optic tract represents the first stage in the visual pathway in which visual information is transferred in a homonymous nature. [15]
The optic chiasm is found in all vertebrates, although in cyclostomes (lampreys and hagfishes), it is located within the brain. [2] [3] This article is about the optic chiasm of vertebrates, which is the best known nerve chiasm, but not every chiasm denotes a crossing of the body midline (e.g., in some invertebrates, see Chiasm (anatomy)).
Enlargement of the optic nerve along with a downward kink in the mid-orbit is usually observed. [5] While CT scans allow for optic nerve evaluation, MRI allows for intracranial evaluation to observe if the tumor has extended to other regions such as the optic chiasm and hypothalamus. [6]
Clinically, no optic field deficits have been observed in a small series of optic nerve sections at the optic nerve-chiasm junction. [3] Several important structures are located adjacent to the optic chiasm. The supraclinoid branches of the internal carotid artery flank the chiasm. The cavernous sinuses are lateral and inferior to the chiasm.
MRI, CT scan Pilocytic astrocytoma (and its variant pilomyxoid astrocytoma ) is a brain tumor that occurs most commonly in children and young adults (in the first 20 years of life). They usually arise in the cerebellum , near the brainstem , in the hypothalamic region, or the optic chiasm , but they may occur in any area where astrocytes are ...
In humans, the optic nerve is derived from optic stalks during the seventh week of development and is composed of retinal ganglion cell axons and glial cells; it extends from the optic disc to the optic chiasma and continues as the optic tract to the lateral geniculate nucleus, pretectal nuclei, and superior colliculus. [1] [2]
If the part of the nerve between the eye and the chiasm is compressed, the result is vision loss in one eye. If the part after the chiasm is affected, visual loss on one side of the visual field occurs. [2] Adjacent to the pituitary lies a part of the skull base known as the cavernous sinus. This contains a number of nerves that control the eye ...
Bitemporal hemianopsia is the medical description of a type of partial blindness where vision is missing in the outer half of both the right and left visual field. It is usually associated with lesions of the optic chiasm, the area where the optic nerves from the right and left eyes cross near the pituitary gland.