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Optic Tract
In neuroanatomy, the optic tract () is a part of the visual system in the brain. 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. It is composed of two individual tracts, the left optic tract and the right optic tract, each of which conveys visual information exclusive to its respective contralateral half of the visual field. Each of these tracts is derived from a combination of temporal and nasal retinal fibers from each eye that corresponds to one half of the visual field. In more specific terms, the optic tract contains fibers from the ipsilateral temporal hemiretina and contralateral nasal hemiretina. Anatomy Arterial supply The optic tract receives arterial supply from the anterior choroidal artery, and posterior communicating artery. Function Visual function The optic tract carries retinal information relating to the whole visua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optic Nerve
In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual system, visual information from the retina to the brain. 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 area, pretectal nuclei, and superior colliculus. Structure The optic nerve has been classified as the second of twelve paired cranial nerves, but it is technically a myelinated tract of the central nervous system, rather than a classical nerve of the peripheral nervous system because it is derived from an out-pouching of the diencephalon (optic stalks) during embryonic development. As a consequence, the fibers of the optic nerve are covered with myelin produced by oligodendrocytes, r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elsevier
Elsevier ( ) is a Dutch academic publishing company specializing in scientific, technical, and medical content. Its products include journals such as ''The Lancet'', ''Cell (journal), Cell'', the ScienceDirect collection of electronic journals, ''Trends (journals), Trends'', the ''Current Opinion (Elsevier), Current Opinion'' series, the online citation database Scopus, the SciVal tool for measuring research performance, the ClinicalKey search engine for clinicians, and the ClinicalPath evidence-based cancer care service. Elsevier's products and services include digital tools for Data management platform, data management, instruction, research analytics, and assessment. Elsevier is part of the RELX Group, known until 2015 as Reed Elsevier, a publicly traded company. According to RELX reports, in 2022 Elsevier published more than 600,000 articles annually in over 2,800 journals. As of 2018, its archives contained over 17 million documents and 40,000 Ebook, e-books, with over one b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bistratified Cell
Bistratified cell or bistratified ganglion cell can refer to either of two kinds of retinal ganglion cells whose cell body is located in the ganglion cell layer of the retina: * the small bistratified cell (SBC), also known as small-field bistratified ganglion cell * the large bistratified cell (LBC) or large-field bistratified ganglion cell Bistratified cells receive their input from bipolar cells and amacrine cells. The bistratified cells project their axons through the optic nerve and optic tract to the koniocellular layers in the lateral geniculate nucleus (LGN), synapsing with koniocellular cells. Koniocellular means "cells as small as dust"; their small size made them hard to find. About 8 to 10% of retinal ganglion cells are bistratified cells. They receive inputs from intermediate numbers of rods and cones. They have moderate spatial resolution, moderate conduction velocity, and can respond to moderate-contrast stimuli. They may be involved in color vision. See also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophthalmic Nerve
The ophthalmic nerve (CN V1) is a sensory nerve of the head. It is one of three divisions of the trigeminal nerve (CN V), a cranial nerve. It has three major branches which provide sensory innervation to the eye, and the skin of the upper face and anterior scalp, as well as other structures of the head. Structure Origin The ophthalmic nerve is the first branch of the trigeminal nerve (CN V), the first and smallest of its three divisions. It arises from the superior part of the trigeminal ganglion. Course It passes anterior-ward along the lateral wall of the cavernous sinus inferior to the oculomotor nerve (CN III) and trochlear nerve (N IV). It exits the skull into the orbit through the superior orbital fissure. Branches Within the skull, the ophthalmic nerve produces: * meningeal branch (tentorial nerve) The ophthalmic nerve divides into three major branches which pass through the superior orbital fissure: * frontal nerve ** supraorbital nerve ** supratrochlea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optic Nerve
In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual system, visual information from the retina to the brain. 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 area, pretectal nuclei, and superior colliculus. Structure The optic nerve has been classified as the second of twelve paired cranial nerves, but it is technically a myelinated tract of the central nervous system, rather than a classical nerve of the peripheral nervous system because it is derived from an out-pouching of the diencephalon (optic stalks) during embryonic development. As a consequence, the fibers of the optic nerve are covered with myelin produced by oligodendrocytes, r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marcus Gunn Pupil
A relative afferent pupillary defect (RAPD), also known as a Marcus Gunn pupil (after Robert Marcus Gunn), is a medical sign observed during the swinging-flashlight test whereupon the patient's pupils excessively dilate when a bright light is swung from the unaffected eye to the affected eye. The affected eye still senses the light and produces pupillary sphincter constriction to some degree, albeit reduced. Depending on severity, different symptoms may appear during the swinging flash light test: Mild RAPD initially presents as a weak pupil constriction, after which dilation occurs. When RAPD is moderate, pupil size initially remains same, after which it dilates. When RAPD is severe, the pupil dilates quickly. Cause The most common cause of Marcus Gunn pupil is a lesion of the optic nerve (between the retina and the optic chiasm) due to glaucoma, a severe retinal disease, or due to multiple sclerosis. It is named after Scottish ophthalmologist Robert Marcus Gunn. A s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corpus Callosotomy
A corpus callosotomy () is a palliative surgical procedure for the treatment of medically refractory epilepsy. The procedure was first performed in 1940 by William P. van Wagenen. In this procedure, the corpus callosum is cut through, in an effort to limit the spread of epileptic activity between the two halves of the brain. Although the corpus callosum is the largest white matter tract connecting the hemispheres, some limited interhemispheric communication is still possible via the anterior and posterior commissures. After the operation, however, the brain often struggles to send messages between hemispheres, which can lead to side effects such as speech irregularities, disconnection syndrome, and alien hand syndrome. History The first instances of corpus callosotomy were performed in the 1940s by William P. van Wagenen, who co-founded and served as president of the American Association of Neurological Surgeons. Attempting to treat epilepsy, van Wagenen studied and publ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Split-brain
Split-brain or callosal syndrome is a type of disconnection syndrome when the corpus callosum connecting the two hemispheres of the brain is severed to some degree. It is an association of symptoms produced by disruption of, or interference with, the connection between the hemispheres of the brain. The surgical operation to produce this condition ( corpus callosotomy) involves transection of the corpus callosum, and is usually a last resort to treat refractory epilepsy. Initially, partial callosotomies are performed; if this operation does not succeed, a complete callosotomy is performed to mitigate the risk of accidental physical injury by reducing the severity and violence of epileptic seizures. Before using callosotomies, epilepsy is instead treated through pharmaceutical means. After surgery, neuropsychological assessments are often performed. After the right and left brain are separated, each hemisphere will have its own separate perception, concepts, and impulses to act ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homonymous Hemianopsia
Hemianopsia, or hemianopia, is a visual field loss on the left or right side of the vertical midline. It can affect one eye but usually affects both eyes. Homonymous hemianopsia (or homonymous hemianopia) is hemianopic visual field loss on the same side of both eyes. Homonymous hemianopsia occurs because the right half of the brain has visual pathways for the left hemifield of both eyes, and the left half of the brain has visual pathways for the right hemifield of both eyes. When one of these pathways is damaged, the corresponding visual field is lost. Signs and symptoms Paris as seen with right homonymous hemianopsia Mobility can be difficult for people with homonymous hemianopsia. "Patients frequently complain of bumping into obstacles on the side of the field loss, thereby bruising their arms and legs." People with homonymous hemianopsia often experience discomfort in crowds. "A patient with this condition may be unaware of what he or she cannot see and frequently bumps ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pupillary Light Reflex
The pupillary light reflex (PLR) or photopupillary reflex is a reflex that controls the diameter of the pupil, in response to the intensity ( luminance) of light that falls on the retinal ganglion cells of the retina in the back of the eye, thereby assisting in adaptation of vision to various levels of lightness/darkness. A greater intensity of light causes the pupil to constrict ( miosis/myosis; thereby allowing less light in), whereas a lower intensity of light causes the pupil to dilate ( mydriasis, expansion; thereby allowing more light in). Thus, the pupillary light reflex regulates the intensity of light entering the eye. Light shone into one eye will cause both pupils to constrict. Terminology The pupil is the dark circular opening in the center of the iris and is where light enters the eye. By analogy with a camera, the pupil is equivalent to aperture, whereas the iris is equivalent to the diaphragm. It may be helpful to consider the ''Pupillary reflex'' as an Iris ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1204 Optic Nerve Vs Optic Tract
1 (one, unit, unity) is a number, numeral, and glyph. It is the first and smallest positive integer of the infinite sequence of natural numbers. This fundamental property has led to its unique uses in other fields, ranging from science to sports, where it commonly denotes the first, leading, or top thing in a group. 1 is the unit of counting or measurement, a determiner for singular nouns, and a gender-neutral pronoun. Historically, the representation of 1 evolved from ancient Sumerian and Babylonian symbols to the modern Arabic numeral. In mathematics, 1 is the multiplicative identity, meaning that any number multiplied by 1 equals the same number. 1 is by convention not considered a prime number. In digital technology, 1 represents the "on" state in binary code, the foundation of computing. Philosophically, 1 symbolizes the ultimate reality or source of existence in various traditions. In mathematics The number 1 is the first natural number after 0. Each natural number, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Posterior Communicating Artery
In human anatomy, the left and right posterior communicating arteries are small arteries at the base of the brain that form part of the circle of Willis. Anteriorly, it unites with the internal carotid artery (ICA) (prior to the terminal bifurcation of the ICA into the anterior cerebral artery and middle cerebral artery); posteriorly, it unites with the posterior cerebral artery. With the anterior communicating artery, the posterior communicating arteries establish a system of collateral circulation in cerebral circulation. Anatomy The arteries contribute to the blood supply of the optic tract. The two posterior communicating arteries often differ in size. Relations Each posterior communicating artery is situated within the interpeduncular cistern, superolateral to the pituitary gland. Each are is situated upon the medial surface of the ipsilateral cerebral peduncle and adjacent to the anterior perforated substance. The ipsilateral oculomotor nerve (CN III) passes inferol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
