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Decussation
Decussation is used in biological contexts to describe a crossing (due to the shape of the Roman numeral for ten, an uppercase 'X' (), ). In Latin anatomical terms, the form is used, e.g. . Similarly, the anatomical term chiasma is named after the Greek uppercase 'Χ' (chi). Whereas a decussation refers to a crossing within the central nervous system, various kinds of crossings in the peripheral nervous system are called chiasma. Examples include: * In the brain, where nerve fibers obliquely cross from one lateral side of the brain to the other, that is to say they cross at a level other than their origin. See for examples Decussation of pyramids and sensory decussation. In neuroanatomy, the term ''chiasma'' is reserved for crossing of- or within nerves such as in the optic chiasm. * In botanical leaf taxology, the word ''decussate'' describes an opposite pattern of leaves which has successive pairs at right angles to each other (i.e. rotated 90 degrees along the st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensory Decussation
In neuroanatomy, the sensory decussation or decussation of the lemnisci is a decussation (i.e. crossover) of axons from the gracile nucleus and cuneate nucleus, which are responsible for fine touch, vibration, proprioception and two-point discrimination of the body. The fibres of this decussation are called the internal arcuate fibres and are found at the superior aspect of the closed medulla superior to the motor decussation. It is part of the second neuron in the posterior column–medial lemniscus pathway. Structure At the level of the closed medulla in the posterior white column, two large nuclei namely the gracile nucleus and the cuneate nucleus can be found. The two nuclei receive the impulse from the two ascending tracts: fasciculus gracilis and fasciculus cuneatus. After the two tracts terminate upon these nuclei, the heavily myelinated fibres arise and ascend anteromedially around the periaqueductal gray as internal arcuate fibres. These fibres decussate (cross) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decussation Of Pyramids
In neuroanatomy, the medullary pyramids are paired white matter structures of the brainstem's medulla oblongata that contain motor fibers of the corticospinal and corticobulbar tracts – known together as the pyramidal tracts. The lower limit of the pyramids is marked when the fibers cross ( decussate). Structure The ventral portion of the medulla oblongata contains the medullary pyramids. These two ridge-like structures travel along the length of the medulla oblongata and are bordered medially by the anterior median fissure. They each have an anterolateral sulcus along their lateral borders, where the hypoglossal nerve emerges from. Also at the side of each pyramid there is a pronounced bulge known as an olive. Fibers of the posterior column, which transmit sensory and proprioceptive information, are located behind the pyramids on the medulla oblongata. The medullary pyramids contain motor fibers that are known as the corticobulbar and corticospinal tracts. The cortico ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contralateral Brain
The contralateral organization of the forebrain ( Latin: contra‚ against; latus‚ side; lateral‚ sided) is the property that the hemispheres of the cerebrum and the thalamus represent mainly the contralateral side of the body. Consequently, the left side of the forebrain mostly represents the right side of the body, and the right side of the brain primarily represents the left side of the body. The contralateral organization involves both executive and sensory functions (e.g., a left-sided brain lesion may cause a right-sided hemiplegia). The contralateral organization is present in all vertebrates but in no invertebrate. According to the current theory, the forebrain is twisted about the long axis of the body, so that not only the left and right sides, but also dorsal and ventral sides, are interchanged. (See below.) Anatomy Anatomically, the contralateral organization is manifested by major decussations (based upon the Latin notation for ten, 'deca,' as an up ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anatomical Terms Of Neuroanatomy
This article describes anatomical terminology that is used to describe the central and peripheral nervous systems - including the brain, brainstem, spinal cord, and nerves. Anatomical terminology in neuroanatomy Neuroanatomy, like other aspects of anatomy, uses specific terminology to describe anatomical structures. This terminology helps ensure that a structure is described accurately, with minimal ambiguity. Terms also help ensure that structures are described consistently, depending on their structure or function. Terms are often derived from Latin and Greek, and like other areas of anatomy are generally standardised based on internationally accepted lexicons such as Terminologia Anatomica. To help with consistency, humans and other species are assumed when described to be in ''standard anatomical position'', with the body standing erect and facing observer, arms at sides, palms forward. Location Anatomical terms of location depend on the location and species that is bei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chiasm (anatomy)
In anatomy a chiasm is the spot where two structures cross, forming an X-shape (). This can be: * A ''tendinous chiasm'' is the spot where two tendons cross. For example, the tendon of the flexor digitorum superficialis muscle, and the tendon of the flexor digitorum longus muscle which even forms two chiasms. * In neuroanatomy, a chiasm is the crossing of fibres of a nerve or the crossing of two nerves. Very different types of crossings of nerves are referred to as chiasm: * Type I : Two nerves can ''cross one over the other'' (sagittal plane) without fusing, e.g., the trochlear nerve (see figure). * Type II :Two nerves can ''merge'' while at least part of the fibres cross the midline (see figure 2). * Type III : The fibres ''within'' a single nerve cross, such that the order of the functional map is reversed, e.g., the optic chiasms of various invertebrates such as insects and cephalopods. * Type IV : A torsion or loop by 180 degrees of a nerve can also reverse the order o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optic Chiasm
In neuroanatomy, the optic chiasm, or optic chiasma (; , ), is the part of the brain where the optic nerves cross. It is located at the bottom of the brain immediately inferior to the hypothalamus. The optic chiasm is found in all vertebrates, although in cyclostomes (lampreys and hagfishes), it is located within the brain. 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)). A midline crossing of nerves inside the brain is called a decussation (see Definition of types of crossings). Structure For the different types of optic chiasm, see In all vertebrates, the optic nerves of the left and the right eye meet in the body midline, ventral to the brain. In many vertebrates the left optic nerve crosses over the right one without fusing with it. In vertebrates with a large overlap of the visual fields of the two eyes, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commissure
A commissure () is the location at which two objects abut or are joined. The term is used especially in the fields of anatomy and biology. * The most common usage of the term refers to the brain's commissures, of which there are five. Such a commissure is a bundle of commissural fibers as a tract that crosses the midline at its level of origin or entry (as opposed to a decussation of fibers that cross obliquely). The five are the anterior commissure, posterior commissure, corpus callosum, commissure of fornix (hippocampal commissure), and habenular commissure. They consist of fibre tracts that connect the two cerebral hemispheres and span the longitudinal fissure. In the spinal cord there are the anterior white commissure, and the gray commissure. ''Commissural neurons'' refer to neuronal cells that grow their axons across the midline of the nervous system within the brain and the spinal cord. * ''Commissure'' also often refers to cardiac anatomy of heart valves. In the hear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dysdercus Decussatus (13476425975)
''Dysdercus'' is a widespread genus of true bugs in the family Pyrrhocoridae; a number of species attacking cotton bolls may be called "cotton stainers". Description Species may be confused with bugs in the family Lygaeidae, but can be distinguished by the lack of ocelli on the head. They can be readily distinguished from most other genera of Pyrrhocoridae by the strong white markings at the junction of the head and thorax, and along the sides of the thorax, and often abdomen. Species ''BioLib'' lists the following: ; subgenus ''Dysdercus'' Guérin-Méneville, 1831 * '' Dysdercus andreae'' (Linnaeus, 1758) * ''Dysdercus bimaculatus'' (Stål, 1854) * ''Dysdercus cardinalis'' Gerstäcker, 1873 * ''Dysdercus concinnus'' Stål, 1861 * ''Dysdercus fasciatus'' Signoret, 1861 - cotton stainer (Africa) * ''Dysdercus mimulus'' Hussey, 1929 * '' Dysdercus mimus'' (Say, 1832) * ''Dysdercus nigrofasciatus'' Stål, 1855 * '' Dysdercus obliquus'' (Herrich-Schaeffer, 1843) * '' Dysdercus obs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxonomy (biology)
In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given a taxonomic rank; groups of a given rank can be aggregated to form a more inclusive group of higher rank, thus creating a taxonomic hierarchy. The principal ranks in modern use are domain, kingdom, phylum (''division'' is sometimes used in botany in place of ''phylum''), class, order, family, genus, and species. The Swedish botanist Carl Linnaeus is regarded as the founder of the current system of taxonomy, as he developed a ranked system known as Linnaean taxonomy for categorizing organisms and binomial nomenclature for naming organisms. With advances in the theory, data and analytical technology of biological systematics, the Linnaean system has transformed into a system of modern biological classification intended to reflect the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binomial Nomenclature
In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomial name (which may be shortened to just "binomial"), a binomen, name or a scientific name; more informally it is also historically called a Latin name. The first part of the name – the '' generic name'' – identifies the genus to which the species belongs, whereas the second part – the specific name or specific epithet – distinguishes the species within the genus. For example, modern humans belong to the genus '' Homo'' and within this genus to the species '' Homo sapiens''. '' Tyrannosaurus rex'' is likely the most widely known binomial. The ''formal'' introduction of this system of naming species is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ramón Y Cajal
Ramón or Ramon may refer to: People Given name *Ramon (footballer, born 1998), Brazilian footballer * Ramón (footballer, born 1990), Brazilian footballer * Ramón (singer), Spanish singer who represented Spain in the 2004 Eurovision Song Contest *Ramón Blanco y Erenas (1833–1906), Spanish brigadier and colonial administrator of the Philippines *Ramón Castillo (1873-1944), former Argentinian president * Ramon Dekkers, Dutch muay thai fighter * Ramón del Valle-Inclán (1866–1936), Spanish dramatist and novelist * Ramón Díaz, Argentine football player and coach * Ramón H. Dovalina (born 1943), American educator *Ramón Emeterio Betances (1827–1898), Puerto Rican nationalist * Ramón Arellano Félix (1964–2002), Mexican drug lord and fugitive * Ramón Fumadó (born 1981), Venezuelan diver * Ramón Fernando García (born 1972), Colombian road cyclist *Ramón Gerardo Antonio Estévez (born 1940), American actor, using the stage name Martin Sheen *Ramón González (athlete) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
