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Decussate
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 stem whe ... [...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] |
Opposite Leaves
In botany, phyllotaxis () or phyllotaxy is the arrangement of leaves on a plant stem. Phyllotactic spirals form a distinctive class of patterns in nature. Leaf arrangement The basic arrangements of leaves on a stem are opposite and alternate (also known as spiral). Leaves may also be whorled if several leaves arise, or appear to arise, from the same level (at the same node) on a stem. With an opposite leaf arrangement, two leaves arise from the stem at the same level (at the same node), on opposite sides of the stem. An opposite leaf pair can be thought of as a whorl of two leaves. With an alternate (spiral) pattern, each leaf arises at a different point (node) on the stem. Distichous phyllotaxis, also called "two-ranked leaf arrangement" is a special case of either opposite or alternate leaf arrangement where the leaves on a stem are arranged in two vertical columns on opposite sides of the stem. Examples include various bulbous plants such as ''Boophone''. It also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phyllotaxis
In botany, phyllotaxis () or phyllotaxy is the arrangement of leaves on a plant stem. Phyllotactic spirals form a distinctive class of patterns in nature. Leaf arrangement The basic arrangements of leaves on a stem are opposite and alternate (also known as spiral). Leaves may also be whorled if several leaves arise, or appear to arise, from the same level (at the same node) on a stem. With an opposite leaf arrangement, two leaves arise from the stem at the same level (at the same node), on opposite sides of the stem. An opposite leaf pair can be thought of as a whorl of two leaves. With an alternate (spiral) pattern, each leaf arises at a different point (node) on the stem. Distichous phyllotaxis, also called "two-ranked leaf arrangement" is a special case of either opposite or alternate leaf arrangement where the leaves on a stem are arranged in two vertical columns on opposite sides of the stem. Examples include various bulbous plants such as ''Boophone''. It also ... [...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] |
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] |
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] |
Tooth Enamel
Tooth enamel is one of the four major tissues that make up the tooth in humans and many other animals, including some species of fish. It makes up the normally visible part of the tooth, covering the crown. The other major tissues are dentin, cementum, and dental pulp. It is a very hard, white to off-white, highly mineralised substance that acts as a barrier to protect the tooth but can become susceptible to degradation, especially by acids from food and drink. Calcium hardens the tooth enamel. In rare circumstances enamel fails to form, leaving the underlying dentin exposed on the surface. Features Enamel is the hardest substance in the human body and contains the highest percentage of minerals (at 96%),Ross ''et al.'', p. 485 with water and organic material composing the rest.Ten Cate's Oral Histology, Nancy, Elsevier, pp. 70–94 The primary mineral is hydroxyapatite, which is a crystalline calcium phosphate. Enamel is formed on the tooth while the tooth develops wit ... [...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] |
Vertebrates
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with currently about 69,963 species described. Vertebrates comprise such groups as the following: * jawless fish, which include hagfish and lampreys * jawed vertebrates, which include: ** cartilaginous fish (sharks, rays, and ratfish) ** bony vertebrates, which include: *** ray-fins (the majority of living bony fish) *** lobe-fins, which include: **** coelacanths and lungfish **** tetrapods (limbed vertebrates) Extant vertebrates range in size from the frog species '' Paedophryne amauensis'', at as little as , to the blue whale, at up to . Vertebrates make up less than five percent of all described animal species; the rest are invertebrates, which lack vertebral columns. The vertebrates traditionally include the hagfish, wh ... [...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] |
Crassula Rupestris-PICT3087
''Crassula'' is a genus of succulent plants containing about 200 accepted species, including the popular jade plant (''Crassula ovata''). They are members of the stonecrop family (Crassulaceae) and are native to many parts of the globe, but cultivated varieties originate almost exclusively from species from the Eastern Cape of South Africa. Crassulas are usually propagated by stem or leaf cuttings. Most cultivated forms will tolerate some small degree of frost, but extremes of cold or heat will cause them to lose foliage and die. Taxonomy ''Crassula'' was first formally described by Carl Linnaeus in 1753 with 10 species. Etymology The name crassula comes from the Latin adjective ''crassus'', meaning thick, referring to the thickening of the succulent leaves. List of selected species *''Crassula alata'' *'' Crassula alba'' *'' Crassula alpestris'' (Sand-Coated Crassula) *''Crassula alstonii'' *''Crassula aquatica'' (common pigmyweed, water pygmyweed) *'' Crassula arbore ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
