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External Medullary Lamina
Medullary laminae of thalamus are layers of myelinated fibres that appear on cross sections of the thalamus. They also are commonly referred to as laminae medullares thalami or medullary layers of thalamus. The specific layers are: *Lamina medullaris lateralis (external medullary lamina) - separates ventral and lateral thalamus from the subthalamus and thalamic reticular nucleus *Lamina medullaris medialis (internal medullary lamina) - positioned between the dorsomedial and ventral nuclei of thalamus, encloses the intralaminar nuclei (centromedian nucleus In the anatomy of the brain, the centromedian nucleus, also known as the centrum medianum, (CM or Cm-Pf) is a part of the intralaminar thalamic nuclei (ITN) in the thalamus. There are two centromedian nuclei arranged bilaterally. In humans, it c ..., paracentral, and central lateral) External links * References Thalamus {{neuroanatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myelin
Myelin is a lipid-rich material that surrounds nerve cell axons (the nervous system's "wires") to insulate them and increase the rate at which electrical impulses (called action potentials) are passed along the axon. The myelinated axon can be likened to an electrical wire (the axon) with insulating material (myelin) around it. However, unlike the plastic covering on an electrical wire, myelin does not form a single long sheath over the entire length of the axon. Rather, myelin sheaths the nerve in segments: in general, each axon is encased with multiple long myelinated sections with short gaps in between called nodes of Ranvier. Myelin is formed in the central nervous system (CNS; brain, spinal cord and optic nerve) by glial cells called oligodendrocytes and in the peripheral nervous system (PNS) by glial cells called Schwann cells. In the CNS, axons carry electrical signals from one nerve cell body to another. In the PNS, axons carry signals to muscles and glands or fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thalamus
The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, allowing hub-like exchanges of information. It has several functions, such as the relaying of sensory signals, including motor signals to the cerebral cortex and the regulation of consciousness, sleep, and alertness. Anatomically, it is a paramedian symmetrical structure of two halves (left and right), within the vertebrate brain, situated between the cerebral cortex and the midbrain. It forms during embryonic development as the main product of the diencephalon, as first recognized by the Swiss embryologist and anatomist Wilhelm His Sr. in 1893. Anatomy The thalamus is a paired structure of gray matter located in the forebrain which is superior to the midbrain, near the center of the brain, with nerve fibers projecting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ventral
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of anatomical planes and anatomical axes. The meaning of terms that are used can change depending on whether an organism is bipedal or quadrupedal. Additionally, for some animals such as invertebrates, some terms may not have any meaning at all; for example, an animal that is radially symmetrical will have no anterior surface, but can still have a description that a part is close to the middle ("proximal") or further from the middle ("distal"). International organisations have determined vocabularies that are often used as standard vocabularies for subdisciplines of anatom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Anatomical Terms
Anatomical terminology is a form of scientific terminology used by anatomists, zoologists, and health professionals such as doctors. Anatomical terminology uses many unique terms, suffixes, and prefixes deriving from Ancient Greek and Latin. These terms can be confusing to those unfamiliar with them, but can be more precise, reducing ambiguity and errors. Also, since these anatomical terms are not used in everyday conversation, their meanings are less likely to change, and less likely to be misinterpreted. To illustrate how inexact day-to-day language can be: a scar "above the wrist" could be located on the forearm two or three inches away from the hand or at the base of the hand; and could be on the palm-side or back-side of the arm. By using precise anatomical terminology such ambiguity is eliminated. An international standard for anatomical terminology, '' Terminologia Anatomica'' has been created. Word formation Anatomical terminology has quite regular morphology: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subthalamus
The subthalamus or prethalamus is a part of the diencephalon. Its most prominent structure is the subthalamic nucleus. The subthalamus connects to the globus pallidus, a basal nucleus of the telencephalon. Structure The subthalamus is located ventral to the thalamus, medial to the internal capsule and lateral to the hypothalamus. It is a region formed by several grey matter nuclei and their associated white matter structures, namely: *The subthalamic nucleus, whose neurons contain glutamate and have excitatory effects over neurons of globus pallidus and substantia nigra *Zona incerta, located between fields of Forel H1 and H2. It is continuous with the thalamic reticular nucleus and receives input from the precentral cortex. * Subthalamic fasciculus, formed by fibers that connect the globus pallidus with the subthalamic nucleus * Fields of Forel * Ansa lenticularis During development the subthalamus is continuous with the hypothalamus, but is separated by white matte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thalamic Reticular Nucleus
The thalamic reticular nucleus is part of the ventral thalamus that forms a capsule around the thalamus laterally. However, recent evidence from mice and fish question this statement and define it as a dorsal thalamic structure. It is separated from the thalamus by the external medullary lamina. Reticular cells are GABAergic, and have discoid dendritic arbors in the plane of the nucleus. Thalamic Reticular Nucleus is variously abbreviated TRN, RTN, NRT, and RT. Input and output The thalamic reticular nucleus receives input from the cerebral cortex and dorsal thalamic nuclei. Most input comes from collaterals of fibers passing through the thalamic reticular nucleus. Primary thalamic reticular nucleus efferent fibers project to dorsal thalamic nuclei, but never to the cerebral cortex. This is the only thalamic nucleus that does not project to the cerebral cortex, instead it modulates the information from other nuclei in the thalamus. Its function is modulatory on signals going th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centromedian Nucleus
In the anatomy of the brain, the centromedian nucleus, also known as the centrum medianum, (CM or Cm-Pf) is a part of the intralaminar thalamic nuclei (ITN) in the thalamus. There are two centromedian nuclei arranged bilaterally. In humans, it contains about 2000 neurons per cubic millimetre and has a volume of about 310 cubic millimetres with 664,000 neurons in total. Input and output It sends nerve fibres to the subthalamic nucleus and putamen. It receives nerve fibres from the cerebral cortex, vestibular nuclei, globus pallidus, superior colliculus, reticular formation, and spinothalamic tract. Function Its physiological role involves attention and arousal, including control of the level of cortical activity. Some frequencies of extracellular electrical stimulation of the centromedian nucleus can cause absence seizures (temporary loss of consciousness) although electrical stimulation can be of therapeutic use in intractable epilepsy and Tourette's syndrome. Specifically, cen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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