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Cerebella
The cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cerebellum plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language as well as emotional control such as regulating fear and pleasure responses, but its movement-related functions are the most solidly established. The human cerebellum does not initiate movement, but contributes to coordination, precision, and accurate timing: it receives input from sensory systems of the spinal cord and from other parts of the brain, and integrates these inputs to fine-tune motor activity. Cerebellar damage produces disorders in fine movement, equilibrium, posture, and motor learning in humans. Anatomically, the human cerebellum has the appearance of a separate structure attached to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Purkinje Cell
Purkinje cells, or Purkinje neurons, are a class of GABAergic inhibitory neurons located in the cerebellum. They are named after their discoverer, Czech people, Czech anatomist Jan Evangelista Purkyně, who characterized the cells in 1839. Structure These Cell (biology), cells are some of the largest neurons in the human brain (Betz cells being the largest), with an intricately elaborate dendrite, dendritic arbor, characterized by a large number of dendritic spines. Purkinje cells are found within the Cerebellum#Microanatomy, Purkinje layer in the cerebellum. Purkinje cells are aligned like dominos stacked one in front of the other. Their large dendritic arbors form nearly two-dimensional layers through which parallel fibers from the deeper-layers pass. These parallel fibers make relatively weaker excitatory synapse, excitatory (glutamatergic) synapses to spines in the Purkinje cell dendrite, whereas climbing fibers originating from the inferior olivary nucleus in the medull ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cerebellum Granule Cell
Cerebellar granule cells form the thick granular layer of the cerebellar cortex and are among the smallest neurons in the brain. (The term granule cell is used for several unrelated types of small neurons in various parts of the brain.) Cerebellar granule cells are also the most numerous neurons in the brain: in humans, estimates of their total number average around 50 billion, which means that they constitute about 3/4 of the brain's neurons. Structure The cell bodies are packed into a thick granular layer at the bottom of the cerebellar cortex. A granule cell emits only four to five dendrites, each of which ends in an enlargement called a ''dendritic claw''. These enlargements are sites of excitatory input from mossy fibers and inhibitory input from Golgi cells. The thin, unmyelinated axons of granule cells rise vertically to the upper (molecular) layer of the cortex, where they split in two, with each branch traveling horizontally to form a parallel fiber; the splittin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superior Cerebellar Artery
The superior cerebellar artery (SCA) is an artery of the head. It arises near the end of the basilar artery. It is a branch of the basilar artery. It supplies parts of the cerebellum, the midbrain, and other nearby structures. It is the cause of trigeminal neuralgia in some patients. Structure The superior cerebellar artery arises near the end of the basilar artery. It passes laterally around the brainstem. This is immediately below the oculomotor nerve, which separates it from the posterior cerebral artery. It then winds around the cerebral peduncle, close to the trochlear nerve. It also lies close to the cerebellar tentorium. When it arrives at the upper surface of the cerebellum, it divides into branches which ramify in the pia mater and anastomose with those of the anterior inferior cerebellar arteries and the posterior inferior cerebellar arteries. Several branches are given to the pineal body, the anterior medullary velum, and the tela chorioidea of the third ventricle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anterior Inferior Cerebellar Artery
The anterior inferior cerebellar artery (AICA) is one of three pairs of arteries that supplies blood to the cerebellum. It arises from the basilar artery on each side at the level of the junction between the medulla oblongata and the pons in the brainstem. It has a variable course, passing backward to be distributed to the anterior part of the undersurface of the cerebellum, anastomosing with both the posterior inferior cerebellar (PICA) branch of the vertebral artery and the superior cerebellar artery. It also gives off the internal auditory or labyrinthine artery in most cases; however, the labyrinthine artery can less commonly emerge as a branch of the basilar artery. The amount of tissue supplied by the AICA is variable, depending upon whether the PICA is more or less dominant, but usually includes the anteroinferior surface of the cerebellum, the flocculus, middle cerebellar peduncle and inferolateral portion of the pons. Clinical significance Occlusion of AICA is conside ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superior Cerebellar Veins
The cerebellar veins are veins which drain the cerebellum. They consist of the superior cerebellar veins and the inferior cerebellar veins (dorsal cerebellar veins). The superior cerebellar veins drain to the straight sinus and the internal cerebral veins. The inferior cerebellar veins drain to the transverse sinus, the superior petrosal sinus, and the occipital sinus. Structure The superior cerebellar veins pass partly forward and medialward, across the superior cerebellar vermis. They end in the straight sinus, and the internal cerebral veins, partly lateralward to the transverse and superior petrosal sinuses. The inferior cerebellar veins are larger. They end in the transverse sinus, the superior petrosal sinus, and the occipital sinus. Clinical significance The cerebellar veins may be affected by infarction or thrombosis Thrombosis (from Ancient Greek "clotting") is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inferior Cerebellar Veins
The cerebellar veins are veins which drain the cerebellum. They consist of the superior cerebellar veins and the inferior cerebellar veins (dorsal cerebellar veins). The superior cerebellar veins drain to the straight sinus and the internal cerebral veins. The inferior cerebellar veins drain to the transverse sinus, the superior petrosal sinus, and the occipital sinus. Structure The superior cerebellar veins pass partly forward and medialward, across the superior cerebellar vermis. They end in the straight sinus, and the internal cerebral veins, partly lateralward to the transverse and superior petrosal sinuses. The inferior cerebellar veins are larger. They end in the transverse sinus, the superior petrosal sinus, and the occipital sinus. Clinical significance The cerebellar veins may be affected by infarction or thrombosis Thrombosis (from Ancient Greek "clotting") is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Equilibrioception
The sense of balance or equilibrioception is the perception of balance and spatial orientation. It helps prevent humans and nonhuman animals from falling over when standing or moving. Equilibrioception is the result of a number of sensory systems working together; the eyes (visual system), the inner ears (vestibular system), and the body's sense of where it is in space (proprioception) ideally need to be intact. The vestibular system, the region of the inner ear where three semicircular canals converge, works with the visual system to keep objects in focus when the head is moving. This is called the vestibulo-ocular reflex (VOR). The balance system works with the visual and skeletal systems (the muscles and joints and their sensors) to maintain orientation or balance. Visual signals sent to the brain about the body's position in relation to its surroundings are processed by the brain and compared to information from the vestibular and skeletal systems. Vestibular system In the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cerebral Hemisphere
The vertebrate cerebrum (brain) is formed by two cerebral hemispheres that are separated by a groove, the longitudinal fissure. The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres has an outer layer of grey matter, the cerebral cortex, that is supported by an inner layer of white matter. In eutherian (placental) mammals, the hemispheres are linked by the corpus callosum, a very large bundle of nerve fibers. Smaller commissures, including the anterior commissure, the posterior commissure and the fornix, also join the hemispheres and these are also present in other vertebrates. These commissures transfer information between the two hemispheres to coordinate localized functions. There are three known poles of the cerebral hemispheres: the ''occipital pole'', the ''frontal pole'', and the ''temporal pole''. The central sulcus is a prominent fissure which separates the parietal lobe from the frontal lobe and the prim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a vertebrate's body. In a human, the cerebral cortex contains approximately 14–16 billion neurons, and the estimated number of neurons in the cerebellum is 55–70 billion. Each neuron is connected by synapses to several thousand other neurons. These neurons typically communicate with one another by means of long fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells. Physiologically, brains exert centralized control over a body's other organs. They act on the rest of the body both by generating patterns of muscle activity and by driving the secretion of chemicals called hormones. This centralized control allows rapid and coordinated respon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Positions
Human positions refer to the different physical configurations that the human body can take. There are several synonyms that refer to human positioning, often used interchangeably, but having specific nuances of meaning. *''Position'' is a general term for a configuration of the human body. *''Posture'' means an intentionally or habitually assumed position. *''Pose'' implies an artistic, aesthetic, athletic, or spiritual intention of the position. *''Attitude'' refers to postures assumed for purpose of imitation, intentional or not, as well as in some standard collocations in reference to some distinguished types of posture: "Freud never assumed a fencer's attitude, yet almost all took him for a swordsman." *''Bearing'' refers to the manner of the posture, as well as of gestures and other aspects of the conduct taking place. Basic positions While not moving, a human is usually in one of the following basic positions: All-fours This is the static form of crawling which is ins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motor Learning
Motor learning refers broadly to changes in an organism's movements that reflect changes in the structure and function of the nervous system. Motor learning occurs over varying timescales and degrees of complexity: humans learn to walk or talk over the course of years, but continue to adjust to changes in height, weight, strength etc. over their lifetimes. Motor learning enables animals to gain new skills, and improves the smoothness and accuracy of movements, in some cases by calibrating simple movements like reflexes. Motor learning research often considers variables that contribute to motor program formation (i.e., underlying skilled motor behaviour), sensitivity of error-detection processes, and strength of movement schemas (see motor program). Motor learning is "relatively permanent", as the capability to respond appropriately is acquired and retained. Temporary gains in performance during practice or in response to some perturbation are often termed motor adaptation, a transi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accordion
Accordions (from 19th-century German ''Akkordeon'', from ''Akkord''—"musical chord, concord of sounds") are a family of box-shaped musical instruments of the bellows-driven free-reed aerophone type (producing sound as air flows past a reed in a frame), colloquially referred to as a squeezebox. A person who plays the accordion is called an accordionist. The concertina , harmoneon and bandoneón are related. The harmonium and American reed organ are in the same family, but are typically larger than an accordion and sit on a surface or the floor. The accordion is played by compressing or expanding the bellows while pressing buttons or keys, causing ''pallets'' to open, which allow air to flow across strips of brass or steel, called '' reeds''. These vibrate to produce sound inside the body. Valves on opposing reeds of each note are used to make the instrument's reeds sound louder without air leaking from each reed block.For the accordion's place among the families of musical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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