Cosmetic surgeons, who have to be meticulous in identifying the smiles that their patients are paying good money to try to achieve, call these three types commissure, cuspid and complex, respectively.
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The commissural fibers make up tracts that include the corpus callosum, the anterior commissure, and the posterior commissure.
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Commissural tracts enable the left and right sides of the cerebrum to communicate with each other. Other commissures are the hippocampal commissure, and the habenular commissure.
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The commissure is the corner of the mouth, where the vermillion border of the superior labium (upper lip) meets that of the inferior labium (lower lip). The commissure is important in facial appearance, particularly during some functions, including smiling. As such it is of interest to dental surgeons. Diseases that involve the commissure include angular chelitis.
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The labia majora are thicker in front, and form the anterior labial commissure where they meet below the mons pubis. Posteriorly, they are not really joined, but appear to become lost in the neighboring integument, ending close to, and nearly parallel to, each other. Together with the connecting skin between them, they form another commissure the posterior labial commissure which is also the posterior boundary of the pudendum. The interval between the posterior commissure and the anus, from 2.5 to 3 cm in length, constitutes the perineum.
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The anterior commissure (also known as the precommissure) is a tract that connects the two temporal lobes of the cerebral hemispheres across the midline, and placed in front of the columns of the fornix. The great majority of fibers connecting the two hemispheres travel through the corpus callosum, which is over 10 times larger than the anterior commissure, and other routes of communication pass through the hippocampal commissure or, indirectly, via subcortical connections. Nevertheless, the anterior commissure is a significant pathway that can be clearly distinguished in the brains of all mammals. Using diffusion tensor imaging, researchers were able to approximate the location of the anterior commissure where it crosses the midline of the brain.
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The anterior commissure (also known as the precommissure) is a white matter tract (a bundle of axons) connecting the two temporal lobes of the cerebral hemispheres across the midline, and placed in front of the columns of the fornix. The great majority of fibers connecting the two hemispheres travel through the corpus callosum, which is over 10 times larger than the anterior commissure, and other routes of communication pass through the hippocampal commissure or, indirectly, via subcortical connections. Nevertheless, the anterior commissure is a significant pathway that can be clearly distinguished in the brains of all mammals. The anterior commissure plays a key role in pain sensation, more specifically sharp, acute pain.
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The habenular commissure, is a brain commissure (a band of nerve fibers) situated in front of the pineal gland that connects the habenular nuclei on both sides of the diencephalon. The habenular commissure is part of the habenular trigone (a small depressed triangular area situated in front of the superior colliculus and on the lateral aspect of the posterior part of the tænia thalami). The trigonum habenulæ also contains groups of nerve cells termed the ganglion habenulæ. Fibers enter the trigonum habenulæ from the stalk of the pineal gland, and the habenular commissure.
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The lateral portions of the body of the fornix are joined by a thin triangular lamina, named the psalterium (lyra). This lamina contains some commissural fibers that connect the two hippocampi across the middle line and constitute the commissure of fornix (also called the hippocampal commissure). The terminal lamina creates the commissure plate. This structure gives existence to the corpus callosum, the septum pellucidum, and the fornix.
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The grey commissure is a thin strip of grey matter that surrounds the central canal of the spinal cord and, along with the anterior white commissure, connects the two halves of the cord. It comprises lamina X in the Rexed classification.
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The commissure of inferior colliculus, also called the commissure of inferior colliculi is a thin white matter structure consisting of myelinated axons of neurons and joining together the paired inferior colliculi. It is evolutionarily one of the most ancient interhemispheric connections.
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The commissure of superior colliculus, also called the commissure of superior colliculi is a thin white matter structure consisting of myelinated axons of neurons and joining together the paired superior colliculi. It is evolutionarily one of the most ancient interhemispheric connections.
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The posterior commissure (also known as the epithalamic commissure) is a rounded nerve tract crossing the middle line on the dorsal aspect of the upper end of the cerebral aqueduct. It is important in the bilateral pupillary light reflex. Evidence suggests the posterior commissure is a tract that plays a role in language processing between the right and left hemispheres of the brain. It connects the pretectal nuclei.
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This approach involves creating a window at the anterior commissure, which is then displaced posteriorly.
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The ventral supraoptic decussation is the crossover (decussation) point for signals from the left and right eye, en route respectively to the right and left sides of the visual cortex. Occupying the posterior part of the commissure of the optic chiasma is a strand of fibers, the Ventral supraoptic decussation (commissure of Gudden, Gudden's inferior commissure), which is not derived from the optic nerves; it forms a connecting link between the medial geniculate bodies.
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Other studies have built on this to imply that the anterior commissure can be a compensatory pathway in those without a corpus callosum, presenting diffusion tensor imaging (DTI) techniques to better elucidate the anterior commissure and how it might be implicated in various functions (Winter & Franz, 2014).
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It also contains decussating fibers from the olfactory tracts, vital for the sense of smell and chemoreception. The anterior commissure works with the posterior commissure to link the two cerebral hemispheres of the brain and also interconnects the amygdalae and temporal lobes, contributing to the role of memory, emotion, speech and hearing. It also is involved in olfaction, instinct, and sexual behavior. In a sagittal section, the anterior commissure is oval in shape, having a long vertical axis that measures about 5 mm.
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At the same operation he had a Kay-type suture plication tricuspid annuloplasty of the posterior-septal commissure.
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A case study described recently in The Irish Medical Journal discussed the role the posterior commissure plays in the connection between the right occipital cortex and the language centers in the left hemisphere. This study explains how visual information from the left side of the visual field is received by the right visual cortex and then transferred to the word form system in the left hemisphere though the posterior commissure and the splenium. Disruption of the posterior commissure can cause alexia without agraphia. It is evident from this case study of alexia without agraphia that the posterior commissure plays a vital role in transferring information from the right occipital cortex to the language centers of the left hemisphere.
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A Hancock's organ could not be detected. The paired pedal ganglia lie posteroventrally to the cerebral ganglia, and are connected by a commissure which is slightly longer than the cerebral commissure. A statocyst with a single otolith is attached dorsally to each pedal ganglion. The static nerve could not be detected.
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A commissure connects the two cerebral hemispheres at the same levels. Examples are the posterior commissure and the corpus callosum. A decussation is a connection made by fibres that cross at different levels (obliquely), such as the sensory decussation. Examples of a fascicle are the subthalamic fasciculus and the lenticular fasciculus.
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The Talairach coordinate system is defined by making two anchors, the anterior commissure and posterior commissure, lie on a straight horizontal line. Since these two points lie on the midsagittal plane, the coordinate system is completely defined by requiring this plane to be vertical. Distances in Talairach coordinates are measured from the anterior commissure as the origin (as defined in the 1998 edition). The y-axis points posterior and anterior to the commissures, the left and right is the x-axis, and the z-axis is in the ventral-dorsal (down and up) directions.
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The posterior commissure (also known as the epithalamic commissure) is a rounded band of white fibers crossing the middle line on the dorsal aspect of the rostral end of the cerebral aqueduct. It is important in the bilateral pupillary light reflex. Its fibers acquire their medullary sheaths early, but their connections have not been definitively determined. Most of them have their origin in a nucleus, the nucleus of the posterior commissure (nucleus of Darkschewitsch), which lies in the periaqueductal grey at rostral end of the cerebral aqueduct, in front of the oculomotor nucleus.
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In 1840 he coined the term "horseshoe-shaped commissure of Wernekinck" as a name for the decussation of the brachium conjunctivum.
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Visceral commissure is long. There is no jaw. Central tooth of radula is bicuspidate, laterals are unicuspidate and marginals are tricuspidate.
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Averaged tracking results of ten normal controls showing the Anterior Commissure. Image from Winter and Franz (2014) The functionality of the anterior commissure is still not completely understood. Researchers have implicated it in functions ranging from colour perception to attention. One such study supported colour perception in callosal agenesis (Those born without a corpus callosum; Barr & Corballis, 2002).
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The frenulum of labia minora (fourchette or posterior commissure of the labia minora) is a frenulum where the labia minora meet posteriorly.
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Amygdala is shown in purple. The amygdalofugal pathway (Latin for "fleeing from the amygdala" and commonly distinguished as the ventral amygdalofugal pathway) is one of the three principal pathways by which fibers leave the amygdala. The other main efferent pathways from the amygdala are the stria terminalis and anterior commissure. The anterior commissure also serves to connect the two amygdala.
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The hind toe is narrowly lobed. The nostril is small and oval and opens close to the base of the commissure of the bill.
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The posterior commissure is at the top of the photo, and the space below the SCO is part of the third ventricle, which is lined with ependymal cells. Cell nuclei are stained blue. The scale bar = 50 microns (0.05 mm). The name of the SCO comes from its location beneath the posterior commissure, a bundle of nerve fibers interconnecting parts of the two hemispheres of the brain.
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Its vittae are small, with 3-5 in each furrow, 6-10 on commissure. They flower in June to July and fruit from August to September.
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The fornix splits into two columns at the front (anterior pillars), and then splits into two posterior crura. These two crura are joined together through the hippocampal commissure. The beginning of the splitting is called the psalterium or Lyra Davidis. The latter name is used because the structure resembles a lyra (or triangular harp): The two crura are the "chassis" of the lyra, and the commissure connections are the fibers.
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The Arytœnoideus approximates the arytenoid cartilages, and thus closes the aperture of the glottis, especially at its back part to eliminate the posterior commissure of the vocal folds.
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In humans the optic tract, commissure, and optic nerve bridge the substantial distance between eyes and diencephalon. Likewise the pineal stalk of Petromyzon elongates very considerably during metamorphosis.
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The cerebral ganglia are more separated than usual in the Holopoda. The cerebral ganglia are connected by a short narrow commissure; the suboesophageal ganglia are as usual in the Bulimulinae.
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The ventral pallidum lies within the basal ganglia, a group of subcortical nuclei. Along with the external globus pallidus, it is separated from other basal ganglia nuclei by the anterior commissure.
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One edge of the "U," – CA4, is embedded into the backward-facing, flexed dentate gyrus. The hippocampus is described as having an anterior and posterior part (in primates) or a ventral and dorsal part in other animals. Both parts are of similar composition but belong to different neural circuits.Moser and Moser, 1998 In the rat, the two hippocampi resemble a pair of bananas, joined at the stems by the commissure of fornix (also called the hippocampal commissure).
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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 primary motor cortex from the primary somatosensory cortex.
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Corpus callosotomy is a palliative surgical procedure for the treatment of medically refractory epilepsy. 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. After the operation the brain has much more difficulty sending messages between the hemispheres. Although the corpus callosum is the largest white matter tract connecting the hemispheres, some limited interhemispheric communication is still possible via the anterior commissure and posterior commissure.
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Smile surgery is performed as a static or dynamic reconstruction. An example of static reconstruction is upper and lower lip shortening or thickening with commissure preservation. Dynamic smile reconstruction procedures restore the facial nerve activity.
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The orbital portion is thicker and of a reddish color; its fibers form a complete ellipse without interruption at the lateral palpebral commissure; the upper fibers of this portion blend with the frontalis and corrugator.
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Another variation of the procedure consists of a lenticular excision of the white skin surrounding the upper oral commissure in order to lift this part of the lips. This technique has also been dubbed "Smile Lift".
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The oil tubes in the fruit, 3 or 4 vittae, form in wrinkles of ridges of the fruit, while 4 to 8 vittae can be found in commissure. The plant bears fruit from August to September.
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Successful reconstruction of the upper lip attempts to maintain the anatomic relationship of the philtrum (central portion of upper lip) and the base of the nose. Not distorting the commissure is also desirable for upper lip reconstruction.
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The anterior junction of the labia majora is called the anterior commissure, which is below the mons pubis and above the clitoris. To the posterior, the labia majora join at the posterior commissure, which is above the perineum and below the frenulum of the labia minora. The grooves between the labia majora and labia minora are known as the interlabial sulci or interlabial folds. The labia minora (obsolete: nymphae), also called inner labia or inner lips, are two soft folds of fat-free, hairless skin between the labia majora.
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The superior part of the posterior border constitutes the habenular commissure, while more centrally it the pineal gland, which regulates sleep and reacts to light levels. Caudal of the pineal gland is the posterior commissure; nerve fibres reach the posterior commissure from the adjacent midbrain, but their onward connection is currently uncertain. The commissures create concavity to the shape of the posterior ventricle border, causing the suprapineal recess above the habenular, and the deeper pineal recess between the habenular and posterior commissures; the recesses being so-named due to the pineal recess being bordered by the pineal gland. The hypothalmic portion of the third ventricle (upper right), and surrounding structures The anterior wall of the ventricle forms the lamina terminalis, within which the vascular organ monitors and regulates the osmotic concentration of the blood; the cerebrum lies beyond the lamina, and causes it to have a slightly concave shape.
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The anatomic requirements are not as limiting for the lower lip because the surrounding anatomy is less complex. The considerations include maintaining a non-distorted vermillion border, hiding incisions in the horizontal crease of the chin, and not distorting the commissure.
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The pedal ganglia are placed beneath the radula sac and joined together by an anterior and a posterior commissure. The abdominal ganglion lies a little to the right of the median line. The visceral ganglia occupy the angle between the lingual sheath and the oesophagus and the buccal ganglia are widely separated but joined together by a commissure nearly as thick as the ganglia themselves. Reproductive system: The hermaphrodite gland (HG) is elongated and large, and is connected with spermoviduct (SO) by means of the hermaphrodite duct (HD) which takes its course through a portion of the albumen gland (AG).
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It is important to note that because the back section of the callosum is preserved, visual information is still sent across both hemispheres. Though the corpus callosum loses a majority of its functioning during a partial callosotomy, it does not completely lose its capabilities. If this operation does not succeed in reducing the seizures, a complete callosotomy is needed to reduce the severity of the seizures. A similar type of procedure, known as a commissurotomy, involves severing a number of interhemispheric tracts (such as the anterior commissure, the hippocampal commissure and the massa intermedia of the thalamus) in addition to the corpus callosum.
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MRI images of three patients in the sagittal plane. A and B: Complete agenesis of the corpus callosum. C: Complete agenesis of both the corpus callosum and the anterior commissure. Signs and symptoms of ACC and other callosal disorders vary greatly among individuals.
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The anterior commissure serves as the primary mode of interhemispheric communication in marsupials,Ashwell, Ken (2010). The Neurobiology of Australian Marsupials: Brain Evolution in the Other Mammalian Radiation, p. 50Armati, Patricia J., Chris R. Dickman, and Ian D. Hume (2006). Marsupials, p.
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The fibers of the anterior commissure can be traced laterally and posteriorly on either side beneath the striatum into the substance of the temporal lobe. It serves in this way to connect the two temporal lobes, but it also contains decussating fibers from the olfactory tracts, and is a part of the neospinothalamic tract for pain. The anterior commissure also serves to connect the two amygdalae. The corpus callosum allows for communication between the two hemispheres and is found only in placental mammals (the eutherians), while it is absent in monotremes and marsupials, as well as other vertebrates such as birds, reptiles, amphibians and fish.
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The epithalamus is a tiny structure that comprises the habenular trigone, the pineal gland, and the habenular commissure. It is wired with the limbic system and basal ganglia. Species that possess a photoreceptive parapineal organ show asymmetry in the epithalamus at the habenula, to the left (dorsal).
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Depending on its usage, commissure may refer to the junction of the upper and lower mandibles,Coues (1890), p. 155. or alternately, to the full-length apposition of the closed mandibles, from the corners of the mouth to the tip of the beak.Campbell & Lack (1985), p. 105.
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The autopsy showed severe hydrocephalus, abnormal neuronal migration, and a small corpus callosum (which connects the two brain hemispheres) and cerebellum. FAS has also been linked to brainstem and cerebellar changes, agenesis of the corpus callosum and anterior commissure, neuronal migration errors, absent olfactory bulbs, meningomyelocele, and porencephaly.
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The epithalamus is a (dorsal) posterior segment of the diencephalon. The diencephalon is a part of the forebrain that also contains the thalamus, the hypothalamus and pituitary gland. The epithalamus includes the habenular nuclei and their interconnecting fibers, the habenular commissure, the stria medullaris and the pineal gland.
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The columns (anterior pillars; fornicolumns) of the fornix arch downward in front of the interventricular foramina and behind the anterior commissure, and each descends through the grey matter in the lateral wall of the third ventricle to the base of the brain, where it ends in the mammillary bodies.
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Commissural tracts connect corresponding cortical areas in the two hemispheres. They cross from one cerebral hemisphere to the other through bridges called commissures. The great majority of commissural tracts pass through the largest commissure the corpus callosum. A few tracts pass through the much smaller anterior and posterior commissures.
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Living a stationary life attached to substrate in marine and brackish environments, they formed shells of an aragonite composition with a low amount of magnesium calcite. The family was named by King in 1850. At least one genus in the family, Hoernesia, has a notably twisted commissure join.
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As such, the lower concentrations of SCO-spondin in the caudal region favor the axonal outgrowth and incorporation of new axons on the posterior commissure and the higher concentrations in the cephalic region promotes the interactions between the neighboring axons. In conjugation with the secretion of SCO-spondin, the midline positioning of the SCO assumes a great importance on the axon guidance process. This positioning facilitates the signaling of the turning points for the axons, through the spreading of spondin. In addition to the functions in axon guidance and related growth of the posterior commissure, the SCO-spondin also appears to have a role on the adhesion of the trophoblast to the uterine walls.
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Left: In their resting state, the labia protect the inner areas of the vulva. Right: Spreading the labia apart exposes inner areas of the vulva. A) Anterior commissure of labia majora B) Clitoral hood C) Labia minora D) Labia majora E) Posterior commissure of labia majora F) Clitoral glans G) Inner surface of labia majora H) Vulvar vestibule I) Urethra J) Vaginal orifice K) Fourchette The labia majora, also commonly called outer labia or outer lips, are lip-like structures consisting mostly of skin and adipose (fatty) tissue, which extend on either side of the vulva to form the pudendal cleft through the middle. The labia majora often have a plump appearance, and are thicker towards the anterior.
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The general layout or body plan of the pallium is already clearly defined in animals with relatively simple brains, including lampreys, sharks and amphibians. In teleost fish, reptiles, birds, and mammals, the pallial architecture is greatly modified (sharply divergently in fish), with differential growth and specialization of diverse sectors of the conserved pallial Bauplan. In all vertebrate brains, the telencephalic forebrain consists of two hemispheres, joined at the midline by a region called the septum. The septum is continuous with the preoptic area across the plane defined by the anterior commissure; it is largely subpallial, but also contains a small pallial portion, where the hippocampal commissure forms, which is contiguous to the medial pallium.
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The fourth pair of ganglions are the olfactory: they are well developed, though very much smaller than those just described, and are joined by a short commissure to the upper surface of the anterior margins of the cerebroid ganglions. The infra- oesophageal ganglions are placed in the usual situation on the buccal mass, below the oesophagus. The buccal ganglions are scarcely larger than the olfactory, and are of an oval form, their inner extremities being connected across the median line by a short commissure; their outer extremities receive a cord of communication from each of the cerebroid ganglions. Two minute elliptical ganglions are almost sessile on the anterior border of the buccal ganglions; these are the gastro-cesophageal ganglions.
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Erythroleukoplakia ("speckled leukoplakia"), left commissure. Biopsy showed mild epithelial dysplasia and candida infection. Antifungal medication may turn this type of lesion into a homogenous leukoplakia (i.e. the red areas would disappear) Erythroleukoplakia (also termed speckled leukoplakia, erythroleukoplasia or leukoerythroplasia) is a non-homogenous lesion of mixed white (keratotic) and red (atrophic) color.
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Some are thought to be derived from the posterior part of the thalamus and from the superior colliculus, whereas others are believed to be continued downward into the medial longitudinal fasciculus. For the pupillary light reflex, the olivary pretectal nucleus innervates both Edinger-Westphal nuclei. To reach the contralateral Edinger-Westphal nucleus, the axons cross in the posterior commissure.
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The Neurobiology of Australian Marsupials: Brain Evolution in the Other Mammalian Radiation, p. 50Armati, Patricia J., Chris R. Dickman, and Ian D. Hume (2006). Marsupials, p. 175 and which carries all the commissural fibers arising from the neocortex (also known as the neopallium), whereas in placental mammals, the anterior commissure carries only some of these fibers.
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Posterior to it is the posterior commissure of the labia minora and the frenulum of labia minora. The sides of the vestibule are visible as Hart's line on the inside of the inner lips. Hart's line is the outer edge of the area and marks the change from vulvar skin to the smoother transitional skin of the vulva.
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Commissurotomy of cardiac valves is called valvulotomy,TheFreeDictionary > valvotomy Citing: WordNet 3.0, Farlex clipart collection. © 2003-2008 Princeton University, Farlex Inc. and consists of making one or more incisions at the edges of the commissure formed between two or three valves, in order to relieve constriction such as occurs in valvular stenosis, especially mitral valve stenosis.
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The large cerebral ganglia are linked by a robust commissure and lie dorsal to the pedal ganglia. Anteroventrally, the robust labiotentacular nerve emerges innervating the labial tentacle. A rhinophoral ganglion is situated anterodorsally to each cerebral ganglion connected by a short, single cerebro- rhinophoral connective. The rhinophoral nerve arises from the rhinophoral ganglion extending to the rhinophore.
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The median preoptic nucleus is located along the midline in a position significantly dorsal to the other three preoptic nuclei, at least in the crab-eating macaque brain. It wraps around the top (dorsal), front, and bottom (ventral) surfaces of the anterior commissure. The median preoptic nucleus generates thirst. Drinking decreases noradrenaline release in the median preoptic nucleus.
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This tract can be observed to be in the shape of a bicycle as it branches through various areas of the brain. Through diffusion tensor imaging results, the anterior commissure was categorized into two fiber systems: 1) the olfactory fibers and 2) the non-olfactory fibers.Kollias, S. (2012). Insights into the Connectivity of the Human Brain Using DTI.
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Like other mammals, monotremes are endothermic with a high metabolic rate (though not as high as other mammals; see below); have hair on their bodies; produce milk through mammary glands to feed their young; have a single bone in their lower jaw; and have three middle-ear bones. In common with reptiles and marsupials, monotremes lack the connective structure (corpus callosum) which in placental mammals is the primary communication route between the right and left brain hemispheres. The anterior commissure does provide an alternate communication route between the two hemispheres, though, and in monotremes and marsupials it carries all the commissural fibers arising from the neocortex, whereas in placental mammals the anterior commissure carries only some of these fibers. Platypus Long-beaked echidna Diagram of a Monotreme Egg.
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Collier's sign (also known as Collier's tucked lid sign or posterior fossa stare) is bilateral or unilateral eyelid retraction. It is an accepted medical sign of a midbrain lesion, first described in 1927 by J Collier.J. Collier, Nuclear Ophthalmoplegia with special reference to retraction of the lids and ptosis and to lesions of the posterior commissure. Brain (journal) 1927; 50; 488 - 498.
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The nervous system is relatively simple. The brain consists of two ganglia, one on either side of the pharynx, connected by a commissure. From these lead a pair of nerve cords which run along either side of the body beside the longitudinal muscle bands. The primary sensory organs are the bristles and ciliated tufts of the body surface which function as mechanoreceptors.
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The casque is much elevated posteriorly, with a strong curved parietal crest; the distance between the commissure of the mouth and the extremity of the casque equals or nearly equals the distance between the end of the snout and the hinder extremity of the mandible; no rostral appendages occur; a strong lateral crest, not reaching the end of the parietal crest, is present; an indication of a dermal occipital lobe is found on each side, not reaching the parietal crest. No enlarged tubercles occur on the body; a feebly serrated dorsal crest is present; a series of conical tubercles form a very distinct crest along the throat and belly. Males have a tarsal process or spur, the tail is longer than head and body. The gular-ventral crest and the commissure of the mouth are white.
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The SCO is one of the first differentiated brain structures to develop. Although it is evolutionarily an ancient structure that is present throughout the chordate phylum, its arrangement varies somewhat among species. Functions of the SCO are unknown; some evidence indicates it may participate in clearance of certain compounds from the cerebrospinal fluid, and possibly in morphogenetic mechanisms, such as development of the posterior commissure.
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The tectospinal, vestibulospinal and reticulospinal descend ipsilaterally in the anterior column but do not synapse across the anterior white commissure. Rather, they only synapse on VM lower motor neurons ipsilaterally. The VM lower motor neurons control the large, postural muscles of the axial skeleton. These lower motor neurons, unlike those of the DL, are located in the ventral horn all the way throughout the spinal cord.
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The cistern of lamina terminalis is one of the a subarachnoid cisterns in the subarachnoid space in the brain. It lies in front of (rostral to) the lamina terminalis and anterior commissure between the two frontal lobes of the cerebrum. The cistern contains cerebrospinal fluid, and connects the chiasmatic cistern to the pericallosal cistern. The anterior cerebral artery and the anterior communicating artery travel within this cistern.
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If the aortic commissure has not previously been marked, the excised coronary arteries will be used to determine the implantation position of the aorta. The aorta is then transplanted onto the pulmonary root, using either absorbable or permanent continuous suture. The aortic clamp is temporarily removed while small sections of the neo-aorta are cut away to accommodate the coronary ostia, and a continuous absorbable suture is then used to anastomose each coronary "button" into the prepared space. In most cases, the coronary implantation sites will be at left and right anterior positions at the base of the neo-aorta; however, if the circumflex coronary artery branches from the right coronary artery, the circumflex coronary artery will be distorted if the pair are not implanted higher than normal on the neo- aorta, and in some cases they may need to be implanted above the aortic commissure, on the native aorta itself.
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The flowers are yellowish and 1.5 mm across, with absent sepals, and the styles form a stylopodium. The fruits are 4–5 mm in size, oblong-ovoid, and are rarely compressed. The commissure is broad, the mericarps are prominent with slender ridges and lateral forming narrow wings; a carpophore is present. There are numerous vittae, with stout pedicels of 2–3 mm in size, and the stigmas are capitate.
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Juvenile hornbills resemble adults of the same sex, but lack the ridges at the base of the upper beak. The beak lacks a true caique but is thickened at its base. It has a number of dark ridges on the upper beak which are absent in the young and increase in number with age up to about seven. The commissure of the beaks is broken for both sexes.
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The remaining 10% of axons descend on the ipsilateral side as the ventral corticospinal tract. These axons also synapse with lower motor neurons in the ventral horns. Most of them will cross to the contralateral side of the cord (via the anterior white commissure) right before synapsing. The midbrain nuclei include four motor tracts that send upper motor neuronal axons down the spinal cord to lower motor neurons.
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This induces the roof plate to begin to secrete BMP, which will induce the alar plate to develop sensory neurons. The alar plate and the basal plate are separated by the sulcus limitans. Additionally, the floor plate also secretes netrins. The netrins act as chemoattractants to decussation of pain and temperature sensory neurons in the alar plate across the anterior white commissure, where they then ascend towards the thalamus.
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The lamina terminalis is a layer of gray matter that connects the optic chiasma and the anterior commissure. The septal nuclei are in the septal area, and are essential in generating the theta rhythm of the hippocampus. The dorsal septum projects to the lateral preoptic area, lateral hypothalamus, periventricular hypothalamus and midline thalamus. Fibers from the ventral half of the septum project topographically to the hippocampal formation, thalamus, hypothalamus and midbrain.
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The corpus callous is located at the sagittal divide and is the primary commissure in the human brain. It connects the left and right hemispheres of the cerebral cortex, which allows them to communicate with each other. With respect to language, males predominantly use their left hemisphere but females use both their right and left hemispheres. The right hemisphere controls emotion, so using the right hemisphere adds more prosody to speech.
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The angle of the chin is closer to the bill tip than to the base of the commissure. The rufous woodpecker is about 25 cm long, overall dark brown with dark bands on the feathers of the wing and tail giving it a black-barred appearance. The head appears paler and underparts are of a darker shade. The bill is short and black with a slight curvature of the culmen.
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Thermal food burns are usually on the palate or posterior buccal mucosa, and appear as zones of erythema and ulceration with necrotic epithelium peripherally. Electrical burns more commonly affect the oral commissure (corner of the mouth). The lesions are usually initially painless, charred and yellow with little bleeding. Swelling then develops and by the fourth day following the burn the area becomes necrotic and the epithelium sloughs off.
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Autopsy examination of 8 cases has shown both developmental and degenerative neuropathologic features in this disease, consistent with clinical duality as both a neurodevelopmental and neurodegenerative disorder. In the central nervous system, accompanying the hypotonia at birth is hypoplasia of the corticospinal tracts. Another developmental feature is seen in the corpus callosum, which varies from absent to hypoplastic. The anterior commissure is almost always absent, but occasionally hypoplastic.
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These fibers cross through the anterior white commissure to form the anterolateral system in the lateral funiculus. The medial division of the dorsal root contains myelinated fibres of larger diameter. These transmit information of discriminative touch, pressure, vibration, and conscious proprioception originating from spinal levels C2 through S5. These fibers are pushed in towards the posterior median sulcus to form the gracile fasciculus and the cuneate fasciculus of the posterior column–medial lemniscus pathway.
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More specifically, it suggests that: the anterior commissure is larger in females than males; massa intermedia is more abundant in females than males; females have a larger ratio of the cross-sectional area of the corpus callosum to cerebral volume and to forebrain size than males. Although, fewer studies have alternatively found otherwise. Typically, male brains are more asymmetric than female brains. Females have less asymmetry than males between left and right hemispheric cortical thickness.
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The cuneate fasciculus carries sensory information from the upper half of the body (upper limbs, trunk, and neck) entering the spinal cord at the cervical level. The gracile fasciculus is wedge-shaped on transverse section and lies next to the posterior median septum. Its base is at the surface of the spinal cord, and its apex directed toward the posterior gray commissure. The gracile fasciculus increases in size from inferior to superior.
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Despite the presence of eyes, there appears to be no optic nerve. The pedal ganglia each send one nerve anteriorly and two posteriorly to control the foot. These ganglia are separated by a long, thin commissure and have one statocyst and statolith each, attached dorsally. It has one subintestinal ganglion, one visceral ganglion, one osphradial ganglion, two gastro- esophageal ganglia, one left parietal ganglion, and two buccal ganglia, along with the necessary commissures and connectives.
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All rhynchonellids are biconvex (have a bulbous shell), and have a fold located in the brachial valve. This means that the commissure, the line between the two valves or shells, is zigzagged, a distinguishing characteristic of this group. The prominent beak of the pedicle valve usually overlaps that of the brachial valve, in order to allow the shell to open and close. There is usually a functional pedicle although the delthyrium may be partially closed.
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Male hornbills have been known to indulge in aerial casque butting, with birds striking each other in flight. The male spreads the preen gland secretion, which is yellow, onto the primary feathers and bill to give them the bright yellow colour. The commissure of the beak is black and has a serrated edge which becomes worn with age. The wing beats are heavy and the sound produced by birds in flight can be heard from a distance.
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With the eyes in the primary position, the sclera can be seen above the cornea, and further upgaze increases the distance between the eyelids and irises. Causes include upper dorsal midbrain supranuclear lesions such as Parinaud's syndrome, 'top of the basilar syndrome', midbrain infarction, neurodegeneration or tumour, multiple sclerosis, encephalitis, and Miller- Fisher syndrome. The cause is thought to be damage to the posterior commissure levator inhibitory fibres which originate in the M-group of neurons.
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Bracts absent, or rarely 1-2; bracteoles 5-8, shorter than pedicels, ciliate, eventually deflexed. Flowers white; sepals absent; outer petals not radiating; styles with enlarged base, forming stylopodium. Fruit usually , slightly laterally compressed, oblong but narrowing toward apex, constricted at commissure; mericarps having broad, rounded ridges; carpophore present; vittae solitary, conspicuous; pedicels without a ring of hairs at apex; styles roughly as long as stylopodium, recurved; stigma capitate. Cotyledons tapered gradually at base without distinct petiole.
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The corpus callosum allows for communication between the two hemispheres and is found only in placental mammals (the eutherians), while it is absent in monotremes and marsupials, as well as other vertebrates such as birds, reptiles, amphibians and fish. The anterior commissure serves as the primary mode of interhemispheric communication in marsupials,Ashwell, Ken (2010). The Neurobiology of Australian Marsupials: Brain Evolution in the Other Mammalian Radiation, p. 50Armati, Patricia J., Chris R. Dickman, and Ian D. Hume (2006).
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White matter tracts within a human brain, as visualized by MRI tractography A nerve tract is a bundle of nerve fibers (axons) connecting nuclei of the central nervous system. In the peripheral nervous system this is known as a nerve, and has associated connective tissue. The main nerve tracts in the central nervous system are of three types: association fibers, commissural fibers, and projection fibers. A tract may also be referred to as a commissure, fasciculus or decussation.
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Nucleus basalis in relation to the globus pallidus (top of image). The nucleus basalis in humans is a somewhat diffuse collection of large cholinergic neurons in the basal forebrain. The main body of the nucleus basalis lies inferior to the anterior commissure and the globus pallidus, and lateral to the anterior hypothalamus in an area known as the substantia innominata. Rostrally, the nucleus basalis is continuous with the cholinergic neurons of the nucleus of the diagonal band of Broca.
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The interthalamic adhesion (also known as the intermediate mass or middle commissure) is a flattened band of tissue that connects both parts of the thalamus at their medial surfaces. The medial surfaces form the upper part of the lateral wall to the third ventricle. In humans it is only about one centimeter long, though in females it is larger by about 50%.Wiley Interscience Sometimes it is in two parts and 20% of the time it is absent.
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The interthalamic adhesion contains nerve cells and nerve fibers; a few of the latter may cross the middle line, but most of them pass toward the middle line and then curve laterally on the same side. It is still uncertain whether the interthalamic adhesion contains fibers that cross the mid-line and for this reason it is inappropriate to call it a commissure. The interthalamic adhesion is notably enlarged in patients with the type II Arnold–Chiari malformation.
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The pretectum is a bilateral group of highly interconnected nuclei located near the junction of the midbrain and forebrain. The pretectum is generally classified as a midbrain structure, although because of its proximity to the forebrain it is sometimes classified as part of the caudal diencephalon (forebrain). Within vertebrates, the pretectum is located directly anterior to the superior colliculus and posterior to the thalamus. It is situated above the periaqueductal grey and nucleus of the posterior commissure.
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Patient W.J. was a World War II paratrooper who got hit in the head with a rifle butt, after which he started having seizures. Before his operation to try to fix the seizures, Gazzaniga tested his brain functions. This included presenting stimuli to the left and right visual fields and identifying objects in his hands that were out of view. He was able to perform these tasks perfectly and afterwards he had the surgery that split his corpus callosum and anterior commissure.
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The dorsal color pattern consists of light brown to deep reddish brown ground color overlaid with 12-18 broad brown or brownish crossbands. Laterally, these crossbands are more lightly colored in the center and usually contain one or two dark spots. The head is clearly marked on either side with two longitudinal light lines: the upper one is narrow and may be broken behind to the eye, while the lower one is wider and separated from the commissure by a dark band.
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The corpus callosum (Latin for "tough body"), also callosal commissure, is a wide, thick nerve tract, consisting of a flat bundle of commissural fibers, beneath the cerebral cortex in the brain. The corpus callosum is only found in placental mammals. It spans part of the longitudinal fissure, connecting the left and right cerebral hemispheres, enabling communication between them. It is the largest white matter structure in the human brain, about ten centimetres in length and consisting of 200-300 million axonal projections.
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The corpus callosum is found only in placental mammals, while it is absent in monotremes and marsupials, as well as other vertebrates such as birds, reptiles, amphibians and fish.Sarnat, Harvey B., and Paolo Curatolo (2007). Malformations of the Nervous System: Handbook of Clinical Neurology, p. 68 (Other groups do have other brain structures that allow for communication between the two hemispheres, such as the anterior commissure, which serves as the primary mode of interhemispheric communication in marsupials,Ashwell, Ken (2010).
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The alar plate and the basal plate are separated by the sulcus limitans. Additionally, the floor plate also secretes netrins. The netrins act as chemoattractants to decussation of pain and temperature sensory neurons in the alar plate across the anterior white commissure, where they then ascend towards the thalamus. Following the closure of the caudal neuropore and formation of the brain's ventricles that contain the choroid plexus tissue, the central canal of the caudal spinal cord is filled with cerebrospinal fluid.
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While the left pleuro-parietal, the parietal-subintestinal/visceral and the right pleuro-parietal/supraintestinal connectives are very short, the subintestinal/visceral-parietal/supraintestinal connective is long. An additional presumed osphradial ganglion is linked to the fused parietal/supraintestinal ganglion. Anteriorly, a nerve emerges and innervates the right body wall; no histologically differentiated osphradium could be detected. The buccal ganglia are positioned posterior to the pharynx and are linked to each other by a short buccal commissure ventral to the oesophagus.
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Aspidogastreans have a nervous system of extraordinary complexity, greater than that of related free-living forms, and a great number of sensory receptors of many different types. The nervous system is of great complexity, consisting of a great number of longitudinal nerves (connectives) connected by circular commissures. The brain (cerebral commissure) is located dorsally, in the anterior part of the body, the eyes dorsally attached to it. A nerve from the main connective enters the pharynx and also supplies the intestine.
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The brain is bilobed and lies just beneath the epidermis close behind the anterior tip of the body; the two main masses consist of a central neuropile and nucleated rind and are connected by a short medial commissure. Like other acoelomorphs, Waminoa brickneri is a simultaneous hermaphrodite. The reproductive organs produce a slightly thickened ridge medially in the terminal quarter of the body. A pair of ventrally situated ovaries extends from about the second quarter of the body length posteriorly behind the mouth.
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The subcommissural organ (SCO) is a small secretory organ located on the ventral surface of the posterior commissure near the anterior entrance of the cerebral aqueduct. It differs from other CVOs in that it lacks a high concentration of fenestrated capillaries, making its BBB less permeable. On the other hand, its role as a neuroendocrine structure associated with the ventricular system qualifies it for classification as a CVO. Related to its secretory function, the SCO is partially composed of ependymal cells.
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The DL neurons are involved in distal limb control. Therefore, these DL neurons are found specifically only in the cervical and lumbosacral enlargements within the spinal cord. There is no decussation in the lateral corticospinal tract after the decussation at the medullary pyramids. The anterior corticospinal tract descends ipsilaterally in the anterior column, where the axons emerge and either synapse on lower ventromedial (VM) motor neurons in the ventral horn ipsilaterally or descussate at the anterior white commissure where they synapse on VM lower motor neurons contralaterally .
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In both groups, the epidermis is renewed from mesodermal stem cells. The nervous system of acoelomorphs is formed by a set of longitudinal nerve bundles beneath the ciliated epidermis. Close to the anterior end, these bundles are united by a ring commissure, but do not form a true brain, although it is hypothesized that such organization was the precursor of the cephalization of the nerve system in more derived bilaterians. After decapitation, such a "brain" (rather, a cerebroid ganglion) regenerates in a few weeks.
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They are attached to the visceral ganglia by long cerebral-visceral connectives, and to each other via a cerebral commissure that extends in an arch dorsally around the esophagus. The cerebral ganglia control the scallop's mouth via the palp nerves, and also connect to statocysts which help the animal sense its position in the surrounding environment. They are connected to the pedal ganglia by short cerebral-pedal connectives. The pedal ganglia, though not fused, are situated very close to each other near the midline.
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The amygdalofugal pathway (Latin for "fleeing from the amygdala" and commonly distinguished as the ventral amygdalofugal pathway) is one of the three major efferent pathways of the amygdala, meaning that it is one of the three principal pathways by which fibers leave the amygdala. It leads from the basolateral nucleus and central nucleus of the amygdala. The amygdala is a limbic structure in the medial temporal lobe of the brain. The other main efferent pathways from the amygdala are the stria terminalis and anterior commissure.
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Lastly, the braincase of Panderichthys demonstrates a key intermediate within the fish-evolution sequence. From the outside, Panderichthys has a tetrapod-like head, but actually retains an intracranial joint that is a characteristic of fish. Panderichthys shares many features with the osteolepiform Eusthenopteron such as similar hyomandibular and basipterygoid processes. Even though its head is shaped similar to that of a tetrapod, tetrapod craniums lack a lateral commissure, jugular groove, basicranial fenestra, arcual plate, and intracranial joint, all of which are present in Panderichthys.
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These are the branchial nerves. The eighth and ninth pairs are large nerves; they issue from the outer border of the pedial ganglions and go to the foot. The posterior margins of these ganglions are united by a stout, shortish commissure, composed of two or three cords, which, passing below the gullet, form the great oesophageal collar. The tenth pair of nerves are given off from the posterior margin of the buccal ganglions; these pass into the buccal mass and go to supply the tongue.
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The dentatothalamic fibers also cross over and ascend to synapse in the ventral intermediate (VI) and ventral anterior (VA) nuclei of the thalamus. The fastigioreticular fibers enter the reticular formation of the midbrain, pons, and medulla oblongata. Afferent pathways include the anterior spinocerebellar and tectocerebellar tracts. The fibers of the anterior spinocerebellar tract originate in Clarke's column of the spinal cord and cross in the anterior white commissure to the lateral funiculus, where they ascend to upper pontine levels before crossing back to enter the cerebellum through the superior peduncle.
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This group is a population of cells immunoreactive for dopamine and tyrosine hydroxylase that are broadly distributed in the rostral forebrain, including such structures as: substantia innominata, diagonal band, olfactory tubercle, prepyriform area, striatum (at levels rostral to the anterior commissure), claustrum, and deep cortical layers of all gyri of the frontal lobe rostral to the head of the caudate nucleus; the cells are also numerous in intervening white matter, including the external capsule, extreme capsule and frontal white matter. They are found in the rodent, the macaque and the human.
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The linea alba (Latin for white line), in dentistry, is a horizontal streak on the buccal mucosa (inner surface of the cheek), level with the occlusion (biting plane). It usually extends from the commissure to the posterior teeth, and can extend to the inner lip mucosa and corners of the mouth. The linea alba is a common finding and most likely associated with pressure, frictional irritation, or sucking trauma from the facial surfaces of the teeth. It may be mistaken for a lesion requiring treatment and may be found in individuals who chew tobacco.
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The aortic root is the portion of the aorta beginning at the aortic annulus and extending to the sinotubular junction. It is sometimes regarded as a part of the ascending aorta, and sometimes regarded as a separate entity from the rest of the ascending aorta. Between each commissure of the aortic valve and opposite the cusps of the aortic valve, three small dilatations called the aortic sinuses. The sinotubular junction is the point in the ascending aorta where the aortic sinuses end and the aorta becomes a tubular structure.
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Laurence was born in Salt Lake City, Utah, with macrocephaly, damage to the cerebellum, and agenesis of the corpus callosum,"The Real Rain Man", documentary by Focus Productions, Bristol, England, UK, 2006. a condition in which the bundle of nerves that connects the two hemispheres of the brain is missing; in Peek's case, secondary connectors such as the anterior commissure were also missing. There is speculation that his neurons made unusual connections due to the absence of a corpus callosum, resulting in an increased memory capacity. Wisconsin Medical Society.
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With a primordial structure, the limbic system is involved in lower order emotional processing of input from sensory systems and consists of the amygdaloid nuclear complex (amygdala), mammillary bodies, stria medullaris, central gray and dorsal and ventral nuclei of Gudden. This processed information is often relayed to a collection of structures from the telencephalon, diencephalon, and mesencephalon, including the prefrontal cortex, cingulate gyrus, limbic thalamus, hippocampus including the parahippocampal gyrus and subiculum, nucleus accumbens (limbic striatum), anterior hypothalamus, ventral tegmental area, midbrain raphe nuclei, habenular commissure, entorhinal cortex, and olfactory bulbs.
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Neuromodulators like acetylcholine, serotonin and norepinephrine all send axons to the olfactory bulb and have been implicated in gain modulation, pattern separation, and memory functions, respectively. The mitral cells leave the olfactory bulb in the lateral olfactory tract, which synapses on five major regions of the cerebrum: the anterior olfactory nucleus, the olfactory tubercle, the amygdala, the piriform cortex, and the entorhinal cortex. The anterior olfactory nucleus projects, via the anterior commissure, to the contralateral olfactory bulb, inhibiting it. The piriform cortex has two major divisions with anatomically distinct organizations and functions.
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The anterior median fissure of the spinal cord has an average depth of about 3 mm, but this is increased in the lower part of the spinal cord. It contains a double fold of pia mater, and its floor is formed by a transverse band of white substance, the anterior white commissure, which is perforated by blood vessels on their way to or from the central part of the medulla spinalis. The anterior median fissure provides a groove in which the anterior spinal artery sits. From here, it provides the anterior part of the spinal cord.
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Despite being a much conserved structure throughout evolution, there are some differences on the SCO from different mammals. It is the first secretory structure to differentiate and remains fully developed and functional during the life of almost every vertebrate, excluding bats, anthropoid apes and humans. More specifically, in humans, the SCO development has a regressive nature. It reaches its apex development in fetus from 3 to 5 month old, functioning as a fully active secretory structure of the brain during this time span, and extending from the pineal recess over the posterior commissure to the mesocoelic recess.
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This was further supported by an observed absence of ventral commissure (i.e. corpus callosum) development in mice lacking either netrin-1 or DCC. Similar results were observed in experiments with the netrin-1 homolog UNC-6 discovered in C. elegans The same early expression and formation of a protein concentration gradient emanating from the ventral midline is observed in epidermal cells of the developing worm. Evidence suggests that this gradient is essential for the long-range function of UNC-6 in guiding the initial circumferential migration of axons to the ventral midline and that the UNC-40 receptor mediates the attractive response.
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A Foley catheter was inserted and the urethra was sutured onto the catheter, about 5 cm distally from its passage through the skin. No skin suture was used in the urethral meatus, and some kind of scar contraction was always foreseen. Two sutures were bilaterally passed through the perianal skin and the levator ani muscles and served to tightly and firmly support an obstetric stent, placed in the neovagina to provide support for the inverted skin flap. A drain was left in the posterior commissure and, finally, excess scrotal skin was resected to obtain a good appearance of the major labia.
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The ventral spinothalamic fasciculus (or anterior spinothalamic tract; Latin: tractus spinothalamicus anterior) situated in the marginal part of the anterior funiculus and intermingled more or less with the vestibulo-spinal fasciculus, is derived from cells in the posterior column or intermediate gray matter of the opposite side. Aβ fibres carry sensory information pertaining to crude touch from the skin. After entering the spinal cord the first order neurons synapse (in the nucleus proprius), and the second order neurons decussate via the anterior white commissure. These second order neurons ascend synapsing in the VPL of the thalamus.
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The second order fibers then cross the cord via the anterior white commissure and ascend in the spinothalamic tract. Before reaching the brain, the spinothalamic tract splits into the lateral, neospinothalamic tract and the medial, paleospinothalamic tract. Second order, spinal cord fibers dedicated to carrying A-delta fiber pain signals, and others that carry both A-delta and C fiber pain signals to the thalamus have been identified. Other spinal cord fibers, known as wide dynamic range neurons, respond to A-delta and C fibers, but also to the large A-beta fibers that carry touch, pressure and vibration signals.
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A number of sections of the brain have been reported to be sexually dimorphic; that is, they vary between men and women. There have also been reports of variations in brain structure corresponding to sexual orientation. In 1990, Dick Swaab and Michel A. Hofman reported a difference in the size of the suprachiasmatic nucleus between homosexual and heterosexual men. In 1992, Allen and Gorski reported a difference related to sexual orientation in the size of the anterior commissure, but this research was refuted by numerous studies, one of which found that the entirety of the variation was caused by a single outlier.
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From 1892 to 1917 Darkshevich was director of the department of neurology at the University of Kazan, where he founded a neurological clinic and laboratory. He was the first editor-in-chief of the Kazan Medical Journal (Казанский медицинский журнал). In 1917 he became a professor of neurological diseases at the University of Moscow. He is remembered for his description of the nucleus of the posterior commissure, also known as the "nucleus of Darkshevich", defined as a cell group located in the central gray substance of the upper end of the cerebral aqueduct, in front of the oculomotor nucleus.
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The midsagittal & fiber numbers in the anterior commissure that connect the temporal poles and mass intermedia that connects the thalami is also larger in women. In the cerebral cortex, it has been observed that there is greater intra-lobe neural communication in male brains and greater inter-lobe (between the left and right hemispheres of the cerebral cortex) neural communication in female brains. In the cerebellum, the region of the brain that plays an important role in motor functions, males showed higher connectivity between hemispheres, and females showed higher connectivity within hemispheres. This potentially provides a neural basis for previous studies that showed sex-specific difference in certain psychological functions.
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Simplified diagram of the mollusc nervous system The cephalic molluscs have two pairs of main nerve cords organized around a number of paired ganglia, the visceral cords serving the internal organs and the pedal ones serving the foot. Most pairs of corresponding ganglia on both sides of the body are linked by commissures (relatively large bundles of nerves). The ganglia above the gut are the cerebral, the pleural, and the visceral, which are located above the esophagus (gullet). The pedal ganglia, which control the foot, are below the esophagus and their commissure and connectives to the cerebral and pleural ganglia surround the esophagus in a circumesophageal nerve ring or nerve collar.
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Clitoral hood (1) and clitoris (2). Labia are spread apart on the bottom image. The clitoral hood projects at the front of the labia commissure, where the edges of the labia majora (outer lips) meet at the base of the pubic mound; it is partially formed by fusion of the upper part of the external folds of the labia minora (inner lips) and covers the glans and external shaft. There is considerable variation in how much of the glans protrudes from the hood and how much is covered by it, ranging from completely covered to fully exposed, and tissue of the labia minora also encircles the base of the glans.
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Dorsal roots and ventral roots come together and exit the intervertebral foramina as they become spinal nerves. The gray matter, in the center of the cord, is shaped like a butterfly and consists of cell bodies of interneurons and motor neurons. It also consists of neuroglia cells and unmyelinated axons. Projections of the gray matter (the “wings”) are called horns. Together, the gray horns and the gray commissure form the “gray H.” The white matter is located outside of the gray matter and consists almost totally of myelinated motor and sensory axons. “Columns” of white matter carry information either up or down the spinal cord.
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The habenular trigone is a small depressed triangular area above the superior colliculus and on the lateral aspect of the posterior part of the taenia thalami. Underlying this area is the habenula. Fibers enter it from the stalk of the pineal gland, and others, forming what is termed the habenular commissure, pass across the middle line to the corresponding ganglion of the opposite side. Most of its fibers are, however, directed downward and form a bundle, the fasciculus retroflexus of Meynert (or habenulointerpeduncular tract), which passes medial to the red nucleus, and, after decussating with the corresponding fasciculus of the opposite side, ends in the interpeduncular nucleus.
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A promising method of identifying the neuroanatomical structures responsible for USWS is continuing comparisons of brains that exhibit USWS with those that do not. Some studies have shown induced asynchronous SWS in non-USWS-exhibiting animals as a result of sagittal transactions of subcortical regions, including the lower brainstem, while leaving the corpus callosum intact. Other comparisons found that mammals exhibiting USWS have a larger posterior commissure and increased decussation of ascending fibres from the locus coeruleus in the brainstem. This is consistent with the fact that one form for neuromodulation, the noradrenergic diffuse modulatory system present in the locus coeruleus, is involved in regulating arousal, attention, and sleep-wake cycles.
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The cave of septum pellucidum is bounded anteriorly by the genu of the corpus callosum, superiorly by the body of the corpus callosum, posteriorly by the anterior limb and pillars of the fornix, inferiorly by the anterior commissure and the rostrum of the corpus callosum, and laterally by the leaflets of the septum pellucidum. In prenatal development of the fetus, the laminae of the septum pellucidum separate to form a small cavity – the cave of septum pellucidum. This is an important normal structure to identify in the sonographic assessment of the fetal brain. In post-natal life, the laminae of the septum pellucidum usually fuse, which obliterates the cavum.
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Bracts usually absent; bracteoles usually 5 in number, longer than pedicels, simple or irregularly (often deeply) divided. Flowers white; sepals small; outer petals not radiating; styles with enlarged base, forming stylopodium. Fruit 30-70mm, more or less cylindrical, slightly compressed laterally, with strongly dorsally flattened beak 3-4 times as long as and plainly distinct from seed-bearing portion, constricted at commissure; mericarps ribbed and scabrid with forward-pointing bristles on margins; carpophore present; vittae solitary and conspicuous; pedicels almost as thick as rays, glabrous at apex; styles 2-4 times as long as stylopodium, erect; stigma tapering. Cotyledons tapered gradually at base, without distinct petiole.
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The diagnosis of an imperforate hymen is usually made based purely on the physical exam, although if necessary the diagnosis can be confirmed by transabdominal, transperineal or transrectal ultrasound. An imperforate hymen can also be diagnosed in newborn babies and it is occasionally detected on ultrasound scans of the foetus during pregnancy. In newborns the diagnosis is based on the findings of an abdominal or pelvic mass or a bulging hymen. Examination of the normal neonatal vagina usually reveals a track of mucus at the posterior commissure of the labia majora; an absence of mucus may indicate an imperforate hymen or another vaginal obstruction.
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Commissurotomy of heart valves is called valvulotomy, valvotomy,TheFreeDictionary > valvotomy Citing: WordNet 3.0, Farlex clipart collection. © 2003-2008 Princeton University, Farlex Inc. valvuloplasty, or valvoplasty and consists of making one or more incisions at the edges of the commissure formed between the two or three valve leaflets, which relieves the constriction of valvular stenosis (especially mitral valve stenosis). As with many other kinds of surgery, valvular commissurotomy may be done by either open or minimally invasive approaches, and sometimes (but not invariably) the terms surgery and surgical are understood to refer only to the open types, with the minimally invasive types then being referred to as interventional procedures.
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Shortly afterwards, he became a professor of psychiatry at the University of Munich. Gudden made many contributions in the field of neuroanatomy, especially in his work of mapping and describing the paths, connections, origins/termini and neuroanatomical centers of cranial and optic nerve networks. The commissural fibers of the optic tract are called the commissure of Gudden in his honor, and he is credited for developing a specialized microtome for sectioning the brain for pathological study. Among his well-known students and assistants are Emil Kraepelin (1856–1926), Franz Nissl (1860–1919), Auguste-Henri Forel (1848–1931), Sigbert Josef Maria Ganser (1853–1931) and Oskar Panizza (1853–1921).
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Deletion of pioneer axons which create the scaffold have an effect on the growth cones of the neurons of the nucleus of the posterior commissure, in that they cannot follow the normal path of extending ventrally, then posteriorly. Despite the compromised pioneer neuron scaffold, the follower growth cones extend ventrally normally. However, around half of the followers do not follow the posterior longitudinal path correctly, while the other half do. This suggests that other cues other than those from pioneer axons play a role in guiding follower axon growth, and that pioneer axons may play different roles in different parts of neuronal development.Patel, C. K., Rodriguez, L. C., & Kuwada, J. Y. (1994).
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Like most molluscs, B. secunda has a circumesophageal nerve ring or nerve collar composed of its pleural and pedal ganglia and their commissures and connectives within the region of the head. The esophagus passes through this nerve ring on its way back to the stomach; the esophageal pouches and salivary glands are located entirely before it. The cerebral ganglia are also located forward of the ring. Behind the nerve ring, the commissure of the pleural ganglia performs a characteristic "twist" common to many gastropods, the evolutionary result of torsion which placed the anus and the openings of the kidneys ("nephridial openings") near the head of the animal in order to accommodate the ancestral presence of a twisted shell (B.
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In nematodes, the ring consists of only two to four large associative cells connected to two paired lateral ganglia, two ventral ganglia, and a single unpaired dorsal ganglion. Among arthropods, the usual arrangement is a single ganglion (the cerebral) positioned above the esophagus, a single ganglion or nerve mass (the subesophageal) below it, and commissures connecting the two in a ring. Among the gastropods, the evolutionary torsion event which relocates the anus to near the head of the animal and allowing it to withdraw into its shell has relocated the commissure of the pleural ganglia into a "twist" (the right ganglion has relocated to the left side, and the left ganglion to the right).
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Sharpirhynchia sharpi has a small shell, subtrigonal to transverse or laterally elongate in adults; unequally biconvex, dorsal valve more convex than ventral one, subglobose in profile. Lateral commissures oblique ventrally; anterior commissure narrowly uniplicate; linguiform extension developed variably, generally low and U-shaped. No clear sulcation on dorsal umbone. Beak relatively long, acute, and suberect, with slightly incurved tip in adult; foramen big, oval, hypothyridid, with well developed rim; deltidial plates narrow, disjunct to just conjunct; beak ridges subangular; interareas small, but well defined and slightly concave, with fine and clear transverse lines. Ventral valve moderately convex; sulcus shallow and wide, well separated from slopes and with rounded bottom, occurring at posterior 1/3 to 1/2 of valve.
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In mice (Mus musculus), laterality in paw usage has been shown to be a learned behavior (rather than inherited), due to which, in any population, half of the mice become left-handed while the other half becomes right-handed. The learning occurs by a gradual reinforcement of randomly occurring weak asymmetries in paw choice early in training, even when training in an unbiased world. Meanwhile, reinforcement relies on short-term and long-term memory skills that are strain-dependent, causing strains to differ in the degree of laterality of its individuals. Long-term memory of previously gained laterality in handedness due to training is heavily diminished in mice with absent corpus callosum and reduced hippocampal commissure.
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Larynx showing vocal ligaments The vibratory portion of the vocal fold in the anterior glottis is connected to the thyroid cartilage anteriorly by the macula flava and anterior commissure tendon, or Broyles' ligament. Posteriorly, this vibratory portion is connected to the vocal process of the arytenoid cartilage by the posterior macula flava. The macula flava in newborn vocal folds is important for the growth and development of the vocal ligament and layered structure of the vocal folds. In the adult, the macula flavae are probably required for metabolism of the extracellular matrices of the vocal fold mucosa, replacing damaged fibers in order to maintain the integrity and elasticity of the vocal fold tissues.
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During sexual arousal, arterial blood flow to the clitoris is increased, and trabecular smooth muscle within the clitoris relaxes allowing blood to engorge the erectile tissues. The ischiocavernosus and bulbocavernosus muscles contract to compress the dorsal vein of the clitoris to stop drainage of the clitoris, trapping the blood. More specifically, the clitoris has two adjoining erectile tissues corpus cavernosa (corpus cavernosa clitoridis) that form a main body that connects to the glans clitoridis. There is also a strip of erectile tissue (similar to the placement of the corpus spongiosum in males) running along the ventral surface of the corpus cavernosa main body that connects the glans clitoridis to the commissure of the vestibular bulbs.
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Deep dissection of brain-stem showing decussation The decussation of superior cerebellar peduncle is the crossing of fibers of the superior cerebellar peduncle across the midline, and is located at the level of the inferior colliculi. It comprises the cerebellothalamic tract, which arises from the dentate nucleus (therefore also known as dentatothalamic tract), as well as the cerebellorubral tract, which arises from the globose and emboliform nuclei and project to the contralateral red nucleus to eventually become the rubrospinal tract. It is also known as horseshoe-shaped commissure of Wernekinck. It is important as an anatomical landmark, as lesions above it cause contralateral cerebellar signs, while lesions below it cause ipsilateral cerebellar signs.
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Branchial ganglia form two oval central masses, resting upon the upper surface of the oesophagus, one on each side of the median line, across which they are united at the anterior extremity by a short but distinct commissure. Their posterior extremities diverge and are slightly bilobed, marking the boundaries of the two ganglia of which each mass is composed, — the anterior lobe indicating the cerebroid, the posterior the branchial. (Branchial ganglia are also fused in Onchidoris bilamellata and in Lamellidoris aspera.) The pedial ganglions are irregularly rounded, being equal in bulk to the cerebroid and branchial together. They lie against the sides of the oesophagus, and are united to the under surface of the central masses.
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Illustration of arterial switch operation Illustration of arterial switch operation The heart is accessed via median sternotomy, and the patient is given heparin to prevent the blood from clotting. A generous section of pericardium is harvested, then disinfected and sterilized with a weak solution of glutaraldehyde; and the coronary and great artery anatomy are examined. The ductus arteriosus and right pulmonary branch, up to and including the first branches in the hilum of the right lung, are separated from the surrounding supportive tissue to allow mobility of the vessels. Silk marking sutures may be placed in the pulmonary trunk at this time, to indicate the commissure of the aorta to the neo-aorta; alternatively, this may be done later in the procedure.
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If the aortic commissure has not yet been marked, it may be done at this point, using the same method as would be used prior to bypass; however, there is a third opportunity for this still later in the procedure. Coronary arteries are examined closely, and the ostia and proximal arterial course are identified, as are any infundibular branches, if they exist. The coronary ostia and a large "button" of surrounding aortic wall are then excised from the aorta, well into the sinus of Valsalva; and the proximal sections of the coronary arteries are separated from the surface of the heart, which prevents tension or distortion after anastomosis to the neo- aorta. Infundibular branches are sometimes unable to be spared, but this is a very rare occurrence.
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Aδ fibers form synapses in laminae I and V, C fibers connect with neurons in lamina II, Aβ fibers connect with lamina I, III, & V. After reaching the specific lamina within the spinal cord, the first order nociceptive project to second order neurons that cross the midline at the anterior white commissure. The second order neurons then send their information via two pathways to the thalamus: the dorsal column medial- lemniscal system and the anterolateral system. The first is reserved more for regular non-painful sensation, while the lateral is reserved for pain sensation. Upon reaching the thalamus, the information is processed in the ventral posterior nucleus and sent to the cerebral cortex in the brain via fibers in the posterior limb of the internal capsule.
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The lateral side of the ventricle is marked by a sulcus - the hypothalamic sulcus - from the inferior side of the interventricular foramina to the anterior side of the cerebral aqueduct. The lateral border posterior/superior of the sulcus constitutes the thalamus, while anterior/inferior of the sulcus it constitutes the hypothalamus. The interthalamic adhesion usually tunnels through the thalamic portion of the ventricle, joining together the left and right halves of the thalamus, although it is sometimes absent, or split into more than one tunnel through the ventricle; it is currently unknown whether any nerve fibres pass between the left and right thalamus via the adhesion (it has more resemblance to a herniation than a commissure). The posterior border of the ventricle primarily constitutes the epithalamus.
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The ventral spinocerebellar tract will cross to the opposite side of the body first in the spinal cord as part of the anterior white commissure and then cross again to end in the cerebellum (referred to as a "double cross"), as compared to the dorsal spinocerebellar tract, which does not decussate, or cross sides, at all through its path. The ventral tract (under L2/L3) gets its proprioceptive/fine touch/vibration information from a first order neuron, with its cell body in a dorsal ganglion. The axon runs via the fila radicularia to the dorsal horn of the grey matter. There it makes a synapse with the dendrites of two neurons: they send their axons bilaterally to the ventral border of the lateral funiculi.
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The tract cells then decussate via the anterior white commissure to the anterolateral corner and ascend to the supraoptic nucleus and paraventricular nucleus in the hypothalamus, where they synapse with oxytocinergic third-order neurons. The somas of these neurons are located in the hypothalamus, but their axon and axon terminals are located in the infundibulum and pars nervosa of the posterior pituitary, respectively. The oxytocin is produced in the neuron's soma in the supraoptic and paraventricular nuclei, and is then transported down the infundibulum via the hypothalamo-neurohypophyseal tract with the help of the carrier protein, neurophysin I, to the pars nervosa of the posterior pituitary, and then stored in Herring bodies, where they are stored until the synapse between second- and third-order neurons. Following the electrical impulse, oxytocin is released into the bloodstream.
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These secondary neurons are situated in the posterior horn, specifically in the Rexed laminae regions I, IV, V and VI. Region II is primarily composed of Golgi II interneurons, which are primarily for the modulation of pain, and largely project to secondary neurons in regions I and V. Secondary neurons from regions I and V decussate across the anterior white commissure and ascend in the (now contralateral) lateral spinothalamic tract. These fibers will ascend through the brainstem, including the medulla oblongata, pons and midbrain, as the spinal lemniscus until synapsing in the ventroposteriorlateral (VPL) nucleus of the thalamus. The third order neurons in the thalamus will then project through the internal capsule and corona radiata to various regions of the cortex, primarily the main somatosensory cortex, Brodmann areas 3, 1, and 2.
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The fornix is a C-shaped bundle of axons that begins in the hippocampal formation of both hemispheres, referred to as the fimbria, and extend through the crus of fornix, also known as the posterior pillars. The fimbria section of the fornix is directly connected to the alveus, which is a portion of the hippocampal formation that arises from the subiculum and the hippocampus (specifically the CA1). Both crura of the fornix form intimate connections with the underside of the corpus callosum and support the hippocampal commissure, a large bundle of axon that connects the left and right hippocampal formations. The fornix plays a key role in hippocampal outputs, specifically in connecting CA3 to a variety of subcortical structures, and connecting CA1 and the subiculum to a variety of parahippocampal regions, via the fimbria.
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The anterior proper fasciculus consists of longitudinal intersegmental fibres which arise from cells in the grey matter, more especially from those of the medial group of the anterior column, and, after a longer or shorter course, re-enter the gray substance; and fibres which cross in the anterior white commissure from the grey matter of the opposite side. The lateral proper fasciculus is made up of the remainder of the lateral column, and is continuous in front with the anterior proper fasciculus. It consists chiefly of intersegmental fibres which arise from cells in the grey matter, and, after a longer or shorter course, re-enter the grey matter and ramify in it. Some of its fibers are, also continued upward into the brain in the medial longitudinal fasciculus.
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The telencephalic part of the rostral choroidal tela (roof plate continuous caudally with a diencephalic part) is inserted at the back of this commissure at a locus where mammals show the subfornical circumventricular organ, and extends laterally over the interventricular foramen into a wing-shaped medial telencephalic territory, the so-called choroidal fissure. Here the choroidal tissue is attached to the fimbria of the hippocampus (also known as the cortical hem area), bordering lengthwise the medial pallium. At its rostral and caudal ends, the medial pallium contacts the ventral pallium, which builds the pallial portion that contacts the subpallium across the pallio subpallial boundary, observed at the lateral telencephalic wall. Inside the ring formed thus by the medial and ventral pallium there is a sort of island that contains the dorsal and lateral pallial portions.
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The greater part of the ascending axons forming the lateral lemniscus will terminate in the ipsilateral CNIC however a few follow the commissure of Probst and terminate on the contralateral CNIC. The axons of most of the CNIC cells form the brachium of IC and leave the brainstem to travel to the ipsilateral thalamus. Cells in different parts of the IC tend to be monaural, responding to input from one ear, or binaural and therefore respond to bilateral stimulation. The spectral processing that occurs in the AVCN and the ability to process binaural stimuli, as seen in the SOC, are replicated in the IC. Lower centres of the IC extract different features of the acoustic signal such as frequencies, frequency bands, onsets, offsets, changes in intensity and localisation.
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The facial artery arises in the carotid triangle from the external carotid artery a little above the lingual artery and, sheltered by the ramus of the mandible, passes obliquely up beneath the digastric and stylohyoid muscles, over which it arches to enter a groove on the posterior surface of the submandibular gland. It then curves upward over the body of the mandible at the antero-inferior angle of the masseter; passes forward and upward across the cheek to the angle of the mouth, then ascends along the side of the nose, and ends at the medial commissure of the eye, under the name of the angular artery. The facial artery is remarkably tortuous. This is to accommodate itself to neck movements such as those of the pharynx in deglutition; and facial movements such as those of the mandible, lips, and cheeks.
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On either side of the corpus callosum, the fibers radiate in the white matter and pass to the various parts of the cerebral cortex; those curving forward from the genu into the frontal lobes constitute the forceps minor (also forceps anterior) and those curving backward from the splenium into the occipital lobes, the forceps major (also forceps posterior). Between these two parts is the main body of the fibers which constitute the tapetum and extend laterally on either side into the temporal lobe, and cover in the central part of the lateral ventricle. The tapetum and anterior commissure share the function of connecting left and right temporal lobes. The anterior cerebral arteries are in contact with the under surface of the rostrum, they arch over the front of the genu and are carried along the trunk, supplying the front four-fifths of the corpus callosum.
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The facial nerve lies some distance from the inferior alveolar nerve within the parotid salivary gland, but in rare cases anesthetic can be injected far enough posteriorly to anesthetize that nerve. The result is a transient facial paralysis, with the injected side of the face having temporary loss of the use of the muscles of facial expression that include the inability to close the eyelid and the drooping of the labial commissure on the affected side for a few hours, which disappears when the anesthesia wears off.Illustrated Anatomy of the Head and Neck, Fehrenbach and Herring, Elsevier, 2012, page 216 In contrast, the superior alveolar nerves are not usually anesthetized directly because they are difficult to approach with a needle. For this reason, the maxillary arch is usually anesthetized locally for dental work by inserting the needle beneath the oral mucosa surrounding the teeth so as to anesthetize the smaller branches.
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As part of the embryonic cerebrospinal fluid (eCSF), SCO-spondin is of the uttermost importance in the development of the neuronal system, being a key protein in the balancing of differentiation and proliferation of the neuroepithelium. It starts being secreted by the diencephalic floor plate in the first embryonic stages playing an important part in the development and differentiation of structures such as the pineal gland. In particular, the SCO-spondin appears to have a major role on the growth of the posterior commissure (PC), which was proved when mutants lacking SCO, and hence having no SCO-spondin, were unable to form a functional PC. On early stages of development the axonal growth is stimulated, being inhibited afterwards. A steep gradient of spondin expression in the neuroepithelium signals the need for different processes to take place, favoring the fasciculation on the cephalic region and the incorporation of new neurons on the caudal region.
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" They also stated that light "constant pressure on the clitoris produced an initial burst of single unit firing (maximum frequencies 170–255 Hz) followed by rapid adaptation and a sustained firing (maximum 40 Hz), which was maintained during the stimulation" and that further examination of tonic firing "indicate that the clitoris is innervated by mechano-sensitive myelinated afferent fibers in the pudental nerve which project centrally to the region of the dorsal commissure in the L7-S1 spinal cord". The external phenotype and reproductive behavior of 21 freemartin sheep and two male pseudohermaphrodite sheep were recorded with the aim of identifying any characteristics that could predict a failure to breed. The vagina's length and the size and shape of the vulva and clitoris were among the aspects analyzed. While the study reported that "a number of physical and behavioural abnormalities were detected," it also concluded that "the only consistent finding in all 23 animals was a short vagina which varied in length from 3.1 to 7.0 cm, compared with 10 to 14 cm in normal animals.
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Rhynchonelloidella alemanica has small sized shells, subtrigonal to slightly subpentagonal in outline, with wide hinge line; inequivalve, almost plano-convex; dorsal valve markedly everted anteriorly, giving shell subcynocephalous to cynocephalus profile. Lateral commissures deflected ventrally at 15 to 30 degrees; anterior commissure highly uniplicate; linguiform extension high and narrow, top truncated. Beak short, pointed, substraight to suberect; foramen large, oval in shape, hypothyridid, with well developed rim; deltidial plates wide, disjunct to just conjunct; beak ridges angular, extending laterally; interareas well defined and slightly concave with fine growth lines. Ventral valve gently convex at posterior and flattened anteriorly; sulcus well developed, deep and narrow, with flat bottom, occurring at about posterior 1/3 of valve, abruptly separated from slopes and turning over towards dorsal valve sharply at frontal margin, resulting in high linguiform extension. Dorsal valve moderately convex at umbonal region, but less tumid than in Rhynchonelloidella smithi, norelliform stage feebly recognizable, sulcation short or even absent; fold eminent, narrow and well elevated over slopes with steep flanks, occurring at about posterior 1/3 to 1/2 of valve and making valve trilobate anteriorly.
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