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Cerebellar Peduncle
The cerebellar peduncles are three paired bundles of Axon, fibres that connect the cerebellum to the brain stem. * Superior cerebellar peduncle is a paired structure of white matter that connects the cerebellum to the mid-brain. * Middle cerebellar peduncles connect the cerebellum to the pons and are composed entirely of centripetal fibers. * Inferior cerebellar peduncle is a thick rope-like strand that occupies the upper part of the posterior district of the medulla oblongata. The peduncles form the lateral border of the fourth ventricle, and form a distinctive diamond the middle peduncle forming the central corners of the diamond, while the superior and inferior peduncles form the superior and inferior edges, respectively. Structural origin Superior cerebellar peduncle The superior cerebellar peduncles (bracchia conjunctiva) emerge from the cerebellum and ascend to form the lateral portion of the roof of the fourth ventricle, where they enter the brainstem below the inferi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axon
An axon (from Greek ἄξων ''áxōn'', axis) or nerve fiber (or nerve fibre: see American and British English spelling differences#-re, -er, spelling differences) is a long, slender cellular extensions, projection of a nerve cell, or neuron, in Vertebrate, vertebrates, that typically conducts electrical impulses known as action potentials away from the Soma (biology), nerve cell body. The function of the axon is to transmit information to different neurons, muscles, and glands. In certain sensory neurons (pseudounipolar neurons), such as those for touch and warmth, the axons are called afferent nerve fibers and the electrical impulse travels along these from the peripheral nervous system, periphery to the cell body and from the cell body to the spinal cord along another branch of the same axon. Axon dysfunction can be the cause of many inherited and acquired neurological disorders that affect both the Peripheral nervous system, peripheral and Central nervous system, central ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emboliform Nucleus
The emboliform nucleus is a deep cerebellar nucleus that lies immediately to the medial side of the dentate nucleus, partly covering its hilum. It is one of the four pairs of deep cerebellar nuclei, which are from lateral to medial: the dentate, emboliform, globose and fastigial. These nuclei can be seen using Weigert's elastic stain. In lower mammals the emboliform nucleus appears to be continuous with the globose nucleus, and these are known together as the interposed nucleus. ''Emboliform'', from Ancient Greek, means "shaped like a plug or wedge". Structure The emboliform nucleus is a wedge-shaped structure of gray matter found at the medial side of the hilum of the dentate nucleus. Its neurons display a similar structure from those of the dentate nucleus. In some mammals the emboliform nucleus is continuous with the globose nucleus, forming together the interposed nucleus. When present, the interposed nucleus can be divided in an anterior and a posterior inte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lateral Funiculus
The most lateral of the bundles of the anterior nerve roots is generally taken as a dividing line that separates the anterolateral system into two parts. These are the anterior funiculus, between the anterior median fissure and the most lateral of the anterior nerve roots, and the lateral funiculus between the exit of these roots and the posterolateral sulcus. The lateral funiculus transmits the contralateral corticospinal and spinothalamic tracts. A lateral cutting of the spinal cord results in the transection of both ipsilateral posterior column and lateral funiculus and this produces Brown-Séquard syndrome.Kaplan Qbook - USMLE Step 1 - 5th edition - page See also * Funiculus (neuroanatomy) * Anterior funiculus * Posterior funiculus References Central nervous system {{Neuroanatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anterior White Commissure
The anterior white commissure (ventral white commissure) is a bundle of nerve fibers which cross the midline of the spinal cord just anterior (in front of) to the gray commissure ( Rexed lamina X). A delta fibers (Aδ fibers) and C fibers carrying pain sensation in the spinothalamic tract contribute to this commissure, as do fibers of the anterior corticospinal tract, which carry motor signals from the primary motor cortex. Two of the five sensory modalities, pain and temperature, cross sides at the anterior white commissure, reaching the contralateral side about two vertebral levels rostral to their origin. The spinothalamic tract thus decussates very soon after entering the spinal cord, ascending in the spinal cord, contralateral to the side from where it provides (pain and temperature) sensory information. Therefore, a lesion that is caudal to the sensory decussation where the remaining three-fifths modalities decussate (at the superior medulla) will result in contralat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clarke's Column
The posterior thoracic nucleus, (Clarke's column, column of Clarke, dorsal nucleus, nucleus dorsalis of Clarke) is a group of interneurons found in the medial part of Rexed lamina VII, also known as the intermediate zone, of the spinal cord. It is located from the cervical segment C8 to lumbar segment L3 of the spinal cord and is an important structure for proprioception of the lower limb. Anatomy It occupies the medial part of the base of the posterior grey column and appears on the transverse section as a well-defined oval area. It begins caudally at the level of the second or third lumbar nerve, and reaches its maximum size opposite the twelfth thoracic nerve. Above the level of the eight thoracic nerve its size diminishes, and the column ends opposite the last cervical or first thoracic nerve. It is represented, however, in the other regions by scattered cells, which become aggregated to form a cervical nucleus opposite the third cervical nerve, and a sacral nucleus in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anterior Spinocerebellar Tract
The spinocerebellar tracts are nerve tracts originating in the spinal cord and terminating in the same side ( ipsilateral) of the cerebellum. The two main tracts are the dorsal spinocerebellar tract, and the ventral spinocerebellar tract. Both of these tracts are located in the peripheral region of the lateral funiculi (white matter columns). Other tracts are the rostral spinocerebellar tract, and the cuneocerebellar tract (posterior external arcuate fibers). They carry proprioceptive, and cutaneous information to the cerebellum, where movement can be coordinated. Origins of proprioceptive information Proprioceptive information is obtained by Golgi tendon organs and muscle spindles. * Golgi tendon organs consist of a fibrous capsule enclosing tendon fascicles and bare nerve endings that respond to tension in the tendon by causing action potentials in type Ib afferents. These fibers are relatively large, myelinated, and quickly conducting. * Muscle spindles monitor the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reticular Formation
The reticular formation is a set of interconnected nuclei in the brainstem that spans from the lower end of the medulla oblongata to the upper end of the midbrain. The neurons of the reticular formation make up a complex set of neural networks in the core of the brainstem. The reticular formation is made up of a diffuse net-like formation of reticular nuclei which is not well-defined. It may be seen as being made up of all the interspersed cells in the brainstem between the more compact and named structures. The reticular formation is functionally divided into the ascending reticular activating system (ARAS), ascending pathways to the cerebral cortex, and the descending reticular system, descending pathways ( reticulospinal tracts) to the spinal cord. Due to its extent along the brainstem it may be divided into different areas such as the midbrain reticular formation, the central mesencephalic reticular formation, the pontine reticular formation, the paramedian pontine reticul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thalamus
The thalamus (: thalami; from Greek language, Greek Wikt:θάλαμος, θάλαμος, "chamber") is a large mass of gray matter on the lateral wall of the third ventricle forming the wikt:dorsal, dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, known as the thalamocortical radiations, allowing hub (network science), hub-like exchanges of information. It has several functions, such as the relaying of sensory neuron, sensory and motor neuron, motor signals to the cerebral cortex and the regulation of consciousness, sleep, and alertness. Anatomically, the thalami are paramedian symmetrical structures (left and right), within the vertebrate brain, situated between the cerebral cortex and the midbrain. It forms during embryonic development as the main product of the diencephalon, as first recognized by the Swiss embryologist and anatomist Wilhelm His Sr. in 1893. Anatomy The thalami ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Nucleus
The red nucleus or nucleus ruber is a structure in the rostral midbrain involved in motor coordination. The red nucleus is pale pink, which is believed to be due to the presence of iron in at least two different forms: hemoglobin and ferritin. The structure is located in the midbrain tegmentum next to the substantia nigra and comprises caudal magnocellular and rostral parvocellular components. The red nucleus and substantia nigra are subcortical centers of the extrapyramidal motor system. Function In a vertebrate without a significant corticospinal tract, gait is mainly controlled by the red nucleus. However, in primates, where the corticospinal tract is dominant, the rubrospinal tract may be regarded as vestigial in motor function. Therefore, the red nucleus is less important in primates than in many other mammals. Nevertheless, the crawling of babies is controlled by the red nucleus, as is arm swinging in typical walking. The red nucleus may play an additional role ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lateral Lemniscus
The lateral lemniscus is a tract of axons in the brainstem that carries information about sound from the cochlear nucleus to various brainstem nuclei and ultimately the contralateral inferior colliculus of the midbrain. Three distinct, primarily inhibitory, cellular groups are located interspersed within these fibers, and are thus named the nuclei of the lateral lemniscus. Connections There are three small nuclei on each of the lateral lemnisci: * the intermediate nucleus of the lateral lemniscus (INLL) * the ventral nucleus of the lateral lemniscus (VNLL) * the dorsal nucleus of the lateral lemniscus (DNLL) Fibers leaving these brainstem nuclei ascending to the inferior colliculus rejoin the lateral lemniscus. In that sense, this is not a ' lemniscus' in the true sense of the word (second order, decussated sensory axons), as there is third (and out of the lateral superior olive, fourth) order information coming out of some of these brainstem nuclei. The lateral lemniscus is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Midbrain Tegmentum
The midbrain is anatomically delineated into the tectum (roof) and the tegmentum (floor). The midbrain tegmentum extends from the substantia nigra to the cerebral aqueduct in a horizontal section of the midbrain. It forms the floor of the midbrain that surrounds below the cerebral aqueduct as well as the floor of the fourth ventricle while the midbrain tectum forms the roof of the fourth ventricle. The tegmentum contains a collection of tracts and nuclei with movement-related, species-specific, and pain-perception functions. The general structures of midbrain tegmentum include red nucleus and the periaqueductal grey matter. Unlike the midbrain tectum (which is a sensory structure located posteriorly), the midbrain tegmentum, which locates anteriorly, is related to a number of motor functions. Within the tegmentum, the red nucleus is in charge of motor coordination (specifically for limb movements) and the periaqueductal gray matter (PAG) contains critical circuits for modulati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fastigial Nucleus
The fastigial nucleus (roof nucleus-1) is located in each cerebellar hemisphere. It is one of the four paired deep cerebellar nuclei of the cerebellum. It is made up of two sections: the rostral fastigial nucleus and the caudal fastigial nucleus. Anatomy The fastigial nuclei is situated atop the roof of the fourth ventricle (thence its name: "''fastigus''" is Latin for "summit"). The fastigial nucleus is a mass of gray matter nearest to the middle line at the anterior end of the superior vermis, immediately over the roof of the fourth ventricle (the peak of which is called the ''fastigium''), from which it is separated by a thin layer of white matter. It is smaller than the dentate nucleus, but somewhat larger than the emboliform nucleus and globose nucleus. Afferents The fastigial nucleus receives afferents from the vestibulocerebellar tract (containing first-order axons from the vestibular nerve as well as second-order axons from the vestibular nuclei), and fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
