|
Interposed Nucleus
The interposed nucleus is the combined paired globose and emboliform nuclei, ( deep cerebellar nuclei) on either side of the cerebellum. It is located in the roof of the fourth ventricle, lateral to the fastigial nucleus. The emboliform nucleus is the ''anterior interposed nucleus'', and the globose nucleus is the ''posterior interposed nucleus''. The interposed nucleus is responsible for coordinating agonist/antagonist muscle pairs, and therefore a lesion in this area causes tremor. Anatomy The interposed nucleus is located in the paravermis of the cerebellum. The interposed nucleus is smaller than the dentate but larger than the fastigial nucleus. Afferents The interposed nuclei receives Purkine cell terminal afferents from the paravermal cortex of the spinocerebellum, as well as collaterals of cerebellar afferents from the restiform body and ventral spinocerebellar tract. It receives input from the ipsilateral posterior external arcuate fibers (cuneocerebellar tract) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Globose Nucleus
The globose nucleus is one of the deep cerebellar nuclei. It is located medial to the emboliform nucleus, and lateral to the fastigial nucleus. The ''globose nucleus'' and emboliform nucleus are known collectively as the interposed nuclei. The globose nucleus is part of a neural circuit giving rise to descending motor tracts involved in motor control of distal musculature of the upper and lower limbs. Anatomy Afferents * Purkinje cells of (the paravermal cortex of) the spinocerebellum * Anterior spinocerebellar tract (via restiform body of inferior cerebellar peduncle) Efferents * Contralateral (magnocellular division of) red nucleus (via the superior cerebellar peduncle). This is the major major efferent projection of the globose nucleus. The red nucleus in turn gives rise to the rubrospinal tract. * Ipsilateral ventral lateral nucleus of thalamus. The VL nucleus in turn projects to the primary motor cortex and premotor cortex (which then give rise to the lateral c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accessory Cuneate Nucleus
The accessory cuneate nucleus (also lateral cuneate nucleus, or external cuneate nucleus) is a nucleus situated in the caudal medulla oblongata just lateral to the cuneate nucleus. It relays unconscious proprioceptive sensory information from the upper limb and upper trunk to the cerebellum via the cuneocerebellar fibers. The neurons of the ACN (as well as those of the lateral portion of the cuneate nucleus) are functionally homologous with the posterior thoracic nucleus; the cuneocerebellar fibers are therefore the upper body functional equivalent of the dorsal spinocerebellar tract. Anatomy Synapses in the ACN are somatotopically organized. Afferents Afferents of the ACN arise from muscle stretch receptors and skin touch receptors of the upper limb; they enter the spinal cord rostral to the posterior thoracic nucleus to ascend in the lateral portion of the cuneate fasciculus. A minority of the fibers of the cuneate fasciculus thus synapse in the ACN. Efferents Effer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lateral Corticospinal Tract
Lateral is a geometric term of location which may also refer to: Biology and healthcare * Lateral (anatomy), a term of location meaning "towards the side" * Lateral cricoarytenoid muscle, an intrinsic muscle of the larynx * Lateral release (surgery), a surgical procedure to release tight capsular structures Other uses * ''Lateral'', a digital journal and production of the Cultural Studies Association * ''Lateral'', a podcast by English YouTuber and web developer Tom Scott * Lateral canal, a canal built along the same right-of-way as an existing stream * Lateral consonant, a consonant in which the airstream proceeds along one or both of the sides of the tongue * Lateral mark, a sea mark used in maritime pilotage to indicate the edge of a channel * Lateral modes, an aspect of dynamic stability and control in the field of aircraft flight dynamics * Lateral pass, a non-advancing move in gridiron football * Lateral release (phonetics), the release of a plosive consonant in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primary Motor Cortex
The primary motor cortex ( Brodmann area 4) is a brain region that in humans is located in the dorsal portion of the frontal lobe. It is the primary region of the motor system and works in association with other motor areas including premotor cortex, the supplementary motor area, posterior parietal cortex, and several subcortical brain regions, to plan and execute voluntary movements. Primary motor cortex is defined anatomically as the region of cortex that contains large neurons known as Betz cells, which, along with other cortical neurons, send long axons down the spinal cord to synapse onto the interneuron circuitry of the spinal cord and also directly onto the alpha motor neurons in the spinal cord which connect to the muscles. At the primary motor cortex, motor representation is orderly arranged (in an inverted fashion) from the toe (at the top of the cerebral hemisphere) to mouth (at the bottom) along a fold in the cortex called the central sulcus. However, some body p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Premotor Cortex
The premotor cortex is an area of the motor cortex lying within the frontal lobe of the brain just anterior to the primary motor cortex. It occupies part of Brodmann's area 6. It has been studied mainly in primates, including monkeys and humans. The functions of the premotor cortex are diverse and not fully understood. It projects directly to the spinal cord and therefore may play a role in the direct control of behavior, with a relative emphasis on the trunk muscles of the body. It may also play a role in planning movement, in the spatial guidance of movement, in the sensory guidance of movement, in understanding the actions of others, and in using abstract rules to perform specific tasks. Different subregions of the premotor cortex have different properties and presumably emphasize different functions. Nerve signals generated in the premotor cortex cause much more complex patterns of movement than the discrete patterns generated in the primary motor cortex. Structure The pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ventral Lateral Nucleus
The ventral lateral nucleus (VL) is a nucleus in the ventral nuclear group of the thalamus. Inputs and outputs It receives neuronal inputs from the basal ganglia which includes the substantia nigra and the globus pallidus (via the thalamic fasciculus). It also has inputs from the cerebellum (via the dentatothalamic tract). It sends neuronal output to the primary motor cortex and premotor cortex. The ventral lateral nucleus in the thalamus forms the motor functional division in the thalamic nuclei along with the ventral anterior nucleus. The ventral lateral nucleus receives motor information from the cerebellum and the globus pallidus. Output from the ventral lateral nucleus then goes to the primary motor cortex. Functions The function of the ventral lateral nucleus is to target efferents including the motor cortex, premotor cortex, and supplementary motor cortex. Therefore, its function helps the coordination and planning of movement. It also plays a role in the learn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rubrospinal Tract
The rubrospinal tract is one of the descending tracts of the spinal cord. It is a motor control pathway that originates in the red nucleus. It is a part of the lateral indirect extrapyramidal tract. The rubrospinal tract fibers are efferent nerve fibers from the magnocellular part of the red nucleus. (Rubro-olivary fibers are efferents from the parvocelluar part of the red nucleus). It is functionally less important in humans. It is involved in motor control of distal flexors of the upper limbespecially of the hand and fingersby promoting flexor tone while inhibiting extensors. Structure The rubrospinal tract originates in the magnocellular red nucleus in the midbrain, and decussates (crosses over) at the midline in the anterior tegmental decussation. In the pons, it is situated medially within the rostral pontine tegmentum. In the medulla oblongata, it descends within the lateral tegmentum medial to the spinocerebellar tract, and posterior to the spinothalamic tract. It ... [...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] |
Superior Cerebellar Peduncle
In the human brain, the superior cerebellar peduncle (brachium conjunctivum) is one of the three paired cerebellar peduncles of bundled fibers that connect the cerebellum to the brainstem. The superior cerebellar peduncle connects to the midbrain. It consists mainly of efferent fibers, the cerebellothalamic tract that runs from a cerebellar hemisphere to the contralateral thalamus, and the cerebellorubral tract that runs from a cerebellar hemisphere to the red nucleus. It also contains afferent tracts, most prominent of which is the ventral spinocerebellar tract. Other afferent tracts are the ventral trigeminal tract, tectocerebellar fibers, and noradrenergic fibers from the locus coeruleus. The superior peduncle emerges from the upper and medial parts of the white matter of each cerebellar hemisphere and is placed under cover of the upper part of the cerebellum. Structure Superior cerebellar peduncles are connected together by the superior medullary velum, which can be fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Posterior Thoracic Nucleus
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 the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dorsal 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 le ... [...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] |
