Gigantocellular reticular nucleus | |
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Details | |
Identifiers | |
Latin | nucleus reticularis gigantocellularis |
NeuroNames | 730 |
NeuroLex ID | nlx_anat_1005001 |
TA98 | A14.1.04.302 |
TA2 | 6028 |
FMA | 72576 |
Anatomical terms of neuroanatomy |
The gigantocellular reticular nucleus (also magnocellular reticular nucleus) is the (efferent/motor) medial zone of the reticular formation of the caudal pons and rostral medulla oblongata. It consists of a substantial quality of giant neurons, but also contains small and medium sized neurons. [1]
It gives rise to the lateral (medullary) reticulospinal tract which influences muscle tone of limb and trunk muscles, is involved in coordination of head-eye movements, promotes parasympathetic reduction of heart rate to decrease blood pressure, induces inspiration, and participates in the descending pain-inhibiting pathway.
It receives connections from the periaqueductal gray, the paraventricular hypothalamic nucleus, central nucleus of the amygdala, lateral hypothalamic area, and parvocellular reticular nucleus.[ citation needed ]
It receives afferent corticoreticular fibers from the premotor cortex and supplementary motor area which modulate the activity of reticulospinal and reticulobulbar efferents of the its. [1]
It receives vestibular, visual, and auditory afferents to mediate head-eye movement coordination. [1]
It receives excitatory enkephalinergic afferents from the periaqueductal gray which influence its descending pain-inhibiting efferents. [1]
It gives rise to the lateral (medullary) reticulospinal tract (which excites flexors and inhibits extensors of the muscles of the axial and proximal limbs). [1]
It is also involved in coordination of head-eye movements (receiving visual, vestibular, and auditory information to this end). [1]
The GGRN forms part of the vasodepressor center which projects through the reticulobulbar tract to synapse upon pre-ganglionic parasympathetic neurons of the nucleus of vagus nerve. It acts to decrease blood pressure by decreasing heart chronotropy (rate) by increasing vagal parasympathetic outflow to the heart. [1]
GGRN induces inspiration (whereas the parvocellular nucleus causes expiration). [1]
The GGRN - together with the nucleus raphe magnus - gives rise to the descending serotonergic raphespinal tract which projects to the spinal cord to inhibit transmission of pain stimuli. The serotonergic analgesic component of the GGRN receives excitatory enkephalinergic afferents from the periaqueductal gray. [1]
Articles related to anatomy include:
The brainstem is the stalk-like part of the brain that interconnects the cerebrum and diencephalon with the spinal cord. In the human brain, the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is continuous with the thalamus of the diencephalon through the tentorial notch.
The glossopharyngeal nerve, also known as the ninth cranial nerve, cranial nerve IX, or simply CN IX, is a cranial nerve that exits the brainstem from the sides of the upper medulla, just anterior to the vagus nerve. Being a mixed nerve (sensorimotor), it carries afferent sensory and efferent motor information. The motor division of the glossopharyngeal nerve is derived from the basal plate of the embryonic medulla oblongata, whereas the sensory division originates from the cranial neural crest.
The nucleus ambiguus is a group of large motor neurons, situated deep in the medullary reticular formation named by Jacob Clarke. The nucleus ambiguus contains the cell bodies of neurons that innervate the muscles of the soft palate, pharynx, and larynx which are associated with speech and swallowing. As well as motor neurons, the nucleus ambiguus contains preganglionic parasympathetic neurons which innervate postganglionic parasympathetic neurons in the heart.
The medial longitudinal fasciculus (MLF) is a prominent bundle of nerve fibres which pass within the ventral/anterior portion of periaqueductal gray of the mesencephalon (midbrain). It contains the interstitial nucleus of Cajal, responsible for oculomotor control, head posture, and vertical eye movement.
The reticular formation is a set of interconnected nuclei that are located in the brainstem, hypothalamus, and other regions. It is not anatomically well defined, because it includes neurons located in different parts of the brain. The neurons of the reticular formation make up a complex set of networks in the core of the brainstem that extend from the upper part of the midbrain to the lower part of the medulla oblongata. The reticular formation includes ascending pathways to the cortex in the ascending reticular activating system (ARAS) and descending pathways to the spinal cord via the reticulospinal tracts.
The fastigial nucleus is located in each hemisphere of the cerebellum. It is one of the four deep cerebellar nuclei.
The dorsal longitudinal fasciculus (DLF) is a longitudinal tract interconnecting the posterior hypothalamus, and the inferior medulla oblongata. It contains both ascending tracts and descending tracts, and serves to link the forebrain, and the visceral autonomic centres of the lower brainstem. It conveys both visceral motor signals, and sensory signals.
The vestibulospinal tract is a neural tract in the central nervous system. Specifically, it is a component of the extrapyramidal system and is classified as a component of the medial pathway. Like other descending motor pathways, the vestibulospinal fibers of the tract relay information from nuclei to motor neurons. The vestibular nuclei receive information through the vestibulocochlear nerve about changes in the orientation of the head. The nuclei relay motor commands through the vestibulospinal tract. The function of these motor commands is to alter muscle tone, extend, and change the position of the limbs and head with the goal of supporting posture and maintaining balance of the body and head.
The nucleus raphe pallidus receives afferent connections from the periaqueductal gray, the Paraventricular nucleus of hypothalamus, central nucleus of the amygdala, lateral hypothalamic area, and parvocellular reticular nucleus.
The nucleus raphe magnus is one of the seven raphe nuclei. It is situated in the pons in the brainstem, just rostral to the nucleus raphe obscurus.
The spinotectal tract and/or spinomesencephalic tract is a component of the ascending reticular activating system that is involved in processing of pain and visceral sensations. The tract is involved in the processing of pain sensation, and reflex turning of the head and trunk in the direction of painful stimuli. It arises in the spinal cord, and projects contralaterally to various structures of the midbrain.
The oral pontine reticular nucleus or rostral pontine reticular nucleus is one of the two components of the medial (efferent/motor) zone of the pontine reticular formation - the other being the caudal pontine reticular nucleus. The efferents of these two structures together give rise to the medial (pontine) reticulospinal tract. A population of their neurons together also form the paramedian pontine reticular formation which is involved in the coordination of horizontal conjugate eye movements in response to head movements.
The reticulospinal tracts are extrapyramidal motor tracts that descend from the reticular formation in two tracts to act on the motor neurons supplying the trunk and proximal limb flexors and extensors. The reticulospinal tracts are involved mainly in locomotion and postural control, although they do have other functions as well.
The spinoreticular tract is a partially decussating (crossed-over) four-neuron sensory pathway of the central nervous system. The tract transmits slow nociceptive/pain information from the spinal cord to reticular formation which in turn relays the information to the thalamus via reticulothalamic fibers as well as to other parts of the brain. Most (85%) second-order axons arising from sensory C first-order fibers ascend in the spinoreticular tract - it is consequently responsible for transmiting "slow", dull, poorly-localised pain. By projecting to the reticular activating system (RAS), the tract also mediates arousal/alertness in response to noxious stimuli. The tract is phylogenetically older than the spinothalamic ("neospinothalamic") tract.
The juxtarestiform body is the smaller, medial subdivision of each inferior cerebellar peduncle.
The parabrachial nuclei, also known as the parabrachial complex, are a group of nuclei in the dorsolateral pons that surrounds the superior cerebellar peduncle as it enters the brainstem from the cerebellum. They are named from the Latin term for the superior cerebellar peduncle, the brachium conjunctivum. In the human brain, the expansion of the superior cerebellar peduncle expands the parabrachial nuclei, which form a thin strip of grey matter over most of the peduncle. The parabrachial nuclei are typically divided along the lines suggested by Baxter and Olszewski in humans, into a medial parabrachial nucleus and lateral parabrachial nucleus. These have in turn been subdivided into a dozen subnuclei: the superior, dorsal, ventral, internal, external and extreme lateral subnuclei; the lateral crescent and subparabrachial nucleus along the ventrolateral margin of the lateral parabrachial complex; and the medial and external medial subnuclei
The raphespinal tract is an unmyelinated descending serotonergic tract involved in pain modulation. It is a descending pain-inhibiting pathway; it is a component of the reticulospinal tract.
The parafacial zone (PZ) is a brain structure located in the brainstem within the medulla oblongata believed to be heavily responsible for non-rapid eye movement (non-REM) sleep regulation, specifically for inducing slow-wave sleep.
It also receives inputs from the pedunculopontine nucleus.