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Published in Bobby Krishnachetty, Abdul Syed, Harriet Scott, Applied Anatomy for the FRCA, 2020
Bobby Krishnachetty, Abdul Syed, Harriet Scott
Centre: the nucleus tractus solitarius (NTS) in the medulla is the major regulator of autonomic nerve outflow to the heart and blood vessels. The hypothalamus and higher centres modify the activity of the medullary centres and are particularly important in stimulating cardiovascular responses to emotion and stress. Neural connections from the NTS modulate sympathetic neuronal activity in the upper ventrolateral medulla, and the activity of parasympathetic neurons located in the dorsal vagal nucleus and nucleus ambiguus. Stimulation of the NTS reciprocally activates vagal neurons and inhibits sympathetic neurons.The sympathetic nerves exit the medulla and travel down the spinal cord where they synapse with the sympathetic ganglia. The fibres within the sympathetic chain originate from the superior, middle and inferior cervical ganglia, along with T1 to T4. Longer postganglionic efferent fibres from the ganglia travel to the heart and vessels.The parasympathetic nerves in the form of vagus nerves (cranial nerve X) exit the medulla as long preganglionic efferent fibres that synapses with short postganglionic fibres within the heart or vasculature.
Regulation of Arterial Blood Pressure
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Caudal ventrolateral medulla (CVLM). CVLM has a depressor effect on the cardiovascular system and reduces peripheral resistance and cardiac contractility. It is thought that CVLM, under the influence of various excitatory and inhibitory inputs, tonically inhibits RVLM cells by GABA release.
Myofascial and Visceral Pain Syndromes: Visceral-Somatic Pain Representations
Published in Robert M. Bennett, The Clinical Neurobiology of Fibromyalgia and Myofascial Pain, 2020
The dorsal columns of the spinal cord transmit visceral pain information. Information carried in the dorsal columns affects pain awareness in humans. For example, midline dorsal column lesions are effective treatment for the relief of pelvic visceral pain (13). This has also been shown to be the case in animals for pain arising from colorectal distention, the duodenum, and the pancreas (14). The dorsal midline of the rat spinal cord contains both ascending tracts to the gracile and cuneate nucleus and descending corticospinal pathways. Ventrolateral cordotomies alone do not abolish visceral stimulation-evoked responses. Both the ventrolateral quadrants and dorsolateral funiculi are important for the transmission of visceral nociceptive information. Dorsal midline structures are important for input into the ventrobasal thalamus, whereas lateral spinothalamic pathways are more important for input into the ventrolateral medullary structures (15). The ventrolateral medulla is greatly involved in autonomic regulation. Visceral input through the lateral spinothalamic tracts to the ventrolateral medulla therefore plays an important role in autonomic reflex activity [such as change in heart rate], and is attenuated by lesions of the lateral column of the spinal cord, but not by midline dorsal lesions. However, the spinal cord dorsal column does not only transmit visceral nociceptive information. The dorsal columns have a more general function in pain, and, for example, have been shown to transmit information in peripheral nerve injuries like experimental mononeuropathy (16).
Novel approaches: targeting sympathetic outflow in the carotid sinus
Published in Blood Pressure, 2023
Dagmara Hering, Krzysztof Narkiewicz
Tonic sympathetic activation and tonic arterial BP control depend on central integrative structures in the brain stem, the rostral ventrolateral medulla (RVLM) [3]. Descending projections to the RVLM arise among others from the neurons in the peri-aqueductal grey and hypothalamic paraventricular nucleus (PVN). The RVLM integrates reflex neural mechanisms from arterial baroreceptors, chemoreceptors and various afferent sensory visceral receptors via direct connection with the upper part of the medulla through the NTS and PVN which modulate vasomotor sympathetic nerve discharge and BP. Under physiological conditions, arterial baroreceptors play a fundamental role in preventing excessive variability in BP. Afferent signals from baroreceptors stimulate the NTS in the upper part of the medulla in response to the distension of the vessel wall caused by transmural pressure. A signal arising from the NTS exerts a parasympathetic vagal effect resulting in slowing HR and reducing tonic sympathetic activity generated in the RVLM (Figure 2).
Overexpression of NaV1.6 in the rostral ventrolateral medulla in rats mediates stress-induced hypertension via glutamate regulation
Published in Clinical and Experimental Hypertension, 2022
Lei Tong, Mengyu Xing, Jiaxiang Wu, Shuai Zhang, Dechang Chu, Haili Zhang, Fuxue Chen, Dongshu Du
Stress-induced hypertension (SIH) caused by central sympathetic nerve disorder is the main type of primary hypertension induced by aggravated social and psychological stress among adults (1). Stress can activate a series of pathological molecular and cellular alterations, leading to induction of cardiovascular disease via the central nervous system (2). For instance, neuron activity and sympathetic overactivity in the rostral ventrolateral medulla (RVLM) are involved in the regulation of hypertension (3). Several studies have demonstrated that the RVLM is responsible for generating the sympathetic drive to the cardiovascular system and eventually determines cardiac output and vascular resistance (4). Recent studies of the signaling axis of the central nervous system, which regulates blood pressure, have found that changes in sodium, potassium, and calcium plasma channels in specific brain regions are related to the regulation of hypertension (5). Our previous studies also found that overexpression of NaV1.6 in the RVLM and increased KV10.2 expression in the paraventricular nucleus after stress are related to increased blood pressure (6,7).
«A case of a pharmacoresistant tachyarrhythmia associated with Arnold-Chiari malformation»
Published in British Journal of Neurosurgery, 2019
I. M. Gilemkhanova, Shamil Safin, Khristina Derevyanko, Albert Gilemkhanov, Igor Buzaev
Indeed, a transient malfunction at the brain stem level could affect several structures involved in sympathetic/parasympathetic cardiovascular regulation constituting the baroreflex system. The baroreflex system is mediated by afferent pathways via the ninth and tenth cranial nerves, relaying information from vascular baroreceptors to the nucleus tractus solitarii (NTS), which sends excitatory projections to the caudal ventrolateral medulla, which in turn inhibits the sympathoexcitatory neurones of the rostral ventrolateral medulla. Lesions of the NTS or efferent/afferent baroreflex pathways result in baroreflex failure, leading typically to a marked lability of blood pressure, with hypertension and tachycardia alternating with hypotension and bradycardia. However, depending on the degree and probably the site of injury of the baroreflex mediating system, other clinical presentations could occur, such as tachycardia.8,10–12