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Journal of Anatomy Dec 1977In the neck, the left phrenic nerve is in a position that corresponds exactly to that of the right phrenic nerve. Both cross and second part of the subclavian arteries....
In the neck, the left phrenic nerve is in a position that corresponds exactly to that of the right phrenic nerve. Both cross and second part of the subclavian arteries. On the left side there is an additional relationship of the nerve to the subclavian artery in the thorax, where it descends in front of the first part of the artery.
Topics: Humans; Neck; Phrenic Nerve; Subclavian Artery
PubMed: 604346
DOI: No ID Found -
The Journal of Physiology Mar 2010Stimulation of respiratory afferents elicits neural activity in the somatosensory region of the cerebral cortex in humans and animals. Respiratory afferents have been...
Stimulation of respiratory afferents elicits neural activity in the somatosensory region of the cerebral cortex in humans and animals. Respiratory afferents have been stimulated with mechanical loads applied to breathing and electrical stimulation of respiratory nerves and muscles. It was hypothesized that stimulation of the phrenic nerve myelinated afferents will activate neurons in the 3a and 3b region of the somatosensory cortex. This was investigated in cats with electrical stimulation of the intrathoracic phrenic nerve and C(5) root of the phrenic nerve. The somatosensory cortical response to phrenic afferent stimulation was recorded from the cortical surface, contralateral to the phrenic nerve, ispilateral to the phrenic nerve and with microelectrodes inserted into the cortical site of the surface dipole. Short-latency, primary cortical evoked potentials (1 degrees CEP) were recorded with stimulation of myelinated afferents of the intrathoracic phrenic nerve in the contralateral post-cruciate gyrus of all animals (n = 42). The mean onset and peak latencies were 8.5 +/- 5.7 ms and 21.8 +/- 9.8 ms, respectively. The rostro-caudal surface location of the 1 degrees CEP was found between the rostral edge of the post-cruciate dimple (PCD) and the rostral edge of the ansate sulcus, medio-lateral location was between 2 mm lateral to the sagittal sulcus and the lateral end of the cruciate sulcus. Histological examination revealed that the 1 degrees CEP sites were recorded over areas 3a and 3b of the SI somatosensory cortex. Intracortical activation of 16 neurons with two patterns of neural activity was recorded: (1) short-latency, short-duration activation of neurons and (2) long-latency, long-duration activation of neurons. Short-latency neurons had a mean onset latency of 10.4 +/- 3.1 ms and mean burst duration of 10.1 +/- 3.2 ms. The short-latency units were recorded at an average depth of 1.7 +/- 0.5 mm below the cortical surface. The long-latency neurons had a mean onset latency of 36.0 +/- 4.2 ms and mean burst duration of 32.2 +/- 8.4 ms. The long-latency units were recorded at an average depth of 2.4 +/- 0.2 mm below the cortical surface. The results of the study demonstrated that phrenic nerve afferents have a short-latency central projection to the SI somatosensory cortex. The phrenic afferents activated neurons in lamina III and IV of areas 3a and 3b. The cortical representation of phrenic nerve afferents is medial to the forelimb, lateral to the hindlimb, similar to thoracic loci, hence the phrenic afferent SI site in the cat homunculus is consistent with body position (thoracic region) rather than spinal segment (C(5)-C(7)). The phrenic afferent activation of the somatosensory cortex is bilateral, with the ipsilateral cortical activation occurring subsequent to the contralateral. These results support the hypothesis that phrenic afferents provide somatosensory information to the cerebral cortex which can be used for diaphragmatic proprioception and somatosensation.
Topics: Afferent Pathways; Animals; Cats; Diaphragm; Female; Male; Phrenic Nerve; Sensory Receptor Cells; Somatosensory Cortex
PubMed: 20064855
DOI: 10.1113/jphysiol.2009.181735 -
Canadian Medical Association Journal Sep 1947
Topics: Humans; Phrenic Nerve
PubMed: 20257640
DOI: No ID Found -
Journal of Neurology, Neurosurgery, and... Jul 1992
Topics: Child; Electric Stimulation; Electrodes; Heart Defects, Congenital; Humans; Motor Neurons; Phrenic Nerve; Postoperative Complications; Prospective Studies; Reaction Time; Reference Values; Respiratory Muscles
PubMed: 1640252
DOI: 10.1136/jnnp.55.7.632-a -
PloS One 2024Orexin-mediated stimulation of orexin receptors 1/2 (OX[1/2]R) may stimulate the diaphragm and genioglossus muscle via activation of inspiratory neurons in the...
Orexin receptor 2 agonist activates diaphragm and genioglossus muscle through stimulating inspiratory neurons in the pre-Bötzinger complex, and phrenic and hypoglossal motoneurons in rodents.
Orexin-mediated stimulation of orexin receptors 1/2 (OX[1/2]R) may stimulate the diaphragm and genioglossus muscle via activation of inspiratory neurons in the pre-Bötzinger complex, which are critical for the generation of inspiratory rhythm, and phrenic and hypoglossal motoneurons. Herein, we assessed the effects of OX2R-selective agonists TAK-925 (danavorexton) and OX-201 on respiratory function. In in vitro electrophysiologic analyses using rat medullary slices, danavorexton and OX-201 showed tendency and significant effect, respectively, in increasing the frequency of inspiratory synaptic currents of inspiratory neurons in the pre-Bötzinger complex. In rat medullary slices, both danavorexton and OX-201 significantly increased the frequency of inspiratory synaptic currents of hypoglossal motoneurons. Danavorexton and OX-201 also showed significant effect and tendency, respectively, in increasing the frequency of burst activity recorded from the cervical (C3-C5) ventral root, which contains axons of phrenic motoneurons, in in vitro electrophysiologic analyses from rat isolated brainstem-spinal cord preparations. Electromyogram recordings revealed that intravenous administration of OX-201 increased burst frequency of the diaphragm and burst amplitude of the genioglossus muscle in isoflurane- and urethane-anesthetized rats, respectively. In whole-body plethysmography analyses, oral administration of OX-201 increased respiratory activity in free-moving mice. Overall, these results suggest that OX2R-selective agonists enhance respiratory function via activation of the diaphragm and genioglossus muscle through stimulation of inspiratory neurons in the pre-Bötzinger complex, and phrenic and hypoglossal motoneurons. OX2R-selective agonists could be promising drugs for various conditions with respiratory dysfunction.
Topics: Animals; Diaphragm; Motor Neurons; Orexin Receptors; Rats; Phrenic Nerve; Mice; Male; Hypoglossal Nerve; Rats, Sprague-Dawley; Inhalation; Medulla Oblongata; Isoquinolines; Pyridines
PubMed: 38917189
DOI: 10.1371/journal.pone.0306099 -
European Journal of Histochemistry : EJH Apr 2010The aim of this study was to examine rat thymus innervation using denervation techniques and to explore the related micro-anatomical localization of dopamine, D1, D2...
The aim of this study was to examine rat thymus innervation using denervation techniques and to explore the related micro-anatomical localization of dopamine, D1, D2 receptors and dopamine membrane transporter (DAT). In the thymus subcapsular region, the parenchymal cholinergic fibers belong exclusively to phrenic nerve branching. No somatic phrenic nerve branching was detected in any other analysed thymus lobule regions. In rats subjected to sympathetic or parasympathetic ablation, it was observed that catecholaminergic and cholinergic nerve fibers respectively contributed to forming plexuses along vessel walls. In the subcapsular and septal region, no parenchymal nerve branching, belonging to sympathetic or parasympathetic nervous system was noted. Instead, in the deep cortical region, cortico-medullary junction (CM-j) and medulla, catecholaminergic and cholinergic nerve fibers were detected along the vessels and parenchyma. Dopamine and dopamine receptors were widely diffused in the lobular cortico-medullary junction region and in the medulla, where the final steps of thymocyte maturation and their trafficking take place. No variation in dopamine and DAT immune reaction was observed following total or partial parasympathectomy or phrenic nerve cutting. After chemical or surgical sympathectomy however, neither dopamine nor DAT immune reaction was noted again. Instead, D1 and D2 dopamine receptor expression was not affected by thymus denervation. In rats subjected to specific denervation, it was observed the direct intraparenchymal branching of the phrenic nerve and sympathetic and parasympathetic fibers into thymus parenchyma along vessels. These findings on the dopaminergic system highlight the importance of neurotransmitter receptor expression in the homeostasis of neuroimmune modulation.
Topics: Animals; Biomarkers; Denervation; Dopamine; Immunohistochemistry; Male; Models, Animal; Phrenic Nerve; Rats; Rats, Sprague-Dawley; Thymus Gland
PubMed: 20558339
DOI: 10.4081/ejh.2010.e17 -
Experimental Neurology Dec 2021Cervical spinal cord injury (cSCI) severs bulbospinal projections to respiratory motor neurons, paralyzing respiratory muscles below the injury. C2 spinal hemisection...
Cervical spinal cord injury (cSCI) severs bulbospinal projections to respiratory motor neurons, paralyzing respiratory muscles below the injury. C2 spinal hemisection (C2Hx) is a model of cSCI often used to study spontaneous and induced plasticity and breathing recovery post-injury. One key assumption is that C2Hx dennervates motor neurons below the injury, but does not affect their survival. However, a recent study reported substantial bilateral motor neuron death caudal to C2Hx. Since phrenic motor neuron (PMN) death following C2Hx would have profound implications for therapeutic strategies designed to target spared neural circuits, we tested the hypothesis that C2Hx minimally impacts PMN survival. Using improved retrograde tracing methods, we observed no loss of PMNs at 2- or 8-weeks post-C2Hx. We also observed no injury-related differences in ChAT or NeuN immunolabeling within labelled PMNs. Although we found no evidence of PMN loss following C2Hx, we cannot rule out neuronal loss in other motor pools. These findings address an essential prerequisite for studies that utilize C2Hx as a model to explore strategies for inducing plasticity and/or regeneration within the phrenic motor system, as they provide important insights into the viability of phrenic motor neurons as therapeutic targets after high cervical injury.
Topics: Animals; Cell Survival; Cervical Cord; Male; Motor Neurons; Phrenic Nerve; Rats; Rats, Sprague-Dawley; Spinal Cord Injuries
PubMed: 34363808
DOI: 10.1016/j.expneurol.2021.113832 -
American Journal of Physiology.... Feb 2008The dorsomedial hypothalamus (DMH) has been proposed to play key roles in both the defense reaction to acute stress and in the thermoregulatory response to cold. We...
The dorsomedial hypothalamus (DMH) has been proposed to play key roles in both the defense reaction to acute stress and in the thermoregulatory response to cold. We reasoned that the autonomic/respiratory motor patterns of these responses would be mediated by at least partly distinct DMH neuron populations. To test this, we made simultaneous recordings of phrenic nerve and plantar cutaneous vasoconstrictor (CVC) activity in 14 vagotomized, ventilated, urethane-anesthetized rats. Microinjections of d,l-homocysteic acid (DLH; 15 nl, 50 mM) were used to cause localized, short-lasting (<1 min) activation of DMH neuron clusters. Cooling the rat's trunk skin by perfusing cold water through a water jacket-activated plantar CVC activity but depressed phrenic burst rate (cold-response pattern). The expected "stress/defense response" pattern would be phrenic activation, with increased blood pressure, heart rate, and possibly CVC activity. DLH microinjections into 76 sites within the DMH region never reduced phrenic activity. They frequently increased phrenic rate and/or plantar CVC activity, but the magnitudes of those two responses were not significantly correlated. Plantar CVC responses were evoked most strongly from the dorsal hypothalamic area and most dorsal part of the dorsomedial nucleus, whereas peak phrenic rate responses were evoked from more caudal sites; their relative magnitudes varied systematically with rostrocaudal position. Tachycardia correlated with plantar CVC responses but not phrenic rate. These findings indicate that localized activation of DMH neurons does not evoke full "cold-response" or stress/defense response patterns, but they demonstrate the existence of significant functional topography within the DMH region.
Topics: Action Potentials; Animals; Brain Mapping; Cold Temperature; Dorsomedial Hypothalamic Nucleus; Homocysteine; Male; Microinjections; Motor Neurons; Phrenic Nerve; Rats; Rats, Sprague-Dawley; Skin Temperature; Stress, Physiological; Vagotomy; Vasoconstriction
PubMed: 18077509
DOI: 10.1152/ajpregu.00633.2007 -
Experimental Neurology Jan 2020Respiratory motor neuron survival is critical for maintenance of adequate ventilation and airway clearance, preventing dependence to mechanical ventilation and...
Respiratory motor neuron survival is critical for maintenance of adequate ventilation and airway clearance, preventing dependence to mechanical ventilation and respiratory tract infections. Phrenic motor neurons are highly vulnerable in rodent models of motor neuron disease versus accessory inspiratory motor pools (e.g. intercostals, scalenus). Thus, strategies that promote phrenic motor neuron survival when faced with disease and/or toxic insults are needed to help preserve breathing ability, airway defense and ventilator independence. Adenosine 2A receptors (A2A) are emerging as a potential target to promote neuroprotection, although their activation can have both beneficial and pathogenic effects. Since the role of A2A receptors in the phrenic motor neuron survival/death is not known, we tested the hypothesis that A2A receptor antagonism promotes phrenic motor neuron survival and preserves diaphragm function when faced with toxic, neurodegenerative insults that lead to phrenic motor neuron death. We utilized a novel neurotoxic model of respiratory motor neuron death recently developed in our laboratory: intrapleural injections of cholera toxin B subunit (CtB) conjugated to the ribosomal toxin, saporin (CtB-Saporin). We demonstrate that intrapleural CtB-Saporin causes: 1) profound phrenic motor neuron death (~5% survival); 2) ~7-fold increase in phrenic motor neuron A2A receptor expression prior to cell death; and 3) diaphragm muscle paralysis (inactive in most rats; ~7% residual diaphragm EMG amplitude during room air breathing). The A2A receptor antagonist istradefylline given after CtB-Saporin: 1) reduced phrenic motor neuron death (~20% survival) and 2) preserved diaphragm EMG activity (~46%). Thus, A2A receptors contribute to neurotoxic phrenic motor neuron death, an effect mitigated by A2A receptor antagonism.
Topics: Adenosine A2 Receptor Antagonists; Animals; Apoptosis; Cholera Toxin; Diaphragm; Male; Motor Neurons; Phrenic Nerve; Purines; Rats; Rats, Sprague-Dawley; Saporins
PubMed: 31629857
DOI: 10.1016/j.expneurol.2019.113067 -
Journal of Visualized Experiments : JoVE Feb 2018Phrenic motor neurons are cervical motor neurons originating from C3 to C6 levels in most mammalian species. Axonal projections converge into phrenic nerves innervating...
Phrenic motor neurons are cervical motor neurons originating from C3 to C6 levels in most mammalian species. Axonal projections converge into phrenic nerves innervating the respiratory diaphragm. In spinal cord slices, phrenic motor neurons cannot be identified from other motor neurons on morphological or biochemical criteria. We provide the description of procedures for visualizing phrenic motor neuron cell bodies in mice, following intrapleural injections of cholera toxin subunit beta (CTB) conjugated to a fluorophore. This fluorescent neuroanatomical tracer has the ability to be caught up at the diaphragm neuromuscular junction, be carried retrogradely along the phrenic axons and reach the phrenic cell bodies. Two methodological approaches of intrapleural CTB delivery are compared: transdiaphragmatic versus transthoracic injections. Both approaches are successful and result in similar number of CTB-labeled phrenic motor neurons. In conclusion, these techniques can be applied to visualize or quantify the phrenic motor neurons in various experimental studies such as those focused on the diaphragm-phrenic circuitry.
Topics: Animals; Mice; Motor Neurons; Phrenic Nerve
PubMed: 29553523
DOI: 10.3791/56758