Nucleus ambiguus

Brain: Nucleus ambiguus
Gray695.png
Transverse section of medulla oblongata below the middle of the olive. ("Nucleus ambiguus" labeled at center right.)
Gray's subject #187 779
NeuroNames hier-762
NeuroLex ID birnlex_2650

The nucleus ambiguus (literally "ambiguous nucleus") is a region of histologically disparate cells located just dorsal (posterior) to the inferior olivary nucleus in the lateral portion of the upper (rostral) medulla. It receives upper motor neuron innervation directly via the corticobulbar tract.

This nucleus gives rise to the branchial efferent motor fibers of the vagus nerve (CN X) terminating in the laryngeal and pharyngeal muscles, as well as to the efferent motor fibers of the glossopharyngeal nerve (CN IX) terminating in the stylopharyngeus.

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Areas supplied

The muscles supplied by the vagus (included with this is the cranial part of the accessory nerve), such as levator veli palatini, are also necessary to swallow properly through integration by the nucleus of the solitary tract. The vagus also supplies the upper part of the esophagus, and other parts of the pharynx and larynx.

As well as motor neurons, the nucleus ambiguus in its "external formation" contains cholinergic preganglionic parasympathetic neurons for the heart.[1] These neurons are cardioinhibitory [2] This cardioinhibitory effect is one of the means by which quick changes in blood pressure are achieved by the central nervous system (the primary means being changes in sympathetic nervous system activity, which constricts arterioles and makes the heart pump faster and harder). That is, through integrated and antagonistic system with sympathetic outflow from the vasomotor center of the brainstem, the parasympathetic outflow arising from the nucleus ambiguus and dorsal motor nucleus of the vagus nerve acts to decrease cardiac activity in response to fast increases in blood pressure. The external formation of the nucleus ambiguus also sends bronchoconstrictor fibers to the bronchopulmonary system, which can produce reflexive decreases in pulmonary bronchial airflow. The pathophysiologic relevance of this system, which may act in concert with the cardioinhibitory system, is poorly understood, but likely plays a role in bronchospastic diseases like COPD/emphysema (in which inhaled anticholinergic medications such as Spiriva/tiotropium or ipratropium are standard-of-care treatment) and asthma, particularly for exercise-related asthma exacerbations, which may have a component of autonomic dysregulation.

Additional images

References

  1. ^ Role of the nucleus ambiguus in the regulation of heart rate and arterial pressure. BH Machado and MJ Brody. http://hyper.ahajournals.org/cgi/content/abstract/11/6/602
  2. ^ Localization of vagal cardioinhibitory preganglionic neurons with rat brain stem. Nosaka S et al. http://www3.interscience.wiley.com/journal/109685993/abstract

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Look at other dictionaries:

  • Nucleus ambiguus — Querschnitt durch das verlängerte Mark in Höhe der Mitte der Oliven. Nr. 11 bezeichnet den Nucleus ambiguus. Der Nucleus ambiguus ist eine Ansammlung von Nervenzellen (Kerngebiet) im Bereich des Tegmentum der Medulla oblongata. Er ist ein… …   Deutsch Wikipedia

  • Nucleus ambiguus — dvejinis branduolys statusas T sritis gyvūnų anatomija, gyvūnų morfologija atitikmenys: lot. Nucleus ambiguus; Nucleus motorius nervorum vagi et glossopharyngei ryšiai: platesnis terminas – pailgųjų smegenų pjūviai …   Veterinarinės anatomijos, histologijos ir embriologijos terminai

  • Nucleus ambiguus — dvejinis branduolys statusas T sritis centrinė nervų sistema atitikmenys: lot. Nucleus ambiguus ryšiai: platesnis terminas – pailgųjų smegenų pjūviai …   Paukščių anatomijos terminai

  • nucleus ambiguus — nucleus am·big·u·us am big yə wəs n an elongated nucleus in the medulla oblongata that is a continuation of a group of cells in the ventral horn of the spinal cord and gives rise to the motor fibers of the glossopharyngeal, vagus, and accessory… …   Medical dictionary

  • ambiguus — see NUCLEUS AMBIGUUS …   Medical dictionary

  • Nucleus accessorius — Der Nervus accessorius (lat.: „zusätzlicher Nerv“) ist der XI. Hirnnerv. Wie auch der Nervus trigeminus bildet sich der Nervus accessorius aus zwei Wurzeln. Jedoch enthalten beide vermutlich ausschließlich motorische Fasern. Radix spinalis Die… …   Deutsch Wikipedia

  • Nucleus motorius nervi accessorii — Der Nervus accessorius (lat.: „zusätzlicher Nerv“) ist der XI. Hirnnerv. Wie auch der Nervus trigeminus bildet sich der Nervus accessorius aus zwei Wurzeln. Jedoch enthalten beide vermutlich ausschließlich motorische Fasern. Radix spinalis Die… …   Deutsch Wikipedia

  • Nucleus nervi accessorii — Der Nervus accessorius (lat.: „zusätzlicher Nerv“) ist der XI. Hirnnerv. Wie auch der Nervus trigeminus bildet sich der Nervus accessorius aus zwei Wurzeln. Jedoch enthalten beide vermutlich ausschließlich motorische Fasern. Radix spinalis Die… …   Deutsch Wikipedia

  • ambiguus — ambi̱gu|us, ...gua, ...gu|um [aus gleichbed. lat. ambiguus]: nach zwei Richtungen tendierend; zweifelhaft, doppeldeutig; z. B. in der Fügung ↑Nucleus ambiguus …   Das Wörterbuch medizinischer Fachausdrücke

  • nucleus reticularis parvocellularis — [TA] parvocellular reticular nucleus: either of a pair of principal lateral column reticular nuclei, lying lateral to the nucleus gigantocellularis and adjacent to the nucleus ambiguus …   Medical dictionary

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