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Posts Tagged ‘parasympathetic’

N.Vagus

July 15, 2010 3 comments

An article on vagus nerve.

A link to the article: N.Vagus – click here

The vagus nerve is the tenth cranial nerve. It has the most extensive distribution of any of the cranial nerves and contains sensory, motor and parasympathetic fibers. The vagus emerges from the brain stem at the medulla oblongata, between the olive and the inferior cerebellar peduncle. It exits the cranium through the jugular foramen with the glossopharyngeal and accessory nerves. The vagus nerve has two ganglia, the superior and inferior ganglia. The superior ganglion lies within the jugular foramen. The inferior ganglion is situated just below. Just below the inferior ganglion, the vagus is joined by the cranial part of the accessory nerve. The vagus then passes downwards within the carotid sheath and enters the thorax at the root of the neck.

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The Innervation of the Heart


An article on the innervation of the heart muscle.

A link to the article: The innervation of the Heart – click here

Initiation of the cardiac cycle is myogenic, originating in the sinuatrial node (SA). It is harmonizied in rate, force and output by autonomic nerves which operate on the nodal tissues and their prolongations, on coronary vessels and on the working atrial and ventricular musculature. All the cardiac branches of the N.vagus, X. cranial nerve, (parasympathetic) and all the sympathetic branches (except the cardiac branch of the superior cervical sympathetic ganglion) contain both afferent and efferent fibres; the cardiac branch of the superior cervical sympathetic ganglion is entirely efferent. Sympathetic fibres accelerate the heart and dilate the coronary arteries when stimulated, whereas parasympathetic (vagal) fibres slow the heart and cause constriction of coronary arteries.