Sunday, September 13, 2015

Heart Efferent Nerves

The human heart receives efferent nervous fibers from two sources; 1) the parasympathetic fibers reach the heart from the medulla oblongata, through the vagus nerve (CN X), and 2) the sympathetic nerve fibers which go to the cardiac muscles from the sympathetic ganglionic chain, or trunk, located in the dorsal (thoracic) region, parallel to the spinal column.

The nerve fibers from the vagus nerve establish connection with the nerve cells of ganglion of Remak and with other intrinsic cardiac ganglia, from which the nervous impulses are carried to the cardiac muscle. The sympathetic fibers from stellate and inferior cervical ganglia penetrate in the superficial and deep cardiac plexuses, where they intertwine with the parasympathetic vagal fibers.

The sympathetic fibers from the cervical ganglionic trunk have an effect on the ventricles, causing the acceleration of the heartbeats, while the parasympathetic fibers make the heartbeat rate slower.