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The pharyngeal plexus is a nerve plexus located upon the outer surface of the pharynx. It contains a motor component (derived from the vagus nerve (cranial nerve X)), a sensory component (derived from the glossopharyngeal nerve (cranial nerve IX)), and sympathetic component (derived from the superior cervical ganglion). [1]
The pharyngeal branch of the vagus nerve is the principal motor nerve of the pharynx. It represents the motor component of the pharyngeal plexus of vagus nerve and ultimately provides motor innervation to most of the muscles of the soft palate (all but the tensor veli palatini muscle), and of the pharynx (all but the stylopharyngeus muscle). [1]
The pharyngeal branches of the glossopharyngeal nerve are three or four filaments which unite, opposite the constrictor pharyngis medius, with the pharyngeal branches of the vagus and sympathetic, to form the pharyngeal plexus. Branches from this plexus perforate the muscular coat of the pharynx and supply its muscles and mucous membrane.
The external branch functions to stretch the vocal cords by activating the cricothyroid muscle, increasing pitch. The external laryngeal nerve gives branches to pharyngeal plexus and the superior portion of the inferior pharyngeal constrictor, and communicates with the superior cardiac nerve behind the common carotid artery.
The vagus nerve is also responsible for regulating inflammation in the body, via the inflammatory reflex. [7] Efferent vagus nerve fibers innervating the pharynx and back of the throat are responsible for the gag reflex. In addition, 5-HT 3 receptor-mediated afferent vagus stimulation in the gut due to gastroenteritis is a cause of vomiting. [8]
The inferior pharyngeal constrictor muscle can be supplied by branches from the pharyngeal plexus, [4] the recurrent laryngeal nerve, the external branch of the superior laryngeal nerve, or a combination of these (the recurrent laryngeal nerve being the most common innervation of the cricopharyngeal part). [5]
The esophageal plexus (oesophageal plexus in British English) is formed by nerve fibers from two sources, branches of the vagus nerve, [1] [2] and visceral branches of the sympathetic trunk. [ 3 ] [ 4 ] The esophageal plexus and the cardiac plexus contain the same types of fibers and are both considered thoracic autonomic plexus .
A nerve plexus is composed of afferent and efferent fibers that arise from the merging of the anterior rami of spinal nerves and blood vessels. There are five spinal nerve plexuses, except in the thoracic region, as well as other forms of autonomic plexuses, many of which are a part of the enteric nervous system .