Vagus nerve in the context of "Vocal cords"

The vocal cords, also known as vocal folds, are folds of throat tissues that are key in creating sounds through vocalization. The length of the vocal cords affects the pitch of voice, similar to a violin string. Open when breathing and vibrating for speech or singing, the folds are controlled via the recurrent laryngeal branch of the vagus nerve. They are composed of twin infoldings of mucous membrane stretched horizontally, from back to front, across the larynx. They vibrate, modulating the flow of air being expelled from the lungs during phonation.

The 'true vocal cords' are distinguished from the 'false vocal folds', known as vestibular folds or ventricular folds, which sit slightly superior to the more delicate true folds. These have a minimal role in normal phonation, but can produce deep sonorous tones, screams and growls.

The enteric nervous system (ENS) is one of the three divisions of the autonomic nervous system (ANS), the others being the sympathetic nervous system (SNS) and parasympathetic nervous system (PSNS). It consists of a mesh-like system of neurons that governs the function of the gastrointestinal tract. The ENS is nicknamed the "second brain". It is derived from neural crest cells.

The enteric nervous system is capable of operating independently of the brain and spinal cord, but is thought to rely on innervation from the vagus nerve and prevertebral ganglia in healthy subjects. However, studies have shown that the system is operable with a severed vagus nerve. The neurons of the enteric nervous system control the motor functions of the system, in addition to the secretion of gastrointestinal enzymes. These neurons communicate through many neurotransmitters similar to the CNS, including acetylcholine, dopamine, and serotonin. The large presence of serotonin and dopamine in the intestines are key areas of research for neurogastroenterology.

The esophagus (American English), oesophagus (British English), or œsophagus (archaic spelling) (see spelling difference) all /iːˈsɒfəɡəs, ɪ-/ ; pl.: ((o)e)(œ)sophagi or ((o)e)(œ)sophaguses), colloquially known also as the food pipe, food tube, or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the stomach. The esophagus is a fibromuscular tube, about 25 cm (10 in) long in adult humans, that travels behind the trachea and heart, passes through the diaphragm, and empties into the uppermost region of the stomach. During swallowing, the epiglottis tilts backwards to prevent food from going down the larynx and lungs. The word esophagus is from Ancient Greek οἰσοφάγος (oisophágos), from οἴσω (oísō), future form of φέρω (phérō, "I carry") + ἔφαγον (éphagon, "I ate").

The wall of the esophagus from the lumen outwards consists of mucosa, submucosa (connective tissue), layers of muscle fibers between layers of fibrous tissue, and an outer layer of connective tissue. The mucosa is a stratified squamous epithelium of around three layers of squamous cells, which contrasts to the single layer of columnar cells of the stomach. The transition between these two types of epithelium is visible as a zig-zag line. Most of the muscle is smooth muscle although striated muscle predominates in its upper third. It has two muscular rings or sphincters in its wall, one at the top and one at the bottom. The lower sphincter helps to prevent reflux of acidic stomach content. The esophagus has a rich blood supply and venous drainage. Its smooth muscle is innervated by involuntary nerves (sympathetic nerves via the sympathetic trunk and parasympathetic nerves via the vagus nerve) and in addition voluntary nerves (lower motor neurons) which are carried in the vagus nerve to innervate its striated muscle.

The recurrent laryngeal nerve (RLN), also known as nervus recurrens, is a branch of the vagus nerve (cranial nerve X) that supplies all the intrinsic muscles of the larynx, with the exception of the cricothyroid muscles. There are two recurrent laryngeal nerves, right and left. The right and left nerves are not symmetrical, with the left nerve looping under the aortic arch, and the right nerve looping under the right subclavian artery, then traveling upwards. They both travel alongside the trachea. Additionally, the nerves are among the few nerves that follow a recurrent course, moving in the opposite direction to the nerve they branch from, a fact from which they gain their name.

The recurrent laryngeal nerves supply sensation to the larynx below the vocal cords, give cardiac branches to the deep cardiac plexus, and branch to the trachea, esophagus and the inferior constrictor muscles. The posterior cricoarytenoid muscles, the only muscles that can open the vocal folds, are innervated by this nerve.

A mixed nerve is any nerve that contains both sensory (afferent) and motor (efferent) nerve fibers. All 31 pairs of spinal nerves are mixed nerves. Four of the twelve cranial nerves – V, VII, IX and X are mixed nerves.

The mediastinum (from Medieval Latin: mediastinus, lit. 'midway';pl.: mediastina) is the central compartment of the thoracic cavity. Surrounded by loose connective tissue, it is a region that contains vital organs and structures within the thorax, mainly the heart and its vessels, the esophagus, the trachea, the vagus, phrenic and cardiac nerves, the thoracic duct, the thymus and the lymph nodes of the central chest.

The gut–brain axis is the two-way biochemical signaling that takes place between the gastrointestinal tract (GI tract) and the central nervous system (CNS). The term "microbiota–gut–brain axis" highlights the putative role of gut microbiota interacting with brain functions, according to preliminary research. Broadly defined, the gut–brain axis includes the central nervous system, neuroendocrine system, neuroimmune systems, the hypothalamic–pituitary–adrenal axis (HPA axis), sympathetic and parasympathetic arms of the autonomic nervous system, the enteric nervous system, vagus nerve, and the gut microbiota.

Chemicals released by the gut microbiome can influence brain development, starting from birth. A review from 2015 states that the gut microbiome influences the CNS by "regulating brain chemistry and influencing neuro-endocrine systems associated with stress response, anxiety and memory function".