sign in sign up
<<
Home , Cranial nerves, Superior laryngeal nerve, Trachea, Vagus nerve

Viva La Vagus! by

Miriam van Mersbergen

Lights, music, excitement: that is what We have ample evidence that voice ceived reality (e.g. sight and ).6 Las Vegas has to offer. The bustle of the training provides excellent protection The basic unit in the Vegas Strip dazzles and amazes. In all the from injury and harm and have begun is called a . Its main function is to drama of that city, however, little atten- to develop sophisticated motor theories communicate.7 contain three tion is given to the electricity that lights especially for voice production.2 Our basic parts: a cell body called a , it up. When one thinks of Las Vegas, they multi-disciplinary perspective of voice dendrites that carry information from may conjure many images, but probably science frequently takes for granted the other structures (other nerves, , none will be of the power cords that nerve that supplies the vocal folds with muscles, etc . . .) to the soma, and , make that city run. power and gives them life. which carry information away from the Similarly, when we wax eloquent or soma to the next structure.8 The relay transcend through , we rarely of messages along these nerves can give thought to the power cord mak- The and its Home, be simple as a refl ex.9 However, nerve ing all of our efforts possible. Over the the Nervous System communication is often much more past fi fty years we have developed rich The nervous system is the commu- complicated, involving many nerves voice training traditions, sophisticated nication network of our body. It sends to and from the in an elaborate theories of voice production, and a commands for us to move, breathe, bucket brigade of signals.10 comprehensive understanding of laryn- digest, pump , secrete hormones Nerves communicate with each geal health. We have come a long way and chemicals, regenerate, feel, and other by way of electrical signals gener- in appreciating the unique nature of the even think.3 It is divided into the Cen- ated in the soma and traveling down tissues of the vocal folds and protecting tral Nervous System (CNS) and the the to an end point.11 At this end their delicate but strong vibrating edge.1 Peripheral Nervous System (PNS).4 point the electrical signal releases a The CNS houses the brain and spinal chemical into the space between the cord, and the PNS is comprised of the axon and the next structure (usually nerves that go out to the muscles, soft another nerve but sometimes a muscle Miriam van Mersbergen is ______tissues, glands, and organs of the body.5 or ).12 Depending on the chemical, Professor of ______and Director The PNS helps maintain homeostasis, the next structure is either activated or of ______at Northern Illinois shuts down. Subsequent sets of electri- University. encourage , control muscles, Email address ……………… release glandular secretions, and decode cal signals travel along dendrites into the environmental phenomena into per- soma of the next nerve.13 This form of

CHORAL JOURNAL Volume 55 Number 3 61 electrical communication continues until and down through the the into the and the system completes is function. to the abdomen.16 Vagus, the Latin for and assist in the regulation of the organs, Most peripheral nerves travel in bun- “wandering,” appropriately refl ects the glands, and soft of these regions.20 dles, similar to electrical wires, and exit nerve’s meandering pathways.17 The vagus nerve carries messages the CNS from the . How- Leaving the brain stem, the vagus from the CNS to the body (efferent/ ever, twelve peripheral nerves, called nerve branches off in different direc- motor) and relays messages to the CNS , exit the . They tions and extends as far down as the from the body (afferent/sensory).21 The regulate the muscles, glands, and sensory abdomen.18 Many of these branches are cell bodies of this nerve are housed in organs of the and and are named according to their function, such four large areas in the brain stem, creat- identifi ed by Roman Numerals.14 Cranial as the auricular branch, which conveys ing a hub where nerves from different Nerve X, the largest of these nerves, is sensory information from the skin inside parts of the body communicate with called Vagus Nerve.15 Beginning in the the external canal and tympanic each other.22 The proximity of nerve cell brainstem, the nerve travels through membrane, and the laryngeal branch, bodies in this area allow various parts of the jugular (the large hole at which innervates the larynx.19 Most the body to communicate complicated the bottom of the ), into the neck, branches of the vagus travel far below information with each other, allowing for sophisticated processing of information.

The Vagus Nerve and Voice Production Three branches of the vagus nerve are involved in voice production: the pharyngeal branch, the recurrent laryn- geal branch, and the superior laryngeal Let your music branch.23 When the pharyngeal branch leaves the brainstem and deviates, it be heard… travels to the mucous membranes and muscles of the , carrying sensory in England! information from this area to the brain.24 When you have a infection, for example, the vagus nerve carries the “This is one of the best groups information that lets you know your that I have had. Performance throat is sore. The pharyngeal branch venues were excellent. Witte also innervates most of the muscles of GLGDQRWKHUPDJQLÀFHQWMRE the pharynx and allows the palate to in making all aspects of our lift, maximizing the resonating space in concert tour run smoothly. our throat and creating those rounded tones we desire. They are the best!” The recurrent laryngeal branch – Phillip McLendon, Director leaves the larger laryngeal branch and Santa Barbara High School terminates in the larynx. It is called re- Madrigal Singers England and France, 2013 current because it travels past the larynx into the thorax and loops up into the larynx from below. On the right side, Witte has been arranging exceptional the nerve travels around the subclavian concert tours through England 800 GO WITTE wittept.com (right below the right ), and the rest of the world since 1975. circling back into the larynx. The left side

62 CHORAL JOURNAL Volume 55 Number 3 travels further, winding around the sided recurrent laryngeal nerve travels before returning back to the larynx.25 around the aorta. So, injuries on the The implications of right and left differ- left-side can be seen often in cardiac sur- ences will be discussed later. The recur- geries when the surgeon has to stretch rent laryngeal nerve innervates most of the nerve to retract it or to gain access 33 the muscles in the larynx, particularly to the . Sometimes the nerve is the muscles responsible for opening severed during tumor removal. At times and closing the vocal folds, which is viral infections reside in the cell bodies necessary for voicing.26 This nerve also of the recurrent laryngeal nerve, causing 34 innervates some of the muscles of the damage to nerve functioning. lower pharynx and to assist Recovery from recurrent laryngeal in . It transmits sensory in- nerve injury is directly related to the 36 formation from the mucous membrane degree and extent of the damage. of the upper right below the Damage from a mild stretch or com- vocal folds.27 pression of the nerve may resolve The also quickly, and normal voicing may return exits the larger laryngeal branch, split- within a few months. When damage is ting off into two smaller branches.28 The considerable, however, recovery might intrinsic branch, which carries sensory not be complete and normal functioning information about the mucous mem- my never return, rendering an impaired 37 branes of the larynx, is active in provid- voice. Treatment for larger nerve in- ing information during a response. juries includes surgical procedures that The extrinsic branch innervates the can assist in vocal fold closure, therapy , a laryngeal muscle to facilitate optimal voicing and reduce responsible for pitch control during poor compensations for weakness, and voicing.29 a combination of both. Such treatments are available at regional and national voice centers where an individual may Vocal Diffi culties from consult with a laryngologist (an ear, nose, Vagus Nerve Damage throat physician specializing in voice), a Voice impairment arises when the speech language pathologist specializing vagus nerve is damaged. The most dev- in voice, a registered nurse, and oc- astating impairment arises when damage casionally a singing teacher who works occurs to the recurrent or superior directly with the medical team. laryngeal nerves.30 Injury to the recur- Superior laryngeal nerve injuries rent laryngeal nerve impairs the ability Individuals with recurrent laryngeal have similarly devastating effects on of the vocal folds to open and close by nerve injuries frequently complain of voicing. Because the superior laryngeal weakening or paralyzing the muscles feeling out of breath during speaking and nerve is responsible for sensation in the responsible for these actions. At best, singing. The cause of nerve injuries arises larynx, damage to this nerve can either poor closure of the vocal folds leaves from complete severing of the nerve, leave an individual with hyposensitivity, a speaker or singer with a soft, breathy, partial tearing of the nerve, stretching placing him or her at risk for aspira- the nerve, compressing the nerve, or tion because saliva and food can enter asthenic voice—unable to sustain sound 38 for more than 4–5 seconds at a time. It disease residing in the nerve cell body.31 the airway without proper detection. can cause irregular vibration of the vocal Because the recurrent laryngeal nerve Additionally, some superior laryngeal folds, leaving the voice not only weak travels into the thorax, any thoracic nerve damage can leave a larynx with but hoarse, with pitch breaks, cracks, places an individual at risk for hypersensitivity, which causes an indi- and diplophonia (two pitches at once). injury.32 As discussed earlier, the left vidual to have excessive coughing with

CHORAL JOURNAL Volume 55 Number 3 63 minor sensory changes.39 In some cases and treatment of the superior laryngeal Master of our Well Being individuals can develop excessive cough- nerve, similar to recovery and treat- Traveling down past the neck and ing reactions after smelling faint odors, ment of the recurrent laryngeal nerve, into the body, the vagus nerve performs in deeply, or changing neck is available at regional and national voice some of its most vital tasks. Its main positions. The superior laryngeal nerve centers. Although vocal fold closure can function is to regulate the Autonomic also innervates the cricothyroid muscle, be achieved surgically, pitch functioning, Nervous System (ANS), a special part which is responsible for pitch changes. which is necessary for singing, unfortu- of the nervous system that maintains 41 A hallmark symptom of damage to this nately cannot be surgically repaired. the homeostasis of body functions, such nerve is the inability to raise pitch above Injuries to the pharyngeal branch as , respiration rate, blood mid-range, despite Herculean efforts.40 of the vagus nerve are far less com- pressure, body temperature, and diges- 42 The vocal folds also have diffi culty mon. Although such an injury does tion.44 When homeostasis is disrupted closing completely, because while the not directly affect voice functioning, through exercise, illness, or stress, a cricothyroid muscle stretches the vocal it can impair an individual’s ability to subsystem of the ANS, the Sympathetic fold, it places the vocal folds on a differ- elevate the and move the Nervous System, kicks in and prepares ent plane. When one vocal fold remains muscle of the pharynx to create the the body to move, respond, or adapt to unstretched due to damage, this plane necessary space for optimal resonance. the change.45 This state of readiness is difference creates a gap, allowing for air Damage can leave an individual sounding also known as the Fight or Flight System. 43 leakage. Superior laryngeal nerve injury hypernasal with a soft, muffl ed quality. When the stress is over, the Parasympa- also arises from severing, tearing, and Prosthetic devices can assist an individual thetic Nervous System down-regulates stretching the nerve. Because the supe- in maintaining a moderately elevated the body, bringing its functions back to rior laryngeal nerve travels through the velum, but at this point they cannot baseline. Working in opposition to the gland, thyroid place an assist in volitionally elevating the velum Fight or Flight System, the Parasympa- individual at risk for damage. Recovery or widening the pharynx during singing. thetic Nervous System is known as the Rest and Digest System.46 We can thank the vagus nerve for keeping the heart rate from elevating too high for too long, maintaining blood vessel constriction (which regulates blood pressure) during activity, reacti- vating the digestive system after being shut down, and stabilizing the respiration rate and making sure it coordinates with the heart. When these branches are disrupted, individuals can experience (irregular heart beat), dizzi- ness, , and a variety The Rudi E. Scheidt of digestive disorders, such as irritable School of Music draws 47 top students and faculty bowel syndrome. from every corner of the globe, offering programs to nurture talent, creating countless opportunities to learn and perform. Here, your music will be heard. New Mysteries Unfolding Let us hear you. Schedule an audition for one of the following dates: Because of its communication be- December 6, 2014 | February 7, 2015 | February 12, 2015 | February 21, 2015 February 28, 2015 tween the viscera and the brain, the

Degrees offered: B.M. M.M. A.D. D.M.A. Ph.D. vagus nerve plays an important role memphis.edu/music | [email protected] in body/brain interactions. Recently, 901.678.2541 have found a link be- A Tennessee Board of Regents Institution An Equal Opportunity/Affirmative Action University tween the presence of good gut bac-

64 CHORAL JOURNAL Volume 55 Number 3 teria (probiotics) and elevated mood gastrointestinal information to the brain fi rming a relationship between vagus and improved cognition. In a series of has made the brain-gut connection an nerve functioning and regulation of and human studies, researchers exciting new area of research.50 infl ammation. have found that organisms with bad The vagus nerve appears to also The vagal body/brain connection gut bacteria show signs of depression assist in regulation of infl ammatory re- does not stop there. The vagus nerve and poor attention, but that this state sponses from the body. Vagal communi- can promote healing following . can be reversed by introducing healthy cation between infl ammatory responses Anti-infl ammatory agents produced by bacteria.48 Apparently, good bacteria and the brain can also allow the brain to the are transmitted to the brain produce approximately 95 percent of regulate this infl ammation and promote via the vagus nerve and have been the body’s serotonin, a adaptations to acute injury and chronic found to reduce extraneous swelling in responsible for improved mood.49 At . Taylor and colleagues51 noted the brain after . Lee at al.52 found fi rst researchers were puzzled by the that , a measure of the vagus’s that simply producing these agents into suggested link between gut bacteria and ability to regulate the PNS, is associated the brain after stroke was not affec- mood. But a growing understanding of with depression and infl ammation in tive; it was the vagal pathway from the the vagus nerve’s role in communicating individuals who smoke tobacco, con- spleen to the brain that was necessary

University of Cambridge

CHORAL JOURNAL Volume 55 Number 3 65 to achieve this anti-infl ammatory effect. vagus nerve has been used to assist in may even regulate behavioral symptoms 53 Other researchers have found that the controlling the communication between of autism.57 Recent applications to vagal production of anti-infl ammatory agents body and brain when the brain malfunc- nerve stimulators assist in controlling from the spleen have been important tions. Vagal nerve stimulators, like pace anxiety, improving cognitive function in in regulating infl ammation observed makers, send regular, clear messages to patients with Alzheimer’s, and managing in arthritis, pancreatitis, and additional the brain, allowing the brain to respond migraines.58 infl ammatory diseases. Vagal connec- in more adaptive ways. The stimulator The vagus nerve’s infl uence in brain/ tions with the visceral organs have also is a small coil that is wrapped around body interaction has led psychologists promoted regulation in the endocrine the nerve and is controlled by a small and neuroscientists to develop theories 54 system. Dockery recently published an magnet placed directly under the skin of how the vagus nerve is responsible article outlining the role of vagal nerve on the chest.55 Vagal nerve stimulators for emotional development in children. pathways in diabetes, obesity, and nutri- have been used to control drug resistant The polyvagal theory59 is one such theo- ent transfer in the . , relieve intractable depression, ry that suggests that the vagus supports Because of its function in communi- which is unresponsive to any forms of social interaction between individuals by cating visceral activity with the brain, the medical and behavioral therapy,56 and preparing an organism to interact with

Hal Leonard

66 CHORAL JOURNAL Volume 55 Number 3 others. The theory suggests that the va- 10 Ibid, 28. the (San Diego: gal role in the parasympathetic nervous 11 Webster, of Communication, 6. Academic Press, 1996), 3. 45 system assists in reducing stress reac- 12 Ibid, 7. Ibid. 13 46 tions that might occur with increased Ibid, 8. Robert W. Hamill, “Peripheral Autonomic Ner- 14 Linda Wilson-Pauwels, Elizabeth J. Akesson, and vous System.” In David Robertson, Phillip physical proximity or communication A. Low, and Ronald J. Polinsky, ed., Primer on that occurs in unknown situations. Patricia A. Stewart, Cranial Nerves: and Clinical Comments (Toronto: B. C. Decker, the Autonomic Nervous System (San Diego: The vagal down-regulation of stress Inc., 1988), vii. Academic Press, 1996), 13. 47 responses can explain why individuals 15 Ibid, 136. Wilson-Pauwels, Akesson, and Stewart, Cranial appear to have reduced heart rate and 16 Frank H. Netter, The Ciba Collection of Medical Nerves, 132. 48 blood pressure when interacting with Illustrations, vol. 1: The Nervous System (New Paul Forsythe, Wolfgang A. Kunze, and John other individuals and , lending Jersey: CIBA, 1991), 126. Bienenstock, “On Communication between 17 Gut Microbes and the Brain,” Immunology 28 support to the notion that petting our Wilson-Pauwels, Akesson, and Stewart, Cranial Nerves,128. no.6 (2012): 557. furry or feathered companion is good 18 49 Duncan A. Groves and Verity J. Brown, “Vagal 60 Ibid. for our cardiovascular health. 19 Ibid. Nerve Stimulation: A Review of its The vagus nerve is a truly amazing 20 Ibid. Applications and Potential Mechanisms that nerve, the superhighway of life respon- 21 Ibid, vii. Mediate its Clinical Effects,” Neuroscience and 22 Ibid, 127. Biobehavioral Reviews 29 (2005): 493. sible for keeping us alive and thriving in 50 an ever-changing environment. Recent 23 Ibid, 126. Paul Forsythe, et al., “Mood and Gut Feelings,” 24 research points to the vagus nerve as Ibid, 128. Brain, Behavior, and Immunity 24 (2010): 11. 25 51 Laine Taylor, et al., “Depression and Smoking: an indispensable link in communication Raymond H. Colton, Janita K. Casper, and Rebecca Leonard, Understanding Voice Problems: A Mediating Role of Vagal Tone and between the brain and body. However, Physiological Perspective for Diagnosis and Infl ammation,” Annals of Behavioral vagal functioning truly shines in its ability Treatment, 4th ed. (Philadelphia: Lippincott 42 (2011): 339. 52 to allow us to voice and speak, to com- Williams, & Wilkins, 2011), 403. Soon-Tae Lee, et al., “Cholinergic Anti- municate our wants, needs, and desires. 26 Ibid, 405. Inflammatory Pathway in Intracerebral What further evidence do we need 27 Ibid. Hemorrhage,” Brain Research 1309 28 Ibid. (2010): 168. than the transcendence of singing to 53 29 Ibid, 402. D. Martelli, M.J. McKinley and R.M. McAllen, “The place voicing as a vital part of the human 30 Cholinergic Anti-Infl ammatory Pathway: A condition. Viva la Vagus! Ibid, 129. 31 Ibid, 130. Critical Review,” Autonomic Neuroscience: 32 Ibid. Basic and Clinical (forthcoming), 3. http://dx.doi. 33 Ibid. org/10.1016/j.autneu.2013.12.007. 54 NOTES 34 Ibid. Graham J. Dockray, “Enteroendocrine Cell 35 Ibid, 131. Signalling Via the Vagus Nerve,” Current 36 1 Ingo R. Titze, Principals of Voice Production, 2nd ed. Ibid, 132. Opinion in Pharmacology 13 (2013): 955. 37 (Iowa City: National Center for Voice and Ibid, 129. http://dx.doi.org/10.1016/j.coph.2013.09.007. 38 55 Speech, 2000), 23–54. Ibid. Groves and Brown, Neuroscience and Biobehavioral 39 2 Ingo R. Titze and Katherine Verdolini Abbott, Ibid, 405. Reviews 29: 493. 40 56 VOCOLOGY: The Science and Practice of Voice Ibid, 130. Martelli, et al., Autonomic Neuroscience: Basic and 41 Nemer Al-Khtoum, Nabil Shawakfeh, Eyad Clinical: 3. Habilitation (Salt Lake City: National Center 57 for Voice and Speech, 2012), 216–240. Al-Safadi, Osama Al-Momani, and Khalid Stephen W. Porges, “The : 3 Douglas B. Webster, Neuroscience of Com- Hamasha, “Acquired Unilateral Vocal Fold Phylogenetic Contributions to Social munication, 2nd ed. (San Diego: Singular Paralysis: Retrospective Analysis of a Single Behavior,” Physiology & Behavior 79 (2003): Institutional Experience,” North American 508. Publishing, 1998), 4. 58 4 Ibid, 5. Journal of Medical Science, 5 no.12 (2013): Groves and Brown, Neuroscience and Biobehavioral 5 Ibid. 699–702. Reviews 29: 496. 42 59 6 Ibid. Wilson-Pauwels, Akesson, and Stewart, Cranial Stephen W. Porges, “The Polyvagal Theory: 7 Leonard L. LaPointe, Atlas of Neuroanatomy for Nerves, 132. Phylogenetic Substrates of a Social 43 Communication Science and Disorders (New Ibid. Nervous System,” International Journal of 44 Rogelio Mosqueda-Garcia, “Central Autonomic Psychophysiology 42 (2001): 125. York: Theime, 2011), 31. 60 8 Ibid, 35. Regulation.” In David Robertson, Phillip A. Porges, Physiology & Behavior 79: 510. 9 Ibid, 37. Low, and Ronald J. Polinsky, ed., Primer on

CHORAL JOURNAL Volume 55 Number 3 67