Pharyngeal plexus of vagus nerve - Wikipedia
It is found posterior to the larynx and communicates with it via the The muscles of the pharynx are mostly innervated by the vagus nerve – the. It is because of this anatomical relationship; an infant is able to swallow . The larynx is innervated by the superior laryngeal nerve, recurrent. The larynx is innervated bilaterally by the superior laryngeal nerve (supplies mucosa from the epiglottis to the level of the cords) and the recurrent laryngeal.
Manipulation of the larynx is used to generate a source sound with a particular fundamental frequency, or pitch. This source sound is altered as it travels through the vocal tractconfigured differently based on the position of the tonguelipsmouthand pharynx.
The process of altering a source sound as it passes through the filter of the vocal tract creates the many different vowel and consonant sounds of the world's languages as well as tone, certain realizations of stress and other types of linguistic prosody.
The larynx also has a similar function to the lungs in creating pressure differences required for sound production; a constricted larynx can be raised or lowered affecting the volume of the oral cavity as necessary in glottalic consonants.
The vocal folds can be held close together by adducting the arytenoid cartilages so that they vibrate see phonation. The muscles attached to the arytenoid cartilages control the degree of opening. Vocal fold length and tension can be controlled by rocking the thyroid cartilage forward and backward on the cricoid cartilage either directly by contracting the cricothyroids or indirectly by changing the vertical position of the larynxby manipulating the tension of the muscles within the vocal folds, and by moving the arytenoids forward or backward.
This causes the pitch produced during phonation to rise or fall. In most males the vocal folds are longer and with a greater mass than most females' vocal folds, producing a lower pitch. The vocal apparatus consists of two pairs of mucosal folds. These folds are false vocal folds vestibular folds and true vocal folds folds. The false vocal folds are covered by respiratory epithelium, while the true vocal folds are covered by stratified squamous epithelium.
The false vocal folds are not responsible for sound production, but rather for resonance. The exceptions to this are found in Tibetan Chant and Kargyraa, a style of Tuvan throat singing. Both make use of the false vocal folds to create an undertone. These false vocal folds do not contain muscle, while the true vocal folds do have skeletal muscle. Other[ edit ] Image of endoscopy The most important role of the larynx is its protecting function; the prevention of foreign objects from entering the lungs by coughing and other reflexive actions.
A cough is initiated by a deep inhalation through the vocal folds, followed by the elevation of the larynx and the tight adduction closing of the vocal folds. The forced expiration that follows, assisted by tissue recoil and the muscles of expiration, blows the vocal folds apart, and the high pressure expels the irritating object out of the throat. Throat clearing is less violent than coughing, but is a similar increased respiratory effort countered by the tightening of the laryngeal musculature.
Both coughing and throat clearing are predictable and necessary actions because they clear the respiratory passageway, but both place the vocal folds under significant strain. This is achieved by a deep inhalation followed by the adduction of the vocal folds. Grunting while lifting heavy objects is the result of some air escaping through the adducted vocal folds ready for phonation.
Stimulation of the larynx by aspirated food or liquid produces a strong cough reflex to protect the lungs. In addition, intrinsic laryngeal muscles are spared from some muscle wasting disorders, such as Duchenne muscular dystrophymay facilitate the development of novel strategies for the prevention and treatment of muscle wasting in a variety of clinical scenarios. ILM have a calcium regulation system profile suggestive of a better ability to handle calcium changes in comparison to other muscles, and this may provide a mechanistic insight for their unique pathophysiological properties  Disorders[ edit ] Endoscopic image of an inflamed human larynx There are several things that can cause a larynx to not function properly.
Larynx transplant is a rare procedure. The world's first successful operation took place in at the Cleveland Clinic and the second took place in October at the University of California Davis Medical Center in Sacramento.
It is caused by the common cold or by excessive shouting.
The Pharynx - Subdivisions - Blood Supply - TeachMeAnatomy
It is not serious. Chronic laryngitis is caused by smoking, dust, frequent yelling, or prolonged exposure to polluted air. It is much more serious than acute laryngitis.
Presbylarynx is a condition in which age-related atrophy of the soft tissues of the larynx results in weak voice and restricted vocal range and stamina.
Bowing of the anterior portion of the vocal folds is found on laryngoscopy. Ulcers may be caused by the prolonged presence of an endotracheal tube. One thing to note is that the epiglottis and its cartilages are not derived from these same pharyngeal arches as the rest of the laryngeal structures. The epiglottis does not appear to have origination from a pharyngeal arch as it develops later in mammals. Blood Supply and Lymphatics Vascular supply for the larynx is derived from the superior and inferior thyroid arteries.
The external carotid artery gives rise to the superior thyroid artery. The thyrocervical artery, which arises from the anterosuperior surface of the subclavian artery gives rise to the inferior thyroid artery and two other branches.
The venous drainage of the larynx is via the inferior, middle, and superior thyroid veins. The inferior thyroid veins continue via the subclavian or left brachiocephalic vein. The middle and superior thyroid veins empty into the internal jugular vein. Lymphatic drainage of the larynx is accomplished via the deep cervical and paratracheal nodes medially, and via the pretracheal and pre-laryngeal nodes medially.
Nerves The larynx is innervated by the superior laryngeal nerve, recurrent laryngeal nerve, and sympathetic fibers. The superior laryngeal nerve [SLN]branches off the vagus approximately 2. The SLN has an internal and external branch. This includes general sensory innervation to the superior portion of the laryngeal cavity, including the epiglottis and superior surface of the vocal folds.
Visceral afferents to the epiglottis also assist in taste. Preganglionic parasympathetic fibers also travel via the internal laryngeal nerve. Recurrent laryngeal nerve [RLN]: The left RLN is found inferior to the aortic arch and posterior to ligamentum arteriosum. The right vagus continues posteriorly to the root of the right lung giving off the right RLN which loops around the right subclavian artery. The recurrent laryngeal nerves then continue superiorly bilaterally and pass posterior to the lobe of the thyroid gland as they travel along the lateral surfaces of the trachea and esophagus in the tracheoesophageal groove.
The nerves pass posterior to the cricothyroid joint as they enter the larynx at this level through fibers of the inferior constrictor muscles of the pharynx. At this point, the RLN becomes the inferior laryngeal nerve. Inferior laryngeal branch of the recurrent laryngeal nerve: The recurrent laryngeal nerves also carry general visceral sensory fibers from the region inferior to the glottis. The recurrent laryngeal nerve also sends branches to the inferior constrictor and cricopharyngeus muscles prior to entering the larynx.
Muscles The muscles of the larynx are can be categorized as intrinsic muscles which function in phonation or extrinsic muscles which produce gross movements of the larynx.
The intrinsic muscles of the larynx are responsible for sound production and the movements of the laryngeal cartilages and folds themselves. Their attachments fall between laryngeal cartilages. With the exception of the transverse arytenoid muscle, these muscles are paired bilaterally.
Contraction widens the inlet and causes depression of the epiglottis. These are the only muscle pair to cause abduction of the vocal folds. They pull the arytenoid anteriorly, relaxing the vocal folds. They also approximate the vocal folds. They continue along the lateral aspect of the vocal ligament and shorten the vocal folds.
They run along the lateral cricoid cartilage. This muscle has two bellies that run superior-inferior. The superior belly attaches to the inferior of the thyroid lamina.
The inferior belly attaches to the inferior horn of the thyroid cartilage. These muscles lengthen the vocal folds. These muscles are found in bilateral pairs and aid in the movement of the larynx at a gross level. Innervations of the extrinsic laryngeal muscles vary and include the following nerves: Inferior pharyngeal constrictor muscles: This muscle elevates the larynx.
Also, it provides the only connection of larynx to the skull. Extrinsic muscles that do not attach directly to the larynx: This differences also exist in the angles of the larynx including the thyroid angles male 95, female degrees. Even with this variation, the larynx shows symmetry when comparing one side to the other. The angles increase when there is a decrease in diameters and dimensions cranial to caudal. This also shows a gender-related difference with males averaging 2.
Other absolute differences exist between male and female populations, but the relative dimensions are not significant.
The differences can be attributed to the anterior-posterior growing nature of the larynx during puberty. This growth is primarily in the sagittal plane.
It is also noted that the thyroid cartilage is noted to be thicker in males as compared to females. In addition to the size of the laryngeal skeleton, there can be a varying degree of accessory cartilages.
These accessory cartilages include the occasional tiny cartilages found within the vocal ligament, interarytenoid, and the critical. Another term for these accessory cartilages is the cartilages of Luschka. Laryngeal Cavities There also notes to be some physiologic variation to the laryngeal ventricle. In addition to extending laterally, the laryngeal ventricle may sometimes continue superiorly and anteriorly, forming a saccule beneath the fold.
Nerve Variation Innervation of the laryngeal structures may also vary. Laryngeal synkinesis is abnormal laryngeal innervation discovered post-trauma to the recurrent laryngeal nerve. These nerves may follow any of the branching nerves and establish motor connections. The nerve fibers from nearby muscles may sprout toward, and re-innervate the once-paralyzed intrinsic laryngeal muscles.
These nerves may include the internal branch of the superior laryngeal nerve, the vagal branches of the pharyngeal constrictor muscles, parasympathetic, sympathetic and intralaryngeal branches. Laryngeal synkinesis differs in classification based upon laryngeal and phonatory patterns.
Variation may also exist the in the branching of the recurrent laryngeal nerve itself.
The anterior branch has been documented to pass either anteriorly or posteriorly to the cricothyroid joint and prior to innervating all intrinsic laryngeal muscles excluding the cricothyroid muscle. The posterior branch typically supplies the arytenoid muscles and posterior cricoarytenoid muscle. The location of the bifurcation or trifurcation has been documented to range between 0. Although extralaryngeal branching typically occurs above the level of the inferior thyroid artery, it can occur at any point.
The course of the recurrent laryngeal nerve may also differ as a consequence of anatomic distortion by masses or inflammation or because of a vascular anomaly. With an incidence of 0. This occurrence is even less likely with regards to the left side and has only been a document to occur a handful of times.
The recurrent laryngeal nerve may also vary in its relationship with the inferior thyroid artery as the nerve approaches the inferior pole of the thyroid gland. As the recurrent laryngeal nerve ascends, it does so within the tracheoesophageal groove. This, however, can vary. In rare circumstances, it ascends anterolateral to the trachea, and as a result, is more exposed and at risk of surgical injury.
Surgical Considerations Gross Anatomic Considerations Based on laryngeal size, there are absolute differences between the dimensions of male and female larynges.
- Pharyngeal plexus of vagus nerve
- Airway innervation
- The Larynx
However, no significant relative differences exist. Thus, surgery should be based upon the relative size and the utilization of anatomic landmarks. An incision is made through the cricothyroid membrane for a cricothyrotomy. This technique is quicker and poses fewer complications than a tracheotomy.
Nerve Considerations Monitoring the recurrent laryngeal nerve and superior laryngeal nerve is important in any neck related procedures including thyroid lobectomy or thyroidectomy An indirect laryngoscopy is an essential tool in confirming the integrity of the recurrent laryngeal nerve pre and postoperatively.
Reinnervation is a technique that can be utilized on the abductors and tensors of the vocal folds by using a nerve-muscle pedicle. This can only be considered if the vocal fold is not fixed.
Clinical Significance Due to is an anatomical relationship with several important structures, the recurrent laryngeal nerve can be affected in various situations. Thyroid masses, mediastinal and lung tumors, as well as cardiovascular lesions, can cause compression or affect the recurrent laryngeal nerve, commonly the left recurrent laryngeal nerve.
Additionally, considering the thyroid glands relationship to the recurrent laryngeal nerve and the superior laryngeal nerve, surgical resection of the thyroid gland can result in injury to both nerves either directly or indirectly.
Consequences of Nerve Injury Injury to the recurrent laryngeal nerve would result in paralysis of all intrinsic muscles of the larynx except the cricothyroid muscle.