Deglutition, the act of swallowing, is an extremely complex process involving approximately 50 pairs of muscles and nerves that are responsible for preparing and transferring food and liquids from the mouth to the stomach. A problem with any of these structures can lead to dysphagia and a decrease in the quality of life in patients suffering from it. To successfully diagnose and treat dysphagia, a thorough understanding of deglutition is essential. The anatomy and physiology of the swallowing process is reviewed as it pertains to operative approach and technique. Deglutition, the act of swallowing, is an extremely complex process involving approximately 50 pairs of muscles and nerves that are responsible for preparing and transferring food and liquids from the mouth to the stomach. A problem with any of these structures can lead to dysphagia and a decrease in the quality of life in patients suffering from it. To successfully diagnose and treat dysphagia, a thorough understanding of deglutition is essential. The anatomy and physiology of the swallowing process is reviewed as it pertains to operative approach and technique. IntroductionDeglutition is a complex process, which transports ingested food and liquid from the mouth to the stomach. Swallowing requires the coordination of 3 anatomically and functionally separate upper aerodigestive tract structures, which comprise the following swallowing apparatus: the oral cavity, the pharynx, and the larynx.1Miller A. Overview of deglutition and swallowing.in: Shaker R. Belafsky P.C. Postma G.N. Principles of Deglutition: A Multidisciplinary Text For Swallowing and its Disorders. Springer Science & Business Media, New York2013: 3-17Crossref Scopus (5) Google Scholar, 2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar, 3Ekberg O. Nylander G. Anatomy and physiology.in: Ekberg Olle Dysphagia: Diagnosis and Treatment. Springer Science & Business Media, New York2012: 1-18Crossref Google Scholar, 4Matsuo K. Palmer J.B. Oral phase preparation and propulsion: anatomy, physiology, rheology, mastication, and transport.in: Shaker R. Belafsky P.C. Postma G.N. Principles of Deglutition: A Multidisciplinary Text for Swallowing and Its Disorders. Springer Science & Business Media, New York2013: 117-131Crossref Scopus (4) Google Scholar These structures act as a hydrodynamic pump with valves that allows food and liquid to be transferred into the stomach without entering the respiratory tract.1Miller A. Overview of deglutition and swallowing.in: Shaker R. Belafsky P.C. Postma G.N. Principles of Deglutition: A Multidisciplinary Text For Swallowing and its Disorders. Springer Science & Business Media, New York2013: 3-17Crossref Scopus (5) Google Scholar, 3Ekberg O. Nylander G. Anatomy and physiology.in: Ekberg Olle Dysphagia: Diagnosis and Treatment. Springer Science & Business Media, New York2012: 1-18Crossref Google Scholar The act of swallowing is divided into the following 3 phases: the oral phase, pharyngeal phase, and esophageal phase, each of which corresponds to the location of the food bolus in the swallowing apparatus. The initial stage of deglutition, the oral phase, is voluntary and triggers the subsequent involuntary pharyngeal and esophageal phases.1Miller A. Overview of deglutition and swallowing.in: Shaker R. Belafsky P.C. Postma G.N. Principles of Deglutition: A Multidisciplinary Text For Swallowing and its Disorders. Springer Science & Business Media, New York2013: 3-17Crossref Scopus (5) Google Scholar, 2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar, 3Ekberg O. Nylander G. Anatomy and physiology.in: Ekberg Olle Dysphagia: Diagnosis and Treatment. Springer Science & Business Media, New York2012: 1-18Crossref Google Scholar Dysphagia is a symptom caused by a multitude of diverse diseases that can affect each phase of deglutition, and cause a serious deterioration in the quality of life of affected patients.3Ekberg O. Nylander G. Anatomy and physiology.in: Ekberg Olle Dysphagia: Diagnosis and Treatment. Springer Science & Business Media, New York2012: 1-18Crossref Google Scholar To surgically treat dysphagia, a thorough understanding of the anatomy and physiology of deglutition is required to both identify the affected stage(s) of swallowing and the appropriate intervention needed to treat them.Anatomy of the oral cavityThe oral phase of swallowing occurs in the oral region that consists of the lips, cheeks, teeth, gums, oral cavity, hard and soft palate, and the palatine tonsils. Food processing and bolus formation occurs in the oral cavity proper that is the space between the upper and lower dental arches. It is limited laterally and anteriorly by the dental arches, superiorly by the palate and inferiorly by the tongue.5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar Posteriorly, the oral cavity proper transitions into the oropharynx that is the superior portion of the pharynx (Figure 1, Figure 2). The lips surround the mouth and form a sphincter using the orbicularis oris muscle that controls entrance and exit from the oral cavity.5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar They are covered externally by specialized skin, internally by a mucous membrane, and contain the superior and inferior labial muscles, vessels, and nerves.5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar The cheeks form the lateral walls of the oral cavity and are continuous with the lips with the same skin and internal mucous membrane. Internally, the cheeks contain the buccinator muscles and the buccal fat pads, which lie superficial to the buccinators.5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar The hard palate composes the anterior two-third of the palate and forms a bony concave roof covered with a mucous membrane. The soft palate is a mobile fibromuscular fold, which comprises the posterior one-third of the palate and separates the nasal cavity from the nasopharynx.6Shah S. Garritano F.G. Pediatric oral anatomy.Operative Tech Otolaryngol-Head and Neck Surg. 2015; 26: 2-7Abstract Full Text Full Text PDF Scopus (4) Google Scholar There is a subtle color change from pink of the hard palate to yellow-red of the soft palate.2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar, 5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar The soft palate is suspended anteriorly from the posterior edge of the hard palate by the palatine aponeurosis, which is thick anteriorly and thins posteriorly as it combines with the muscular section.5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar Posterior and inferiorly, the soft palate has a curved free margin from which the uvula hangs. Laterally, the soft palate is continuous with the palatoglossal and the palatopharyngeal folds, which join it to the tongue and the pharynx respectively.5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar The space between the oral cavity and the pharynx is termed the fauces, and is bound superiorly by the soft palate, laterally by the palatoglossus and the palatopharyngeal arches, and inferiorly by the root of the tongue. The soft palate contains 5 muscles which emanate from the base of the skull and descend to the palate.3Ekberg O. Nylander G. Anatomy and physiology.in: Ekberg Olle Dysphagia: Diagnosis and Treatment. Springer Science & Business Media, New York2012: 1-18Crossref Google Scholar, 5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar The levator palatini muscle that moves the soft palate upwards and backwards during swallowing, extends inferiorly, medially, and anteriorly from both the petrous part of the temporal bone and the cartilage pharyngotympanic tube, and inserts on the mid partition of the palatine aponeurosis.2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar The tensor veli palatini muscle, responsible for tensing the soft palate and opening the pharyngotympanic tube during swallowing, extends from the scaphoid fossa of the medial pterygoid plate, spine of sphenoid bone, and cartilage of pharyngotympanic tube.3Ekberg O. Nylander G. Anatomy and physiology.in: Ekberg Olle Dysphagia: Diagnosis and Treatment. Springer Science & Business Media, New York2012: 1-18Crossref Google Scholar, 5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar It extends first inferiorly, and then turns at a 90° angle medially over the pterygoid hamulus to disperse horizontally in the palatine aponeurosis. This course allows the tensor veli palatine tendon to form a pulley around the pterygoid hamulus to pull horizontally on the aponeurosis.2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar, 3Ekberg O. Nylander G. Anatomy and physiology.in: Ekberg Olle Dysphagia: Diagnosis and Treatment. Springer Science & Business Media, New York2012: 1-18Crossref Google Scholar, 5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar The paired palotopharyngeal muscles constitute the arch of the soft palate, and elevate the pharynx and larynx during the pharyngeal phase of swallowing as well as depress the tensed palate at the end of the oral phase.2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar, 5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar They originate from the hard palate and palatine aponeurosis and extend inferiorly and posteriorly to form part of the lateral wall of the pharynx.3Ekberg O. Nylander G. Anatomy and physiology.in: Ekberg Olle Dysphagia: Diagnosis and Treatment. Springer Science & Business Media, New York2012: 1-18Crossref Google Scholar, 5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar The palatoglossus muscle extends inferiorly from the palatine aponeurosis to the lateral side of the tongue and draws the soft palate and tongue together by elevating the posterior aspect of the tongue.2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar, 5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar The musculus uvulae shortens the uvula and pulls it superiorly during swallowing.5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar The muscles of the soft palate are innervated by the pharyngeal branch of the vagus nerve with the exception of the tensor veli palatini, which receives its innervation from the mandibular division of the trigeminal nerve.2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar, 5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar Both the hard and soft palate receive their blood supply via the greater and lesser palatine branches of the maxillary artery.2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar The tongue is a mobile muscular structure that sits partly in the oral cavity and partly in the oropharynx.2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar, 5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar It is covered in a mucous membrane and has 8 pairs of muscles that are grouped into intrinsic and extrinsic sets. The 4 intrinsic muscles control the shape of the tongue and consist of the vertical, transverse, superior longitudinal, and inferior longitudinal muscles. The 4 extrinsic muscles control the position of the tongue and are composed of the genioglossus, hyoglossus, palatoglossus, and styloglossus muscles.2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar, 5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar, 6Shah S. Garritano F.G. Pediatric oral anatomy.Operative Tech Otolaryngol-Head and Neck Surg. 2015; 26: 2-7Abstract Full Text Full Text PDF Scopus (4) Google Scholar The extrinsic muscles originate outside of the tongue and insert on the tongue.6Shah S. Garritano F.G. Pediatric oral anatomy.Operative Tech Otolaryngol-Head and Neck Surg. 2015; 26: 2-7Abstract Full Text Full Text PDF Scopus (4) Google Scholar All the muscles of the tongue are innervated by the hypoglossal nerve with the exception of the extrinsic palatoglossus muscles, which receive their innervation from the pharyngeal plexus.6Shah S. Garritano F.G. Pediatric oral anatomy.Operative Tech Otolaryngol-Head and Neck Surg. 2015; 26: 2-7Abstract Full Text Full Text PDF Scopus (4) Google Scholar The tongue is divided into 2 areas of sensation. General sensory information in the anterior two-third of the tongue is carried by the trigeminal nerve, whereas the posterior one-third is served by the lingual-tonsillar branch of the glossopharyngeal nerve.6Shah S. Garritano F.G. Pediatric oral anatomy.Operative Tech Otolaryngol-Head and Neck Surg. 2015; 26: 2-7Abstract Full Text Full Text PDF Scopus (4) Google Scholar The arteries of the tongue are derived from the lingual artery that branches from the external carotid artery.5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google ScholarFigure 2Anterior wall of the pharynx. The posterior wall has been excised to show the connections of the pharynx to the oral cavity and esophagus.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Physiology of the oral phaseThe oral phase of deglutition occurs in the oral cavity and consists of 2 stages, the preparatory stage and propulsive stage.2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar, 5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar The preparatory stage begins as food or liquid is placed into the mouth and results in the formation of a bolus. Bolus formation occurs through the coordination of lip, buccal, mandibular, and tongue movements, as well as the closure of the upper esophageal sphincter to maintain the food or liquid in the oral cavity until the person is ready to initiate swallowing.2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar Liquids require no preparation for bolus formation, whereas solid food requires processing to reduce the size of particles through mastication and softening by saliva.1Miller A. Overview of deglutition and swallowing.in: Shaker R. Belafsky P.C. Postma G.N. Principles of Deglutition: A Multidisciplinary Text For Swallowing and its Disorders. Springer Science & Business Media, New York2013: 3-17Crossref Scopus (5) Google Scholar, 4Matsuo K. Palmer J.B. Oral phase preparation and propulsion: anatomy, physiology, rheology, mastication, and transport.in: Shaker R. Belafsky P.C. Postma G.N. Principles of Deglutition: A Multidisciplinary Text for Swallowing and Its Disorders. Springer Science & Business Media, New York2013: 117-131Crossref Scopus (4) Google Scholar This process is under voluntary control via 3 cranial nerves. The trigeminal nerve coordinates mastication and relays sensory information, the facial nerve coordinates lip and buccal movement to assist in food positioning and retention, and the hypoglossal nerve controls tongue movement.2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar Once a suitable bolus for swallowing is formed, it is positioned in a groove formed by the tongue against the hard palate, and the propulsive stage of the oral phase begins.2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar, 4Matsuo K. Palmer J.B. Oral phase preparation and propulsion: anatomy, physiology, rheology, mastication, and transport.in: Shaker R. Belafsky P.C. Postma G.N. Principles of Deglutition: A Multidisciplinary Text for Swallowing and Its Disorders. Springer Science & Business Media, New York2013: 117-131Crossref Scopus (4) Google Scholar Via a wave-like elevation of the tongue that starts from the tip and moves posteriorly, the bolus is propelled posteriorly in a squeeze-like action through the fauces into the opening of the pharynx1Miller A. Overview of deglutition and swallowing.in: Shaker R. Belafsky P.C. Postma G.N. Principles of Deglutition: A Multidisciplinary Text For Swallowing and its Disorders. Springer Science & Business Media, New York2013: 3-17Crossref Scopus (5) Google Scholar, 2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar, 3Ekberg O. Nylander G. Anatomy and physiology.in: Ekberg Olle Dysphagia: Diagnosis and Treatment. Springer Science & Business Media, New York2012: 1-18Crossref Google Scholar, 4Matsuo K. Palmer J.B. Oral phase preparation and propulsion: anatomy, physiology, rheology, mastication, and transport.in: Shaker R. Belafsky P.C. Postma G.N. Principles of Deglutition: A Multidisciplinary Text for Swallowing and Its Disorders. Springer Science & Business Media, New York2013: 117-131Crossref Scopus (4) Google Scholar (Figure 3A).Figure 3Bolus propagation during swallowing. (A) Wave-like elevation of the tongue propels the bolus into the oropharynx. (B) Soft palate elevation closes the opening of the nasal cavity as the bolus passes into the pharynx. (C) Bolus is propelled through the pharynx past the closed epiglottis and enters the esophagus through the upper esophageal sphincter. (D) Bolus travels through the esophagus via peristaltic waves to the stomach. The soft palate and tongue relax and the epiglottis opens to resume respiration.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Anatomy of pharyngeal phaseThe pharynx extends from the cranial base to the inferior border of the cricoid cartilage anteriorly and the inferior border of the C6 vertebra posteriorly. It is divided into the following 3 parts: the nasopharynx, posterior to the nose and superior to the soft palate; the oropharynx, from the soft palate to the hyoid bone; and the laryngopharynx, posterior to the larynx (Figure 1, Figure 2).5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar, 7Belafsky P. Lintzenich C. Development, anatomy, and physiology of the pharynx.in: Shaker R. Belafsky P.C. Postma G.N. Principles of Deglutition: A Multidisciplinary Text for Swallowing and Its Disorders. Springer Science & Business Media, New York2013: 165-173Crossref Scopus (3) Google Scholar The wall of the pharynx is a muscular wall composed of longitudinal muscles internally surrounded by an external circular layer of muscles, giving it a tubular shape. The external muscles consist of the superior, middle, and inferior constrictor muscles, and are responsible for constricting the walls of the pharynx during swallowing (Figure 4). They contract involuntarily in a sequential manner from the superior-to-inferior end of the pharynx to propel the bolus through the pharynx and into the esophagus. The superior pharyngeal constrictor has complex attachments, and originates from the pterygoid hamulus, pterygomandibular raphe, posterior end of mylohyoid line of mandible, and the transverse musculature of tongue. These muscle extensions join and extend posteriorly to insert on the pharyngeal tubercle on the basilar part of the occipital bone. The middle pharyngeal constrictor muscle originates from greater and lesser horns of the hyoid bone and the stylohyoid ligament which runs from the styloid process in the skull base to the minor processes of the hyoid bone.3Ekberg O. Nylander G. Anatomy and physiology.in: Ekberg Olle Dysphagia: Diagnosis and Treatment. Springer Science & Business Media, New York2012: 1-18Crossref Google Scholar, 5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar The middle constrictor then inserts in the posterior midline to the pharyngeal raphe. The inferior pharyngeal constrictor is the thickest of the pharyngeal constrictor muscles and consists of 2 parts, the thyropharyngeus and the cricopharyngeus (Figure 5).2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar The thyropharyngeus part originates from the oblique line of the thyroid cartilage, the lateral aspect of the cricoid cartilage, and the thyroid ligament. It extends posteriorly surrounding the pharynx, and inserts into the median pharyngeal raphe. The upper fibers ascend obliquely to overlap the middle constrictor.2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar, 3Ekberg O. Nylander G. Anatomy and physiology.in: Ekberg Olle Dysphagia: Diagnosis and Treatment. Springer Science & Business Media, New York2012: 1-18Crossref Google Scholar The cricopharyngeus part of the inferior constrictor originates from the side of the cricoid cartilage between the origin of the cricothryroid and the articular facet of the inferior horn of the thyroid cartilage. Its fibers pass horizontally and posteriorly encircling the pharyngo-esophageal junction to insert at the same site on the opposite side of the cricoid cartilage, and are continuous with the inner circular fibers of the esophagus.2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar Posteriorly, between the lower fibers of the thyropharyngeus and the upper fibers of the cricopharyngeus, there is a small triangular space known as Killian dehiscence. This space is anatomically normal but lacks the support that is present in the rest of the inferior constrictor. This leads Killian dehiscence to be prone to the formation of a diverticulum during abnormal uncoordinated pharyngeal peristalsis, in which the peristaltic waves reach the cricopharyngeus before it has relaxed.2Johnson A. Deglutition.in: Gleeson M. Scott-Brown’s Otolarynology, Volume 1: Basic Sciences. ed 6. Butterwoeth-Heinemann, 1997Google Scholar The superior pharyngeal constrictor is innervated by the pharyngeal branch of the vagus and pharyngeal nerves, whereas the middle and inferior constrictors are innervated by the pharyngeal branch of the vagus nerve and pharyngeal plexus, as well as branches of the external and recurrent laryngeal nerves.5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar All the pharyngeal constrictor muscles receive blood supply from branches of the ascending pharyngeal artery. The superior pharyngeal constrictor muscle receives additional blood from the tonsillar branch of the facial artery.Figure 4The muscles of the pharynx. (A) Lateral view of the pharyngeal constrictor muscles. (B) A posterior view of the muscles of the pharynx cut down the pharyngeal raphe to display the internal longitudinal pharyngeal muscles.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 5The constrictor muscles of the pharynx. The separation of the inferior pharyngeal constrictor into the thyropharyngeus and cricopharyngeus aspects can be seen clearly here.View Large Image Figure ViewerDownload Hi-res image Download (PPT)The internal longitudinal muscles of the pharynx consist of the palatopharyngeus, stylopharyngeus, and salpingopharyngeus (Figure 4). These muscles shorten and widen the pharynx during swallowing by elevating the pharynx and larynx. The palatopharyngeus is the largest of the longitudinal muscles. It originates from the hard palate, palatine aponeurosis, and pterygoid process and extends inferiorly to insert on the posterior border of the thyroid cartilage, as well as within the pharyngeal constrictor musculature and esophagus.3Ekberg O. Nylander G. Anatomy and physiology.in: Ekberg Olle Dysphagia: Diagnosis and Treatment. Springer Science & Business Media, New York2012: 1-18Crossref Google Scholar, 5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar The stylopharyngeus muscle extends from the styloid process of the temporal bone inferiorly and anteriorly in a gap between the superior and middle pharyngeal constrictors. It extends inferiorly to insert on the posterior and superior borders of the thyroid cartilage with the palatopharyngeus as well as to the edges of the epiglottis.3Ekberg O. Nylander G. Anatomy and physiology.in: Ekberg Olle Dysphagia: Diagnosis and Treatment. Springer Science & Business Media, New York2012: 1-18Crossref Google Scholar The salpingopharyngeus originates from the cartilaginous part of the pharyngotynpanic tube and extends downward to merge with the palatopharyngeus.5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google Scholar The palatopharyngeus and salpingopharyngeus muscles receive their innervation from the pharyngeal branch of the vagus nerve and the pharyngeal plexus, whereas the stylopharyngeus muscle is innervated by the glossopharyngeal nerve.5Moore Keith L. Dalley Arthur F. Agur Anne M.R. Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Baltimore, MD2013: 981-1052Google ScholarDuring swallowing, the larynx must be closed to prevent aspiration of ingested material into the airway. As stated before, this is accomplished by elevation of the larynx to underneath the base of the tongue, closure of the vocal folds, and closure of the epiglottis over the laryngeal vestibule. Laryngeal elevation is accomplished by the 4 suprahyoid muscles, which elevate the following hyoid bone: the digastric, mylohyoid, stylohyoid, and geniohyoid muscles.3Ekberg O. Nylander G. Anatomy and physiology.in: Ekberg Olle Dysphagia: Diagnosis and Treatment. Springer Science & Business Media, New York2012: 1-18Crossref Google Scholar The anterior belly of the digastric muscle originates from the digastric fossa of the mandible, and the posterior belly originates from the mastoid notch of the temporal bone. As these muscle bellies descend toward the hyoid bone, they are j