1 FISIOLOGIA DIGESTIVA (BCM II)Clase 2: Deglución, Secreción salival, motilidad esofágica Dr. Michel Baró Aliste

2 Hambre vs. Apetito Hambre: Deseo intrínseco por los alimentosApetito: Preferencia por determinado alimento

3 Masticación Rama motora V par Integrado a nivel del tronco cerebralCentro del gusto de la zona reticular Hipotálamo, Amígdala Corteza cerebral (zona sensitiva del gusto y olfato) Reflejo masticatorio Bolo alimentario provoca reflejo inhibitorio Descenso de la mandíbula Elevación de la mandíbula (25 a 100 Kg de fuerza) Contracción de rebote

4 Masticación Disrupción membranas de celulosaAumento de área de exposición a enzimas Evitar excoriación de la mucosa Facilita vaciamiento gástrico

5 Deglución Fase Voluntaria: presión supero-posterior de la lengua contra el paladar Fase Faríngea: Cierre de las coanas: evita reflujo hacia cavidad nasal Aproximación de pliegues palatofaríngeos: función selectiva Cierre de las cuerdas vocales y epiglotis Ascenso de la laringe y apertura del EES Peristalsis de la faringe

6 (Tracto solitario) (V,IX,X,XII,cervicales)

7 Musculature of oral cavity, pharynx, larynx, and proximal esophagus* * Figure 1-1. Musculature of the oral cavity, pharynx, larynx, and proximal esophagus as displayed in a cutaway view. The oral cavity, pharynx, and larynx are all involved in transferring food from the mouth to the esophagus. Within the oral cavity, the lips, teeth, tongue, soft palate, mandible, and floor of the mouth serve functions in chewing and manipulating food to create a bolus that is suitable for transfer to the pharynx. The walls of the oropharynx are composed of the superior, middle, and inferior constrictors posteriorly and the tongue base, which opposes constrictors anteriorly. The superior constrictor arises from the pterygoid hamulus, pterygomandibular raphe, mandible, and tongue, passes posteromedially, and inserts into the posterior median raphe. The middle constrictor arises from the hyoid bone and stylohyoid ligament, passes posteromedially, and also inserts into the posterior median raphe. The inferior constrictor is composed of the thyropharyngeus superiorly and the cricopharyngeus inferiorly. The thyropharyngeus arises from the thyroid cartilage and passes posteromedially to insert into the median raphe. The cricopharyngeus, however, has superior and inferior components that arise from both sides of the cricoid lamina such that the superior fibers course posteromedially to the median raphe and the inferior fibers loop around the esophageal inlet without a median raphe. The cricopharyngeus muscle separates the pharynx from the esophagus.The pharyngeal walls are supported by attachments to the epiglottic, arytenoid, cuneiform, corniculate, and cricoid cartilages. The larynx and trachea are suspended in the neck between the hyoid bone superiorly and the sternum inferiorly. The laryngeal strap muscles contribute to this suspension and with the intrinsic elasticity of the trachea permit the larynx to be elevated and lowered. The hyoid bone serves as the base for the tongue and is positioned as a fulcrum, crucial in directing forces anteriorly and superiorly toward the larynx and hence esophageal inlet. Laryngeal movement is critical in permitting the swallow response as the laryngeal inlet is closed and physically removed from the bolus path during the course of the swallow. Failure to achieve laryngeal elevation can result in aspiration. (Adapted from Kahrilas [6].) References: [6]. Kahrilas PJ, The anatomy and physiology of dysphagia. In Dysphagia, Diagnosis, and Treatment. Edited by Gelfand DW, Richter JE. New York: Igaku-Shoin; * *

8 Pharynx showing oropharyngeal configuration at rest and during swallowFigure 1-2. Posterior view of the pharynx showing the oropharyngeal anatomic configuration at rest (A) and during swallow (B). The pharyngeal constrictors are cut at the midline and laid open to reveal the anterior pharyngeal wall. The spaces formed between the lateral insertion of the inferior constrictor and the lateral walls of the thyroid cartilage are the pyriform sinuses. Panel B shows the anatomic configuration during swallow illustrating laryngeal elevation and closure (arrows show the bilateral path taken around the epiglottis by the swallowed material). (Adapted from Kahrilas [6].) References: [6]. Kahrilas PJ, The anatomy and physiology of dysphagia. In Dysphagia, Diagnosis, and Treatment. Edited by Gelfand DW, Richter JE. New York: Igaku-Shoin;

9 * * * * Schematics of pharynx from posterior and lateral views (a)Figure 2-1. Schematic drawings of the pharynx from posterior (A) and lateral (B) perspectives. Note the relationships of the valleculae and piriform sinuses to the base of tongue, epiglottis, and larynx. Because the pharynx is part of both the respiratory and alimentary tracts, both the nasopharynx and larynx must be effectively isolated from the pharynx during swallowing. (Adapted from Donner et al. [1].) References: [1]. Donner MW, Basoma F, Robertson DL, Anatomy and physiology of the pharynx. Gastrointestinal Radiol *

10 * * * Schematics of pharynx from posterior and lateral views (b)Figure 2-1. Schematic drawings of the pharynx from posterior (A) and lateral (B) perspectives. Note the relationships of the valleculae and piriform sinuses to the base of tongue, epiglottis, and larynx. Because the pharynx is part of both the respiratory and alimentary tracts, both the nasopharynx and larynx must be effectively isolated from the pharynx during swallowing. (Adapted from Donner et al. [1].) References: [1]. Donner MW, Basoma F, Robertson DL, Anatomy and physiology of the pharynx. Gastrointestinal Radiol *

11 Sequence of a normal swallowFigure 1-3. Sequence of a normal swallow. Swallowing can be divided into an oral phase and a subsequent pharyngeal phase. The pharyngeal phase is a complex motor event referred to as the swallow response. The oral phase of the swallowing is highly voluntary and variable, depending on taste and motivation. It is functionally accomplished by (1) manipulation of the bolus by the tongue to contain the food in the mouth until ready to swallow and (2) the propulsion of the bolus by the posterior tongue squeezing the tongue against the palate with the central groove exhibiting centripetal then centrifugal motion [6]. Close to the time that the bolus reaches the posterior tongue, the pharyngeal swallow is triggered. There is then (3) simultaneous apposition of the muscular soft palate to the posterior pharyngeal wall to prevent nasal regurgitation and elevation of the larynx and hyoid bone to close the airway and pull open the upper esophageal sphincter (UES) [7]. This is followed by (4) clearance of any remaining hypopharyngeal residue by the pharyngeal constrictors [7]. After the pharyngeal swallow has been initiated, the sequence of events is involuntary.A, At 0 seconds, the bolus is in the oral cavity, resting on the tongue, with the laryngeal vestibule open and the UES closed. B, At 0.25 seconds into the swallow the bolus has been pushed back into the valleculae by the posterior tongue, the nasopharynx has been sealed off, and the larynx has begun to elevate. C, By 0.32 seconds the hyoid is maximally elevated, the UES is opened, and the tongue base has been fully retracted against the posterior pharyngeal wall. D, Structures are beginning to return back to the rest position 1.27 seconds after the initiation of the swallow. E, The rest position. (Adapted from Kahrilas et al. [9].) References: [6]. Kahrilas PJ, The anatomy and physiology of dysphagia. In Dysphagia, Diagnosis, and Treatment. Edited by Gelfand DW, Richter JE. New York: Igaku-Shoin; [7]. Kahrilas PJ, Lin S, Logemann JA, et al. Deglutitive tongue action: Volume accommodation and bolus propulsion. Gastroenterology [9]. Kahrilas PJ, Logemann JA, Gibbons P, Food intake by maneuver: An extreme compensation for impaired swallowing. Dysphagia

12 Progression of a normal swallow imaged by cineradiography (a)Figure 1-4. Progression of a normal swallow imaged by cineradiography. A, Normal preswallow tongue and pharyngeal surface contour are shown before administration of bolus. B, With administration of barium, bolus propulsion begins with the loading phase of the tongue and bolus containment through adaptation of the lingual central groove. C, Bolus is propelled into the pharynx with the tongue central groove exhibiting centripetal then centrifugal motion. D, Nasopharyngeal closure is achieved by soft-palate elevation and apposition to the posterior pharyngeal wall. Airway protection is achieved by laryngeal elevation, vocal cord closure, and arytenoid tilting. Upper esophageal sphincter opening occurs through relaxation of the sphincter and anterior hyoid traction with laryngeal elevation. E, Pharyngeal clearance of ingested contents is achieved by profound shortening of the pharynx, eliminating bolus access to the larynx and the propagating pharyngeal contraction. After the bolus has passed into the proximal esophagus, the epiglottis returns upright, the larynx reopens, and the resting positions are resumed (not shown).

13 Progression of a normal swallow imaged by cineradiography (b)Figure 1-4. Progression of a normal swallow imaged by cineradiography. A, Normal preswallow tongue and pharyngeal surface contour are shown before administration of bolus. B, With administration of barium, bolus propulsion begins with the loading phase of the tongue and bolus containment through adaptation of the lingual central groove. C, Bolus is propelled into the pharynx with the tongue central groove exhibiting centripetal then centrifugal motion. D, Nasopharyngeal closure is achieved by soft-palate elevation and apposition to the posterior pharyngeal wall. Airway protection is achieved by laryngeal elevation, vocal cord closure, and arytenoid tilting. Upper esophageal sphincter opening occurs through relaxation of the sphincter and anterior hyoid traction with laryngeal elevation. E, Pharyngeal clearance of ingested contents is achieved by profound shortening of the pharynx, eliminating bolus access to the larynx and the propagating pharyngeal contraction. After the bolus has passed into the proximal esophagus, the epiglottis returns upright, the larynx reopens, and the resting positions are resumed (not shown).

14 Progression of a normal swallow imaged by cineradiography (c)Figure 1-4. Progression of a normal swallow imaged by cineradiography. A, Normal preswallow tongue and pharyngeal surface contour are shown before administration of bolus. B, With administration of barium, bolus propulsion begins with the loading phase of the tongue and bolus containment through adaptation of the lingual central groove. C, Bolus is propelled into the pharynx with the tongue central groove exhibiting centripetal then centrifugal motion. D, Nasopharyngeal closure is achieved by soft-palate elevation and apposition to the posterior pharyngeal wall. Airway protection is achieved by laryngeal elevation, vocal cord closure, and arytenoid tilting. Upper esophageal sphincter opening occurs through relaxation of the sphincter and anterior hyoid traction with laryngeal elevation. E, Pharyngeal clearance of ingested contents is achieved by profound shortening of the pharynx, eliminating bolus access to the larynx and the propagating pharyngeal contraction. After the bolus has passed into the proximal esophagus, the epiglottis returns upright, the larynx reopens, and the resting positions are resumed (not shown).

15 Progression of a normal swallow imaged by cineradiography (d)Figure 1-4. Progression of a normal swallow imaged by cineradiography. A, Normal preswallow tongue and pharyngeal surface contour are shown before administration of bolus. B, With administration of barium, bolus propulsion begins with the loading phase of the tongue and bolus containment through adaptation of the lingual central groove. C, Bolus is propelled into the pharynx with the tongue central groove exhibiting centripetal then centrifugal motion. D, Nasopharyngeal closure is achieved by soft-palate elevation and apposition to the posterior pharyngeal wall. Airway protection is achieved by laryngeal elevation, vocal cord closure, and arytenoid tilting. Upper esophageal sphincter opening occurs through relaxation of the sphincter and anterior hyoid traction with laryngeal elevation. E, Pharyngeal clearance of ingested contents is achieved by profound shortening of the pharynx, eliminating bolus access to the larynx and the propagating pharyngeal contraction. After the bolus has passed into the proximal esophagus, the epiglottis returns upright, the larynx reopens, and the resting positions are resumed (not shown).

16 Progression of a normal swallow imaged by cineradiography (e)Figure 1-4. Progression of a normal swallow imaged by cineradiography. A, Normal preswallow tongue and pharyngeal surface contour are shown before administration of bolus. B, With administration of barium, bolus propulsion begins with the loading phase of the tongue and bolus containment through adaptation of the lingual central groove. C, Bolus is propelled into the pharynx with the tongue central groove exhibiting centripetal then centrifugal motion. D, Nasopharyngeal closure is achieved by soft-palate elevation and apposition to the posterior pharyngeal wall. Airway protection is achieved by laryngeal elevation, vocal cord closure, and arytenoid tilting. Upper esophageal sphincter opening occurs through relaxation of the sphincter and anterior hyoid traction with laryngeal elevation. E, Pharyngeal clearance of ingested contents is achieved by profound shortening of the pharynx, eliminating bolus access to the larynx and the propagating pharyngeal contraction. After the bolus has passed into the proximal esophagus, the epiglottis returns upright, the larynx reopens, and the resting positions are resumed (not shown).

17 Endoscopic view of pharynx as seen when traversed down to upper esophageal sphincter (a)Figure 2-2. Endoscopic view of the regions of the pharynx as seen when traversed transnasally down to the region of the upper esophageal sphincter. A, The nasopharynx at rest as seen from the posterior nares superior constrictor; seen bilaterally, the soft palate is in a resting position located anteriorly. The base of the skull is visible straight ahead. A glimpse of the distal nasopharynx is seen between the skull base and soft palate. B, The soft palate is now elevated toward the tip of the scope, and the superior constrictors are adducted toward the midline. These two events have sealed the nasopharynx during a swallow. The opening of the eustachian tubes is seen bilaterally. C, With the endoscope just entering the proximal region of the nasopharynx, the posterior pharyngeal wall is seen at 6 o'clock, the soft palate and uvula are visible at 12 o'clock, and the lateral pharyngeal wall is seen bilaterally. The lateral diameter of the pharynx is significantly larger than its anteroposterior diameter. D, The tip of the endoscope has advanced further distally. The uvula is seen at 12 o'clock, and the edge of the epiglottis is now visible. E, The tip of the endoscope has advanced beyond the uvula and now is located in the oropharynx. The base of the tongue is at 12 o'clock, and the epiglottis, in resting position, is at the center of the image. The vallecular spaces between the tongue and anterior aspect of the epiglottis are wide open. The posterior wall is at 6 o'clock. The glottal structures are barely visible in the distance just posterior to the epiglottis. F, The tip of the endoscope is now advanced to the level of the epiglottal tip. The vocal cords are visible as the two arms of a `V.´ Arytenoids processing are seen at the posterior end of the cords, and the aryepiglottic folds are visible between the arytenoids and the epiglottis. The posterior commissure is located between the arytenoids. The piriform sinuses are seen bilaterally on two sides of the glottis. The area of the opening of the upper esophageal sphincter is seen between the posterior commissure and the posterior pharyngeal wall. G, The tip of the endoscope has advanced distal to the free margin of the epiglottis. The vocal cords are seen partially closed, the arytenoids are adducted, and the aryepiglottic folds and piriform sinuses are seen bilaterally. The area of the opening of the upper esophageal sphincter is visualized between the posterior aspect of the glottis and the posterior pharyngeal wall.

18 Endoscopic view of pharynx as seen when traversed down to upper esophageal sphincter (b)Figure 2-2. Endoscopic view of the regions of the pharynx as seen when traversed transnasally down to the region of the upper esophageal sphincter. A, The nasopharynx at rest as seen from the posterior nares superior constrictor; seen bilaterally, the soft palate is in a resting position located anteriorly. The base of the skull is visible straight ahead. A glimpse of the distal nasopharynx is seen between the skull base and soft palate. B, The soft palate is now elevated toward the tip of the scope, and the superior constrictors are adducted toward the midline. These two events have sealed the nasopharynx during a swallow. The opening of the eustachian tubes is seen bilaterally. C, With the endoscope just entering the proximal region of the nasopharynx, the posterior pharyngeal wall is seen at 6 o'clock, the soft palate and uvula are visible at 12 o'clock, and the lateral pharyngeal wall is seen bilaterally. The lateral diameter of the pharynx is significantly larger than its anteroposterior diameter. D, The tip of the endoscope has advanced further distally. The uvula is seen at 12 o'clock, and the edge of the epiglottis is now visible. E, The tip of the endoscope has advanced beyond the uvula and now is located in the oropharynx. The base of the tongue is at 12 o'clock, and the epiglottis, in resting position, is at the center of the image. The vallecular spaces between the tongue and anterior aspect of the epiglottis are wide open. The posterior wall is at 6 o'clock. The glottal structures are barely visible in the distance just posterior to the epiglottis. F, The tip of the endoscope is now advanced to the level of the epiglottal tip. The vocal cords are visible as the two arms of a `V.´ Arytenoids processing are seen at the posterior end of the cords, and the aryepiglottic folds are visible between the arytenoids and the epiglottis. The posterior commissure is located between the arytenoids. The piriform sinuses are seen bilaterally on two sides of the glottis. The area of the opening of the upper esophageal sphincter is seen between the posterior commissure and the posterior pharyngeal wall. G, The tip of the endoscope has advanced distal to the free margin of the epiglottis. The vocal cords are seen partially closed, the arytenoids are adducted, and the aryepiglottic folds and piriform sinuses are seen bilaterally. The area of the opening of the upper esophageal sphincter is visualized between the posterior aspect of the glottis and the posterior pharyngeal wall.

19 Endoscopic view of pharynx as seen when traversed down to upper esophageal sphincter (c)Figure 2-2. Endoscopic view of the regions of the pharynx as seen when traversed transnasally down to the region of the upper esophageal sphincter. A, The nasopharynx at rest as seen from the posterior nares superior constrictor; seen bilaterally, the soft palate is in a resting position located anteriorly. The base of the skull is visible straight ahead. A glimpse of the distal nasopharynx is seen between the skull base and soft palate. B, The soft palate is now elevated toward the tip of the scope, and the superior constrictors are adducted toward the midline. These two events have sealed the nasopharynx during a swallow. The opening of the eustachian tubes is seen bilaterally. C, With the endoscope just entering the proximal region of the nasopharynx, the posterior pharyngeal wall is seen at 6 o'clock, the soft palate and uvula are visible at 12 o'clock, and the lateral pharyngeal wall is seen bilaterally. The lateral diameter of the pharynx is significantly larger than its anteroposterior diameter. D, The tip of the endoscope has advanced further distally. The uvula is seen at 12 o'clock, and the edge of the epiglottis is now visible. E, The tip of the endoscope has advanced beyond the uvula and now is located in the oropharynx. The base of the tongue is at 12 o'clock, and the epiglottis, in resting position, is at the center of the image. The vallecular spaces between the tongue and anterior aspect of the epiglottis are wide open. The posterior wall is at 6 o'clock. The glottal structures are barely visible in the distance just posterior to the epiglottis. F, The tip of the endoscope is now advanced to the level of the epiglottal tip. The vocal cords are visible as the two arms of a `V.´ Arytenoids processing are seen at the posterior end of the cords, and the aryepiglottic folds are visible between the arytenoids and the epiglottis. The posterior commissure is located between the arytenoids. The piriform sinuses are seen bilaterally on two sides of the glottis. The area of the opening of the upper esophageal sphincter is seen between the posterior commissure and the posterior pharyngeal wall. G, The tip of the endoscope has advanced distal to the free margin of the epiglottis. The vocal cords are seen partially closed, the arytenoids are adducted, and the aryepiglottic folds and piriform sinuses are seen bilaterally. The area of the opening of the upper esophageal sphincter is visualized between the posterior aspect of the glottis and the posterior pharyngeal wall.

20 Endoscopic view of pharynx as seen when traversed down to upper esophageal sphincter (d)Figure 2-2. Endoscopic view of the regions of the pharynx as seen when traversed transnasally down to the region of the upper esophageal sphincter. A, The nasopharynx at rest as seen from the posterior nares superior constrictor; seen bilaterally, the soft palate is in a resting position located anteriorly. The base of the skull is visible straight ahead. A glimpse of the distal nasopharynx is seen between the skull base and soft palate. B, The soft palate is now elevated toward the tip of the scope, and the superior constrictors are adducted toward the midline. These two events have sealed the nasopharynx during a swallow. The opening of the eustachian tubes is seen bilaterally. C, With the endoscope just entering the proximal region of the nasopharynx, the posterior pharyngeal wall is seen at 6 o'clock, the soft palate and uvula are visible at 12 o'clock, and the lateral pharyngeal wall is seen bilaterally. The lateral diameter of the pharynx is significantly larger than its anteroposterior diameter. D, The tip of the endoscope has advanced further distally. The uvula is seen at 12 o'clock, and the edge of the epiglottis is now visible. E, The tip of the endoscope has advanced beyond the uvula and now is located in the oropharynx. The base of the tongue is at 12 o'clock, and the epiglottis, in resting position, is at the center of the image. The vallecular spaces between the tongue and anterior aspect of the epiglottis are wide open. The posterior wall is at 6 o'clock. The glottal structures are barely visible in the distance just posterior to the epiglottis. F, The tip of the endoscope is now advanced to the level of the epiglottal tip. The vocal cords are visible as the two arms of a `V.´ Arytenoids processing are seen at the posterior end of the cords, and the aryepiglottic folds are visible between the arytenoids and the epiglottis. The posterior commissure is located between the arytenoids. The piriform sinuses are seen bilaterally on two sides of the glottis. The area of the opening of the upper esophageal sphincter is seen between the posterior commissure and the posterior pharyngeal wall. G, The tip of the endoscope has advanced distal to the free margin of the epiglottis. The vocal cords are seen partially closed, the arytenoids are adducted, and the aryepiglottic folds and piriform sinuses are seen bilaterally. The area of the opening of the upper esophageal sphincter is visualized between the posterior aspect of the glottis and the posterior pharyngeal wall.

21 Endoscopic view of pharynx as seen when traversed down to upper esophageal sphincter (e)Figure 2-2. Endoscopic view of the regions of the pharynx as seen when traversed transnasally down to the region of the upper esophageal sphincter. A, The nasopharynx at rest as seen from the posterior nares superior constrictor; seen bilaterally, the soft palate is in a resting position located anteriorly. The base of the skull is visible straight ahead. A glimpse of the distal nasopharynx is seen between the skull base and soft palate. B, The soft palate is now elevated toward the tip of the scope, and the superior constrictors are adducted toward the midline. These two events have sealed the nasopharynx during a swallow. The opening of the eustachian tubes is seen bilaterally. C, With the endoscope just entering the proximal region of the nasopharynx, the posterior pharyngeal wall is seen at 6 o'clock, the soft palate and uvula are visible at 12 o'clock, and the lateral pharyngeal wall is seen bilaterally. The lateral diameter of the pharynx is significantly larger than its anteroposterior diameter. D, The tip of the endoscope has advanced further distally. The uvula is seen at 12 o'clock, and the edge of the epiglottis is now visible. E, The tip of the endoscope has advanced beyond the uvula and now is located in the oropharynx. The base of the tongue is at 12 o'clock, and the epiglottis, in resting position, is at the center of the image. The vallecular spaces between the tongue and anterior aspect of the epiglottis are wide open. The posterior wall is at 6 o'clock. The glottal structures are barely visible in the distance just posterior to the epiglottis. F, The tip of the endoscope is now advanced to the level of the epiglottal tip. The vocal cords are visible as the two arms of a `V.´ Arytenoids processing are seen at the posterior end of the cords, and the aryepiglottic folds are visible between the arytenoids and the epiglottis. The posterior commissure is located between the arytenoids. The piriform sinuses are seen bilaterally on two sides of the glottis. The area of the opening of the upper esophageal sphincter is seen between the posterior commissure and the posterior pharyngeal wall. G, The tip of the endoscope has advanced distal to the free margin of the epiglottis. The vocal cords are seen partially closed, the arytenoids are adducted, and the aryepiglottic folds and piriform sinuses are seen bilaterally. The area of the opening of the upper esophageal sphincter is visualized between the posterior aspect of the glottis and the posterior pharyngeal wall.

22 Endoscopic view of pharynx as seen when traversed down to upper esophageal sphincter (f)Figure 2-2. Endoscopic view of the regions of the pharynx as seen when traversed transnasally down to the region of the upper esophageal sphincter. A, The nasopharynx at rest as seen from the posterior nares superior constrictor; seen bilaterally, the soft palate is in a resting position located anteriorly. The base of the skull is visible straight ahead. A glimpse of the distal nasopharynx is seen between the skull base and soft palate. B, The soft palate is now elevated toward the tip of the scope, and the superior constrictors are adducted toward the midline. These two events have sealed the nasopharynx during a swallow. The opening of the eustachian tubes is seen bilaterally. C, With the endoscope just entering the proximal region of the nasopharynx, the posterior pharyngeal wall is seen at 6 o'clock, the soft palate and uvula are visible at 12 o'clock, and the lateral pharyngeal wall is seen bilaterally. The lateral diameter of the pharynx is significantly larger than its anteroposterior diameter. D, The tip of the endoscope has advanced further distally. The uvula is seen at 12 o'clock, and the edge of the epiglottis is now visible. E, The tip of the endoscope has advanced beyond the uvula and now is located in the oropharynx. The base of the tongue is at 12 o'clock, and the epiglottis, in resting position, is at the center of the image. The vallecular spaces between the tongue and anterior aspect of the epiglottis are wide open. The posterior wall is at 6 o'clock. The glottal structures are barely visible in the distance just posterior to the epiglottis. F, The tip of the endoscope is now advanced to the level of the epiglottal tip. The vocal cords are visible as the two arms of a `V.´ Arytenoids processing are seen at the posterior end of the cords, and the aryepiglottic folds are visible between the arytenoids and the epiglottis. The posterior commissure is located between the arytenoids. The piriform sinuses are seen bilaterally on two sides of the glottis. The area of the opening of the upper esophageal sphincter is seen between the posterior commissure and the posterior pharyngeal wall. G, The tip of the endoscope has advanced distal to the free margin of the epiglottis. The vocal cords are seen partially closed, the arytenoids are adducted, and the aryepiglottic folds and piriform sinuses are seen bilaterally. The area of the opening of the upper esophageal sphincter is visualized between the posterior aspect of the glottis and the posterior pharyngeal wall.

23 Endoscopic view of pharynx as seen when traversed down to upper esophageal sphincter (g)Figure 2-2. Endoscopic view of the regions of the pharynx as seen when traversed transnasally down to the region of the upper esophageal sphincter. A, The nasopharynx at rest as seen from the posterior nares superior constrictor; seen bilaterally, the soft palate is in a resting position located anteriorly. The base of the skull is visible straight ahead. A glimpse of the distal nasopharynx is seen between the skull base and soft palate. B, The soft palate is now elevated toward the tip of the scope, and the superior constrictors are adducted toward the midline. These two events have sealed the nasopharynx during a swallow. The opening of the eustachian tubes is seen bilaterally. C, With the endoscope just entering the proximal region of the nasopharynx, the posterior pharyngeal wall is seen at 6 o'clock, the soft palate and uvula are visible at 12 o'clock, and the lateral pharyngeal wall is seen bilaterally. The lateral diameter of the pharynx is significantly larger than its anteroposterior diameter. D, The tip of the endoscope has advanced further distally. The uvula is seen at 12 o'clock, and the edge of the epiglottis is now visible. E, The tip of the endoscope has advanced beyond the uvula and now is located in the oropharynx. The base of the tongue is at 12 o'clock, and the epiglottis, in resting position, is at the center of the image. The vallecular spaces between the tongue and anterior aspect of the epiglottis are wide open. The posterior wall is at 6 o'clock. The glottal structures are barely visible in the distance just posterior to the epiglottis. F, The tip of the endoscope is now advanced to the level of the epiglottal tip. The vocal cords are visible as the two arms of a `V.´ Arytenoids processing are seen at the posterior end of the cords, and the aryepiglottic folds are visible between the arytenoids and the epiglottis. The posterior commissure is located between the arytenoids. The piriform sinuses are seen bilaterally on two sides of the glottis. The area of the opening of the upper esophageal sphincter is seen between the posterior commissure and the posterior pharyngeal wall. G, The tip of the endoscope has advanced distal to the free margin of the epiglottis. The vocal cords are seen partially closed, the arytenoids are adducted, and the aryepiglottic folds and piriform sinuses are seen bilaterally. The area of the opening of the upper esophageal sphincter is visualized between the posterior aspect of the glottis and the posterior pharyngeal wall.

24 CNS organization of swallow responseNMDV Figure 1-5. Central nervous system organization of the swallow response. Afferent information from the periphery enters into the solitary tract. This sensory information can initiate deglutition and modify ongoing motor activity within reflexes affecting the esophageal body and sphincters independent of swallowing. Sensory information from the oropharyngeal area enters through the extravagal cranial nerves (trigeminal, facial, hypoglossal, and glossopharyngeal) and vagal nerve pathways. Sensory information from the entire esophagus, including the sphincters, is carried in the vagus nerve with the cell bodies in the nodose ganglion. Sensory information also passes by way of the sympathetics to the spinal cord segments C1 to L3.The portion of the swallowing center that programs the entire swallowing sequence is located in the solitary tract nucleus and the neighboring reticular substance. The dorsal portion within this center is involved in the initiation of the swallow and the organization of the entire swallowing sequence. The ventral portion appears to serve as a connecting pathway to the various motor neuron pools involved in the swallowing sequence, such as integration of the swallowing sequence with the respiratory center in the medulla.The motor neurons involved in the efferent output of the swallowing sequence lie mainly in the trigeminal, facial, and hypoglossal nuclei, the nucleus ambiguus of the vagus (for esophageal striated muscle), and the dorsal motor nuclei of the vagus (for esophageal smooth muscle) with some input to striated muscle. (Adapted from Castell [10].) References: [10]. Castell DO, In The Esophagus. Edited by Castell DO. Boston: Little, Brown, and Co; Secuencia del reflejo centro respiratorio (también V,VII,XII)

25 Sensory field of superior laryngeal nerveaferencia proximal: glosofaríngeo (aferencia distal) Figure 1-6. Sensory field of the superior laryngeal nerve in humans. Electrical stimulation of the superior laryngeal nerve (SLN) elicits the pharyngeal swallow response. The structures innervated by the SLN are relatively distal, supporting the notion that in vivo afferents initiating swallowing probably also travel through the glossopharyngeal nerve. More than likely, reflexive swallows aimed at keeping the pharynx clear of secretions are initiated by stimulation of SLN afferents whereas deglutitive swallows are initiated by proximal stimulation or volition. (Adapted from Kahrilas [6].) References: [6]. Kahrilas PJ, The anatomy and physiology of dysphagia. In Dysphagia, Diagnosis, and Treatment. Edited by Gelfand DW, Richter JE. New York: Igaku-Shoin; eferentetes: -constrictor inferior -cricofaríngeo

26 Neuroanatomy of the swallow responseFigure 1-7. Neuroanatomy of the swallow response. The location of the swallowing center is estimated to be in the reticular substance about 1.5 mm from the midline and 1 to 3 mm dorsal to the inferior olive at a level between the rostral pole of the inferior olive and caudal pole of the facial nucleus. A swallowing center exists bilaterally in each atmosphere, which is capable of independently coordinating swallowing activity, although both sides are extensively interconnected. The swallow center has dominant access to motoneurons and exerts strong inhibitory influence on centers competing for access to these motoneurons. Therefore, an apneic pause of 0.5 to 3.5 seconds occurs to accompany swallowing.

27 Time lines of 1- and 20-mL swallows, biomechanical termsFigure 1-8. Time lines of 1- and 20-mL swallows viewed in biomechanical terms. In addition to neurophysiologic electromyographic patterns, deglutition can also be described in biomechanical terms. Biomechanical analysis concentrates on the swallowed bolus and how the bolus is manipulated by oropharyngeal structures. Therefore, in biomechanical terms the pharyngeal swallow encompasses several closely coordinated actions: elevation and retraction of the soft palate with the closure of the nasopharynx, upper esophageal sphincter opening, laryngeal closure at the level of the laryngeal vestibule, tongue loading (ramping), tongue pulsion, and pharyngeal clearance. These biomechanical events that comprise the swallow response exhibit systematic variability with the volume of the swallowed bolus.This figure shows time lines of 1- and 20-mL swallows. The upper unshaded area depicts time relationships among swallow events during 1-mL swallows whereas the shaded area below depicts time relationships during 20-mL swallows. In both cases, time 0 is the end of the swallow, determined by the timing of the UES closure, and all other events are given negative timing values. When viewed in this way, the apparent prolongation of the 20-mL swallow is associated with an earlier mechanical configuration of the pharynx from a respiratory to a swallowing conduit. This earlier configuration is associated with a prolonged tongue loading phase that starts earlier and takes longer [6]. UES opening along with the associated closure of the laryngeal vestibule also commences sooner and persists longer [8]. Propulsive events occur with a very similar time frame, resulting from more vigorous expulsion of a larger boluses. The mechanics and timing of the pharyngeal contraction, important in pharyngeal clearance and in UES closure, on the other hand, is extraordinarily constant among swallow volumes [7]. (Adapted from Kahrilas [12].) References: [6]. Kahrilas PJ, The anatomy and physiology of dysphagia. In Dysphagia, Diagnosis, and Treatment. Edited by Gelfand DW, Richter JE. New York: Igaku-Shoin; [7]. Kahrilas PJ, Lin S, Logemann JA, et al. Deglutitive tongue action: Volume accommodation and bolus propulsion. Gastroenterology [8]. Kahrilas PJ, Logemann JA, Lin S, et al. Pharyngeal clearance during swallowing: A combined manometric and videofluoroscopic study. Gastroenterology [12]. Kahrilas PJ, Volume accommodation during swallowing. Dysphagia

28 Deglutitive vocal cord kinetics and other oropharyngeal phase eventsTB-O­onset of tongue base movement; SH-O­onset of superior hyoid movement; SM-O­onset of submental myoelectrical activity; UESO­upper esophageal sphincter opening; OT-O­onset of bolus movement from the mouth; PT-O­arrival of bolus into pharynx. Figure 2-4. Relationship of deglutitive vocal cord kinetics to other events of the oropharyngeal phase of swallowing during 5-mL barium swallows. Bolus transit through the pharynx and across the UES begins and ends while the vocal cords are at maximal adduction.Swallowing is a highly coordinated physiologic event that involves sequential and overlapping contractions of the facial, cervical, oral, pharyngeal, laryngeal, and esophageal muscular apparatus, and results in transit of ingested material and saliva from the mouth into the stomach. Swallowing can be divided into four consecutive phases representing the anatomic regions traversed by the bolus: preparatory, oral, pharyngeal, and esophageal. From a functional point of view, events that take place during oropharyngeal swallowing contribute to transit of the bolus and protection of the airway. The transit and protective aspects of oropharyngeal swallowing are highly coordinated. Oropharyngeal transit occurs during the full activation of the protective aspect of swallowing. A successful oropharyngeal swallow requires the effective and coordinated actions of the anatomical elements involved in these two functions. TB-O­onset of tongue base movement; SH-O­onset of superior hyoid movement; SM-O­onset of submental myoelectrical activity; UESO­upper esophageal sphincter opening; OT-O­onset of bolus movement from the mouth; PT-O­arrival of bolus into pharynx. (Adapted from Shaker [2].) References: [2]. Shaker R, Semin Gastrointest Dis (3)

29 Upper esophageal sphincter (UES) imaged by ultrafast CT (a)Componentes: -cricofaríngeo -pared del esófago -constrictor inf. faringe Longitud axial: 1 cm Inervación: -rama faríngea del Vago Figure 1-9. Upper esophageal sphincter (UES) imaged by ultrafast CT. The muscular elements of the UES are striated muscle with the cricopharyngeus as well as the adjacent portion of the cervical esophagus and the inferior pharyngeal constrictor contributing to sphincteric function. The cricopharyngeus receives its motor nerve supply through the pharyngeal branch of the vagus. The zone of maximal intraluminal pressure is approximately 1 cm in length axially, and when viewed in cross-section, the closed sphincter has a slitlike configuration with the lamina of the cricoid cartilage anterior and the cricopharyngeus attached in a C configuration making up the lateral and posterior walls.A, Representative cross-sectional image at the level of the UES as imaged by ultrafast CT. The tracings (B) illustrate the dynamic changes of the bolus cavity during the course of the swallow, ending with luminal closure at time zero. Note how the sphincter is tightly confined between the cricoid cartilage and cervical vertebrae. Despite this confinement, the opened sphincter maintains an ovoid rather than a dumbbell configuration. (Panel A from Ergun et al. [13]; with permission.) References: [13]. Ergun GA, Kahrilas PJ, Lin S, et al. Shape, volume, and content of the deglutitive pharyngeal chamber imaged by ultrafast CT. Gastroenterology

30 Upper esophageal sphincter (UES) imaged by ultrafast CT (b)Figure 1-9. Upper esophageal sphincter (UES) imaged by ultrafast CT. The muscular elements of the UES are striated muscle with the cricopharyngeus as well as the adjacent portion of the cervical esophagus and the inferior pharyngeal constrictor contributing to sphincteric function. The cricopharyngeus receives its motor nerve supply through the pharyngeal branch of the vagus. The zone of maximal intraluminal pressure is approximately 1 cm in length axially, and when viewed in cross-section, the closed sphincter has a slitlike configuration with the lamina of the cricoid cartilage anterior and the cricopharyngeus attached in a C configuration making up the lateral and posterior walls.A, Representative cross-sectional image at the level of the UES as imaged by ultrafast CT. The tracings (B) illustrate the dynamic changes of the bolus cavity during the course of the swallow, ending with luminal closure at time zero. Note how the sphincter is tightly confined between the cricoid cartilage and cervical vertebrae. Despite this confinement, the opened sphincter maintains an ovoid rather than a dumbbell configuration. (Panel A from Ergun et al. [13]; with permission.) References: [13]. Ergun GA, Kahrilas PJ, Lin S, et al. Shape, volume, and content of the deglutitive pharyngeal chamber imaged by ultrafast CT. Gastroenterology

31 Continuous cricopharyngeal electromyography (EMG) recordingpresión de reposo residual Figure Continuous cricopharyngeal electromyography (EMG) recording. These sample data tracings from a dog show the upper esophageal sphincter (UES) intraluminal pressure recorded by sleeve sensor in panel A, the raw EMG recording of the cricopharyngeus in panel B, and the integrated cricopharyngeal EMG activity in panel C while the animal was awake (left) and sedated with pentobarbital (right). The most typical EMG activity pattern of the UES is the brief interval of inhibition followed by a pulse of maximal excitation, regardless of the pre-existing tone or activity pattern of the UES. In the awake state, the swallow is associated with inhibition of the cricopharyngeal EMG followed by a burst of activity corresponding to the passage of the pharyngeal contraction. While sedated, there is no detectable resting cricopharyngeal EMG activity and therefore no detectable cricopharyngeal inhibition at the time of UES relaxation. These findings suggest that the residual UES pressure (approximately 15 mm Hg) in the sedated animal is the result of passive elastic forces in the neck rather than active cricopharyngeal contraction. (Adapted from Jacob et al. [14].) References: [14]. Jacob P, Kahrilas PJ, Herzon G, et al. Determinants of upper esophageal sphincter pressure in dogs. Am J Physiol G245-G251

32 Movement of hyoid bone, 1- and 10-mL barium swallowsFigure Movement pattern of the hyoid bone during 1- and 10-mL barium swallows. The upper esophageal sphincter (UES) is tonically closed at rest because of continuous neural excitation. Within 0.2 seconds after a swallow, excitatory discharge to the UES transiently ceases and laryngeal elevation followed by anterior traction of the hyoid work together to pull open the sphincter. Because the only insertion of the sphincteric musculature is anterior to the cartilages of the larynx, the sphincter and larynx are obliged to move in unison during axial laryngeal movement so that the primary mechanism for opening the relaxed UES also serves to produce a uniform conduit for directing the bolus into the esophagus.The contraction of the suprahyoid and infrahyoid musculature that provides the anterior traction for UES opening also results in the characteristic pattern of hyoid displacement shown in this figure. Each circle represents the hyoid position during a single video frame of the recorded fluoroscopic sequence (1/30th second interval) and the arrows indicate the direction of movement. The open circles indicate frames during which the sphincter was closed, closed circles indicate frames when the sphincter was open, and the gray circles indicate frames during which the sphincter was variably open, depending on the subject. Both the diameter and duration of sphincter opening increase with increased bolus volume. The increased duration of sphincter opening is related to the persistence of the hyoid excursion, whereas changes in the diameter of the opening are related to increased intrabolus pressure with larger volume swallows. (Adapted from Jacob et al. [11].) References: [11]. Jacob P, Kahrilas PJ, Logemann JA, et al. Upper esophageal sphincter opening and modulation during swallowing. Gastroenterology UES cerrado UES abierto Hioides

33 Three-dimensional model of oropharynx during swallowFigure Three-dimensional modeling of the oropharynx during swallowing. This figure shows the reconstructions of nine representative pharyngeal configurations during a 10-mL swallow. In each image the bolus chamber is white, the supraglottic airway is blue, the infraglottic airway is purple, the vertebrae are light brown, the hyoid is orange, the epiglottis is yellow, the arytenoid cartilage is dark green, the cricoid cartilage is red, the tracheal rings are cyan, and the hemisected thyroid cartilage is light green. The times next to the images refer to the upper esophageal sphincter (UES) opening (time, 0.0 seconds). Many mechanical events are encompassed during the act of deglutition. The preswallow configuration (−0.40 seconds) is characterized by the bolus chamber being segregated from the airway by the sealed glossopalatal junction. At the time of velopharyngeal closure (−0.13 seconds) the nasopharynx is sealed from the bolus chamber by elevation of the soft palate and the bolus chamber expands to the retrolingual space as the glossopalatal junction opens. The central groove of the tongue blade has deepened and the posterior oral portion of the pharyngeal propulsive chamber is forming. The larynx has begun elevating and the arytenoid cartilage is tilting toward the base of the epiglottis. At the instant of UES opening the laryngeal vestibule has been obliterated by contact of the arytenoid cartilage against the epiglottic base. Note that the UES (at the inferior aspect of the cricoid cartilage) has elevated relative to its preswallow position and that the pharyngeal bolus chamber is fully formed. During lingual bolus propulsion (0.13 seconds) the volume of the bolus chamber is reduced by the centrifugal motion of the tongue surface and bolus expulsion results in full distension of the UES and proximal esophagus. The epiglottis is folded over the arytenoid cartilage and there is maximal pharyngeal shortening. The next four reconstructions­early pharyngeal clearance (0.27 seconds), midpharyngeal clearance (0.40 seconds), late pharyngeal clearance (0.53 seconds), and UES closure (0.67 seconds)­show the caudal progression of the pharyngeal contraction stripping the residua from the oropharynx into the esophagus. Finally, with airway reopening (0.87 seconds) the pharynx commences its return to the respiratory configuration as the larynx descends, the epiglottis flips up, and the velopharyngeal junction reopens. (From Kahrilas et al. [15]; with permission.) References: [15]. Kahrilas PJ, Lin S, Chen J, et al. Three dimensional modeling of the oropharynx during swallowing. Radiology

34

35 Fisiología de la Salivación

36 Digestive process is initiated by sensory signalsFigure 2-2. The digestive process is initiated by sensory signals elicited by the thought, sight, taste, and smell of food (cephalic phase). The signals are processed in the cortex and relayed through the hypothalamus to vagal and glossopharyngeal nuclei in the brain stem. This results in increased cholinergic activity in efferent nerves (vagus and glossopharyngeus), which supply salivary glands, stomach, and pancreas. The increase in cholinergic activity stimulates salivary, gastric, and pancreatic secretion. The secretory response is about 20% to 40% of maximal secretory capacity.

37 Oral cavity has important functions in initial processingTable 2-4. The oral cavity has important functions in the initial processing of solid food. Careful chewing breaks solid food into smaller pieces, which facilitates the swallowing process. The taste of food stimulates increased salivary secretion to moisten solid food and mix food with salivary amylase R-factors, and lingual lipase. [5]. The taste of food further stimulates gastric acid secretion through sensory impulses to vagal nuclei in the brain stem, which leads to increased efferent vagal activity (sham feeding response). References: [5]. Lerner A, Rosenthal MA, Liebow C, Lebenthal E, Salivary secretion. In Textbook of Gastroenterology. Edited by Yamada T. Philadelphia: JB Lippincott;

38 ( )

39 Saliva: Tipos de secreciónSerosa: rica en ptialina (-amilasa) Parótida Mucosa: rica en mucina Submandibulares Sublingulaes (secretan ambos tipos) Moco: glándulas bucales

40 acinos conductos transporte activo(rica en potasio y bicarbonato pH= 6,0 – 7,0)

41 Saliva: funciones protectorasArrastre mecánico de bacterias y partículas Factores bactericidas iones tiocianato enzimas proteolíticas (lisozima) atacan las bacterias favorecen penetración del tiocianato digieren partículas alimenticias Anticuerpos (IgA)

42 Saliva: regulación nerviosaOlfato Apetito Náuseas Símpático Vasodilatación (calicreína- bradicinina)

43

44 Fase esofágica de la degluciónOndas primarias Continuación de la contracción peristáltica faríngea Recorre de faringe al estómago en 8 a 10 segundos El alimento llega en 5 a 8 segundos (supino) Ondas secundarias Peristaltismo inducido por distensión de la pared Relajación receptiva del EEI Relajación receptiva del estómago

45 Cutaway view of anatomy of tubular esophagusFigure Cutaway view showing anatomy of the tubular esophagus. The esophagus is a muscular tube that is composed of longitudinal and circular muscle with extensive neural network in between. Auerbach's plexus (myenteric) lies between the longitudinal and circular muscle layers. Another nerve network, Meissner's plexus (submucosal), is situated between the muscularis mucosa and the circular muscle layer. Note that there is no serosa to the esophagus and that the lumen is collapsed and empty. In fact, activity of both esophageal sphincters preserves the vacuum of the esophagus; the upper esophageal sphincter acts to exclude air during respiration and the lower esophageal sphincter excludes gastric contents from refluxing back into the esophagus. (Adapted from Kahrilas [6].) References: [6]. Kahrilas PJ, The anatomy and physiology of dysphagia. In Dysphagia, Diagnosis, and Treatment. Edited by Gelfand DW, Richter JE. New York: Igaku-Shoin;

46 Extrinsic/intrinsic motor innervation of esophagusFigure Extrinsic and intrinsic motor innervation of the esophagus. The control mechanisms that govern the striated and smooth musculature of the esophagus are distinct. The extrinsic innervation of the esophagus is through the vagus nerve. The striated muscle receives excitatory vagal innervation exclusively from axons of lower motor neurons with cell bodies in the nucleus ambiguus. Peristaltic contraction of this segment results from sequential activation of motor units in a craniocaudal sequence caused by programming by the medullary swallowing center that is potentiated by stimulation of afferent fibers from the esophagus designed to mimic the effect of a bolus being pushed ahead of a peristaltic contraction. Moreover, vagal motor fibers are inhibited during the pharyngeal phase of swallowing, supporting the concept that deglutitive inhibition has a central origin. Similarly, primary peristalsis of the smooth muscle exists following deviation of the bolus path and curarization of the oropharyngeal and cervical esophagus, suggesting that primary peristalsis in the smooth muscle segment is at least partially governed by the medullary swallowing center. Vagal control of the smooth muscle esophagus is more complex, with vagal innervation provided by the dorsal motor nucleus of the vagus and vagal fibers synapsing on myenteric plexus neurons rather than directly on neuromuscular junctions. There is, however, no vagal activity during secondary peristalsis, supporting the notion that the organization of peristalsis in the smooth muscle is an intramural process.With respect to the intrinsic control of peristalsis, the entire esophagus has an intramural nerve network (see Fig. 1-13). Interestingly, the function of the myenteric plexus in the striated esophagus is unknown. The morphology and function in the smooth muscle esophagus have yet to be determined; however, there are two main types of effector neurons within the myenteric plexus. Excitatory neurons mediate contraction of both the longitudinal and circular smooth muscle through cholinergic M2 receptors, and inhibitory neurons affect predominantly the circular muscle layer through a nonadrenergic, noncholinergic neurotransmitter (NANC), now believed to be nitric oxide. Cholinergic excitation of the excitatory neurons is nicotinic whereas cholinergic excitation of the NANC can be muscarinic (M1) as well. LES­lower esophageal sphincter. (Adapted from Kahrilas [20].) References: [20]. Kahrilas PJ, Functional anatomy and physiology of the esophagus. In The Esophagus. Edited by Castell DO. Boston: Little, Brown, and Co;

47 Normal histology of the esophagusFigure Normal histology of the esophagus. The lining of the esophagus is a partially or nonkeratinized stratified squamous epithelium that overlies the connective tissue of the submucosa and the thick circular and longitudinal muscle layers (not shown). (Courtesy of Dr. Sambastiva Rao, Northwestern University Medical School.)

48 Endoscopic ultrasound of the esophagusFigure Endoscopic ultrasound of the esophagus. This endosonographic image of the esophageal wall demonstrates the five-layer structure that is seen throughout the gastrointestinal tract. These layers correspond to the mucosa (e, d), submucosa (c), muscularis (b), adventitia (a). Because of balloon filling, the layer structure is not recognizable in all parts of the circumference. (Courtesy of Dr. Arvydas Vanagunas, Northwestern University Medical School.)

49 Venous layers of the esophagusFigure Venous layers of the esophagus. There are three parts of the venous system related to the esophagus: intrinsic veins, associated veins, and extrinsic veins. The two layers of veins in the wall of the esophagus are the superficial venous plexus (located in the lamina propria and muscularis mucosa) and the submucosal plexus (within the circular muscle). In the distal esophagus, venous blood drains first from a superficial mucosal network of small intraepithelial blood vessels into submucosal, longitudinally oriented deep intrinsic veins. Once in the intrinsic veins, blood drains through a system of transverse perforating veins with unidirectional valves into extrinsic serosal and periesophageal veins and ultimately into the left gastric vein inferiorly and the azygos vein superiorly. (Adapted from Kitano et al. [17].) References: [17]. Kitano S, Terblanche J, Kahn D, et al. Venous anatomy of the lower oesophagus in portal hypertension: Practical implications. Br J Surg

50 Normal manometric recording and primary peristalsisFigure Normal manometric recording and primary peristalsis. This figure shows a normal manometric tracing using a sleeve sensor. Distance above the center of the sleeve device positioned in the lower esophageal sphincter (LES) is shown on the left with time of contraction onset on the right. At rest, the esophageal body is quiet and there is no motor activity, whereas the upper esophageal sphincter and LES both maintain a contraction that can be measured manometrically and characterized as resting or basal tone. During deglutition the classic coordinated motor pattern of the esophagus, called primary peristalsis, is initiated. With transfer of the bolus into the esophagus, a progressive circular contraction begins in the upper esophagus and proceeds down the esophageal body to propel the bolus through a relaxed LES, which subsequently closes with a prolonged contraction.

51 Relationship of peristaltic function and esophageal volume clearanceFigure Relationship between peristaltic function and esophageal volume clearance. The mechanical equivalent of peristalsis is a stripping wave that clears the esophagus proximally down with the velocity of the stripping wave corresponding to the manometrically recorded contraction such that the point of the inverted V seen fluoroscopically at each manometric sensor occurs simultaneous to the upstroke of the pressure wave. Data defining the relationship between the amplitude of esophageal peristalsis and the efficacy with which the stripping wave empties the esophagus are demonstrated in this figure.This figure also shows concurrent manometric and video recordings of a 5-mL barium swallow. The tracings of the sequential fluoroscopic images show the distribution of the barium column at the times indicated above the images and by closed arrows on the manometric tracings. Here, a single peristaltic sequence completely cleared the barium from the esophagus. Administration of the barium occurred at 1.0 second, causing some esophageal distension and slightly increasing intraluminal pressure, shown by the open arrows on the manometric record. With onset of peristalsis, luminal closure is achieved as the tail of the barium bolus passes each recording site concurrent with the onset of the manometric pressure wave. LES­lower esophageal sphincter; UES­upper esophageal sphincter. (Adapted from Kahrilas [18].) References: [18]. Kahrilas PJ, The effect of peristaltic dysfunction on esophageal volume clearance. Gastroenterology

52 Deglutitive inhibitionFigure Deglutitive inhibition. It has been suggested that swallowing not only induces primary peristalsis, but also triggers a wave of inhibition of the smooth muscle that precedes the arrival of the peristaltic contraction (deglutitive inhibition). This idea was based on in vivo experiments in animals but was never studied in humans in detail because inhibition is difficult to visualize. This figure shows resting pressure and deglutitive pressure waves in the human esophagus with an artificial high pressure zone created originally at 13 cm (A) and then at 8 cm (B) above the lower esophageal sphincter (LES). Note that after swallowing a relaxation of the artificial high pressure zone started simultaneously at 13 cm and 8 cm above the LES. The end of the relaxation coincided with the start of the peristaltic contraction at that level.This study shows direct evidence that a wave of inhibition precedes a swallow-induced peristaltic contraction in the smooth muscle of the human esophagus. This inhibitory wave was visualized by the appearance, after swallow, of a relaxation of the sustained contraction that was induced by insufflation of a balloon at different levels of the distal esophagus. This relaxation started simultaneously over the entire distal esophageal body but lasted progressively longer in progressively more distal segments. The timing of the relaxation of the artificial high pressure zone strongly suggests that it represents the manometric equivalent of the electrical postdeglutitive smooth muscle membrane hyperpolarization described in animal studies and the esophageal body equivalent of the postdeglutitive LES relaxation. (Adapted from Sifrim [21].) References: [21]. Sifrim D, Inhibition in the human esophageal body: Its role in normal and disordered motility [thesis]. Leuven, Belgium: Katholieke Universiteit Leuven; 1994

53 Anatomy of gastroesophageal junction at diaphragm and lower esophageal sphincterFigure Anatomy of the gastroesophageal junction highlighting the relationship between the diaphragm and the lower esophageal sphincter (LES). The esophagus, vagal trunks, and esophageal branches of the left gastric vein traverse the diaphragm through the esophageal hiatus. The crural fibers of the diaphragm encircle the esophagus in such a manner that a contraction of the muscle during inspiration constricts the esophagus.

54 Axial hiatus hernia Figure Axial hiatus hernia. Most hiatal hernias are classified as axial or sliding. With the axial hiatal hernia there is decreased tethering by the phrenoesophageal ligaments and enlargement of the esophageal hiatus, which allows the gastric cardia to herniate upward into the thorax. The degree of herniation is highly variable. With small hernias only a small amount of the lesser curve and part of the fundus may be apparent, and with large hernias the entire fundus of the stomach may be visible in the thorax.

55 Paraesophageal herniaFigure Paraesophageal hernia. In patients with paraesophageal hiatal hernias the cardioesophageal junction characteristically maintains normal position because the paraesophageal ligaments are normally arranged around most of the esophagus. A break in the continuity of the phrenoesophageal membrane allows the esophageal hiatus to enlarge, allowing a variable portion of the gastric fundus access into the thorax alongside the esophagus. As the hernia enlarges the body of the stomach is also drawn into the hernial sac whereas the pylorus and duodenum remain in the abdominal cavity, still tethered by their normal attachments.

56 Intrinsic lower esophageal sphincter (LES) pressureFigure Intrinsic lower esophageal sphincter (LES) pressure. The LES is a 3- to 4-cm segment of tonically contracted smooth muscle with a resting tone that varies from 10 to 30 mm Hg relative to gastric pressure. This positive pressure gradient between the stomach and the esophagus can be considered the driving force for gastroesophageal reflux, with the high pressure zone at the gastroesophageal junction considered a barrier to the prevention of reflux of gastric contents. The high pressure zone has two components: (1) a tonic pressure caused by the LES, which is believed to be caused by a combination of myogenic factors, active tonic neural excitation, and complex interactions of other neural and hormonal factors [22], and (2) superimposed phasic pressure oscillations resulting from contractions of the diaphragmatic crus that encircles the LES [23], [24], [25], [26].This figure shows the contribution of diaphragm contraction (green portion) to basal LES pressure (orange portion). Note that a significant component of LES pressure is contributed by the diaphragm and that augmentation of the LES pressure corresponds temporally and quantitatively with the augmentation of crural electromyographic activity. (Courtesy of Dr. R. Mittal, Charlottesville, VA.) References: [22]. Goyal RK, Rattan S, Neurohumoral, hormonal, and drug receptors for the lower esophageal sphincter. Gastroenterology [23]. Mittal RK, Rochester DF, McCallum RW, Sphincteric action of the diaphragm during a relaxed lower esophageal sphincter. Am J Physiol G139-G144 [24]. Boyle JT, Altschuler SM, Nixon TE, et al. Role of the diaphragm in the genesis of lower esophageal sphincter pressure in the cat. Gastroenterology [25]. Mittal RK, Rochester DF, McCallum RW, Electrical and mechanical activity in the human lower esophageal sphincter during diaphragmatic contraction. J Clin Invest [26]. Mittal RK, Rochester DF, McCallum RW, Sphincteric action of the diaphragm during a relaxed lower esophageal sphincter in humans. Am J Physiol G139-G144

57 Extrinsic control of LESFigure Extrinsic control of the lower esophageal sphincter (LES). The LES tone is subject to both vagal and adrenergic influences, with vagal stimulation activating both excitatory (cholinergic) and inhibitory (nitric oxide) myenteric neurons. This figure illustrates the extrinsic control of the LES. A, Myelohyoid electromyography (arrow indicates the time of the pharyngeal swallow). B and C, Activity of the vagal inhibitory and excitatory fibers, respectively, to the LES at the time of swallow. D, Intraballoon (bolus) pressure at time of swallow. Note that the excitatory component is selectively activated under basal conditions and the inhibitory component is activated during swallow and mediates LES relaxation. (Adapted from Miolan and Roman [27].) References: [27]. Miolan JP, Roman C, Activit des fibres vagales efferentes destines la musculature lessé du cardia du chien. J Physiol Paris

58 Substances influencing LES pressureFigure Substances influencing lower esophageal sphincter (LES) pressure. Intra-abdominal pressure, gastric distension, food, and many peptides and drugs affect LES pressure.

59 Transient LES relaxationMecanismos de RGE: -Relajación transitoria del LES -Valsalva -LES patológico Figure Transient lower esophageal sphincter (LES) relaxation. Individual gastroesophageal reflux events occur by one of three mechanisms: transient LES relaxations, abdominal strain, or free reflux across a patulous LES [28]. Transient LES relaxations occur in both normal individuals and in patients with gastroesophageal reflux; they are the only potential mechanism for reflux during periods in which the LES is normal. These relaxations are part of the reflex that normally allows for gas venting from the stomach and may be triggered by fundic distension with air [29], [30].This example of transient LES relaxation was recorded in an asymptomatic individual. LES pressure is referenced to gastric pressure. Note that the transient LES relaxation persisted for almost 30 seconds whereas the swallow-induced LES relaxation (Sw) lasted for only 5 seconds. Also note the absence of an electromyographic (EMG) signal from a submental electrode during the transient LES relaxation, signifying the absence of a pharyngeal swallow. (Adapted from Kahrilas and Gupta [31].) References: [28]. Dent J, Dodds WJ, Friedman RH, et al. Mechanism of gastroesophageal reflux in recumbent asymptomatic human subjects. J Clin Invest [29]. Patrikios J, Martin CJ, Dent J, Relationship of transient lower esophageal sphincter relaxation to postprandial gastroesophageal reflux and belching in dogs. Gastroenterology [30]. Martin CJ, Patrikios J, Dent J, Abolition of gas reflux and transient lower esophageal relaxation by vagal blockade in the dog. Gastroenterology [31]. Kahrilas PJ, Gupta RR, Mechanisms of acid reflux associated with cigarette smoking. Gut

60 Fin M.B.