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## Resting Pressure Profile of the Foregut The resting pressure profile of the foregut shows the pressure differential between atmospheric pharyngeal pressure "P" and the less-than-midesophageal pressure "E" and greater-than-atmospheric intragastric pressure "G". There are also interposed high-pres...

## Resting Pressure Profile of the Foregut The resting pressure profile of the foregut shows the pressure differential between atmospheric pharyngeal pressure "P" and the less-than-midesophageal pressure "E" and greater-than-atmospheric intragastric pressure "G". There are also interposed high-pressure zones of the cricopharyngeus "C" and distal esophageal sphincter (DES). ### Swallowing * The entire pharyngeal part of swallowing occurs at 1.5 seconds. * The bolus is propelled by: * Peristaltic contraction of the posterior pharyngeal constrictor. * Being sucked into the thoracic esophagus. * The resting pressure is 30mmHg. * Swallowing can be started at will/reflex (anterior and posterior tonsillar pillars or the posterior lateral walls of the hypopharynx). * This is coordinated by: * Afferent sensory nerves of the pharynx: Glossopharyngeal nerves. * Superior laryngeal branches of the vagus nerves. ### Swallowing Center of the Medulla * The swallowing center of the medulla coordinates the complete act of swallowing. * The nerves involved are CN V, CN VII, X, XI, and XII and C1 to C3. * Primary peristalsis travels 2 to 4cm/second (9 seconds to the distal esophagus). * Secondary peristalsis can occur as an independent local reflex to clear the esophagus of any ingested material left behind after the passage of the primary wave. ### Anti-Reflux Mechanisms * **LES:** Reflux is prevented if the LES is **competent**. * The inability to relax upon swallowing is what traps particles in the esophagus. * **Esophageal clearance:** When the esophagus effectively transports food from the mouth to the stomach. ### Gastric Reservoir The lower 1/3 of the esophagus creates a gastric reservoir.