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عدد المساهمات : 9680 تاريخ التسجيل : 06/08/2009
| موضوع: stages of swallowing الأحد نوفمبر 28, 2010 7:17 pm | |
| Stages of Swallowing I-Oral Stage: · The oral stage is voluntary and requires control of oral structures, including the anterior position of the soft palate. · Following mastication, the food is pulled together into a cohesive mass. · Next, in a second or less, the tongue propels the bolus posteriorly. · The oral stage ends once the material passes the anterior faucial arches at the back of the throat. · This posterior tongue movement and the material passing along the anterior faucial arches help activate the involuntary or reflexive swallow that constitutes the pharyngeal stage. · The reflex is believed to originate in the fauces, soft palate, base of the tongue, and posterior pharyngeal wall. · Innervation is primarily from the vagus in the brain stem, but involves cranial nerves IX through XI. II-Pharyngeal Stage · This is a reflexive stage that begins with the raising of the hyoid and larynx, and closing of the thyroarytenoid and ventricular cords to create a velopharyngeal seal. · Next, the epiglottis tilts and the cricopharyngeus muscle, or superior esophageal sphincter, is relaxed, opening the esophagus. · With the help of accessory muscles, a peristaltic wave moves the bolus through the hypopharynx and into the esophagus in approximately one second.. III-Esophageal Stage: · This phase begins as the superior esophageal sphincter opens and, propelled by the peristaltic wave contractions that were started in the pharyngeal phase, the bolus passes through the esophagus and inferior esophageal sphincter into the stomach. · This stage takes from 8 to 20 seconds. | |
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admin Admin
عدد المساهمات : 9680 تاريخ التسجيل : 06/08/2009
| موضوع: رد: stages of swallowing الأحد نوفمبر 28, 2010 7:18 pm | |
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