Swallowing (1).ppt

Learning Objectives  Describe the stages of swallowing with its nerve supply  Highlight the clinical implications of swallowing  To pass (food, drink, etc.) through the mouth to the stomach by means of the pharynx and into the esophagus, while shutting the epiglottis.  Also known as...

Learning Objectives  Describe the stages of swallowing with its nerve supply  Highlight the clinical implications of swallowing  To pass (food, drink, etc.) through the mouth to the stomach by means of the pharynx and into the esophagus, while shutting the epiglottis.  Also known as ‘deglutition’. Phases of Swallowing  Swallowing 3 stages:  1.Oral/buccal stage ;voluntary  2. Pharyngeal stage; involuntary  3. Esophageal stage Voluntary/ Oral phase of swallowing: Initiated by contraction of muscles of tongue and floor of mouth, pushes the bolus posteriorly to Pharynx. 2. Pharyngeal Stage  Swallowing receptors(specially around tonsillar pillars) convey impulses to brainstem (pons & medulla oblongata) causing pharyngeal muscle contractions as mentioned:  (Swallowing center inhibits respiration in this phase)  Steps of involuntary Pharyngeal Stage   Upward movement of soft palate  Closure of posterior nares  Medial approximation of Palatopharyngeal folds  Tight approximation of vocal cords  Larynx pulled upward & anteriorly by neck muscles,  Epiglottis covers opening of Larynx  Pharynx contracts and food propelled into oesophagus. Nervous Regulation 3. Esophageal Stage  Starts with relaxation of upper esophageal sphincters.  When food passes, the sphincters close, glottis opens and breathing resumes.  Food traverses the esophagus in about 6-10 sec. Two types of Peristaltic movements in the esophagus: A. Primary Peristalsis (Continuation of pharyngeal peristaltic movement ) B. Secondary Peristalsis (from distention of esophagus by retained food)  Clinical Significance  Gastroesophageal reflux disease can damage the esophagus causing heart burn  Dysphagia means ineffective swallowing. (stroke , head injury, Parkinsonism ) & oesophageal motility disorder Achalasia  The gag reflex initiated by tactile stimulation of soft tissue in the posterior tongue, soft palate, tonsillar regions. Helps prevent choking. HGR (Hypersensitive gag reflex)  SUMMARY by Students…. MCQ Sample Which of the following statement is correct regarding primary peristalsis in esophagus  a. initiated by distension in the esophagus  b. continuation of peristalsis in the pharynx  c. dominated by enteric nervous system  d. myenteric plexus involvement