Mechanism of Swallowing, Animation in Baby model

swallowing or deglutition is the process
by which food passes from the mouth through the pharynx and into the
esophagus as simple as it might seem to healthy people swallowing is actually a
very complex action that requires an extremely precise coordination with
breathing since both of these processes share the same entrance the pharynx
failure to coordinate would result in choking or pulmonary aspiration
swallowing involves over 20 muscles of the mouth throat and esophagus which are
controlled by several cortical areas and by the swallowing centers in the
brainstem the brain communicates with the muscles through several cranial
nerves swallowing consists of three phases oral or buccal phase this is the
voluntary part of swallowing the food is moistened with saliva and chewed a food
bolus is formed and the tongue pushes it to the back of the throat the pharynx
this process is under neural control of several areas of cerebral cortex
including the motor cortex pharyngeal phase starts with the stimulation of
tactile receptors in the oral pharynx by the food bolus the swallow reflex is
initiated and is under involuntary neuromuscular control the following
actions are taken to ensure the passage of food or drink into the esophagus the
tongue blocks the oral cavity to prevent food from going back to the mouth the
soft palate blocks entry to the nasal cavity the vocal folds closed to protect
the airway to the lungs the larynx is pulled up with the epiglottis flipping
over covering the entry to the trachea this is the most important step since
entry of food or drink into the lungs may potentially be life-threatening the
upper esophageal sphincter opens to allow passage to the esophagus
esophageal phase the food bolus is propelled down the esophagus by
peristalsis a wave of muscular contraction that pushes the bolus ahead
of it the larynx moves down back to the original position

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