1997 Volume 1 Issue 1 Pages 33-44
Swallowing movements and pharyngeal anatomy of a nine-month old female infant and a male adult were compared by using a hypersensitive X-ray TV system．Each subject had no oral or pharyngeal function disorders．According to anatomical measurement of both subjects，the diameters of the infant's oro- and esopharynx were nearly the same as those of the adult．The infant's hyoid bone was located anterior，and nearer to the mandibular than that of the adult．ln the infant，the tip of the soft palate， oropharyngeal border，and the apex of the epiglottis were located at a similar distance from the pharyngoesophageal segment， suggesting that the infant's oropharynx would be very short．By comparing swallowing movements between the infant and the adult after the swallowing reflexes were elicited，the following sequences appeared in the same order for each subject： closing of the nasopharynx，transport of bolus (milk or Barium solution) from the oral cavity to the pharynx by the tongue blade， and closing of the larynx with the epiglottis．Then bolus was transported to the esophagus by pharyngeal contraction．Each subject's nasopharynx closed right after swallowing reflexes were elicited．lt was reconfirmed that not only the adult but the infant as well stopped respiration during swallowing．However，the way the nasopharynx was closed differed between the subjects．The adult sealed the nasopharynx by lifting the soft palate，but the infant did so by retraction．Aspects of release at this site after swallowing were analogous in the infant and adult，with the soft palate and pharyngeal wall separating．A distinct difference between infant and adult swallowing would be the timing when reflexes were elicited．Although in the adult transport of bolus from the mouth to the oropharynx and the reflex took place at almost the same time，in the infant the bolus entered the pharynx almost 1 second before a reflex was induced，and passed over epiglottis and thorough the sinus piriform before finally reaching the pharyngoesophageal segment．There were only slight movements of the soft palate，pharynx，tongue blade，and epiglottis before the reflex．In this paper relevant functional and anatomical differences between the infant's and adult's swallowing were discussed．
