[Dimensions of the pharynx in function of the posture, in neonates and infants]. 
The authors measured the pharyngeal patency of 25 wakeful newborns and infants on X-ray films of the lateral upper airway.  The upper airway patency depends on the head position.  The velopharyngeal and the posterior tongue space are smaller in supine position than in ventral position.  In supine position the airway space behind the base of the tongue is significantly greater when the head is extended than when the head is in neutral position (p less than 0.007).