Development of the movement of the epiglottis in infant and juvenile pigs

Abstract

Although backward folding of the epiglottis is one of the signal events of the mammalian adult swallow, the epiglottis does not fold during the infant swallow. How this functional change occurs is unknown, but we hypothesize that a change in swallow mechanism occurs with maturation, prior to weaning. Using videofluoroscopy, we found three characteristic patterns of swallowing movement at different ages in the pig: an infant swallow, a transitional swallow and a post-weaning (juvenile or adult) swallow. In animals of all ages, the dorsal region of the epiglottis and larynx was held in an intranarial position by a muscular sphincter formed by the palatopharyngeal arch. In the infant swallow, increasing pressure in the oropharynx forced a liquid bolus through the piriform recesses on either side of a relatively stationary epiglottis into the esophagus. As the infant matured, the palatopharyngeal arch and the soft palate elevated at the beginning of the swallow, so exposing a larger area of the epiglottis to bolus pressure. In transitional swallows, the epiglottis was tilted backward relatively slowly by a combination of bolus pressure and squeezing of the epiglottis by closure of the palatopharyngeal sphincter. The bolus, however, traveled alongside but never over the tip of the epiglottis. In the juvenile swallow, the bolus always passed over the tip of the epiglottis. The tilting of the epiglottis resulted from several factors, including the action of the palatopharyngeal sphincter, higher bolus pressure exerted on the epiglottis and the allometry of increased size. In both transitional and juvenile swallows, the subsequent relaxation of the palatopharyngeal sphincter released the epiglottis, which sprang back to its original intranarial position.

Premature infant swallowing: Patterns of tongue-soft palate coordination based upon videofluoroscopy

“…What do these three functional changes achieve? One possibility is that stabilization of a synergic spatial arrangement among these specific parts of the oral anatomy transforms the mouth for a specialized function, namely, sensory-regulated pumping (Crompton et al, 2008). A positive displacement, or fluid-static, pump accumulates liquid within a confined space, reduces the volume of that space, and then forces the liquid to leave by a specific outlet (Vogel, 2003).…”

“…Muscular timing may also capture potential energy for the work of swallowing as the tongue changes its shape, so that the dorsum is in an anti-phase location with respect to soft palate elevation. The palato-pharyngeal arch is, upon dissection, surprisingly large, and has structural properties amenable for storing elastic potential energy, as it holds together the laryngeal cartilages (Crompton et al, 2008). With each lowering, the palato-pharyngeus muscle shortens and, during elevation, may release this energy to support the pharyngeal swallow.…”

Animal Models for Dysphagia Studies: What Have We Learnt So Far

“…For age-based studies, either of the very old [29, 42] or the very young [7, 9, 15], animal models answer both ethical and logistic challenges. The old and the young tend to be frailer than young or mid-aged adults.…”

Variation in the Timing and Frequency of Sucking and Swallowing over an Entire Feeding Session in the Infant Pig Sus scrofa

“…The biomechanics and muscle activity patterns, as well as basic information on the neural control of infant feeding, are well documented [6, 15, 29–31]. Several authors have described various problems with infant feeding [1, 7, 26, 27, 33].…”