Endoscopic observations on the deglutition reflex in the horse.

This study utilized a filmmaking endoscopy to investigate how the swallowing mechanism works in healthy horses. Emphasis is placed on understanding the role of the nasopharyngeal sphincter’s closing process involving a lowering of the pharyngeal roof and a lifting of the soft palate.

About the Study

In this study, cine-endoscopy, a technique which enables specialists to view the internal areas of the body by using a flexible tube with a light and camera at one end, was employed to investigate the swallowing or deglutition reflex in two horses that appeared to have normal health. This research focuses especially on the closing of the nasopharyngeal sphincter, a muscular ring in the nasopharynx.

• The process of closing this muscle involves the simultaneous lowering of the pharyngeal roof and the elevation of the soft palate located behind the openings of the auditory tubes, referred as “pharyngeal ostia”.
• The research discovered that the medial cartilages of these ostia were not directly involved in the process of closing the sphincter.

Understanding Deglutition

Deglutition, or the process of swallowing, relies heavily on the coordination of many different muscles in the oral cavity and the throat.

• In this study, it is hypothesized that the opening of ostia of the auditory tubes during swallowing happens due to the collective action of three specific muscles—palatopharyngeus, pterygopharyngeus, and tensor veli palatini.
• To understand it in simpler terms: the study proposes that these muscles team up to assist in the function of deglutition by regulating the opening and closing of the orifices, which act as a connection between the nasopharynx and the middle ear.

Implications of the Research

The function of swallowing is vital for normal feeding and digestive processes in all animals including horses.

• Getting insights into the precise movement and mechanics of this process—how the soft palate lifts, how the roof of the throat descends, along with the precise functioning and role of different muscles—can help in understanding difficulties horses may experience while swallowing.
• It can also assist in correctly diagnosing any deglutination related health issues in horses and possibly lead to superior preventive measures and interventions.