I think, again, history is key. The way to understand it is to understand what normally happens. Normally oropharyngeal swallowing involves four phases. First is initiation. This involves chewing the material, you have to have intact teeth.
Teeth are a big problem.
If you have a patient with poorly fitting or no dentures, it s no wonder they have dysphagia. I send a lot of patients off for dental-type consults whenever I can t find another problem. The second thing that happens is the nasopharynx is sealed. This rarely goes astray but it has to be done to get the bolus to go the right way. The airway by the epiglottis flipping over is protected, which channels the food down in the correct direction, the bolus.