As outlined previously the first functional unit of swallowing consists of the muscular pump of the mouth and pharynx, the upper esophageal sphincter and the the esophageal resevoir.
Disorders in this unit typically cause crico-pharyngeal dysphagia. This may be due to lack of saliva (eg. Sicca syndrome), weak muscles (eg polymyositis, polymyalgia rheumatica, dermatomyositis), and lack of coordination in swallowing due to problems in the swallowing center (eg. stroke, multiple sclerosis).
Patients with this type of dysphagia may have an underlying neurological condition such as stroke, Parkinson's disease, bulbar palsy or pseudo-bulbar palsy. Some develop a pulsion type diverticulum through the muscles of the pharynx at the top of the upper esophageal sphincter. They often complain of aspiration, or present with repeated respiratory tract infections. If they devlop a pouch, they may experience regurgitation of food that has been eaten many hours previously back from the pouch into their mouth or lungs.
After passage of the bolus into the esophagus, there is a reflex muscular contraction (peristalsis) that aids the bolus in passing down the esophagus this is the pump of the second functional component.