Swallowing is a complex neuromuscular process involving the mouth, pharynx and oesophagus. Efficient swallowing ensures the safe passage of food and drink from the mouth to the stomach. This process also protects the airways by preventing material from entering the lungs. Dysphagia or swallowing difficulty can be described as anything that interrupts this process and interferes with the safe passage of food or drink.

The swallowing process is effectively divided into three distinct phases; the oral, pharyngeal and oesophageal phase.

The oral phase: involves the preparation of food for swallowing. The food is broken down by chewing and moistened by saliva to produce material of an appropriate consistency for ingestion; this material is then shaped into a bolus and propelled backwards by the tongue towards the pharynx.

The pharyngeal phase: is initiated by the backward movement of the tongue and the detection of the food bolus within the pharynx. The upward movement of the soft palate prevents the bolus from entering the nasal passage, whilst closure of the larynx by the vocal cords and the epiglottis prevents the bolus from entering the respiratory tract, and diverts the bolus towards the oesophagus. The upward movement of the larynx also enables the oesophageal sphincter to open whilst at the same time the pharyngeal muscles push the bolus into the oesophagus.

The oesophageal phase: this describes the peristaltic muscle contractions that propel the bolus through the oesophagus into the stomach.