Mastication and Deglutition

Mastication is a term used to describe the processes involved in food preparation, which include progressing unchewed food onto the teeth's grinding surface, chewing it, and combining it with saliva in preparation for swallowing. Mastication is also used to describe the processes involved in food digestion.

Meanwhile, the act of swallowing is referred to as deglutition. Lingual, velar, pharyngeal, and facial muscle action must be coordinated with laryngeal adjustments and respiratory control in order for these two biological processes to be completed successfully.

All muscles entering into the orbicularis oris may be activated throughout the mature mastication and deglutition processes to open, shut, purse, and withdraw the lips when food is received. All intrinsic and extrinsic tongue muscles will be activated to position the food for chewing and to prepare the bolus (liquid or bulk/mass of food) for swallowing.

To prevent regurgitation, the velar elevators must close the nasal cavity, and the pharyngeal constrictors must contract in a very predictable manner to drive the bolus down the pharynx and into the esophagus. With the addition of laryngeal elevation, we have now activated more than 55 pairs of muscles whose timing and innervation patterns must be coordinated via correct cranial and spinal nerve activation.

Normal Adult Swallow Physiology

o The normal adult swallowing process includes four phases:

▪ Oral Preparatory Phase (mastication)

• Primary phase

• Food put initially on mouth breaks down with chewing; forms into a bolus

▪ Oral Transit Phase (propulsion of bolus)

• Food particle separates to several pieces

▪ Pharyngeal Phase (pharyngeal swallow)

• Bolus moves or is transmitted from oral cavity to the esophagus pharyngeal cavity

▪ Esophageal Phase (esophageal transit)

• Last phase