Mastication

chewing

 or mastication

Up-and-down and side-to-side movements of the lower jaw, using the teeth to grind food for easier swallowing. During chewing, the tongue shapes food into a lump and saliva lubricates it for swallowing. Chewing softens tough meat or vegetable fibres and exposes them to digestive enzymes.

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Mastication 

the mechanical processing of food in the oral cavity; consists of grinding and mixing the food with saliva. The process entails the biting off of food and mashing, crushing, and grinding it between the teeth. In animals, including man, mastication is accomplished by vertical, front-to-back, and lateral movements of the lower jaw in relation to the upper jaw, brought about by the contraction of the masticatory muscles. Movements of the tongue and cheeks, which shift the food around the oral cavity, are of auxiliary significance. Considerable pressure is exerted on the teeth during mastication.

Mastication is a complex coordinated action, regulated by a special nerve center in the medulla oblongata and also by the subcortical and cortical sections of the cerebral hemisphere. Damage to the masticatory apparatus, particularly anodontia or tooth disorders, interferes with the normal processing and assimilation of food and may cause disorders in the digestive tract.