Mastication

Mastication, or chewing, is the rhythmic mechanical reduction of food in the mouth. Coordinated movements of the jaw, tongue, cheeks, and teeth break food into smaller particles and mix it with saliva, forming a cohesive bolus that is safe and easy to swallow. It is a sensory-motor process: continuous feedback from the teeth, periodontal ligament, oral mucosa, and muscles shapes the force, rhythm, and number of chewing cycles.

Definition

Mastication is the process by which food taken into the mouth is mechanically broken down by the teeth through rhythmic jaw movements and mixed with saliva until it forms a bolus suitable for swallowing.

Scope

This topic covers the mechanics and neural control of chewing in normal physiology: the masticatory cycle, the muscles and movements involved, how food is reduced and a bolus is formed, and the sensory feedback and central pattern generator that regulate the process. It does not address the management of chewing disorders.

Core questions

• How is the masticatory cycle organized and rhythmically generated?
• Which muscles and movements reduce food and reposition it between the teeth?
• How do sensory receptors adapt chewing force and duration to food properties?
• How does chewing combine particle breakdown with salivary mixing to form a swallowable bolus?

Key concepts

• Masticatory cycle (opening, closing, occlusal phases)
• Central pattern generator for chewing
• Muscles of mastication and jaw movement
• Periodontal and muscle mechanoreceptors
• Food comminution and particle size reduction
• Bolus formation and the swallowing threshold
• Bite force and chewing efficiency

Mechanisms

Chewing is produced by rhythmic activation of the jaw-closing muscles (masseter, temporalis, medial pterygoid) and jaw-opening and positioning muscles, organized into repeating cycles of opening, closing, and an occlusal phase in which food is crushed between the teeth. A brainstem central pattern generator establishes the basic rhythm, which is continuously modulated by sensory input from periodontal mechanoreceptors, muscle spindles, and oral mucosal receptors so that force and cycle number adapt to the hardness and size of the food. The tongue and cheeks reposition particles onto the occlusal surfaces between cycles, while saliva moistens and binds the fragments. Chewing continues until particles are sufficiently reduced and cohesive, at which point the bolus reaches a threshold that triggers swallowing.

Clinical relevance

Chewing efficiency depends on factors such as the number and condition of teeth, bite force, and salivary flow, and reduced masticatory function can affect food choice and the bolus that is presented for swallowing. This entry describes normal masticatory physiology and how it is assessed; it is reference material and not advice for evaluating or treating any individual.

Evidence & guidelines

The mechanistic understanding summarized here is drawn from physiology and oral rehabilitation reviews integrating electromyography, jaw-tracking, bite-force measurement, and chewing-performance testing; these methods quantify masticatory rhythm, force, and particle-size reduction.

Seminal works

• vanderbilt-2011
• vanderbilt-2006
• woda-2006

Frequently asked questions

What determines when chewing stops and swallowing begins?

Chewing continues until the food particles are reduced and lubricated into a cohesive bolus; sensory feedback signals that this swallowing threshold has been reached, triggering the swallow.

What controls the rhythm of chewing?

A central pattern generator in the brainstem sets the basic rhythm, which is continuously adjusted by sensory feedback from the teeth, muscles, and oral tissues according to the food being chewed.