Characteristics of rhythmic jaw movements of the rabbit.

The jaw-movement pattern of the rabbit during chewing foods of different consistency was analysed. The basic movement trajectory on the frontal plane showed a crescent loop, irrespective of the food type. Difference in food consistency exerted only minor effects on the maximum gape, extent of lateral excursion and the chewing rate. These parameters of jaw movement and also the duration of a single masticatory cycle (TCL) appeared to change with physical properties other than the hardness of food. On the other hand, the number of chewing cycles in a masticatory sequence increased with increasing the hardness of food. The TCL ranged between 250 and 300 ms (frequency: 3.3-4 Hz). When a single masticatory cycle was divided into three phases (opening, closing and power phases), the TCL depended more on the duration of the opening phase than that of other two phases.