Functional morphology of mammalian mastication

Abstract

SYNOPSIS. While chewing is not unique to mammals, it is one of their most distinctive characteristics. Historically, studies of food processing in mammals were intended to provide evolutionary insights, but more progress has been made in understanding mechanistic aspects. Mastication is considered under five headings. (1) Interaction of teeth with food.Knowledge of comparative dental anatomy and function is advanced in comparison to understanding of foods and how they are broken down. (2) Chewing force and its resistance by the skull. The traditional assumption that occlusal force is maximized is not always justified, and experimental results suggest that skull loading is far more dynamic and variable than had been envisioned from theoretical analyses. (3) How the jaw moves. The most important masticatory movement is that of the power stroke, and in most but not all species this is influenced more by the inclined planes of the teeth and jaw joints than by the musculature. (4) The role of muscles in producing both force and movement. The most fundamental distinction among jaw muscles is whether they have a rostral or caudal direction of pull, as this determines their role in transverse jaw movements. Reliance on anatomical names tends to obscure functional similarities and differences among species. (5) Intraoral structures. Because they are difficult to study, the actions of the tongue and pharynx are still debated. Even the fundamental question of whether mammals can breathe and swallow at the same time has not been definitively answered. © 1993 by the American Society of Zoologists.