© 1988 by The Society for Integrative and Comparative Biology
Morphological and Functional Questions on the Growth and Plasticity of Mammalian and Avian Jaw Muscles1
Department of Biological Science, Florida State University Tallahassee, Florida 32306
SYNOPSIS: Growth studies of mammalian jaw muscles and studies determining the degree of plasticity of these muscles are few. There are questions concerning the degrees and types of morphological and physiological change occurring in these muscles during normal growth and the ability of external forces to modify this growth process. There are also questions on the effects of sensory loss on muscle growth and on changes in the motor system as these muscles change. In this report, questions are proposed and hypotheses presented that deal with these areas relative to the jaw muscles. It is suggested that (1) changes in the morphology and function of jaw muscles during growth vary regionally and are related to the action of the muscle and the loading forces imposed; (2) the degree of muscle plasticity varies regionally and varies depending on the type of loading forces and age of the animal; (3) loss of sensory input during the growth of the jaw muscles would produce marked changes in the histochemical profile, the distribution of motor neurons, and the activity pattern of these muscles; and (4) organization of the trigeminal motor nucleus changes as the jaw muscles grow and may also change in response to sensory loss or application of different types of loading forces. In addition, possible approaches to these questions are discussed.