The adaptive response of jaw muscles to varying functional demands

Abstract

Jaw muscles are versatile entities that are able to adapt their anatomical characteristics, such as size, cross-sectional area, and fibre properties, to altered functional demands. The dynamic nature of muscle fibres allows them to change their phenotype to optimize the required contractile function while minimizing energy use. Changes in these anatomical parameters are associated with changes in neuromuscular activity as the pattern of muscle activation by the central nervous system plays an important role in the modulation of muscle properties. This review summarizes the adaptive response of jaw muscles to various stimuli or perturbations in the orofacial system and addresses general changes in muscles as they adapt, specific adaptive changes in jaw muscles under various physiologic and pathologic conditions, and their adaptive response to non-surgical and surgical therapeutic interventions. Although the jaw muscles are used concertedly in the masticatory system, their adaptive changes are not always uniform and vary with the nature, intensity, and duration of the stimulus. In general, stretch, increases neuromuscular activity, and resistance training result in hypertrophy, elicits increases in mitochondrial content and cross-sectional area of the fibres, and may change the fibre-type composition of the muscle towards a larger percentage of slow-type fibres. In contrast, changes in the opposite direction occur when neuromuscular activity is reduced, the muscle is immobilized in a shortened position, or paralysed. The broad range of stimuli that affect the properties of jaw muscles might help explain the large variability in the anatomical and physiological characteristics found among individuals, muscles, and muscle portions.

Expression of muscle-specific integrins in masseter muscle fibers during malocclusion disease

“…Thus, since masseter muscle is subject to continuous mechanical stress, as a result of continuous control of the position and motion of the mandible and creation of forces at the teeth and temporomandibular joint (53), this muscle is characterized by a particular high turnover, which produces a regeneration process initiating by fibers typical for developing muscle.…”

Cognitive status of edentate elders wearing complete denture: Does quality of denture matter?

“…Scatter plots of functional assessment of dentures total score on mini-mental state examination total score for individuals with satisfactory masticatory ability and with unsatisfactory masticatory ability. could have decreased masticatory capacity because of age-related atrophy of mastication muscles, or other pathways such as reduced ability to chew food, sensory feedback via gingival tissues in the absence of periodontal receptors, and associated reduced force production [40]. Thus functional quality of dentures appeared to be an important factor in helping to preserve bone and muscle tissue.…”

Influence of Myofunctional Therapy on Upper Intercanine Distance

“…Muscle tissue has a great capability to adjust its anatomical, histo-chemical, physiological and biochemical properties to meet altered functional requirements [15]. Adaption processes on the anatomical level take place by muscular changes such as in size, cross-sectional diameter or fibre properties [16]. Typically, resistance training of a skeletal muscle, by means of repeated isometric contraction and relaxation, causes an increase in the thickness of the muscle and enhances muscular strength [17].…”