Both dissection and ultrasound demonstrate that the structure of the masseter muscle is very complex, composed of three distinct parts and organized in layers (1): the superficial masseter is formed by two layers (internal and external), the middle masseter has only one layer and the deep masseter has three separate layers (outward, central and inward). When speaking of the function of the musc...

PURPOSE To characterize the electrical activity of the masseter muscle during swallowing of liquids in healthy young adults. METHODS Participants were 14 volunteers considered healthy according to the inclusion and exclusion criteria established for this study. The bilateral electromyographic evaluation of the masseter muscle was conducted at rest and in swallowing tasks of 14.5 ml, 20 ml and...

This study examined the effects of the textural properties and chemical components of foods on masseter activity patterns. Ten healthy young participants (seven men and three women) were asked to chew four gummy candies with different flavors while their masseter activities were recorded by a surface electromyogram. The masseter activity patterns during chewing were analyzed quantitatively usin...

The synthesis rates of different myosin isoenzymes in a single muscle, and of the same isoenzymes in different muscles (soleus, masseter and plantaris), were measured. The rate of total protein synthesis was significantly higher in the soleus [greater than 95% slow myosin (SM)] than in the plantaris [greater than 95% fast myosin (FM)]. Two fast isoenzymes, FM2 and FM3, were synthesized at diffe...

In a previous experiment, we found that masseter muscle spindles show functional plasticity after 5 to 15 days under increased occlusal vertical dimension (iOVD). In the present study, we hypothesized that spindle function would eventually recover if longer observation periods were allowed. Therefore, in this study we investigated changes in masseter muscle spindle function over periods of 1 da...

introduction: bilateral sagittal split osteotomy (bsso) of mandible is vastly used in treatment of mandibular deficiencies and discrepancies. since this method could affect esthetic as well as function, evaluating these effects from various aspects is crucial. this study assessed the effects of this technique on the function of masseter muscle, jaw movements, and sensory changes along with fail...

Background The mechanisms underlying tooth pulp hypersensitivity associated with masseter muscle hyperalgesia remain largely underinvestigated. In the present study, we aimed to determine whether masseter muscle contraction induced by daily electrical stimulation influences the mechanical head-withdrawal threshold and genioglossus electromyography activity caused by the application of capsaicin...

Introduction: Bilateral sagittal split osteotomy (BSSO) of mandible is vastly used in treatment of mandibular deficiencies and discrepancies. Since this method could affect esthetic as well as function, evaluating these effects from various aspects is crucial. This study assessed the effects of this technique on the function of masseter muscle, jaw movements, and sensory changes along with fail...

The masseter muscle is involved in the complex and coordinated oromotor behaviors such as mastication during wakefulness. The masseter electromyographic (EMG) activity decreases but does not disappear completely during sleep: the EMG activity is generally of low level and inhomogeneous for the duration, amplitude and intervals. The decreased excitability of the masseter motoneurons can be deter...

Histochemical properties, muscle fiber cross-sectional area, muscle fiber length, and the oxidative capacity of masticatory muscles of female rhesus monkeys were assessed following alteration in functional length by an intraoral appliance or by detachment of the muscle. Experimental groups received the appliance only (A); the appliance and subsequent detachment of the masseter (AD); the applian...