The AMP-activated protein kinase (AMPK) acts as a fuel gauge during exercise and stress-induced energy crisis. The function of the masseter muscle changes during postnatal development, along with an alteration in type of muscle fiber. We investigated expression of AMPK subunit isoforms in masseter muscle by quantitative real-time RT-PCR and Western blotting, and compared it with that in tibiali...

Masseter muscle hypertrophy also called as Benign Massetric hypertrophy (BMH) or Idiopathic Massetric Muscle Hypertrophy (IMMH) is a rare condition of unknown cause which is important in the differential diagnosis of head and neck masses, located in the cheek. It can occur unilaterally or bilaterally. Most patients consult a physician for esthetic correction of the resultant facial asymmetry. S...

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...

The jaw muscle activity of rats has been investigated for specific tasks. However, the daily jaw muscle use remains unclear. The purpose of the present study was to examine daily jaw muscle activity, and its variability over time, in the rat (n = 12) by the use of radio-telemetry. A telemetric device was implanted for the continuous recording of masseter muscle and digastric muscle activity. Da...

Masseter muscle hypertrophy is a rare condition characterized by unilateral or bilateral enlargement of the masseter muscle affecting both males and females following puberty. It usually manifests in late adolescence or early adulthood. Its etiology remains unknown. Masseter muscle hypertrophy produces facial asymmetry and familiarity with this condition is important to rule out other pathologi...

We have previously reported that the level of 5-HT in the masseter muscle is increased in patients with fibromyalgia as compared with healthy subjects and that high intramuscular level of 5-HT is associated with muscle pain. We have also reported that injection of the 5-HT(3) receptor antagonist granisetron (GRA) into the masseter muscle of healthy subjects reduced pain induced by 5-HT and abol...

[Purpose] This study verified the changes in muscle activities and grasping power during maximal isometric exercise of the forearm and masseter muscle with and without a mandibular orthopedic repositioning appliance (MORA). It also offers basic data for defining the correlation of function of hand with mouth. [Methods] EMG was used to measure masticatory muscle, flexor bundle and extensor bundl...

Although the effects of sustained jaw-closing activities on somatosensory sensitivity and fatigue have been investigated, jaw-opening in masticatory muscles remain unclear. Therefore, this study aimed to investigate jaw opening（e.g. during dental treatment）on fatigue, pressure pain sensations, stiffness muscles. A total 35 healthy volunteers performed 30 minutes each two motor tasks, with a 1-w...

Previous results have shown that the adult human masseter muscle contains myosin isoforms that are specific to early stages of development in trunk and limb muscles, i.e. embryonic and fetal (neonatal) myosin heavy chains (MHC) and embryonic myosin light chain (MLC1emb). We wanted to know if this specific pattern is the result of a late maturation or of a distinct evolution during development. ...