Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Masticatory Muscles”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
PubMed1975

[Uptake and transport of exogenous peroxidase in the masticatory muscles of the cat. Localization of motor neurons].

In the present work, a topographical localization of masticatory muscle motoneurons was undertaken. Horseradish peroxydase injected in each muscle can be transported in the retrograde direction to the corresponding motoneurons cell bodies. Jaw-closing muscle motoneurons were identified in the dorsal part of the motor trigeminal nucleus whereas jaw-opening muscle motoneurons were observed in the ventro-medial region.

Animals↗
PubMed2000

Lamination of the masticatory muscles in the kangaroo according to their innervation.

An analysis of the laminations of the masseteric, zygomaticomandibular and temporalis muscles of the Red Kangaroo (Macropus Rufus) and all of the masticatory muscles of the Eastern Gray Kangaroo (Macropus Giganteus) was carried out based on their innervation. The masseteric muscle was divided into superficial and deep layers; the superficial layer was further subdivided into three laminae from the rostro-lateral portion to caudo-internal portion. The deep layer was divided into lateral, caudo-internal and rostro-internal laminae. The zygomaticomandibular muscle which was located between the masseteric and temporal muscles was divided into lateral, internal and rostral laminae, on the basis of its innervation. The lateral and internal laminae were innervated by the nerve which arises between the masseteric nerve and the posterior deep temporal nerve. A small rostral portion of the muscle was innervated by masseteric nerves, which passed through the internal lamina of the deep layer of the masseteric muscle. The temporalis muscle was innervated by an anterior deep temporal nerve and posterior deep temporal nerve. Only the most rostro-internal lamina of the temporalis muscle was innervated by the anterior deep temporal nerve. The anterior deep temporal nerve and lateral pterygoid nerve had a common trunk. We believe that the rostro-internal lamina was closely related to the lateral pterygoid muscle. The lateral pterygoid muscle displayed one lamina, whereas the medial pterygoid muscle was divided into internal and lateral laminae. The lateral lamina was further divided into rostro-internal and caudo-lateral laminae.

Animals↗
PubMed1981

Representation of the masticatory muscles in the motor trigeminal nucleus of the macaque monkey.

The pattern of representation of the masticatory muscles in the motor trigeminal nucleus was examined in macaque monkeys by the horseradish peroxidase method. The motor trigeminal nucleus was divided cytoarchitectonically into the dorsolateral and ventromedial divisions. The temporalis, masseter and pterygoid muscles were represented in the dorsomedial, central and ventrolateral parts of the dorsolateral division, respectively. In the ventromedial division, which was located at the level of the caudal half of the nucleus. The anterior digastric or mylohyoid muscle was represented in the dorsomedial or ventrolateral part of the division, respectively.

Animals↗
PubMed2003

Human masticatory muscle forces during static biting.

Muscle forces determine joint loads, but the objectives governing the mix of muscle forces involved are unknown. This study tested the hypothesis that masticatory muscle forces exerted during static biting are consistent with objectives of minimization of joint loads (MJL) or muscle effort (MME). To do this, we compared numerical model predictions with data measured from six subjects. Biting tasks which produced moments on molar and incisor teeth were modeled based on MJL or MME. The slope of predicted vs. electromyographic (EMG) data for an individual was compared with a perfect match slope of 1.00. Predictions based on MME matched best with EMG activity for molar biting (slopes, 0.89-1.16). Predictions from either or both models matched EMG results for incisor biting (best-match slopes, 0.95-1.07). Muscle forces during isometric biting appear to be consistent with objectives of MJL or MME, depending on the individual, biting location, and moment.

Adult↗
PubMed2001

Migraine and masticatory muscle volume, bite force, and craniofacial morphology.

The purpose of this investigation was to compare the masticatory muscle volume, bite force, and craniofacial morphology of migrainous subjects with age- and sex-matched controls. Ten adult dentate migraineurs were matched with 10 dentate age- and sex-matched controls. The groups consisted of nine women and one man (mean age, 43 years; range, 29 to 51 years). Volumetric analysis of the masseter and medial pterygoid muscles was performed using magnetic resonance imaging. Craniofacial morphology was analyzed from standard cephalometric radiographs using 30 angular and linear variables. Recordings of bite force were made using a strain gauge transducer. There was a significant difference in the volume of both masseter and medial pterygoid muscles between the two subject groups (P<.0001), with the muscles of the migraineurs nearly 70% larger. The migraineurs recorded significantly higher maximal bite forces (P<.0001) than did the controls. No significant differences for any craniofacial morphological measurement were demonstrated between the two groups. It was concluded that the migraineurs had larger masseter and medial pterygoid muscle volumes, and greater bite forces than the controls, which could not be explained by any change in craniofacial morphology.

Adult↗
PubMed1994

Assessment of motor pathways to masticatory muscles: an examination technique using electrical and magnetic stimulation.

To study motor pathways to masticatory muscles, a new recording technique using surface electrodes was developed. The recording electrode was mounted on a spatula and inserted enorally into the pterygomandibular plica over the belly of m. masseter. Using this technique, mean latencies/amplitudes of the compound action potentials (CMAPs) in 18 healthy subjects were 1.2 ms/4.9 mV after electrical stimulation of the trigeminal nerve below the zygomatic arch, and 5.5 ms/1.1 mV after magnetic stimulation of the cortex. In 15 patients with unilateral lesions of the facial nerve, masticatory CMAPs had virtually symmetrical configuration, latency, and amplitude, excluding a major contribution of volume conducted activity from other cranial muscles. The technique was evaluated in patients after surgical treatment for trigeminal neuralgia. Patients with retrogasserian thermocoagulation and central demyelinating lesions were consistently identified.

Action Potentials↗
PubMed1985

A qualitative investigation of the topographical representation of masticatory muscles within the motor trigeminal nucleus of the rat: a horseradish peroxidase study.

The topographical representation of the masticatory muscles of the rat was investigated by studying retrograde transport of horseradish peroxidase (HRP) from individual muscles. Contrary to the classically accepted scheme, the temporalis and masseter are separately represented dorsolaterally, the pterygoids dorsomedially and the jaw-opening mylohyoid and anterior belly of digastric ventrally within the motor nucleus, corresponding to the arrangement of the muscles on the head. Phylogenetic and ontogenetic justifications for this organization are adduced.

Animals↗
PubMed1998

Balancing function of the masticatory muscles during incisal biting in two murid rodents, Apodemus speciosus and Clethrionomys rufocanus.

The functional significance of masticatory muscle direction was estimated using a mechanical model in two murid rodents: the Japanese field mouse (Apodemus speciosus) and the gray red-backed vole (Clethrionomys rufocanus). Theoretical analyses of the data suggest that a balancing mechanism among the muscle forces occurs during incisal power stroke. The activation of the large deep masseter in both murids results in marked tensile separation of two hemimandibles at the flexible mandibular symphysis. Activation of the internal pterygoid decreases this large tensile force at the symphysis more efficiently than other muscles. The lines of action of the deep masseter and internal pterygoid are aligned to produce such a balancing function in both species studied here. The resultant force generated by the deep masseter on both sides is opposite in direction to the reaction force at the lower incisor tip. Therefore, the large deep masseter forms an effective mandibular support mechanism when the reaction forces during biting push the mandible downward. Because of the area of insertion and the line of action, the posterior temporalis appears to have an important role in stabilizing the position of the mandibular condyle in the glenoid fossa during incisal biting.

Animals↗
PubMedDate not supplied

[The determination of the intensity of premolar and molar maximal forces during the isometric contraction of the masticatory muscles due to forced mandibular closure].

The purpose of this study to quantify the activity of the masticatory muscles. For this we recorded the maximum bite force of opposing teeth during voluntary clenching. The study was carried out on 31 students aged 21 to 28 with a satisfactory dental arch. The measurements were obtained on one side only. Nine thickness of the traducers were used for the premolar zone and two for the molar zone. We determined an optimal thickness enabling the highest measurement: 6.5 mm for the premolars and 5.2 for the molars. The highest measurements were averaged and the following results were obtained: premolars-35 kgf for females and 50 kgf for males; molars 100 kgf for females and 130 kgf for males.

Adult↗
PubMed2003

Sex differences in masticatory muscle pain after chewing.

Neither the etiology of muscle-related temporomandibular disorders (TMD) nor the reason for the disproportionate number of women suffering from these disorders is well-established. We tested the hypothesis that physiologically relevant exercise (i.e., chewing bubble gum for 6 min) increases masticatory muscle pain in patients, but not in asymptomatic control subjects, and that female patients experience a significantly greater increase than males. Chewing increased pain in both female and male patients and, unexpectedly, also in female control subjects. One hour after chewing, the pain remained above pre-test levels for female patients but not for the other groups. Thus, sex differences in chewing-induced pain were found in control subjects but not as hypothesized in patients. Because chewing-induced masticatory muscle pain was significantly greater in female control subjects than in males, and persisted longer in female patients than in males, these results suggest greater susceptibility in women.

Adult↗
PubMed1976

[The masticatory muscle synchronizer. Guided functional therapy of myoarthropathies of the tempors-mandibular joint].

In the myoarthropathies of the masticatory organ, psychic factors, often coupled with occlusal disturbances, have a trigger function. If the psychic factors prevail, the disturbances of the occlusion as etiologic factors diminish or are totally absent. In such patients, we often find fronto-lateral bruxism without any premature contacts in evidence. A guided functional therapy is introduced. With the so-called synchronator for masticatory muscles, a backfeed programming of the dysfunctional mandibular motion pattern is provoked into the normal neuromuscular harmony. This is done by obtaining centric relation and by blocking the fronto-lateral parafunctional pattern by rebuilding measures.

Bruxism↗
PubMed2006

Masticatory muscle pain and disordered jaw motor behaviour: Literature review over the past decade.

The clinically important relationship between masticatory muscle pain (MMP) and disordered jaw motor behaviour is subject of this concise, evidence-based review of the literature that was published during the past 10 years. Mainly based on studies that used some sort of experimental MMP (e.g., the intramuscular injection of noxious substances like hypertonic saline), it was concluded that MMP has pronounced effects on jaw motor functions like maximal clenching and mastication. The pain-related modulation of oral reflexes further illustrated the effects of MMP on masticatory motor control. Protecting the painful muscle tissues against further damage and allowing for time to heal the damaged tissues by immobilization of the masticatory system seem to be the key outcomes of these effects. Further, MMP was shown to influence the cervical motor system, which may partly explain the mechanism behind the frequently observed co-occurrence of pain in the neck and the jaw. Finally, it was concluded that, even though the evidence is not yet conclusive, also remote pain (non-MMP) can modulate jaw motor behaviour, which indicates the involvement of central mechanisms in this modulation.

Facial Pain↗
PubMed2002

[Detachment and retraction of masticatory muscles from the jaw possibly transfers the residual tumor cells and causes extopic recurrence of ameloblastoma].

OBJECTIVE: To The purpose of this article was to report a series of patients with ectopic recurrence of ameloblastoma and reveal the possible mechanism of ectopic recurrence. METHODS: To retrospectively review the medical records of ameloblastoma in twenty years of two hospitals and choose ectopic recurrent cases and analyse the possible factors related to ectopic recurrence of ameloblastoma. RESULTS: 31 cases of recurrent ameloblastoma in twenty years medical records of two hospitals were found, 6 of which were ectopic recurrent cases and all the primary sites were located in the mandible. Patients with ectopic recurrent ameloblastoma exclusively underwent conservative initial surgical procedures (curettage and enucleation) and all the primary tumors involved the insertions of the masticatory muscles. The recurrent sites included temporal region. parotid gland, floor of mouth, ventral tongue and intracranial site. A specific muscle was related both to the primary sites and the recurrent regions. CONCLUSION: The detachment and retraction of the masticatory muscles from the insertion of the jaw, which may transfer residual tumor cells from the insertion (the primary) to the initial point of the muscles, is the possible mechanism of ectopic recurrence of ameloblastoma.

English Abstract↗
PubMed2004

Neuromuscular coordination of masticatory muscles in subjects with two types of implant-supported prostheses.

OBJECTIVES: To compare the electromyographic (EMG) characteristics of masticatory muscles in patients with fixed implant-supported prostheses and implant overdentures. MATERIAL AND METHODS: Nineteen subjects aged 45-79 years were examined. Fourteen were edentulous and had been successfully rehabilitated with (a) maxillary and mandibular implant-supported fixed prostheses (seven patients); (b) mandibular implant overdentures and maxillary complete dentures (seven patients). Five control subjects had natural dentition or single/partial (no more than two teeth) tooth or implant fixed dentures. Surface EMG of the masseter and temporal muscles was performed during unilateral gum chewing and during maximum teeth clenching. To reduce biological and instrumental noise, all values were standardized as percentage of a maximum clenching on cotton rolls. RESULTS: During clenching, temporal muscle symmetry was larger in control subjects and fixed implant-supported prosthesis patients than in overdenture patients (analysis of variance, P=0.005). No differences were found in masseter muscle symmetry or in muscular torque. Muscle activities (integrated areas of the EMG potentials over time) were significantly larger in control subjects than in implant-supported prosthesis patients (P=0.014). In both patient groups, a poor neuromuscular coordination during chewing, with altered muscular patterns, and a smaller left-right symmetry than in control subjects were found (P=0.05). No differences in masticatory frequency were found. CONCLUSION: Surface EMG analysis of clenching and chewing showed that fixed implant-supported prostheses and implant overdentures were functionally equivalent. Neuromuscular coordination during chewing was inferior to that found in subjects with natural dentition.

Adaptation, Physiological↗
PubMed1998

Masticatory muscle responses associated with unloading of biting force during food crushing.

The aim of this study was to evaluate masticatory muscle responses during food crushing. Electromyograms were recorded simultaneously with mandibular movement and the sound of food fracture in eight healthy adult males at the superior and inferior heads of the lateral pterygoid muscles, the anterior belly of the digastric muscle, the temporal muscle, and the masseter muscle. After fracture of the food, silent periods of the elevator muscles and excitatory responses of the depressor muscles were observed. The latency and duration of the silent periods increased significantly with increasing incisal velocity after fracture. The mean latency of the excitatory responses of the depressor muscle was stable. After the application of anaesthetic into the temporomandibular joint capsule, the excitatory response disappeared, whereas the silent period was partly maintained. These findings suggest that the excitatory response of the depressor muscle occurs via a polysynaptic reflex arc, and that several reflex arcs are involved in the development of the silent period during food crushing. An important role for the temporomandibular joint receptors is implied.

Adult↗
PubMed1979

Relation between integrated electromyographic activity and biting force during voluntary isometric contraction in human masticatory muscles.

The relation between integrated electromyographic activity and computed biting force during voluntary isometric contraction was evaluated in the masticatory muscles of healthy subjects. The slopes of the curves relating integrated electromyographic activity to computed biting force in masseter muscles were steeper on the non-preferred chewing side than on the preferred chewing side, and they progressively became steeper during the course of continuous isometric contraction of a given biting force.

Action Potentials↗