Size and Orientation of Masticatory Muscles in Patients with Mandibular Laterognathism

Size measurements of jaw muscles reflect their force capabilities and correlate with facial morphology. Using MRI, we examined the size and orientation of jaw muscles in patients with mandibular laterognathism in comparison with a control group. We hypothesized that the muscles of the deviated side would be smaller than those of the non-deviated side, and that the muscles of both sides would be smaller than in controls. In patients, a comparison of deviated and non-deviated sides showed, in orientation, differences for masseter and medial pterygoid muscles, but, in size, differences only for the masseter muscle. Nevertheless, muscle sizes in patients were much smaller than in controls. Lateral displacement of the mandible can explain the orientation differences, but not the smaller muscle size, in patients. It is possible that the laterodeviation initiates an adaptive process in the entire jaw system, resulting in extensive atrophy of the jaw muscles.

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Volume Changes in Human Masticatory Muscles between Jaw Closing and Opening

Journal of Dental Research ◽

10.1177/154405910208100614 ◽

2002 ◽

Vol 81 (6) ◽

pp. 428-432 ◽

Cited By ~ 32

Author(s):

T.K. Goto ◽

K. Tokumori ◽

Y. Nakamura ◽

M. Yahagi ◽

K. Yuasa ◽

...

Keyword(s):

Masticatory Muscles ◽

Magnetic Resonance Images ◽

Normative Values ◽

Volume Changes ◽

Jaw Muscles ◽

Multiple Components ◽

Jaw Opening ◽

Medial Pterygoid ◽

Before And After ◽

Pterygoid Muscles

Most jaw muscles are complex, multipennate with multiple components. The morphologic heterogeneity of masticatory muscles reflects their functions. We hypothesized that the volume of masticatory muscles changes between jaw closing and opening, and that there is a difference in the volume change among the muscles. Magnetic resonance images of the entire head were obtained in ten normal young adult subjects before and after maximum jaw opening. The volume changes of the masseter, medial, and lateral pterygoid muscles were measured. Only slight changes were seen in the masseter and medial pterygoid muscles. The lateral pterygoid muscle, however, significantly decreased its volume during jaw opening. The results provide normative values of muscle volume in living subjects, and suggest that the volume changes differ among jaw muscles.

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Intramuscular Injections and Dry Needling within Masticatory Muscles in Management of Myofascial Pain. Systematic Review of Clinical Trials

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18189552 ◽

2021 ◽

Vol 18 (18) ◽

pp. 9552

Author(s):

Zuzanna Nowak ◽

Maciej Chęciński ◽

Aleksandra Nitecka-Buchta ◽

Sylwia Bulanda ◽

Danuta Ilczuk-Rypuła ◽

...

Keyword(s):

Clinical Trials ◽

Myofascial Pain ◽

Platelet Rich Plasma ◽

Masticatory Muscles ◽

Temporomandibular Joint Disorders ◽

Common Symptom ◽

Dry Needling ◽

Medial Pterygoid ◽

Manual Palpation ◽

Pterygoid Muscles

(1) Background: Myofascial pain is an important cause of disability among the whole population, and it is a common symptom of temporomandibular joint disorders (TMDs). Its management techniques vary widely; however, in recent years, there has been a growing interest especially in needling therapies within masticatory muscles, due to their simplicity and effectiveness in pain reduction. (2) Methods: The construction of the following study is based on PICOS and PRISMA protocols. A systematic literature search was conducted based on the PubMed and BASE search engines. Searching the abovementioned databases yielded a total of 367 articles. The screening procedure and analysis of full texts resulted in the inclusion of 28 articles for detailed analysis. (3) Results: According to analyzed data, clinicians manage myofascial pain either with wet or dry needling therapies. The most thoroughly studied approach that prevails significantly within the clinical trials is injecting the botulinum toxin into the masseter and temporalis. Other common methods are the application of local anesthetics or dry needling; however, we notice the introduction of entirely new substances, such as platelet-rich plasma or collagen. In the analyzed articles, the target muscles for the needling therapies are most commonly localized by manual palpation although there are a variety of navigational support systems described: EMG, MRI or EIP electrotherapy equipment, which often aid the access to located deeper lateral and medial pterygoid muscle. (4) Conclusions: Needling therapies within masticatory muscles provide satisfactory effects while being simple, safe and accessible procedures although there still is a need for high quality clinical trials investigating especially injections of non-Botox substances and needling within lateral and medial pterygoid muscles.

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Masticatory function in temporomandibular dysfunction patients: electromyographic evaluation

Journal of Applied Oral Science ◽

10.1590/s1678-77572005000400009 ◽

2005 ◽

Vol 13 (4) ◽

pp. 360-365 ◽

Cited By ~ 20

Author(s):

Giédre Berretin-Felix ◽

Katia Flores Genaro ◽

Inge Elly Kiemle Trindade ◽

Alceu Sergio Trindade Júnior

Keyword(s):

Masseter Muscle ◽

Computer Software ◽

Masticatory Muscles ◽

Control Group ◽

Electromyographic Activity ◽

Temporomandibular Dysfunction ◽

Masticatory Function ◽

Cashew Nut ◽

Materials Used ◽

Number Of Cycles

Temporomandibular dysfunction (TMD) is a complex disturbance that involves the masticatory muscles and/or temporomandibular joint, causing damage to the masticatory function. This study evaluated the electromyographic activity of the masseter muscle during habitual mastication of bread, apple, banana, cashew nut and paraffin film (Parafilm M) in 25 adult subjects, of both gender, with TMD. The results were compared to those of a control group, composed of 15 adult subjects, of both sexes, free of signs and/or symptoms of TMD. The MYO-TRONICS Inc., K6-I computer software was used for electromyographic processing and analyzed the following parameters: duration of the act, duration of the masticatory cycle and number of cycles. No significant differences were found between subjects in the control group and individuals with TMD as to duration of the masticatory act and of the masticatory cycle, considering all materials used for mastication. The duration of the masticatory act and cycle was longer during mastication of paraffin film in both groups. The number of masticatory cycles was higher for mastication of apple in comparison to mastication of banana, in both groups. It can be concluded that the consistency of foods influences the duration parameters of the act, duration of the cycle and the number of masticatory cycles, and the behavior of the masticatory muscles in individuals with TMD during habitual mastication is similar to that verified in individuals without TMD.

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Diagnosis and perfection of the complex treatment of patients with neuromuscular dysfunction syndrome of the temporomandibular joints

Kazan medical journal ◽

10.17816/kmj1557 ◽

2012 ◽

Vol 93 (4) ◽

pp. 627-631

Author(s):

A N Sidorenko

Keyword(s):

Sagittal Plane ◽

Lateral Displacement ◽

Mouth Opening ◽

Masticatory Muscles ◽

Control Group ◽

Complex Treatment ◽

Neuromuscular Dysfunction ◽

Temporomandibular Joints ◽

Transcranial Electrostimulation ◽

Palm Of The Hand

Aim. To improve the complex treatment of patients with neuromuscular dysfunction syndrome of the temporomandibular joints. Methods. Clinical examination, electromyography of masticatory muscles, computed tomography in 24 patients (main group) with a neuromuscular dysfunction syndrome of the temporomandibular joints. The control group included 10 healthy individuals aged 18 to 32 years with intact tooth rows, orthognatic bite, and without pathology of the temporomandibular joints. In cases of deviation of the mandible at the time of opening the mouth in 7 (29.2%) patients the complex of therapeutic measures included a myo-gymnastic exercise, which consisted of shifting the mandible with the palm of the hand towards the opposite side of the deviation. During zigzag movements of the mandible in 12 (50%) patients assigned was myo-gymnastic exercise, aimed at keeping the lower jaw with the palms of both hands in the sagittal plane during a vertical opening of the mouth. In 5 (20.8%) patients with a small limitation of mouth opening and lateral displacement of the mandible myo-gymnastics were used that included exercises designed to stretch and cause reflex relaxation of the masticatory muscles, as well as the displacement of the mandible in the palm of the hand to the side opposite to its deviation. All patients from the start of treatment were prescribed a course (10 sessions) of therapeutic massage of the masticatory muscles and 10 sessions of transcranial electrostimulation in 8 (33.3%) patients to relax the chewing muscles in its hypertonicity, to relieve spasm of the lateral pterygoid muscle, and removal the significant pain syndrome. Results. By the 5-6th session of transcranial electrostimulation the pain and tension in the masticatory muscles on the affected side with neuromuscular dysfunction disappeared, the range of motion of the mandible was restored, atypical movement of the mandible stopped. Examination of 24 patients at 2 years after treatment showed that 22 patients had a sustained, positive result, no complaints or recurrences were observed. In 2 patients after treatment noted was significant tension in the masticatory muscles, they were re-appointed for transcranial electrostimulation. Conclusion. Developed and proposed was an improved method of complex treatment of patients with neuromuscular dysfunction syndrome of the temporomandibular joints without the use of drugs, which has shown high effectiveness.

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Comparison of mandibular movement trajectories and associated patterns of oral muscle electromyographic activity during spontaneous and apomorphine-induced rhythmic jaw movements in the guinea pig

Journal of Neurophysiology ◽

10.1152/jn.1986.55.2.301 ◽

1986 ◽

Vol 55 (2) ◽

pp. 301-319 ◽

Cited By ~ 23

Author(s):

R. W. Lambert ◽

L. J. Goldberg ◽

S. H. Chandler

Keyword(s):

Masseter Muscle ◽

Emg Activity ◽

Lateral Movement ◽

Jaw Movements ◽

Jaw Opening ◽

Medial Pterygoid ◽

Pterygoid Muscles ◽

Opening And Closing ◽

Mandibular Movements ◽

Masseter Muscles

Vertical and horizontal movements of the lower jaw (mandible) of ketamine-anesthetized guinea pigs were recorded in association with electromyographic (EMG) activity in the anterior digastric, lateral pterygoid, medial pterygoid, and deep masseter muscles during spontaneously occurring rhythmic jaw movements (SRJMs) and during rhythmical jaw movements induced by the intravenous administration of apomorphine (ARJMs). Both ARJMs and SRJMs were near periodic and occurred at frequencies in the 2- to 5-Hz range. However, the profiles of the mandibular movements and associated patterns of jaw muscle EMG activity differed dramatically for SRJMs versus ARJMs. SRJMs were characterized by prominent lateral excursions of the mandible that occurred in association with both the jaw opening and closing movements. The lateral excursions were directed to the left side on some SRJM cycles and to the right side on others. The direction of the lateral component alternated irregularly, but no more than three consecutive cycles with horizontal movements to the same side were observed at any time. Each SRJM cycle was generated by the occurrence of one of two coordinated sequences of EMG activity. One sequence produced right-sided cycles, the other produced left-sided cycles. Each sequence was initiated by an EMG burst in the digastric muscle ipsilateral to the direction of the horizontal excursion of the mandible, followed by EMG bursts in the contralateral digastric, lateral pterygoid, and medial pterygoid muscles. The EMG bursts in the digastrics and contralateral lateral pterygoid muscles were associated with jaw opening and the initial stage of lateral movement. EMG activity in the contralateral medial pterygoid muscle was associated with the onset of closing and a second stage of lateral movement. Masseter muscle activity was also observed during SRJMs, but only in a subset of the animals tested (3 of 12). When present, the masseter activity began well after the onset of jaw closing. No significant horizontal mandibular movements were observed during ARJMs. The mandibular trajectories during opening and closing always remained close to the midline. The opening phase of ARJM cycles was associated with bilaterally synchronized activity in the digastric and lateral pterygoid muscles. The closing phase was associated with bilaterally symmetric activity in the masseter muscles. The medial pterygoid muscles displayed little or no EMG activity during ARJMs. The durations of the EMG bursts recorded in the masseter muscle were correlated with cycle time during SRJMs, as were the burst durations of the digastric and lateral pterygoid muscles during ARJMs.(ABSTRACT TRUNCATED AT 400 WORDS)

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Overall Activity of All Masticatory Muscles during Lateral Excursion

Journal of Dental Research ◽

10.1177/154405910608500112 ◽

2006 ◽

Vol 85 (1) ◽

pp. 69-73 ◽

Cited By ~ 12

Author(s):

S. Yamaguchi ◽

H. Rikimaru ◽

K. Yamaguchi ◽

M. Itoh ◽

M. Watanabe

Keyword(s):

Positron Emission Tomography ◽

Masticatory Muscles ◽

Emission Tomography ◽

Masticatory Muscle ◽

Lateral Pterygoid Muscle ◽

Relative Contribution ◽

Medial Pterygoid Muscle ◽

Positron Emission ◽

Medial Pterygoid ◽

Pterygoid Muscles

Quantification of the overall activity of every masticatory muscle is requisite for the analysis of stomatognathic function, which has not been accomplished by conventional electromyography. We used positron emission tomography and 18F-fluoro-deoxy-glucose to quantify the overall activity of every masticatory muscle during lateral excursion, and to evaluate the relative contribution of each masticatory muscle to lateral excursion. The present study suggested that lateral and medial pterygoid muscles are more responsible for lateral excursion than are masseter and temporal muscles. In particular, the contralateral lateral pterygoid muscle plays a major role, followed by the contralateral medial pterygoid muscle.

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Ultrasonographic Thickness of the Masseter Muscle in Growing Individuals with Unilateral Crossbite

The Angle Orthodontist ◽

10.2319/101105-360 ◽

2007 ◽

Vol 77 (4) ◽

pp. 607-611 ◽

Cited By ~ 39

Author(s):

Stavros Kiliaridis ◽

Payam H. Mahboubi ◽

Maarten C. Raadsheer ◽

Christos Katsaros

Keyword(s):

Masseter Muscle ◽

Treated Group ◽

Masticatory Muscles ◽

Untreated Group ◽

Permanent Teeth ◽

Control Group ◽

Array Transducer ◽

Bilateral Differences ◽

The Right ◽

Untreated Individuals

Abstract Objective: To study the bilateral differences in the thickness of the masseter muscles in untreated individuals with lateral crossbite, as well as in subjects with successfully treated functional lateral crossbite, at least three years after the end of treatment. Materials and Methods: Three groups of growing individuals were studied: (1) untreated group: 38 individuals with unilateral crossbite, (2) control group: 224 subjects without transversal malocclusions, and (3) treated group: 18 individuals with functional lateral crossbite, treated with a quad helix, and at least three years out of retention with all permanent teeth erupted. The thickness of the masseter muscle was measured bilaterally with ultrasonography, using a real time scanner with a 7.5 MHz linear array transducer. Results: In the untreated group, the thickness of the masseter muscle on the crossbite side was statistically significantly thinner than the one on the normal side (P = .025). No statistically significant differences were found in the thickness of the masseter muscle between the left and the right side in the control group. In the treated group, no statistically significant differences were found in the thickness of the masseter muscle between the former crossbite side and the normal one. Conclusion: The masseter muscle in untreated individuals with unilateral crossbite is thinner in the crossbite side when compared to the non-crossbite side possibly due to asymmetric activity of the masticatory muscles. Such an asymmetry in thickness of the masseter muscle could not be detected some years after the successful correction of the crossbite.

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Local Anesthetics Inhibit Ca-ATPase in Masticatory Muscles

Journal of Dental Research ◽

10.1177/0022034510363220 ◽

2010 ◽

Vol 89 (4) ◽

pp. 372-377 ◽

Cited By ~ 9

Author(s):

G.A. Sánchez ◽

D. Takara ◽

G.L. Alonso

Keyword(s):

Atpase Activity ◽

Local Anesthetics ◽

Calcium Binding ◽

Calcium Transport ◽

Skeletal Muscles ◽

Calcium Ionophore ◽

Masticatory Muscles ◽

Medial Pterygoid ◽

Pterygoid Muscles ◽

Colorimetric Methods

Local anesthetics have myotoxic effects and inhibit Ca-ATPase activity and Ca transport in skeletal muscles. Such effects have not been fully elucidated in masticatory muscles. We tested the hypothesis that local anesthetics increase myoplasmic calcium in masticatory muscles by inhibiting Ca-ATPase at a concentration similar to that of dental cartridges. The effects of lidocaine and bupivacaine on Ca-ATPase from rabbit masseter and medial pterygoid muscles were tested with radioisotopic and colorimetric methods. Bupivacaine had an action similar to that of lidocaine on Ca-ATPase activity, but less effect on calcium transport. The pre-exposure of the membranes to the anesthetics enhanced the Ca-ATPase activity in the absence of calcium ionophore, supporting their permeabilizing effect. The results demonstrate that amide-type anesthetics do not inhibit calcium binding, but do reduce calcium transport and enzyme phosphorylation by ATP, and suggest that the myoplasmic calcium increase induced by lidocaine and bupivacaine might promote masticatory muscle contraction and eventual rigidity.

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Changes in the muscles of mastication before and after primary stereotactic radiosurgery in patients with idiopathic trigeminal neuralgia

Journal of Neurosurgery ◽

10.3171/2019.8.jns191455 ◽

2019 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Nasser Mohammed ◽

Yi-Chieh Hung ◽

Thomas J. Eluvathingal Muttikkal ◽

Roy C. Bliley ◽

Zhiyuan Xu ◽

...

Keyword(s):

Trigeminal Neuralgia ◽

Muscle Atrophy ◽

Motor Neuropathy ◽

Significant Pain ◽

Medial Pterygoid ◽

Before And After ◽

Pterygoid Muscles ◽

Masseter Muscles ◽

Muscles Of Mastication ◽

New Onset

OBJECTIVEThe motor root of the trigeminal nerve runs close to the sensory root and receives considerable radiation during Gamma Knife radiosurgery (GKRS) for trigeminal neuralgia (TN). The object of this study was to evaluate via MRI the changes in the muscles of mastication before and after upfront GKRS in patients with idiopathic TN.METHODSIn this single-institution retrospective cohort study, all patients with idiopathic unilateral TN treated with primary GKRS at the University of Virginia in the period from 2007 to 2017 were included provided that they had pre- and post-GKRS MRI data. The thicknesses of the temporalis, pterygoid, and masseter muscles were measured on both pre- and post-GKRS MRI in a blinded fashion. Changes in the muscles like fatty infiltration, MRI signal, or atrophy were noted.RESULTSAmong the 68 patients eligible for inclusion in the study, 136 temporalis muscles, 136 medial pterygoid muscles, 136 lateral pterygoid muscles, and 136 masseter muscles were assessed. A subset of patients was found to have muscle atrophy even prior to GKRS. Pre-GKRS atrophy of the masseter, medial pterygoid, lateral pterygoid, and temporalis muscles was seen in 18 (26%), 16 (24%), 9 (13%), and 16 (24%) patients, respectively. Logistic regression analysis showed that distribution of pain in the V3 territory (p = 0.01, OR 5.43, 95% CI 1.46–20.12) and significant pain on chewing (p = 0.02, OR 5.32, 95% CI 1.25–22.48) were predictive of pre-GKRS atrophy. Reversal of atrophy of these muscles occurred after GKRS in a majority of the patients. The incidence of new-onset permanent post-GKRS muscle atrophy was 1.5%. The median follow-up was 39 months (range 6–108 months).CONCLUSIONSA subset of patients with TN with significant pain on chewing have pre-GKRS disuse atrophy of the muscles of mastication. A reversal of the atrophy occurs in a majority of the patients following GKRS. New-onset motor neuropathy post-GKRS was rare.

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Effect of isometric exercises on the masseter muscle in older adults with missing dentition: a randomized controlled trial

Scientific Reports ◽

10.1038/s41598-021-86807-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Satoru Takano ◽

Kohei Yamaguchi ◽

Kazuharu Nakagawa ◽

Kanako Yoshimi ◽

Ayako Nakane ◽

...

Keyword(s):

Older Adults ◽

Masseter Muscle ◽

Controlled Trial ◽

Intervention Group ◽

Muscle Thickness ◽

Control Group ◽

Older Individuals ◽

Muscle Properties ◽

Oral Function ◽

Masticatory Ability

AbstractMaintaining oral function in older individuals with missing teeth is important for leading a healthy and independent life. This study aimed to evaluate whether simple isometric exercises can maintain and improve the oral function [maximum occlusal force (MOF) and masticatory ability (MA)] and the masticatory muscle properties [masseter muscle thickness (MMT) and echo intensity (MMEI)] in older adults during the maintenance phase of removable prosthetic treatment. Participants were randomly categorized into the intervention and control groups. The mouthpieces were distributed, and participants were instructed to use them for exercising. The intervention group was instructed to perform maximum clenching for 10 s, whereas the control group was instructed to tap the teeth at an arbitrary speed for 10 s. Both were repeated five times at an interval of 5 s between each activity and twice daily for 4 weeks. The outcomes were measured after a month of exercise. The intervention group showed a significant improvement in the MOF, MMT during contraction, MMT at rest and MMEI during contraction. There were no significant differences in the MA and MMEI at rest. In the control group, no improvement was observed in any of the parameters. When the isometric exercises were performed using a mouthpiece, there was an improvement in the oral function and masseter muscle properties in older individuals with Eichner B status who used dentures.

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