SEARCH · PubMed Health

Results for “Pterygoid Muscles”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 109 records · Page 6Linked to original sources

PubMed1989

Association between craniofacial morphology and fiber-type distributions in human masseter and medial pterygoid muscles.

Numerous experimental studies and clinical anecdotal evidence demonstrate a close interaction between masticatory muscle function and skeletal form. The purpose of this study was to determine whether a relationship existed between histochemical characteristics of human masseter and medial pterygoid muscles and cephalometric measurements of the 11 subjects from whom specimens were collected. Muscular specimens were obtained at the time of corrective surgery through incisions made to expose the mandibular ramus. Histochemical analysis was used to determine the size and distribution of fiber types. Angular and linear measurements were obtained from lateral cephalometric radiographs taken 1 week prior to surgery. Linear regression analysis revealed one significant negative correlation between ramus length and the percentage of Type I fibers in the medial pterygoid muscle. However, the results of this study do not support the hypothesis that a relationship exists between facial type and selected histochemical characteristics.

Adolescent↗

PubMed1982

Electromyographic analysis of the functional components of the lateral pterygoid muscle in the rhesus monkey (Macaca mulatta).

Electromyographic recordings (EMG) obtained from intramuscular electrodes inserted in the lateral pterygoid muscle (lat. pt.) of 29 juvenile and adolescent monkeys were assessed in relation to the recorded activity of three jaw elevating muscles, temporalis, masseter and medial pterygoid, and a jaw muscle depressor, the geniohyoid. The lat. pt. was recruited in one of three patterns: (1) only during mandibular depression, (2) during both depression and elevation, or (3) only during elevation of the jaw. The discharge of fibres in the lat. pt. during closing movements occurred bilaterally in 9 of 21 recordings. Simultaneous recordings from the anterior temporalis, medial pterygoid and the ipsilateral lat. pt. indicated completely different discharge patterns of the three muscles. In 9 recording sessions, two pairs of electrodes were placed in the same lat. pt. The discharge patterns from the two pairs were different in 5 of the recordings. In one region, the fibres were active only during depression, whereas in the other region fibres discharged only during elevation of the mandible. The data support the concept of two groups of fibres with separate functions within the lat. pt. and suggest that adaptation to oral respiration utilizes the two groups in distinctive patterns.

Animals↗

PubMed1981

Medial pterygoid muscle activity during the closing and compressive phases of human mastication.

The lack of specific data correlating activity in the human medial pterygoid muscle with displacement of the jaw during mastication, and the hint of possible differences in function between certain mammalian species, prompted a study of unilateral mastication in six adult subjects. Muscle activity in the medial pterygoid, masseter, and anterior temporal muscles was recorded simultaneously with three-dimensional movement of an incisor point on the mandible. Signals from muscles and displacement transducer were sampled by a disc-based computer system programmed to analyze data averaged over 30 chewing cycles on each side and in some instances over 30 open-close and clench cycles. Patterns of medial pterygoid activity were consistent for the group as a whole, demonstrating activation of both muscles early in the closing cycle with strong ipsilateral muscle activity before and throughout the intercuspal phase of the cycle, reappearing in some subjects just before the end of intercuspation. Medial pterygoid activity mirrored masseter and anterior temporal activity only during certain phases of the closing cycle, suggesting that these muscles should be considered as being selectively coactivated with, rather than synergists of, the major elevators of the jaw. The muscles were active during horizontal components of movement of the incisor teeth in chewing, but were inactive during the open-close and clench task despite vigorous contraction of the masseter muscles. Overall, the observations complement previous reports of medial pterygoid muscle activity in humans. They also confirm, for these muscles at least, a general similarity between man and the little brown bat, a relationship hitherto suspected but unsubstantiated.

Electromyography↗

PubMed1995

The morphology and innervation of the lateral pterygoid muscle of the dog.

The number of heads possessed by the lateral pterygoid muscle was investigated in the dog. Only a single head was observed which it is suggested may correspond to the lower head in other mammals. It inserted both onto the condyle and into the articular disc. The nerve which innervated this muscle arose directly from the mandibular nerve, separate from the medial pterygoid nerve. Because of this, it should be termed the lateral pterygoid nerve and not the pterygoid nerve.

Animals↗

PubMed1991

[The external pterygoid muscle. Functional aspects].

This study, starting from the revision of traditional anatomy proposed to value TMJ and its components through dissection of human TMJ, and especially to examine the anatomic function of the lateral pterygoid muscle. Twenty dissections of left human TMJ were made. Every block was fixed in solution of 10% of formalin and dissections were made to show every components of articulation. Further thin sections were made for histological examination. The purpose of the study was to evaluate the lateral pterygoid muscle as a single unit compared to the function.

Humans↗

PubMed2000

Human lateral pterygoid muscle activity on the return phase of contralateral and protrusive jaw movements.

Normal function of the lateral pterygoid muscle is not well understood. The principal aim of this study was to determine whether there is a progressive decrease in lateral pterygoid activity as the condyle moves posteriorly and superiorly during the return phase of a contralateral or protrusive jaw movement, as would be expected if the muscle is involved in controlling or stabilizing the condyle during the return phase of these movements. In seven humans, electromyographic activity was recorded in the superior (SHLP) and inferior (IHLP) heads of the lateral pterygoid, the masseter, anterior temporal, posterior temporal and submandibular group of muscles, together with condylar movement, during contralateral and protrusive jaw movement. In most individuals, there was a progressive decrease in rectified and smoothed IHLP activity in relation to condylar movement during the return phase of contralateral and protrusive jaw movement. However, this pattern usually was not seen when SHLP activity was studied in relation to condylar movement. Further, there was a high correlation coefficient between condylar displacement and the rectified and smoothed IHLP and anterior temporal muscle activities during the return phase of contralateral or protrusive jaw movement, while SHLP presented a much lower correlation. For example, the mean (+/-SD) correlation coefficient between posterior condylar movement (along anteroposterior axis) and IHLP activity during the return phase of a protrusive jaw movement was -0.73+/-0.36 (for contralateral movement: -0.71+/-0.56), for the anterior temporal 0.69+/-0.21 (contralateral: 0.81+/-0.09), and for the submandibular muscles, -0. 77+/-0.15 (contralateral: -0.34+/-0.71). For the SHLP, masseter and posterior temporal, values were -0.34+/-0.61 (contralateral: -0. 48+/-0.37), -0.24+/-0.57 (contralateral: 0.16+/-0.80), and 0.16+/-0. 77 (contralateral: 0.64+/-0.14), respectively. These findings suggest an important role for the IHLP and anterior temporal in controlling the movement of the condyle to the glenoid fossa on the return phase of contralateral and protrusive jaw movements. Further studies are needed to clarify the function of the lateral pterygoid muscle during these and other jaw movements.

Adult↗

PubMed1997

[The development and morphofunctional characteristics of the human lateral pterygoid muscle].

Peculiarities of the development of superior and inferior heads of lateral pterygoid muscle (LPM) as well as their micro- and ultramicroscopic structure were studied as related to the temporomandibular joint elements in human fetuses and newborns. As a result, heterogeneity and asynchronism of the development of myogenic elements of certain LPM heads were demonstrated. The process of muscle fibres differentiation in LPM superior head leads to more mature structural organization and runs faster than in the inferior head. By the moment of birth average section area of superior head muscle fibres is significantly higher than the inferior head similar parameter.

Fetus↗

PubMed2000

Clinical anatomy and palpability of the inferior lateral pterygoid muscle.

STATEMENT OF PROBLEM: The intraoral palpation technique of the inferior belly of the inferior lateral pterygoid (ILP) muscle is a standard diagnostic examination method for temporomandibular joint dysfunction syndrome, although different studies have revealed inconsistent results. PURPOSE: This study assessed the feasibility of the ILP muscle palpation by a simulated clinical setting. MATERIAL AND METHODS: Three dentists performed a bilateral palpation of the ILP muscle in 53 fresh and unfixed human cadavers and decided whether the muscle was palpable or unpalpable. In a second step, it was observed through the dissected infratemporal fossa, whether the examiner's finger did or did not touch the ILP muscle by simulating the performed palpation. Palpatory findings were supplemented by 1-dimensional measurements for determination of topographic relations of the ILP muscle within the infratemporal fossa. For statistical analysis, sensitivity, specificity, and negative and positive predictive values of the palpation technique were calculated. Interexaminer agreement was estimated with the kappa value. RESULTS: In 86 of 106 dissected specimens, a superficial fascicle of the medial pterygoid muscle was found in direct proximity to the ILP muscle. In these cases, a residual distance of 7.8 +/- 3.2 mm remained between the ILP muscle and buccinator fascia indented by the tip of the examiner's finger. In 10 of 20 specimens with an absent superficial fascicle, the finger was able to reach the ILP muscle. CONCLUSION: It is recommended that the ILP muscle palpation technique should no longer be considered as a standard clinical procedure because it is nearly impossible to palpate the ILP muscle anatomically and because the risk of false-positive findings (by palpation of the medial pterygoid muscle) is high.

Facial Pain↗

PubMed2000

Calcified leiomyoma of the lateral pterygoid muscle in an 8-year-old boy.

Deep soft tissue leiomyomas are extremely rare benign tumors in childhood. An unusual case of benign calcified leiomyoma of the pterygoid muscle in an 8-year old boy is presented. Clinical manifestations and radiographic and histologicpathologic findings, as well as the differential diagnosis and possible histogenesis of this rare tumor, are discussed.

Calcinosis↗

PubMed1993

Investigations of the run and the attachment of the lateral pterygoid muscle in Japanese.

Studies of the run and the attachment of the lateral pterygoid muscle were made on 79 samples from 41 cadavers in the collection of the Department of Anatomy of the Tokyo Dental College. Origin shapes were classified into 3 types: type I, in which there is a clear boundary between the muscle venter adhesion for the upper muscle venter and the lower muscle venter; type II, where the boundary between them is unclear; and type III, where the difference between the two cannot be distinguished at all. When this classification was applied to the specimens, all 21 of the 1-venter specimens fell into type III; 37 (69.8%) of the 2-venter specimens fell into type I; 10 (18.9%) of the 2-venter specimens fell into type II, and 6 (11.3%) of the 2-venter specimens fell into type III. All 5 of the 3-venter specimens were type II. From the results of this studies, we saw that, regardless of which investigation method was employed, the number of venter runs and the origin configuration did not correlate at all.

Asian People↗

PubMed1988

Intraoral myotomy of the lateral pterygoid muscle for treatment of recurrent dislocation of the mandibular condyle.

This article describes an intraoral procedure for myotomy of the lateral pterygoid muscle as treatment of recurrent dislocation of the mandibular condyle and five treated cases are presented. In none of the cases were anatomic structures damaged, and none of the patients has developed recurrence. The main effect of this treatment is ascribed to scarring anterior to the joint capsule, limiting excursion of the condyle. Although the follow-up is limited, the results seem promising.

Adolescent↗

PubMed1999

Electromyographic activity of the human lateral pterygoid muscle during contralateral and protrusive jaw movements.

Understanding of the normal function of the lateral pterygoid muscle is limited. The principal aim here was to determine whether there is a progressive increase in lateral pterygoid activity as the mandibular condyle moves downwards and forwards as would be expected if the muscle is concerned with the precise horizontal positioning of the mandible. In eight humans, recordings were made of the activity of the superior (SHLP) and inferior (IHLP) heads of the lateral pterygoid and the masseter, anterior temporal, posterior temporal and digastric muscles, together with the movement of the palpated lateral condylar pole (JAWS-3D tracking system) during trials of a contralateral and a protrusive jaw movement. Recording sites in SHLP and, in one participant, IHLP were verified by computed tomography. In each participant there was a progressive increase in the rectified and smoothed SHLP and IHLP activity in association with condylar movement during the contralateral and protrusive jaw movement. Further, irregularities in condylar movement, which reflected variations in the rate at which the jaw was moved, were correlated in time with prominent bursts of SHLP and IHLP activity. In all participants there was a consistently high correlation coefficient between the rectified and smoothed SHLP and IHLP activity and condylar displacement during the contralateral or protrusive jaw movements. For example, the mean (+/-SD) correlation between anterior condylar translation during contralateral excursion and SHLP activity was 0.91+/-0.09, and for IHLP 0.96+/-0.02. For the masseter, anterior temporal, posterior temporal and digastric muscles, mean r-values were, respectively, 0.10+/-0.77; -0.14+/-0.72; 0.24+/-0.78; 0.54+/-0.47. When treated as a group the correlation coefficients for SHLP and IHLP were statistically significantly different from the correlation coefficients for the other muscles treated as a group (ANOVA; p < 0.002 for correlation with anterior translation). These observations support the notion that the lateral pterygoid provides the principal driving force for moving the jaw forwards or laterally in protrusive or lateral excursive condylar movements. Further, the data suggest that the muscle plays a part in the fine control of jaw movements.

Adult↗

PubMed1991

Longitudinal growth of the lateral pterygoid muscle in human fetuses.

The length of the upper and lower heads of the lateral pterygoid muscle was estimated in 44 fetuses aged 9 to 35 weeks. The lower head of the muscle is always longer than the upper one. Intensive increase in the length of the muscle is observed between 11th and 20th week.

Embryonic and Fetal Development↗

PubMed2005

Fatigue-related changes in discharge patterns of motor units in the inferior head of the lateral pterygoid muscle in humans.

OBJECTIVE: To investigate single motor unit (SMU) firing patterns of the inferior head of the human lateral pterygoid muscle (IHLP) during sustained isometric contractions, and to examine IHLP fatigability. DESIGN: In 5 subjects, EMG was recorded from the right IHLP during generation of horizontal isometric mandibular force towards left side. Subjects tracked a target on an oscilloscope, slowly increasing the force to 25% of maximum voluntary contraction, and then maintained that force for 120 s (endurance task). Subjects rested for 30 s after each test, and three 10s recovery tests were performed every 30 s (recovery task). Fatigue data were obtained from 23 SMUs. RESULTS: Twelve of 23 SMUs (52.2%) continued to fire throughout the 120 s, and each subject had at least one of these units. These units were classified as tonic pattern (T-unit). The firing rate of 6 of the 12 T-units (50.0%) decreased gradually with time. Comparison of the mean firing rate and coefficient of variance (CV) of interspike interval (ISI) of the 12 T-units between pre-fatigue, post-fatigue and the three recovery tasks showed that the mean firing rate decreased and CV of ISI increased after fatigue. Mean firing rate and CV of ISI recovered after 30 s of rest after the endurance task. CONCLUSIONS: The firing patterns of IHLP units changed with the passing of time during sustained isometric contractions leading to fatigue.

Action Potentials↗

PubMed2001

The role of the human lateral pterygoid muscle in the control of horizontal jaw movements.

There is a limited understanding of the normal function of the lateral pterygoid muscle (LP) and the role that this muscle plays in temporomandibular disorders. This article addresses the hypothesis that a major function of the LP is in the control of horizontal jaw movements. The range of fiber alignments suited to generating a major horizontal force vector (magnitude and direction), together with the likelihood of independent activation of subcompartments (that is, functionally heterogeneous zones) within each head, provide the possibility of a finely graded range of force vectors on the condyle to effect the fine control of horizontal jaw movements. This level of control does not appear to extend to the control of resting jaw posture, as recent single motor unit (SMU) data indicate that the LP is inactive with the jaw in the postural jaw position. Available electromyographic data demonstrate graded changes in multiunit and SMU activity with small horizontal jaw displacements at low force levels, a single preferred direction of the SMU firing rate during horizontal isometric jaw tasks, and graded changes in the SMU firing rate with horizontal force magnitude and direction. The evidence suggests that a major function of the LP is in the generation and fine control of the horizontal component of jaw movement by the graded activation of a subset of SMUs within the LP. The data also suggest that the LP is involved in the generation of horizontal force vectors, as required in parafunctional activities and heavy mastication.

Electromyography↗

PubMed1989

A comparative electromyographic study of the lateral pterygoid muscle and arthrography in patients with temporomandibular joint disturbance syndrome sounds.

To explore the relationships among dysfunction of the two heads of the lateral pterygoid muscle, temporomandibular joint (TMJ) internal derangement, and the mechanism of TMJ sounds, a comparative study was undertaken with electromyography of the two heads of the muscle and arthrography in 38 patients with temporomandibular joint disturbance syndrome sounds. Results suggested that the electromyograph shows various characteristics of dysfunction, when compared with the electromyograph of normal adults, that are significantly relevant to temporomandibular joint internal derangement, especially anterior disk displacement with reduction and without reduction. The mechanism of the sounds was further explained on the basis of the observation of this study. Summing up the data, the authors propose that the dysfunction of the superior head of the muscle is one cause of temporomandibular anterior disk displacement.

Adolescent↗

PubMed2001

Functional properties of single motor units in inferior head of human lateral pterygoid muscle: task relations and thresholds.

The aim of this study was to clarify the normal function of the inferior head of the human lateral pterygoid muscle (IHLP). The hypothesis was that an important function of the IHLP is in the fine control of horizontal jaw movements. The activities of 99 single motor units (SMUs) were recorded from IHLP (22 recordings from 16 subjects). Most recording sites were identified by computer tomography (CT). All 99 SMUs were active during contralateral jaw movements with the teeth apart, and protrusive jaw movements with the teeth apart, and 81% (48 of 59 units studied during all 3 tasks) were active during submaximal jaw-opening movements. None were active on maximal ipsilateral or retrusive jaw movements with the teeth apart nor on jaw closing/clenching in intercuspal position; nor were they spontaneously active when the jaw was at the clinically determined postural jaw position. Thresholds of SMUs ranged from <0.2 mm of contralateral or protrusive horizontal displacements to 61-89% of the maximum contralateral or protrusive displacement, respectively. For the 35 units continuously active during the contralateral task, 23 (66%) were recruited within 2 mm of contralateral displacement [25 (63% of 40 units) for protrusion]. Recruitment thresholds (mm) of some of the units were rate dependent with thresholds significantly decreasing with increasing rate of horizontal jaw movement in protrusion and contralateral movements. At eight recording sites where up to six SMUs were able to be discriminated, the average thresholds of successively recruited SMUs were within a 1-mm increment of horizontal jaw displacement. After dividing IHLP into four regions, the SMUs recorded in the superior-medial zone exhibited significantly lower mean threshold values than for the SMUs recorded in the other zones (no units were recorded in the inferior-lateral zone). This provides suggestive evidence supporting previously proposed notions of functional heterogeneity within IHLP. Taken together, the data suggest that specific regions of the IHLP are capable of selective activation in a finely controlled manner to allow the application of the appropriate force vector (magnitude and direction) to effect the required condylar movement needed for the generation and control of horizontal jaw movements.

Adult↗

PubMed1989

The anatomic relationship of the insertion of the superior lateral pterygoid muscle to the articular disc in the temporomandibular joint of human cadavers.

Confusion has existed as to whether the major insertion of the superior lateral pterygoid muscle is into the articular disc or the condyle. Five human cadaver joints were studied under the dissecting microscope. This allowed superior lateral pterygoid fibres to be selectively placed under tension to determine their point of insertion and to examine the integrity of the anterior joint capsule. All superior lateral pterygoid fibres gained either direct or indirect insertion to the condyle. A classification for the variation in insertion is suggested. The fibres of the anterior joint capsule extended from the anterior rim of the condyle to the roof of the infratemporal fossa but under the foot of the disc they blended with and became indistinguishable from disc fibres.

Cadaver↗