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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of oral rehabilitation 14 (1987), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The relationships of the lateral pterygoid muscle within the infratemporal fossa were observed by conventional dissections and by examination of specimens sectioned in the horizontal and frontal planes. The following less well-known features were noted. At the origins of the superior and inferior heads there are regions in which the fibres are interlaced or closely overlapped by fibres of either the temporalis muscle or the medial pterygoid muscle. Fibres of the superior head insert not only into the meniscus of the temporomandibular joint, but also into the pterygoid fovea at the neck of the mandibular condyle. Specimens sectioned through the origin of the inferior head of the muscle show internal tendon lamellae consistent with a pennate structure.Electromyographic (EMG) activity was recorded in five healthy subjects using concentric needle and fine-wire electrodes. Strong to very strong activity was consistently observed in the superior head during clenching and tooth gnashing. The inferior heads were silent or had negligible to slight activity most of the time during ipsilateral movements or clenching, but were co-activated bilaterally, with strong to very strong activity during jaw opening, protrusion, swallowing, tooth gnashing and during passive retrusion. They showed marked activity unilaterally during contra-lateral movements.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of oral rehabilitation 30 (2003), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: summary  There are conflicting opinions about the frequency range of temporomandibular joint (TMJ) sounds. Some authors claim that the upper limit is about 650 Hz. The aim was to test the hypothesis that TMJ sounds may contain frequencies well above 650 Hz but that significant amounts of their energy are lost if the vibrations are recorded using contact sensors and/or travel far through the head tissues. Time–frequency distributions of 172 TMJ clickings (three subjects) were compared between recordings with one microphone in the ear canal and a skin contact transducer above the clicking joint and between recordings from two microphones, one in each ear canal. The energy peaks of the clickings recorded with a microphone in the ear canal on the clicking side were often well above 650 Hz and always in a significantly higher area (range 117–1922 Hz, P 〈 0·05 or lower) than in recordings obtained with contact sensors (range 47–375 Hz) or in microphone recordings from the opposite ear canal (range 141–703 Hz). Future studies are required to establish normative frequency range values of TMJ sounds but need methods also capable of recording the high frequency vibrations.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of oral rehabilitation 26 (1999), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of oral rehabilitation 17 (1990), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: It is important to have an objective method for recording jaw muscle capacity such as EMG before, during and after treatment of muscle dysfunction and also for oral rehabilitation with dentures, implants or other types of restorations. Because measurements of motor unit potentials (MUPs) are needed in several areas of EMG analysis, algorithms have been developed in our laboratory for use in a small computer-aided system for semi-automatic detection and pattern recognition of MUPs. Based upon the test recordings it is suggested that a characteristic ‘maximal voltage increase per μs during the spike-phase’ can be used as a supplement to the more generally used parameter ‘rise-time’. Examples are given of how the programs can be useful in the study of the functional anatomy of jaw muscles by recording normative values for MUPs and their recruitment patterns.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of oral rehabilitation 15 (1988), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The techniques and sites for EMG recordings from the digastric muscles are controversial. To re-evaluate old techniques for recording from the digastric muscles, especially the posterior bellies, the morphology of the muscles was studied by conventional dissections and by examination of specimens sectioned in the frontal and the horizontal planes. Based on these anatomical findings, recording sites and approaches to them were developed for the anterior and posterior bellies of the digastric muscles. EMG recordings from the two bellies of the muscle were obtained from five healthy subjects. The EMG recordings were ranked according to muscle activity level and the activity within single muscles and between muscles compared using the Wilcoxon signed rank test. The anterior and posterior bellies had synchronized activity in all mandibular movements but were silent or had negligible activity with the mandible in the rest position, when the head was rotated, and while clenching. Both bellies had marked to very marked activity during jaw opening, and moderate to marked activity during protrusion, retrusion and lateral movements. During swallowing the anterior and posterior bellies had patterns characterized by bursts of activity of high amplitude and short duration. The two bellies were not, however, always synchronously active.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of oral rehabilitation 12 (1985), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Dissection of seven cadavers showed that the platysma muscle may cover large parts of the masseter muscle. The platysma may thus be a significant source of artefact activity when recording the masseteric activity with surface electrodes. This is illustrated by a patient-case.The electrical activity of the platysma muscle was studied during jaw movements in normal, healthy subjects. Activity was regularly recorded during the latter half of large vertical jaw opening movements and, in five of the seven subjects, in the ipsilateral platysma muscle also during combined lateral–vertical jaw opening movements. The platysma may, therefore, in some individuals, have a functional role during the opening phase of chewing cycles when this has a marked lateral component.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Temporomandibular joint (TMJ) sound is one of the most commonly recognized signs in patients with temporomandibular disorders (TMD) but is also frequently seen in asymptomatic individuals. Sound recording is therefore only meaningful if the sounds from a normal healthy joint can be differentiated from those in patients. In this study, the amplitude and power spectrum of the TMJ sounds from symptomatic patients and asymptomatic individuals were recorded and compared. The result showed that TMJ sounds from symptomatic patients had a larger amplitude than sounds from asymptomatic subjects. A significant proportion of sounds had frequencies between 2000 and 3000 Hz. It was concluded that the characteristic amplitude is worthy of further study as a sign of possible diagnostic value. Secondly, the bandwidth of the sensors used at electronic TMJ sound recording should not be less than 3000 Hz.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of oral rehabilitation 29 (2002), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: summary  Differential diagnosis depends in cases with disk displacement on accurate identification of sound source. Mistakes may occur when clicking from one temporomandibular joint (TMJ) is heard on both sides of the head at auscultation and neither examiner nor patient, is sure about side. The hypothesis was that the head tissues affect spectral characteristics of TMJ sounds and that differences due to different positioning of sensors can be used in localization of source. The aim was to compare bilateral electronic recordings of unilateral TMJ sounds to obtain and compare attenuation, phase shift and time delay. Recordings were made from 12 subjects with unilateral clicking. Small electret condenser microphones, bandwidth 40–20 000 Hz, were placed at the openings of the auditory canals and the sounds were recorded at a sampling rate of 48 000 Hz. The head tissues acted as a filter causing a frequency dependent attenuation and phase shift. There was a time difference between the ipsi- and the contra lateral recordings, the latter always having a longer delay time (range 0·2–1·2 ms, group mean 0·68 ms, s.d. 0·292 ms). In conclusion, spectral analysis of bilateral electronic TMJ sound recordings is of diagnostic value when bilateral clicking is heard at auscultation and can help to avoid diagnosing a silent joint as clicking.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of oral rehabilitation 30 (2003), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: summary  It is of clinical interest to record the amplitudes of temporomandibular joint (TMJ) sounds. The aim was to test the hypothesis that sealing the meatus, when placing a microphone in the ear canal affects such recording by increasing the sound pressure level (SPL). Bilateral recordings of 249 TMJ clickings were made from three subjects, using sampling rates of 48 or 96 kHz and 24 bits A/D conversion, with and without the ear canals sealed by Silicone putty. The peak-to-peak equivalent sound pressure level (peSPL) was higher (P 〈 0·001) when the ear canal was sealed (range of mean differences was 8·3–24·9 dB peSPL). This means that the signal to noise ratio can be improved by sealing the meatus because the electronic noise level is not increased. Most important is that the dynamic range of the clicking sounds was 62 dB that is larger than the effective dynamic range of a 16 bits sound card. Future studies are needed to establish normative peSPL values. However, cards with at least 24 bits A/D conversion will be required, especially in patients with suspected disc displacement with reduction, where the difference in loudness between opening and closing clicking often is large.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Joint effusion has been associated with temporomandibular joint (TMJ) pain but can only be diagnosed by magnetic resonance imaging (MRI). For screening of patients with suspected effusion a simple and less expensive method would be desirable. We recorded joint sounds during jaw opening and closing movement from 34 TMJs with internal derangement (ID). Seventeen joints had joint effusion seen on MRI. Spectrograms of the sounds were displayed as waterfall plots showing profiles of the consecutive Hamming windows. If the profiles were similar, as judged by initial evaluation, the displayed pattern was classified as stable. If some profiles were distinctly deviating in their pattern, this was classified as unstable. Joints with effusion showed unstable sound pattern more often than joints without effusion (P 〈 0·001). It was concluded that TMJ sound analyses have a potential to identify joints with effusion based on their unstable sound pattern.
    Type of Medium: Electronic Resource
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