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Refining Toxin Treatment for the Masseters
Published in Yates Yen-Yu Chao, Optimizing Aesthetic Toxin Results, 2022
Though masseter muscle toxin injection is still off-label, it is popular in some areas, even surpassing the official label uses. The target of the masseter muscle is functional for mastication, unlike the other facial uses on mimetic muscles that work for expressive movements. Sometimes the block for mimetic muscles is thorough and complete and the muscles after treatment are almost flaccid, but the masticatory muscle cannot be deadened completely. The masseter muscle has to be preserved for the basic functions of jaw-closing and chewing. As toxin is also indicated in patients with bruxism, trismus, masticatory muscle myalgia, and temporomandibular joint dysfunction, toxin for the masseter is not just for aesthetic purposes.
Head and Neck Muscles
Published in Eve K. Boyle, Vondel S. E. Mahon, Rui Diogo, Handbook of Muscle Variations and Anomalies in Humans, 2022
Eve K. Boyle, Vondel S. E. Mahon, Rui Diogo, Warrenkevin Henderson, Hannah Jacobson, Noelle Purcell, Kylar Wiltz
The presentation of the masseter muscle is often affected by congenital malformations, cephalic disorders, and various syndromes. Macalister (1875) notes that Dumeril found the masseter muscles absent in a specimen with phocomelia. The masseter can be underdeveloped in cases of hemifacial microsomia (e.g., Takashima et al. 2003) or hypertrophic in cases of congenital hemifacial hyperplasia (e.g., Rončević 1986; Tsuneki et al. 2019).
Diagnosis of Chronic Fatigue Syndrome
Published in Jay A. Goldstein, Chronic Fatigue Syndromes, 2020
The major otologic finding relates to TMPDS causing otalgia. Palpation of the medial pterygoid and superior masseter muscles will help to make the diagnosis. Evaluation of vertigo, tinnitus, and auditory discrimination disorders, common in CFS, has been previously discussed, although trigger points in the clavicular division of the sternomastoid can disturb proprioception and cause postural dizziness. Tinnitus can be caused by trigger points in the superior masseter.
Chewing Entrains Cyclical Actions but Interferes With Discrete Actions in Children
Published in Journal of Motor Behavior, 2021
Jessica Prebor, Brittany Samulski, Cortney Armitano-Lago, Steven Morrison
Chewing rates were determined from changes in the EMG activity of the masseter muscle. The EMG sensor was positioned over the belly of the masseter muscle on the dominant chewing side as determined by the participant at the start of the session. All EMG activity was recorded using the Delsys Trigno system (Delsys, Boston, MA) at a sample rate of 2000 Hz. Processing of the surface EMG signals involved down-sampling the signal to 1000 Hz, rectification and filtering using a second-order low-pass Butterworth filter (cutoff frequency 400 Hz). The number of peaks of the filtered EMG signal, which are reflective of the contraction of the masseter muscle during chewing, were calculated using a purposely designed Matlab algorithm. Accuracy of the results from the algorithm for determining chewing rates was verified by visual inspection of 50% of the trials for each subject. All signal processing was performed using custom software developed in Matlab (Mathworks R14).
Comparison of immediate effects of sling-based manual therapy on specific spine levels in subjects with neck pain and forward head posture: a randomized clinical trial
Published in Disability and Rehabilitation, 2020
Forward head posture (FHP) is identified as the flexion of the lower cervical spine (C4-7) along with the extension of the upper cervical spine (C1-3), with an overall increase in the cervical curve, referred to as hyperlordosis [2]. This abnormal position appears mainly in office workers and students in the modern society. It has been reported that as the head position increases, the tension of the muscles that maintain the posture of the neck increases and the joint compression force of the cervical vertebra increases [3]. Yip et al. [4] also reported that the severity of neck pain and dysfunction levels increased as the head shifted forward. In addition, extension of the craniocervical area has been reported to increase the muscle activity of the temporal and masseter muscles due to the change in the position and movement of the mandible in the chewing process [2].
The diagnosis and management of temporal arteritis
Published in Clinical and Experimental Optometry, 2020
Melvin Lh Ling, Jason Yosar, Brendon Wh Lee, Saumil A Shah, Ivy W Jiang, Anna Finniss, Alexandra Allende, Ian C Francis
Jaw claudication occurs in up to 50 per cent of patients with TA and may be misdiagnosed as temporomandibular joint disorder (TMJD).1997 In TA, jaw claudication is caused by masseter muscle ischaemia and is characterised by pain that develops with or soon after chewing, and subsides with rest. In contrast, TMJD causes jaw pain with any movement, emphasising the difference between the mechanical and ischaemic nature of the pain.2009 Patients with jaw claudication often avoid chewy foods or meat, although this is not a distinguishing feature from TMJD.1991 In one study, 54 per cent of patients with positive temporal artery biopsies had jaw claudication compared with only three per cent who had negative biopsies.1995 Asking a patient to chew gum is a simple method of evaluating jaw claudication,2016 but in the absence of chewing gum in the clinic, the authors simply ask the patient to open and close the jaw rapidly and forcefully 20 times. Jaw claudication alone should not be used to rule in TA due to the potential morbidity associated with steroid treatment, as demonstrated in one case by the authors of mandibular osteomyelitis misdiagnosed as TA.2011