At the angle of the mouth, spoke-like muscle bundles converge at the \"modiolus,\" which is believed to appear in utero. The aim of this study was to investigate the growth of the modiolus histologically. We studied frontal histological sections of the face from 12 midterm and six near-term fetuses. At midterm, a convergence of the levator anguli oris (LAOM) and depressor anguli oris (DAOM) was frequently present, and another convergence of the LAOM with the platysma (PM) or orbicularis oris (OOM) was also often evident. At near-term, muscle fiber merging or interdigitation was classified into nine combinations, five of which were frequently seen: LAOM-PM, LAOM-DAOM, zygomaticus major (ZMM)-orbicularis oris (OOM), buccinator (BM)-LAOM, and BM-PM. These combinations existed at slightly different depths and/or sites, thus allowing the angle of the mouth to receive multiple muscles. Notably, tissues interposed between the muscle fibers were limited to a thin epimysium at each crossing or interdigitation. Therefore, the LAOM, DAOM, OOM, BM, and PM appear to form a basic configuration at birth, but the development and growth were much delayed than the classical description. The modiolus is not a specific fibromuscular structure but simply represents a cluster of muscle convergence sites. Even at meeting between an elevator and depressor, a specific fibrous structure seems unlikely to connect the epimysium for the muscle convergence. Instead, the central nervous system appears to regulate the activity of related muscles to minimize tension or friction stress at the meeting site.

The purpose of the study was to assess the effects of a novel technique involving facial stretching of the unaffected side along with a structured exercise for the affected side on facial symmetry and facial functions as compared to conventional exercise. A hospital-based parallel-group randomized trial was completed among patients with acute Bell\'s palsy in Mangalore, India. Participants were randomized to receive facial stretching and a structured exercise program (experimental group) or the conventional exercise regimen (conventional group). Primary outcomes were facial symmetry and voluntary movement; assessed by the Sunnybrook Facial Grading System (SFGS). Both regimens were given for 3 weeks, with baseline, 10th day, and 20th day assessments. Out of 31 participants screened, 24 were eligible and 12 participants each were assigned to experimental and conventional groups. Change scores revealed greater improvement in the SFGS score (p = 0.002) for the experimental group participants. Facial stretching and structured exercise program exhibited promising results in enhancing facial symmetry and function in acute Bell\'s palsy when compared to conventional exercise regimen.

OBJECTIVE: To investigate oropharyngeal structures and functions in a pediatric population with Down Syndrome (DS) and obstructive sleep apnea (OSA) and to correlate with the apnea/hypopnea index (AHI) and sleep questionnaires.
METHODS: 12 Children with DS and OSA, between the age of 4 and 12 years old, underwent polysomnography (PSG); sleep questionnaires, Pediatric Sleep Questionnaire (PSQ) and Obstructive Sleep Apnea-18 (OSA-18); and speech-language evaluation using the Short Evaluation of Orofacial Myofunctional Protocol (ShOM).
RESULTS: There was a positive correlation between ShoM higher scores and the apnea-hypopnea index (AHI) and between ShoM and the number of hypopneas. The orofacial myofunctional alterations observed in the studied group were: oral breathing, alteration in lip tonus and competence, tongue posture at rest and in swallowing, and occlusal alteration. There was also an increased risk for OSA according to the sleep questionnaires, as well as the presence of obesity and overweight, but without correlation with the severity of OSA.
CONCLUSIONS: All DS children show alterations in orofacial characteristics, higher scores being associated to severe OSA. Orofacial myofunctional evaluation may help to identify different phenotypes in Down syndrome children with Obstructive sleep Apnea, enhancing the need for a multidisciplinary approach.
OBJECTIVE: Investigar as estruturas e funções orofaríngeas de uma população pediátrica com Síndrome de Down (SD) e apneia obstrutiva do sono (AOS) e correlacionar com o índice de apneia/hipopneia (IAH) e questionários do sono.
UNASSIGNED: 12 Crianças com SD e AOS, entre 4 e 12 anos, foram submetidas à polissonografia (PSG); questionários do sono, Pediatric Sleep Questionnaire (PSQ) e Obstructive Sleep Apnea-18 (OSA-18); e triagem fonoaudiológica por meio do Short Evaluation of Orofacial Myofunctional Protocol (ShOM).
RESULTS: Verificou-se uma correlação positiva entre pontuações mais elevadas no ShOM e o índice de apneia hipopneia (IAH) e entre o ShOM e número de hipopneias. As alterações miofuncionais orofaciais observadas no grupo estudado foram: respiração oral, alteração no tônus e competência labial, na postura de língua em repouso e na deglutição e alteração oclusal. Verificou-se também, um risco aumentado para AOS conforme os questionários do sono, bem como presença de obesidade e sobrepeso, mas sem correlação com a gravidade da AOS.
UNASSIGNED: Todas as crianças apresentaram alterações miofuncionais orofaciais, sendo que escores mais altos no ShOM, ou seja, um maior comprometimento miofuncional orofacial, estavam associados à maior gravidade de AOS, sugerindo que a avaliação miofuncional orofacial dentro de uma abordagem multidisciplinar pode auxiliar na identificação de fatores de risco para AOS em crianças com SD.

OBJECTIVE: Development of a technique for measuring the mechanical properties of zygomaticus major (ZM) may aid advances in clinical treatments for correcting abnormal oral posture. The objective of this work was to demonstrate the feasibility of measuring the stiffness of ZM using an MR elastography technique that incorporates a custom local driver and a phase-gradient (PG) inversion.
METHODS: 2D MRE investigations were performed for 3 healthy subjects using a vibration frequency of 90 Hz to test the prediction that the stiffness of ZM would be greater in the mouth-open compared to the mouth-closed position. MRE wave images were acquired along the long axis of ZM and processed using a 2D spatial-temporal directional filter applied in the direction of wave propagation along the long axis of the muscle. Stiffness measurements were obtained by applying the PG technique to a 1D-profile drawn in the phase image of the first harmonic of the wave images and a one-tailed paired t-test was used to compare the ZM stiffness between the two mouth postures (p < 0.05).
RESULTS: The mean stiffness and standard deviation (SD) of ZM across the three participants in the mouth-closed and mouth-open postures was 6.75 kPa (SD 3.36 kPa) and 15.5 kPa (SD 5.15 kPa), respectively. Changes of ZM stiffness were significantly greater in the mouth-open than the mouth-closed posture (p = 0.038).
CONCLUSIONS: The feasibility of using the PG MRE technique to measure stiffness changes in a small muscle such as ZM for different mouth postures has been demonstrated. Further investigations are required in a larger cohort of participants to investigate the sensitivity and reproducibility of the technique for potential clinical application as well as in health and beauty related studies.

Striated muscle insertions into the skin and mucosa are present in the head, neck, and pelvic floor. We reexamined the histology of these tissues to elucidate their role in transmission of the force. We examined histological sections of 25 human fetuses (gestational ages of ~11-19 weeks and ~26-40 weeks) and 6 cadavers of elderly individuals. Facial muscle insertion or terminal almost always formed as an interdigitation with another muscle or as a circular arrangement in which muscle fiber insertions were sandwiched and mechanically supported by other muscle fibers (like an in-series muscle). Our examination of the face revealed some limited exceptions in which muscle fibers that approached the dermis were always in the nasalis and mentalis muscles, and often in the levator labii superioris alaeque nasi muscle. The buccinator muscle was consistently inserted into the basement membrane of the oral mucosa. Parts of the uvulae muscle in the soft palate and of the intrinsic vertical muscle of the tongue were likely to direct toward the mucosa. In contrast, the pelvic floor did not contain striated muscle fibers that were directed toward the skin or mucosa. Although \'cutaneous muscle\' is a common term, the actual insertion of a muscle into the skin or mucosa seemed to be very rare. Instead, superficial muscle insertion often consisted of interdigitated muscle bundles that had different functional vectors. In this case, the terminal of one muscle bundle was sandwiched and fixed mechanically by other bundles.

BACKGROUND: Facial muscles, particularly those involved in mastication, play a pivotal role in the chewing process. Despite their influence on chewing, these muscles undergo alterations during mastication. Examining the relationship between chewed substances and muscle activity can provide insights into various pathological processes and aid in the development of therapeutic chewing techniques.
OBJECTIVE: This study aimed to evaluate the impact of different commercially available chewing gums on the activity of key masticatory muscles.
METHODS: Twenty-two participants were recruited for the study. They were instructed to chew four commercially available gums: group 1 comprised sugar gum with a strong flavor; group 2 included gum containing sorbitol; group 3 consisted of gum containing xylitol; and group 4 provided sugar gum with a mild flavor. Electromyogram (EMG) recordings were utilized to assess muscle activity. Various aspects of muscle activity, including chewing time, maximum muscle potential, and coordination between different muscles, were evaluated. Data tabulation and analysis were performed using IBM SPSS software version 23.0 (IBM Corp., Armonk, NY).
RESULTS: Analysis revealed that in terms of temporalis symmetry, group 2 exhibited the highest mean deviation, while for masseter symmetry, group 3 demonstrated the highest mean deviation. The total deviation for the temporalis and masseter muscles was 72.16% and 65.55%, respectively, indicating greater symmetry in the temporalis muscle. Additionally, group 3 displayed the highest mean deviation in both left and right-sided synergic activity of the muscles. The total deviation for the right and left sides was 64.34% and 65.67%, respectively.
CONCLUSIONS: The findings suggest that sugar-free chewing gums elicit increased muscle activity compared to sugar-containing chewing gums. Furthermore, the utilization of calorie-free chewing gums with a firm texture was associated with better-coordinated muscle activity. These results provide valuable insights into the effects of different chewing gums on masticatory muscle function and coordination, which may have implications for therapeutic interventions and oral health management.

Dysfunction of the facial musculature can have significant physical, social, and psychological consequences. In surgeries such as cleft surgery or craniofacial bimaxillary osteotomies, the perioral facial muscles may be detached or severed, potentially altering their functional vectors and mimicry capabilities. Ensuring correct reconstruction and maintenance of anatomical sites and muscle vectors is crucial in these procedures. However, a standardized method for perioperative assessment of the facial musculature and function is currently lacking. The aim of this study was to develop a workflow to analyse the three-dimensional vectors of the facial musculature using magnetic resonance imaging (MRI) scans. A protocol for localizing the origins and insertions of these muscles was established. The protocol was implemented using the 3DMedX computer program and tested on 7 Tesla MRI scans obtained from 10 healthy volunteers. Inter- and intra-observer variability were assessed to validate the protocol. The absolute intra-observer variability was 2.6 mm (standard deviation 2.0 mm), and absolute inter-observer variability was 2.6 mm (standard deviation 1.5 mm). This study presents a reliable and reproducible method for analysing the spatial relationships and functional significance of the facial muscles. The workflow developed facilitates perioperative assessment of the facial musculature, potentially aiding clinicians in surgical planning and potentially enhancing the outcomes of midface surgery.

BACKGROUND: There is no information about muscle growth in eyelids with infrequent blinking in fetuses.
METHODS: To examine the muscle and nerve morphology, we morphometrically and immunohistochemically examined sagittal sections of unilateral upper eyelids obtained from 21 term fetuses (approximately 30-42 weeks of gestation) and, for the comparison, those from 10 midterm fetuses (12-15 weeks).
RESULTS: The approximation margin of the upper eyelid always corresponded to the entire free margin in midterm fetuses, whereas it was often (18/21) restricted in the posterior part in term fetuses. Thus, in the latter, the thickness at the approximation site to the lower lid often ranged from 0.8 to 1.6 mm and corresponded to 18-56% of the nearly maximum thickness of the lid. In the lower part of the upper eyelid, a layer of the orbicularis oculi muscles often (14/21) provided posterior flexion at 90-120° to extend posteriorly. Nerve fibers running along the mediolateral axis were rich along the approximation surface at term, but they might not be reported in the upper eyelid of adults.
CONCLUSIONS: Being different from adult morphologies, the term eyelid was much thicker than the approximation surface and it carried a flexed muscle layer and transversely-running nerve. The infrequent blinking in fetuses seemed to provide a specific condition for the muscle-nerve growth. Plastic and pediatric surgeons should pay attention to a fact that infants\' upper eyelid was unlikely to be a mini-version of the adult morphology.

The experience of empathy for pain is underpinned by sensorimotor and affective dimensions which, although interconnected, are at least in part behaviorally and neurally distinct. Spinal cord injuries (SCI) induce a massive, below-lesion level, sensorimotor body-brain disconnection. This condition may make it possible to test whether sensorimotor deprivation alters specific dimensions of empathic reactivity to observed pain. To explore this issue, we asked SCI people with paraplegia and healthy controls to observe videos of painful or neutral stimuli administered to a hand (intact) or a foot (deafferented). The stimuli were displayed by means of a virtual reality set-up and seen from a first person (1PP) or third person (3PP) visual perspective. A number of measures were recorded ranging from explicit behaviors like explicit verbal reports on the videos, to implicit measures of muscular activity (like EMG from the corrugator and zygomatic muscles that may represent a proxy of sensorimotor empathy) and of autonomic reactivity (like the electrodermal response and Respiratory Sinus Arrhythmia that may represent a general proxy of affective empathy). While no across group differences in explicit verbal reports about the pain stimuli were found, SCI people exhibited reduced facial muscle reactivity to the stimuli applied to the foot (but not the hand) seen from the 1PP. Tellingly, the corrugator activity correlated with SCI participants\' neuropathic pain. There were no across group differences in autonomic reactivity suggesting that SCI lesions may affect sensorimotor dimensions connected to empathy for pain.

The use of wearable sensors for real-time monitoring of exercise-related measures has been extensively studied in recent years (e.g., performance enhancement, optimizing athlete\'s training, and preventing injuries). Surface electromyography (sEMG), which measures muscle activity, is a widely researched technology in exercise monitoring. However, due to their cumbersome nature, traditional sEMG electrodes are limited. In particular, facial EMG (fEMG) studies in physical training have been limited, with some scarce evidence suggesting that fEMG may be used to monitor exercise-related measurements. Altogether, sEMG recordings from facial muscles in the context of exercise have been examined relatively inadequately. In this feasibility study, we assessed the ability of a new wearable sEMG technology to measure facial muscle activity during exercise. Six young, healthy, and recreationally active participants (5 females), performed an incremental cycling exercise test until exhaustion, while facial sEMG and vastus lateralis (VL) EMG were measured. Facial sEMG signals from both natural expressions and voluntary smiles were successfully recorded. Stable recordings and high-resolution facial muscle activity mapping were achieved during different exercise intensities until exhaustion. Strong correlations were found between VL and multiple facial muscles\' activity during voluntary smiles during exercise, with statistically significant coefficients ranging from 0.80 to 0.95 (p<0.05). This study demonstrates the feasibility of monitoring facial muscle activity during exercise, with potential implications for sports medicine and exercise physiology, particularly in monitoring exercise intensity and fatigue.