The development of spontaneous facial responses to others' emotions in infancy: An EMG study.

Viewing facial expressions often evokes facial responses in the observer. These spontaneous facial reactions (SFRs) are believed to play an important role for social interactions. However, their developmental trajectory and the underlying neurocognitive mechanisms are still little understood. In the current study, 4- and 7-month old infants were presented with facial expressions of happiness, anger, and fear. Electromyography (EMG) was used to measure activation in muscles relevant for forming these expressions: zygomaticus major (smiling), corrugator supercilii (frowning), and frontalis (forehead raising). The results indicated no selective activation of the facial muscles for the expressions in 4-month-old infants. For 7-month-old infants, evidence for selective facial reactions was found especially for happy (leading to increased zygomaticus major activation) and fearful faces (leading to increased frontalis activation), while angry faces did not show a clear differential response. These results suggest that emotional SFRs may be the result of complex neurocognitive mechanisms which lead to partial mimicry but are also likely to be influenced by evaluative processes. Such mechanisms seem to undergo important developments at least until the second half of the first year of life.

Unilateral nasal obstruction affects motor representation development within the face primary motor cortex in growing rats.

Postnatal growth is influenced by genetic and environmental factors. Nasal obstruction during growth alters the electromyographic activity of orofacial muscles. The facial primary motor area represents muscles of the tongue and jaw, which are essential in regulating orofacial motor functions, including chewing and jaw opening. This study aimed to evaluate the effect of chronic unilateral nasal obstruction during growth on the motor representations within the face primary motor cortex (M1). Seventy-two 6-day-old male Wistar rats were randomly divided into control (n = 36) and experimental (n = 36) groups. Rats in the experimental group underwent unilateral nasal obstruction after cauterization of the external nostril at 8 days of age. Intracortical microstimulation (ICMS) mapping was performed when the rats were 5, 7, 9, and 11 wk old in control and experimental groups (n = 9 per group per time point). Repeated-measures multivariate ANOVA was used for intergroup and intragroup statistical comparisons. In the control and experimental groups, the total number of positive ICMS sites for the genioglossus and anterior digastric muscles was significantly higher at 5, 7, and 9 wk, but there was no significant difference between 9 and 11 wk of age. Moreover, the total number of positive ICMS sites was significantly smaller in the experimental group than in the control at each age. It is possible that nasal obstruction induced the initial changes in orofacial motor behavior in response to the altered respiratory pattern, which eventually contributed to face-M1 neuroplasticity.NEW & NOTEWORTHY Unilateral nasal obstruction in rats during growth periods induced changes in arterial oxygen saturation (SpO2) and altered development of the motor representation within the face primary cortex. Unilateral nasal obstruction occurring during growth periods may greatly affect not only respiratory function but also craniofacial function in rats. Nasal obstruction should be treated as soon as possible to avoid adverse effects on normal growth, development, and physiological functions.

A influência do aleitamento materno no crescimento e desenvolvimento craniofacial, sob o conceito da reabilitação neuroclusal / Influence of breastfeeding on craniofacial growth and development under the concept of neuro oclusion rehabilitation

Os benefícios do aleitamento materno, tanto para a mãe como para o bebê, do ponto de vista imunológico, nutritivo, afetivo, psicológico, entre outros, é um consenso entre os profissionais da saúde. Entretanto, nesta revisão da literatura objetivou-se demonstrar que a amamentação propicia mais do que isso. O aleitamento materno é o fator decisivo e primordial para a correta maturação e crescimento craniofacial em nível ósseo, muscular e funcional, mantendo essas estruturas aptas para exercerem o desenvolvimento da musculatura orofacial, que guiará e estimulará o desenvolvimento das funções fisiológicas, garantindo não somente a sobrevivência, mas também uma melhor qualidade de vida. Assim sendo, procurou-se enfatizar nesta pesquisa o efeito do aleitamento materno sobre o desenvolvimento do sistema estomatognático e seu efeito protetor na prevenção de hábitos de sucção e más-oclusões...

The benefits of breastfeeding for both mother and baby, in view of immunology, nutrition, affection, among others are a consensus among health professionals. However, this literature review aimed to demonstrate that breastfeeding provides more than that. Breastfeeding is the primary and decisive factor for proper maturation and craniofacial growth in bone, muscle and functional level; keeping those structures able to pursue orofacial muscles development, which will guide and stimulate physiological functions, not only ensuring survival, but also a better quality of life. Therefore, this research seeks to emphasize the effect of breastfeeding on the development of stomatognathic system and its protecting effect preventing suction habits and malocclusions under the concept of neuro occlusion rehabilitation...

Small heat shock protein HSPB1 regulates growth of embryonic zebrafish craniofacial muscles.

The small heat shock protein HspB1 (Hsp27) is abundantly expressed in embryonic muscle tissues of a wide variety of vertebrate species. However, the functional significance of this expression pattern is not well established. In the present study, we observed specific, high level expression of HspB1 protein and an HspB1 gene reporter in developing craniofacial muscles of the zebrafish, Danio rerio, and examined the consequences of reducing HspB1 expression to the development and growth of these muscles. Quantitative morphometric analyses revealed a reduction in the cross-sectional area of myofibers in embryos expressing reduced HspB1 levels by as much as 47% compared to controls. In contrast, we detected no differences in the number of myofibrils or associated nuclei, nor the number, size or development of chondrocytes in surrounding tissues. We also did not detect changes to the overall organization of sarcomeres or myofibrils in embryos expressing reduced levels of HspB1. Together our results reveal a critical role for HspB1 in the growth of myofibrils and provide new insight into the mechanism underlying its developmental function.

Effects of environmental stimulation on infant vocalizations and orofacial dynamics at the onset of canonical babbling.

The vocalizations and jaw kinematics of 30 infants aged 6-8 months were recorded using a Motion Analysis System and audiovisual technologies. This study represents the first attempt to determine the effect of play environment on infants' rate of vocalization and jaw movement. Four play conditions were compared: watching videos, social contingent reinforcement and vocal modeling with an adult, playing alone with small toys, and playing alone with large toys. The fewest vocalizations and spontaneous movement were observed when infants were watching videos or interacting with an adult. Infants vocalized most when playing with large toys. The small toys, which naturally elicited gross motor movement (e.g., waving, banging, shaking), educed fewer vocalizations. This study was also the first to quantify the kinematics of vocalized and non-vocalized jaw movements of 6-8 month-old infants. Jaw kinematics did not differentiate infants who produced canonical syllables from those who did not. All infants produced many jaw movements without vocalization. However, during vocalization, infants were unlikely to move their jaw. This contradicts current theories that infant protophonic vocalizations are jaw-dominant. Results of the current study can inform socio-linguistic and kinematic theories of canonical babbling.

Craniofacial growth variations in nasal-breathing, oral-breathing, and tracheotomized children.

INTRODUCTION: Childhood oral breathing can alter muscular balance and lead to facial deformities. No articles in the literature have reported on the alteration of facial growth patterns in patients who have received tracheotomies. The purpose of this study was to evaluate craniofacial developmental consequences originating from variations in breathing mechanisms in children who are nasal breathers or oral breathers, and those who have been tracheotomized. METHODS: The sample was divided into 3 groups of 10 each. The nasal group had a mean age of 13.9 years, the oral group had a mean age of 12.7 years, and the tracheotomy group had a mean age of 12.8 years. The masseter and suprahyoid muscles were evaluated with electromyography. The following measurements were made: facial, maxillary, and mandibular widths; nasion-sella-gnathion angle; and facial index. RESULTS: The tracheotomized group was similar to the nasal group for greater activity of the masseter muscles than of the suprahyoid muscles during mastication, as well as in the measurements of facial, maxillary, and mandibular widths. The oral group showed reductions in each category. The tracheotomized group was similar to the oral group during maximum dental occlusion for significantly higher activity of the suprahyoid muscles compared with the masseter muscles, with reductions in vertical values. CONCLUSIONS: A childhood tracheotomy might affect facial development in a way comparable with that of oral breathers, including abnormal facial growth variations.

An eye on the head: the development and evolution of craniofacial muscles.

Skeletal muscles exert diverse functions, enabling both crushing with great force and movement with exquisite precision. A remarkably distinct repertoire of genes and ontological features characterise this tissue, and recent evidence has shown that skeletal muscles of the head, the craniofacial muscles, are evolutionarily, morphologically and molecularly distinct from those of the trunk. Here, we review the molecular basis of craniofacial muscle development and discuss how this process is different to trunk and limb muscle development. Through evolutionary comparisons of primitive chordates (such as amphioxus) and jawless vertebrates (such as lampreys) with jawed vertebrates, we also provide some clues as to how this dichotomy arose.

[Supraclusion origins]. / La genèse de la supraclusion.

Orthodontists often observe the clinical sign of supraclusion, or deep overbite, in their patients, a condition that is difficult to correct and that relapses frequently. In order to treat it with the most appropriate therapy, orthodontists should have a precise understanding of its etiology, which can be skeletal, neuromuscular, or dental and may often result from an intricate web of factors. In preparing their diagnoses, orthodontists should examine the possible mechanisms of its installation and evaluate them in an architectural cephalometric analysis of the oral prehensile complex.

[Convergent development of the subcutaneous muscles in moles and golden moles].

The goal of the investigation was to clarify the ways of subcutaneous muscles development in burrowing forms of insectivores--moles (Talpidae) and golden moles (Chrysochloridae). To achieve the goal the comparative morpho-functional analysis of subcutaneous and facial musculature of six mole genera (Neurotrichus, Urotrichus, Talpa, Mogera, Scalopus, Parascalops), two genera of chrysochlorids (Chrysochloris, Eremitalpa), and some other non-specialized forms of insectivorous mammals from Erinaceidae, Tenrecidae, Soricidae and Solenodontidae was carried out. It was shown that some of m. cutaneus trunci derivatives interact intimately with facial musculature. Besides, subcutaneous muscle forms additional layers that facilitate the operation of shaking ground particles off the for, which is rather important for burrowers. Overall complication of subcutaneous musculature in moles and chrysochlorids is accompanied by convergent similarity in the development of some musculature portions. At the same time some layers of m. cutaneus trunci seem to have evolved in different, special ways.

Heart and craniofacial muscle development: a new developmental theme of distinct myogenic fields.

Head muscle development has been studied less intensively than myogenesis in the trunk, although this situation is gradually changing, as embryological and genetic insights accumulate. This review focuses on novel studies of the origins, composition and evolution of distinct craniofacial muscles. Cellular and molecular parallels are drawn between cardiac and branchiomeric muscle developmental programs, both of which utilize multiple lineages with distinct developmental histories, and argue for the tissues' common evolutionary origin. In addition, there is increasing evidence that the specification of skeletal muscles in the head appears to be distinct from that operating in the trunk: considerable variation among the different craniofacial muscle groups is seen, in a manner resembling myogenic specification in lower organisms.

Comparison of maximum mouth-opening capacity and condylar path length in adults and children during the growth period.

A group of 80 children ranging in age from 6 to 10 years (subdivided into groups 1-5 according to chronological age) has been compared with an adult group on the basis of condylar path length and maximum mouth-opening capacity. The condylar path length and the mouth-opening capacity were measured using the ultrasonic JMA-System for registration. In the development of the temporomandibular joint (TMJ), condylar path length and mouth-opening capacity were found to increase with age in the juvenile group. In the oldest juvenile subgroup (subgroup 5; average age: 10.3 years) the condylar path length reached 17.6mm on the left and 17.3mm on the right. This is equivalent to 90.3% (left) and 91.1% (right) of the size in the adult group. The mean maximum mouth-opening capacity of the oldest juvenile subgroup was 56.3mm and reached 98.9% of the size in the adult group.

FGF signalling in craniofacial development and developmental disorders.

The Fgf signalling pathway is highly conserved in evolution and plays crucial roles in development. In the craniofacial region, it is involved in almost all structure development from early patterning to growth regulation. In craniofacial skeletogenesis, the Fgf signal pathway plays important roles in suture and synchondrosis regulation. Mutations of FGF receptors relate to syndromatic and non-syndromatic craniosynostosis. The Fgf10/Fgfr2b signal loop is critical for palatogenesis and submandibular gland formation. Perturbation of the Fgf signal is a possible mechanism of palatal cleft. Fgf10 haploinsufficiency has been identified as the cause of autosomal dominant aplasia of lacrimal and salivary glands. The Fgf signal is also a key regulator of tooth formation: in the absence of Fgfr2b tooth development is arrested at the bud stage. Fgfr4 has recently been identified as the key signal mediator in myogenesis. In this review, these aspects are discussed in detail with a focus on the most recent advances.

Effect of unilateral partial facial paralysis on periosteal growth at the muscle-bone interface of facial muscles and facial bones.

In a previous study, the influence of the midfacial musculature upon growth and development of the maxilla and mandible was established macroscopically. Dry skull measurements revealed a reduced premaxillary, maxillary, mandibular, and anterior corpus length with a simultaneous increase in mandibular ramal height on the paralyzed side. It was demonstrated that these reduced premaxillary and maxillary lengths were among others the result of reduced nasofrontal growth, whereas the increased ramal height was accompanied by condylar growth alterations. This study investigated whether the growth alterations at the mandibular corpus region could be explained by altered periosteal growth at the muscle-bone interface of the zygomatico-auricular muscle and the mandibular corpus, caused by altered muscle activity acting upon the periosteal sleeve. Fifty-six 12-day-old New Zealand White rabbits were randomly assigned to either a control or an experimental group. In the experimental group, left-sided partial facial paralysis was induced surgically when the animals were 12 days old. To study the muscle-bone interface, seven follow-up time intervals were defined between 3.5 and 60 days following the surgery. At these time intervals, four randomly selected control animals and four randomly selected experimental animals were killed. The anterior mandibular corpus region with the muscle-bone interface of the left control hemimandible and the left and right experimental hemimandibles was processed for undecalcified tissue preparation. Quantitative analysis of the total bone area at the muscle-bone interface revealed no significant differences between the left control hemimandible and the left and right experimental hemimandibles. Also, qualitative study of the histologic sections showed no major changes in the appearance or development of the trabecular pattern between the groups. However, slight differences in the distribution pattern of osteoblasts and osteoclasts along the bony surface were found between the left control hemimandible and the left and right experimental hemimandibles, which seemed to explain the alterations in mandibular corpus shape between these groups. It was suggested that these changes in the distribution pattern of osteoblasts and osteoclasts were the result of changes in the loading distribution pattern acting upon the mandible, caused by an altered neuromuscular recruitment pattern of the remaining functionally intact, mandibularly attached muscles. The latter was probably the result of adaptive mandibular positioning in response to an altered occlusal relationship, which was induced by the abnormal maxillary growth as a result of the unilateral partial facial paralysis.

Control of facial muscle development by MyoR and capsulin.

Members of the MyoD family of basic helix-loop-helix (bHLH) transcription factors control the formation of all skeletal muscles in vertebrates, but little is known of the molecules or mechanisms that confer unique identities to different types of skeletal muscles. MyoR and capsulin are related bHLH transcription factors expressed in specific facial muscle precursors. We show that specific facial muscles are missing in mice lacking both MyoR and capsulin, reflecting the absence of MyoD family gene expression and ablation of the corresponding myogenic lineages. These findings identify MyoR and capsulin as unique transcription factors for the development of specific head muscles.

Effects of post-natal serotonin levels on craniofacial complex.

Although the role of serotonin (5-hydroxytryptamine or 5-HT) in pre-natal craniofacial growth and development has been studied, no research has been done on the effects of serotonin on post-natal craniofacial growth and development. The following experimental question was tested: What effect does increasing in vivo serotonin levels adjacent to trigeminal motoneurons have on post-natal craniofacial structures in young, actively growing rats? Forty male Sprague-Dawley rats were divided into 4 experimental groups (10% serotonin microspheres, 15% serotonin microspheres, blank microspheres, sham surgeries) and underwent stereotactic neurosurgery at post-natal day 35; 5 rats of each group were killed at 14 and 21 post-surgical days for data collection. Statistical analyses by mixed-model, 4 x 2 repeated-measures ANOVA, and post hoc Fisher LSD tests revealed significant (P < or = 0.05, 0.01) differences between groups and sides for muscle weight, cranial dimension, and TMJ dimension data. Data described here indicate that significant alterations of post-natal craniofacial structures can be caused by altered in vivo levels of serotonin adjacent to trigeminal motoneurons.

The extracellular matrix of muscle--implications for manipulation of the craniofacial musculature.

Successful adaptation of craniofacial skeletal muscle is dependent upon the connective tissue component of the muscle. This is exemplified by procedures such as distraction histo/osteogenesis. The mechanisms underlying remodelling of intramuscular connective tissue are complex and multifactorial and involve extracellular matrix (ECM) molecules, receptors for the ECM (integrins) and enzymes that remodel the ECM (MMPs). This review discusses the current state of knowledge and clinical implications of connective tissue biology as applied to craniofacial skeletal muscle.

Mandibular arch musculature of anuran tadpoles, with comments on homologies of amphibian jaw muscles.

This study analyzes the structure of the mandibular arch musculature in larval, metamorphic, and postmetamorphic anurans of 26 species and makes comparisons with larvae of three caudate and one gymnophione species. Major transformations in early evolution of anuran larvae comprise, for example, the powering of the larval upper jaw cartilages by relocating insertion sites of mandibular arch levators; splitting of some larval muscles into two muscles or muscle heads (m. intermandibularis, m. lev. mand. externus, m. lev. mand. longus); evolution of a muscle invading the lower lip of the oral disk (m. mandibulolabialis), and shift of origin of the internus and longus muscles from dorsal on the cranium to sites on the ventral otic capsule and palatoquadrate, respectively. In all these characters, Ascaphus truei shares the plesiomorphic conditions with caudates. The larva of Xenopus laevis is remarkable because the insertion pattern of three larval mandibular muscles anticipates the postmetamorphic condition of frogs in general and also resembles the caudate condition. Discoglossids, bombinatorids, pelobatids, and neobatrachians are largely similar in their muscle arrangements. The filter-feeding microhylids, however, have most clearly modified the general neobatrachian pattern. Past conflicts in the interpretation and naming of muscles can be attributed to the implicit or explicit homology assumptions used. In particular, the muscles' relations to the branches of the trigeminal nerve have been the dominant criteria for inferring homology and has led to inconsistencies. This concept is questioned herein. It is observed that the relative position of the ramus mandibularis (V(3)) is more variable interspecifically in anuran larvae than previously thought. The relations of the nerve branches and muscles in larvae are maintained during metamorphosis. Considering the muscle pattern to be more conserved in interspecific comparisons than the position of the nerve branches results in a new interpretation of muscle homologies and a hypothesis of jaw muscle evolution in amphibians that is more parsimonious than earlier views. A new, simplified terminology for the jaw musculature is proposed that is applicable for larvae and adults. It maximizes information content and reflects the hypothesized homologies of amphibian jaw muscles.

The influence of the muscles of facial expression on the development of the midface and the nose in cleft lip and palate patients. A reflection of functional anatomy, facial esthetics and physiology of the nose.

The further improvement of well-established techniques in primary and secondary cleft surgery requires a detailed and interdisciplinary knowledge and observation of anatomical, functional and developmental problems. An investigation into the macroscopic and microscopic anatomy of the perinasal and perioral muscles and parts of the human nasal septum, as well as into the pathomorphology of ancient skulls with untreated clefts is presented. On this basis an interpretation of clinical findings in untreated newborns compared with surgically treated CLP-patients has been undertaken. The 3D-CT, superimposing photography and coloured experimental settings of nasal airflow complete the visualisation of the anatomical and functional findings.