Labial Muscles Research Articles

Anatomy in dentistry: From the beginnings to contemporary reality.

The history of dentistry and medicine has a deep and ancient bond with the history of anatomy. From the ancient times to the present, the study of the human body represents the basis for research and clinical therapy. The historical contribution of anatomists to the development of dental medicine also helped in its characterization as an integrated but special and independent branch of medicine. From Galen's studies on animals to the discoveries of dental hard tissues characteristics using a microscope, this paper provides a brief literature review of how anatomy broadly contributed to the development of the dental sciences and how it still allows us to direct critical and fundamental anatomical-clinical paths for modern patient care. The history of the anatomy of teeth, description of skull bones, maxillary sinus characterization, the salivary glands, the tongue and labial musculature, and the microscopic anatomy of dental hard tissues will be examined. Historical research on the understanding of and progress in the oral field is of utmost importance in current clinical practice, thus inducing a future orientation in research. Most of the research especially that connected to the more distant historical periods has seen as main characters great personalities of morphological sciences, which contributes constituted fundamental basis for dental clinical aspects. Through a punctual and continuous historical assay, the ancient insights are reconnected to more recent knowledge and distinct research, thus permitting a detailed reconstruction of the historical-anatomical course in the progress of knowledge regarding the oral cavity and related anatomical structures.

Comparison of the Anterior Tooth and Lip Esthetic Characteristics of Hani and Han Youth in China When Speaking.

ObjectiveThis study aims to measure and analyze the lip and tooth dynamic esthetic characteristics at rest and during speech in order to provide a reference for its esthetic design and restoration among the Hani and Han populations in Yunnan Province, China.MethodsSubjects of Hani and Han ethnicity in Yunnan were selected using multistage stratified sampling and inclusive criteria. The lip and tooth dynamic esthetic characteristics of the subjects at rest and during the pinyin pronunciation of “me”, “yi”, “fu”, and “si” were recorded using digital photography and analyzed with computer software.ResultsNo statistical difference was detected between the Hani and Han groups in the upper central-incisor display, when pronouncing the pinyin “yi”. Furthermore, there were no statistical differences in lip dynamic esthetic parameters between the Hani and Han groups, except for the distance between the upper and lower lips when pronouncing “si”. There were three kinds of correlation between the upper central-incisor edge and lower lip: separation, contact, and overlap.ConclusionThe display of upper central incisors and the mouth width of Hani people are larger than those of Han people when at rest. When the pinyin “si” is pronounced, the display of upper central incisors and the upper–lower lip distance of Hani people is less than that of Han people due to labial muscle movement.

Combined mentalis weakening and periosteal flaps in mandibular anterior alveolar corticotomy-assisted orthodontics with bone grafting

Inter-alveolar augmented corticotomies with bone grafting may be used before orthodontic treatment in cases of root out or in major proclination movements in the lower anterior region. Bone graft particle spreading with reduced confinement and strong labial muscle contractions may cause graft resorption. Herein we describe a combined orthodontic corticotomy technique involving periosteal flap grafting confinement and a surgical muscle-weakening flap to avoid resorption.

Tailored Microform Cleft Lip Repair: Personalizing Small Incisions, Orbicularis Reconstruction, and Rhinoplasty.

In the last decade, many surgeons have reported their perspectives on microform cleft lip repair, including techniques for incision placement and size, philtral reconstruction, and nasal base reconstruction. This interest demonstrates continued controversy in the repair of microform cleft lip. This is a retrospective cohort of patients from 2010 to 2016. The authors included patients with microform cleft lip repaired by our described technique who had both preoperative photographs, as well as photographs taken at >1-year follow-up. Patient outcomes were assessed through anthropometric measurements and also subjectively by 3 senior residents of plastic surgery. The inclusion criteria yielded 36 microform cleft lip patients. Most patients were satisfied with their results. Regarding subjective assessment, the scar appearance and symmetry was fairly good. Objective measurements indicated excellent symmetry, with the cleft side achieving 92.58% of the height and measurements of the non-cleft side. Our method of combining labial muscle reconstruction through a personalized, small incision effectively corrects microform cleft lip deformity with minimal scar burden.

The head morphology of Micromalthus debilis (Coleoptera: Micromalthidae) - an archostematan beetle with an unusual morphology and a unique life cycle

Cephalic features of Micromalthus debilis were examined and described in detail for the first time. The head displays several seemingly plesiomorphic features compared to other extant species of Archostemata, especially representatives of Cupedidae and Ommatidae. Cephalic protuberances characteristic for species of these two families are missing and antennal grooves are also absent. The surface of the head capsule is largely smooth, without the characteristic tubercles found in stemgroup beetles and ommatid and cupedid species. Cuticular scales, probably ancestral for Archostemata and possibly for Coleoptera, are also completely absent. The arrangement of three mandibular teeth in a vertical row and an immobilized labrum are derived features shared with Ommatidae. The maxillary endite lobes are absent, as in the very small Crowsoniella relicta (Crowsoniellidae). Like in all other examined archostematan species, mandibular molae and prosthecae are missing. The simplified maxillae apparently play no role in the food uptake but rather function as accessory “ventral antennae”. Derived features include the partly reduced maxillary musculature and lack of extrinsic labial muscles. Apomorphies of the digestive tract include the sclerotized median protuberances of the anterior epipharynx and hypopharynx, and the presence of a vertical anterior pharyngeal loop and a subcerebral postpharyngeal pouch. The tentorium is strongly reduced. Consequently, all antennal muscles originate from the head capsule. A very unusual and possibly plesiomorphic feature is the presence of a short salivary tube and two associated muscles. This is a unique condition in Coleoptera as far as known at present. Structural features suggest that Micromalthus probably feeds on wood infested with fungi. A robust phylogenetic evaluation of anatomical features is presently not possible due to the lack of data for Crowsoniella (Crowsoniellidae) and Sikhotealinia zhiltzovae (Jurodidae). Moreover, phylogenetic and evolutionary interpretations are impeded by possible effects of vestigialization of adults possibly resulting from endosymbionts (e.g. Wolbachia, Rickettsiales).

Perspectives on the Psychosocial Management of Oromandibular Dystonia.

AbstractOromandibular dystonia (OMD) is a rare disorder of movement characterized by tonic muscle contractions that can result in involuntary, repetitive, and patterned muscle contractions of the lingual musculature, labial musculature, and/or muscles of mastication. As a result, dysarthria can be present that can lead to reduced speech intelligibility and have an adverse impact on psychosocial functioning. In this article, we will describe the clinical and speech characteristics of OMD and the various methods of treatment. Then we will introduce and describe patient-reported outcome measures that assess two aspects of psychosocial functioning: communicative participation and quality of life. We will describe the current state of knowledge as it relates to communicative participation and quality of life in this clinical population, and, finally, we will advocate that speech-language pathologists have a unique role in the care of individuals with OMD through the inclusion of patient-reported outcome measures to provide a comprehensive and holistic management plan.

Prevalence of transverse upper labial crease

The presence or hyperactivity of the depressor septi nasi muscle has been proposed to cause a visible crease in the upper labial region that is esthetically disturbing to patients. The objective of this paper was to determine how often an upper labial crease is evident in women and to find a straightforward treatment. Muscular creases can be ameliorated with botulinum toxin. However, weakening the depressor septi nasi muscles with botulinum toxin did not eradicate existing upper labial creases at rest or during facial animation. Therefore, we proposed that a complex interplay exists between the upper labial muscles, and we sought to determine which of these muscles are responsible for the existence of the upper labial crease. A total of 100 consecutive female volunteers who visited a plastic surgery clinic were prospectively examined. The presence and localization of the upper labial crease were assessed at rest and during animation prompted with the “smile test” and during snuffling. Additionally, the appearance and symmetry of the upper labial crease were assessed and correlated with the type of smile to identify the dominant muscles involved. In total, 38% of women older than 40 years presented with an upper labial crease at rest, and 70% presented with a crease during animation. Only one third of the women were aware that they had such a crease when they smiled. When the crease was present, it was bilateral in 98% of the women. When it was asymmetrical, which was the case for 10% of women, the fold was longer, shorter, or less visible on one half of the upper lip. The localization was highly variable and ranged from the base of the columella to the caudal third of the upper lip. When an upper labial crease was present at rest and/or during facial animation, it was associated with a type B smile, i.e., the “canine” smile, due a dominant levator labii superioris muscle. This study showed that upper labial creases are present more often than women are aware of them. The injection of botulinum toxin into the levator labii superioris muscles can eradicate an upper labial crease. Level of Evidence: Level IV, risk / prognostic study.

Gross anatomy of the narial and labial musculatures of one humped Camel (Camelus dromedarius)

Abstract Introduction: The objective of this study was to clarify the anatomy of the narial and labial musculatures of the one-humped camel (Camelus dromedarius) and their nerve supply. Materials and Methods: Sixteen head specimens from adult and symptomatically healthy camels of both sexes were used. The muscles of the nostrils and lips were carefully dissected and illustrated to demonstrate their origin, insertion and relations. The nerves in this area were also dissected to show their branches and distribution. Results: The dissection of these regions revealed that their muscles were arranged in three layers; the superficial layer included M. dilator naris apicalis, M. dilator naris medialis and M. levator nasolabialis, the middle layer was formed of maxillo-labial group of muscles (M. levator labii superioris, M. dilator naris lateralis and M. depressor labii superioris) and the deep layer was formed by M. lateralis nasi. Moreover, the lips had M. orbicularis oris, M. incisivus superioris, M. incisivus inferioris and M. mentalis, however, the M. depressor labii inferioris was absent in the animal under investigation. The muscles of nostrils and lips were innervated by N. trigeminus (V) and N. facialis (VII). Conclusion: The arrangement of the narial and labial muscles is unique and may relate to its living conditions of frequent sand-storms and direct sun rays, where the camel is the only domesticated animal known for its ability to close its nostril.

Surgical anatomy and physiology of swallowing

Deglutition, the act of swallowing, is an extremely complex process involving approximately 50 pairs of muscles and nerves that are responsible for preparing and transferring food and liquids from the mouth to the stomach. A problem with any of these structures can lead to dysphagia and a decrease in the quality of life in patients suffering from it. To successfully diagnose and treat dysphagia, a thorough understanding of deglutition is essential. The anatomy and physiology of the swallowing process is reviewed as it pertains to operative approach and technique.

The first skull of Sivameryx africanus (Anthracotheriidae, Bothriodontinae) from the early Miocene of East Africa

ABSTRACT Here we describe the first known skull and associated postcrania of the small bothriodontine anthracotheriid Sivameryx africanus, which fills an important gap in the current knowledge of morphological diversity within the Anthracotheriidae of Africa. The skull was recovered from the latest early Miocene sediments of the Kalodirr Member in the Turkana Basin of Northern Kenya, and the age is well constrained between two tephra dated to 17.5 ± 0.2 and 16.8 ± 0.2 Ma. A partial mandible of Sivameryx from Kalodirr is also described because it may belong to the same individual. The new anatomical data were incorporated into a genus-level phylogenetic analysis of Bothriodontinae that reveals that Sivameryx is the sister taxon to Hemimeryx and belongs to a clade of advanced bothriodontine anthracotheriids alongside the genera Merycopotamus, Libycosaurus, and Afromeryx. The new material of Sivameryx from Kalodirr greatly expands our knowledge of the cranial anatomy of the genus, because the skull of Sivameryx does not reveal any specializations for aquatic habitats, such as those seen in Libycosaurus. Here we suggest, based on the preserved cranial and postcranial evidence, that Sivameryx may have been a small browser that inhabited denser stands of vegetation at Kalodirr based on evidence from its narrow snout and well-developed labial musculature. However, its masticatory muscles were also relatively well developed, suggesting repetitive loading of the jaw when chewing tough vegetation.

Cephalic muscles of Cyclostomes (hagfishes and lampreys) and Chondrichthyes (sharks, rays and holocephalans): comparative anatomy and early evolution of the vertebrate head muscles

Living vertebrate diversity comprises hagfishes and lampreys (Cyclostomata), elasmobranchs and holocephalans (Chondrichthyes), and bony fish which include tetrapods (Osteichthyes). Based on dissections and an extensive comparative analysis, we provide an updated overview of the anatomy, homologies and evolution of cyclostome and chondrichthyan cephalic muscles, with osteichthyans as primary comparative taxa. The analysis also infers plesiomorphic conditions for vertebrates and gnathostomes. We follow a uniform myological terminology for the Gnathostomata to demonstrate that the last common ancestor of extant vertebrates probably had a single intermandibularis and other mandibular muscles (labial muscles), some constrictores hyoidei and branchiales, and epibranchial and hypobranchial muscle sheets. The division of the cucullaris into levatores arcuum branchialium and protractor pectoralis is an osteichthyan synapomorphy and reflects an evolutionary trend towards a greater separation between the head and pectoral girdle that culminated in the formation of the tetrapod neck. Hence, this paper addresses a long-standing, central issue regarding vertebrate comparative anatomy. It thus provides a valuable basis for future evolutionary, developmental and functional studies of vertebrates and/or of specific vertebrate subgroups/model organisms. © 2014 The Linnean Society of London

Head morphology of Tricholepidion gertschi indicates monophyletic Zygentoma.

The relic silverfish Tricholepidion gertschi is the sole extant representative of the family Lepidotrichidae. Its phylogenetic position is of special interest, since it may provide crucial insights into the early phenotypic evolution of the dicondylian insects. However, the phylogenetic position of T. gertschi is unclear. Originally, it was classified among silverfish (Zygentoma), but various alternative relationships within Zygentoma as well as a sistergroup relationship to all remaining Zygentoma + Pterygota are discussed, the latter implying a paraphyly of Zygentoma with respect to Pterygota. Since characters of the head anatomy play a major role in this discussion, we here present the so far most detailed description of the head of T. gertschi based on anatomical studies by synchrotron micro-computer tomography and scanning electron microscopy. A strong focus is put on the documentation of mouthparts and the anatomy of the endoskeleton as well as the muscle equipment. In contrast to former studies we could confirm the presence of a Musculus hypopharyngomandibularis (0md4). The ligamentous connection between the mandibles composed of Musculus tentoriomandibularis inferior (0md6) is also in contact with the anterior tentorium. Phylogenetic analysis of cephalic data results in monophyletic Zygentoma including T. gertschi. Zygentoma are supported by the presence of a set of labial muscles originating at the postocciput, presence of an additional intralabral muscle, and four labial palpomeres. Character systems like the genitalic system, the mating behaviour, the segmentation of the tarsi, the overall body form, and the presence of ocelli which were proposed in other studies as potentially useful for phylogenetic reconstruction are evaluated.

The functional impact of incidental orofacial muscle activity

Repetitive use of specific muscle groups is known to increase both strength and the ability to sustain muscle activity (i.e., endurance) of those muscle groups. Certain orofacial muscles are necessarily recruited in the course of playing a brass instrument, and thus regular performers may incidentally gain strength and endurance in the orofacial muscles used to perform. To test this possibility, 16 skilled trumpet players and 16 non-playing controls contributed strength and endurance (at 50% of maximum strength) measures for buccal, lingual, and labial muscle groups. Results indicate that trumpet players had greater cheek strength and lip endurance, but there were no differences between test and control groups for tongue strength or endurance. Findings suggest that incidental orofacial muscle activity may have a positive functional impact on orofacial muscle strength and/or endurance. This finding supports a clinically useful, objective measure for diagnosis and may be useful for functional rehabilitation for patients with orofacial disorders including those with Bell's palsy, complications associated with otitis media, acoustic neuromas, or other facial- or cranial nerve damage due to surgery, trauma, or disease.

Esthetic evaluation of dynamic smiles with attention to facial muscle activity

Numerous studies of smile esthetics have used still photos. Photos, however, do not capture the dynamics of a smile, an element that can contribute to overall smile esthetics. In this study, we assessed the esthetics of dynamic smiles. Four facially balanced female dental students were trained to produce 8 distinct smiles using the facial action coding system. Videos of the models' whole faces were presented to 2 panels of raters: dental students and nondental undergraduate students. Smile attractiveness was rated using a Web-based survey. The smile that used 4 labial muscles was rated significantly better than the smile involving only the risorius muscle (P <0.05). The orbicularis oculi improved smile attractiveness (P <0.04), especially among smiles rated less favorably (P <0.05). Visibility of the models' eyes, however, did not influence the ratings (P >0.05), perhaps because orbicularis oculi activation altered activations in other muscles in such a way that smile attractiveness was increased in the lower face. Smile esthetics increased with increased recruitment of muscles involved in smile production. The results were robust across the models, suggesting that objective rating methods of smile-dynamic esthetics could become an important clinical tool.

Structural and functional comparison of the proboscis between tapirs and other extant and extinct vertebrates

Tapirs (Perissodactyla: Tapiridae) are the only living vertebrates, beyond the order Proboscidea, found to possess a true proboscis, defined as a flexible tubular extension of the joint narial and upper labial musculature that serves, at least in part, to grasp food. Tapirs show only partial homology and analogy with elephants in the narial and upper labial structures, as well as in the skull bones and teeth. However, superficially similar extensions in other extant vertebrates differ greatly in anatomy and function. Therefore, they deserve new names: prorhiscis (e.g. Mammalia: Saiga tatarica), prorhinosis (e.g. Chondrichthyes: Callorhinchus spp.), prorhynchis (e.g. Osteichthyes: Campylomormyrus spp.) and progeneiontis (e.g. Osteichthyes: Gnathonemus spp.). Among non-mammalian vertebrates, no bird or reptile is known to possess a proboscis. Among fishes, there are various extensions of the rostrum, jaws, 'nose' and 'chin' that lack the required narial involvement. The skulls of extinct mammals within (e.g. deinotheres) and beyond (e.g. astrapotheres) the Proboscidea confirm that a proboscis evolved independently in several mammalian lineages before the Pliocene. This convergence with tapirs presumably reflects, in part, the advantages of concentrating the olfactory sensor on what is, effectively, the tip of a long mobile upper lip. However, the proboscis does not appear to have arisen de novo in any vertebrate post-Pliocene, and its continued evolution has apparently depended on the further development of its length, flexibility and innervations, as epitomized by elephants.

Functional morphology and evolution of specialized mouthparts of Cephenniini (Insecta, Coleoptera, Staphylinidae, Scydmaeninae)

We present the results of a morphological study of the labium and labial (premental) discs in Cephenniini, ant-like stone beetles feeding on oribatid mites. The discs are composed of a cuticular plate connected by a circumferential ring with the hypopharyngeal suspensorium. The discs have likely developed from the premental cuticle and from internal sclerotizations of the labium. The shape of the external plate can be changed from flat to concave and vice versa by contractions and relaxations of the labial muscles. Contractions result in a flat or only slightly concave shape whereas during relaxation the discs become strongly concave and adhere tightly to the captured mite. Once this is achieved, detaining of the prey is energy-free. Based on known hypotheses concerning the evolution of Oribatida and Staphylinidae, we exclude the possibility of a co-evolution of “proto-Cephenniini” with yet unarmored “proto-Oribatida”, and suggest three alternative scenarios: i) the predators co-evolved with a particular early lineage of Oribatida that has acquired the hard armor relatively recently; ii) ancestors of Cephenniini gradually shifted from feeding on other types of prey towards fully armored Oribatida; or iii) the labial discs have originally developed for functions not related to feeding.

Revival of Palaeoptera-head characters support a monophyletic origin of Odonata and Ephemeroptera (Insecta).

The earliest branching event in winged insects, one of the core problems regarding early insect evolution, was addressed using characters of the head. The head is arguably one of the most complex body regions in insects and the phylogenetic information content of its features has been demonstrated. In contrast, the wings and other body parts related to the flight apparatus and sperm transmission are not useful in the context of this problem, as the outgroups (silverfish and bristletails) are wingless and transmit spermatophores externally. Therefore, they show profound differences in the organization of the postcephalic body, and assessment of homology and subsequent phylogenetic analysis of features of these body regions is extremely difficult. The core of this study is the investigation of head structures of representatives of the major clades of dragonflies. A detailed description of the head of Lestes virens is presented and was used as a starting point for the compilation of a character set and a character state matrix for the entire Dicondylia (winged insects + silverfish), with a main focus on the placement of dragonflies and consequently the basal branching event within winged insects. Our results indicate a sister-group relationship between a clade Palaeoptera (dragonflies + mayflies) and the megadiverse monophyletic lineage Neoptera. We show that despite considerable structural similarity between the odonate and neopteran mandible, the muscle equipment in dragonflies is more plesiomorphic with respect to Dicondylia than previously known. Odonata and Ephemeroptera also share presumably derived features of the antenna, maxilla, and labial musculature. Parsimony analyses of the head data unambiguously support a clade Palaeoptera. © The Willi Hennig Society 2012.

Adjunctive Treatment of Gummy Smile Using Botulinum Toxin Type-A (Case Report)

A 13 Year old female came for a consultation with chief complaints of protrusive lips and a gummy smile. The clinical examination showed a convex profile, a retrognathic mandible, excessively proclined and extruded maxillary incisors, and skeletal class II malocclusion with bimaxillary dento alveolar protrusion. Treatment was started using conventional mechanics for intrusion and retraction of upper anterior teeth, thereby improving soft tissue profile and correction of gummy smile. But only orthodontic treatment was not enough for correction of excessive gingival display during smile secondary to hyperactive upper labial muscle activity. Thus injection of Botulinum toxin type-A was given to correct gummy smile as an adjunctive treatment. Excellent correction of gummy smile following 2 weeks of Botox injection was achieved without any side effects. The patient received a satisfactory occlusion and an attractive smile.

Multidisciplinary management of a case of anterior infraocclusion

Class I Ballard, skeletal hyperdivergence. Class I Angle, arch length discrepancy. Anterior infraocclusion 5 mm. Maxillary midline deviation of 1.5 mm to the right. Hypoplastic amelogenesis imperfecta. Provisionary restoration of the mandibular incisors and of the maxillary central incisors. A functional examination revealed that the patient had dysfunctional swallowing with a tongue thrust. The labial musculature was hypotonic with contraction of the menton musculature. We noticed clinical signs of TMD pain with alteration of the path of closure.

Comparative morphology of the head of selected sporophagous and non‐sporophagous aleocharinae (Coleoptera: Staphylinidae): Musculature and hypopharynx‐prementum complex

To investigate whether specialization to spore- (or pollen-) feeding in advanced Aleocharinae is mirrored by their head anatomy, we compiled and compared synchrotron X-ray micro-tomography datasets for 11 Aleocharinae in conjunction with previous data for two aleocharine and six outgroup species (two nonstaphylinids, four staphylinids). We describe the presence/absence of head muscles and investigate the variability of points of origin by character mapping analyses. Monophyly of Aleocharinae is supported by the absence of M. 48 (M. tentoriobuccalis anterior), and by changes in the origins of Mm. 1, 2, 17, 18, 28, 29, 30. Within Aleocharinae the origins of the labial muscles (Mm. 28-30) have shifted posteriorly to the gula, which might enhance the movement posterad of the hypopharynx and partly compensate for the loss of M. 48. We also analyzed the general organization of the hypopharynx-prementum complex and the fine structure of the mandibles through SEM studies. In the absence of grinding mandibular molae like those of most mycophagous Coleoptera, seven aleocharine species studied have evolved "pseudomolae" at the ventral side of the mandibles that replace true molae as secondary grinding surfaces. In these species, the hypopharynx is elevated and displaced anteriorly, bearing a bowl-like depression on its surface that functions as a mortar where spores are ground between the hypopharynx and the mandibles. Two of these species are not yet known to feed on spores or pollen. Another species (Oxypoda alternans) is thought to feed on fungus material but bears no pseudomolae on its mandibles.