Muscle Attachment Research Articles

Entheseal Changes: Benefits, Limitations and Applications in Bioarchaeology

Reconstructing physical activities in ancient humans has long been pursued in bioarchaeology to understand our history and development. Entheseal changes (EC)––variations to muscle, tendon, and ligament attachment sites on bone––have been used in bioarchaeology since the 1980s to reconstruct activities in past populations such as changes in mobility, subsistence strategy, and gendered division of labour. EC research is based on bone functional adaptation, where bone responds to mechanical stress on entheses through bone formation or destruction in varying degrees of expression. However, the relationship between EC and activity is more complex than simple cause-and-effect, as it involves multiple confounding variables, which can affect EC morphology. This article addresses the use of EC research in bioarchaeology through two parts: Part 1 defines entheses and EC, including observational and quantitative methods developed in bioarchaeology to study EC. Part 2 will summarize the main known factors that influence EC beyond activity such as age, sex, and body size. The article concludes with a discussion of varying benefits and limitations to EC research in bioarchaeology including the use of archaeological samples, historical collections, and animal experimental models. Overall, EC research can be difficult to link with activity due to its multifactorial etiology, challenges of efficacy in developing methods, and limitations of working with human remains. However, recent studies are showing more positive results, demonstrating the usefulness of EC as a way to reconstruct activity.

Thin patient-specific clavicle fracture fixation plates can mechanically outperform commercial plates: An in silico approach.

Current fixation plates used to operatively stabilize clavicular fractures are suboptimal, leading to reoperation rates up to 53%. Plate irritation, which can be caused by a poor geometric fit and plate thickness, has been found to be an important factor for reoperation. Moreover, muscle attachment sites (MAS) have to be detached occasionally. To improve current surgical clavicle fracture treatment with plate osteosynthesis, a change in plate design is required. The goal of this study was to design a patient-specific clavicle fracture fixation plate that includes geometrical optimization and stiffness determination. Its biomechanical performance has been compared with a commercial plate by examining the geometric fit, anatomical outline, stresses and interfragmentary motion using a finite element analysis with physiological loading and boundary conditions. Evaluation showed a better geometrical fit of the patient-specific plate as well as an improved fracture reduction. Displacements between fracture fragments were lower in case of the patient-specific plate, both when a fracture gap and no fracture gap were present. Results indicate a superior mechanical performance in terms of all investigated outcomes of the patient-specific plate compared to the commercial plate, while better aligning with the patient-specific geometry and without the need for MAS release. Due to the patient-specific geometry and reduced thickness, these fixation plates are expected to decrease the operation time, as intraoperative contouring will become irrelevant, and to decrease reoperation rates as implant irritation will be minimized.

A Research Protocol to Evaluate the Efficacy of Powerball versus Mulligan Mobilization with Movement on Pain and Function in Patients with Lateral Epicondylitis

Background: Amongst the most frequently repeated stress conditions within the elbow joint includes lateral epicondylitis (LE). The extensor carpi radialis brevis muscle attachment is affected mostly. The management of an individual with LE that manifests itself in repetitive upper extremity motions is the purpose of this research. There seems to be no study on the effects of PowerBall device training on the pain and function in individuals with Lateral Epicondylitis. “PowerBall device” practice is a type of strength training.
 Methods / Design: After conducting initial evaluations and allocation, the subjects (n=50) with LE will be involved in a randomized controlled study and classified either in an intervention group or a conventional group. The interventional group will do “PowerBall device” exercises, while others in the control group, doing MMWM. These groups will receive basic movements and ultrasound in accordance with the procedures.
 Discussion: The PRTEE scale measured the intervention's impact on pain and function in patients with LE, and a Hand-held Dynamometer was utilized to quantify grip strength. The findings will give considerable support for the use of the "PowerBall device" exercise and MMWM on LE patients.
 Conclusion: Conclusion will be drawn post study so as to see whether PowerBall device is more helpful or Mulligan Mobilization with Movement on pain and function in patients with LE. This study will give better approach to the therapist in managing the condition.

Morphological diversity of peroneus tertius: a cadaveric study

Objective: The objective of this study was to demonstrate morphological anatomical variations of the peroneus tertius muscle which may have important clinical and surgical implications. Materials and methods: Fifty four specimens of anterior compartment of the leg which were dissected routinely according to the undergraduate course were examined for variations of the above muscles and the anatomy was further defined using appropriate dissection methods. Results: A wide variation was found with regard to the morphology of peroneus tertius and the extensor digitorum longus muscles with considerable differences between the legs of the same cadaver. When considering important variations deviating considerably from the normal structure, a variation of the distal attachment of peroneus tertius muscle in two specimens revealed that in addition to the normal attachment to the shaft of the fifth metatarsal, an additional slip inserted to the extensor expansion of the fifth toe. It apparently replaced the fourth tendon of extensor digitorum longus, which only had three divisions in these specimens. Seventeen of the specimens had a single muscle belly giving rise to 5 tendons which had the usual distal attachments of the peroneus tertius and the extensor digitorum longus muscle as stated below. Absence of peroneus tertius was noted in one specimen. Conclusion: The anatomical structure of the peroneus tertius vary substantially from individual to individual, inclusive of differences existing between the left and the right lower limbs of the same cadaver.

Biomechanical Evaluation on the Bilateral Asymmetry of Complete Humeral Diaphysis in Chinese Archaeological Populations

Diaphyseal cross-sectional geometry (CSG) is an effective indicator of humeral bilateral asymmetry. However, previous studies primarily focused on CSG properties from limited locations to represent the overall bilateral biomechanical performance of humeral diaphysis. In this study, the complete humeral diaphyses of 40 pairs of humeri from three Chinese archaeological populations were scanned using high-resolution micro-CT, and their biomechanical asymmetries were quantified by morphometric mapping. Patterns of humeral asymmetry were compared between sub-groups defined by sex and population, and the representativeness of torsional rigidity asymmetry at the 35% and 50% cross-sections (J35 and J50 asymmetry) was testified. Inter-group differences were observed on the mean morphometric maps, but were not statistically significant. Analogous distribution patterns of highly asymmetrical regions, which correspond to major muscle attachments, were observed across nearly all the sexes and populations. The diaphyseal regions with high variability of bilateral asymmetry tended to present a low asymmetrical level. The J35 and J50 asymmetry were related to the overall humeral asymmetry, but the correlation was moderate and they could not reflect localized asymmetrical features across the diaphysis. This study suggests that the overall asymmetry pattern of humeral diaphysis is more complicated than previously revealed by individual sections.

Analysis of the lower jaw exoskeleton in finite element programs

A special place in the methods of surgical treatment of bone fractures is occupied by transosseous osteosynthesis using external fixation devices of various designs.Objective: to analyze the lower jaw exoskeleton in finite element programs.Materials and research methods. During the research, 36 human lower jaws were involved from the museum of the Department of Oper-ative Surgery and Topographic Anatomy of the Volgograd State Medical University. They were scanned in 3D. All obtained images were loaded into a virtual scene reconstruction program. Fractures of the lower jaws in the corner area were modeled, an apparatus for external fixation of the lower jaw exoskeleton was installed, and the chewing load on the lower jaw was simulated. The place of application of the force was an area on a small fragment of a repositioned 3D model of the mandibular bone corresponding to the place of attachment of the masseter muscle. The evaluation of virtual studies was carried out according to the results of the stress-strain states of the bones and apparatus, the schedule of displacements of objects and the results of the analysis of the safety factor.Research results and discussion. In the course of evaluating the virtual placement of the mini-fixator wires of the apparatus for external fixation of the lower jaw exoskeleton, it was revealed that the main load is applied to the mini-fixator wires on a large fragment and the bone in the area of the wires. For the possibility of precise positioning of the osteofixers of the external fixation device, a device for the safe installation of the spokes of the lower jaw exoskeleton was also developed.Conclusion. Thus, on the basis of computer mathematical analysis, it can be argued that the developed design of the apparatus for external fixation of the lower jaw exoskeleton works under conditions of the maxillofacial region, performs reposition and fixation of bone fragments of the lower jaw under conditions of chewing functioning of the restored fracture of the lower jaw.

Effects of selective breeding for voluntary exercise, chronic exercise, and their interaction on muscle attachment site morphology in house mice.

Skeletal muscles attach to bone at their origins and insertions, and the interface where tendon meets bone is termed the attachment site or enthesis. Mechanical stresses at the muscle/tendon-bone interface are proportional to the surface area of the bony attachment sites, such that a larger attachment site will distribute loads over a wider area. Muscles that are frequently active and/or are of larger size should cause attachment sites to hypertrophy (training effect); however, experimental studies of animals subjected to exercise have provided mixed results. To enhance our ability to detect training effects (a type of phenotypic plasticity), we studied a mouse model in which 4 replicate lines of High Runner (HR) mice have been selectively bred for 57generations. Selection is based on the average number of wheel revolutions on days 5 & 6 of a 6-day period of wheel access as young adults (6-8weeks old). Four additional lines are bred without regard to running and serve as non-selected controls (C). On average, mice from HR lines voluntarily run ~3 times more than C mice on a daily basis. For this study, we housed 50 females (half HR, half C) with wheels (Active group) and 50 (half HR, half C) without wheels (Sedentary group) for 12weeks starting at weaning (~3weeks old). We tested for evolved differences in muscle attachment site surface area between HR and C mice, plastic changes resulting from chronic exercise, and their interaction. We used a precise, highly repeatable method for quantifying the three-dimensional (3D) surface area of four muscle attachment sites: the humerus deltoid tuberosity (the insertion point for the spinodeltoideus, superficial pectoralis, and acromiodeltoideus), the femoral third trochanter (the insertion point for the quadratus femoris), the femoral lesser trochanter (the insertion point for the iliacus muscle), and the femoral greater trochanter (insertion point for the middle gluteal muscles). In univariate analyses, with body mass as a covariate, mice in the Active group had significantly larger humerus deltoid tuberosities than Sedentary mice, with no significant difference between HR and C mice and no interaction between exercise treatment and linetype. These differences between Active and Sedentary mice were also apparent in the multivariate analyses. Surface areas of the femoral third trochanter, femoral lesser trochanter, and femoral greater trochanter were unaffected by either chronic wheel access or selective breeding. Our results, which used robust measurement protocols and relatively large sample sizes, demonstrate that muscle attachment site morphology can be (but is not always) affected by chronic exercise experienced during ontogeny. However, contrary to previous results for other aspects of long bone morphology, we did not find evidence for evolutionary coadaptation of muscle attachments with voluntary exercise behavior in the HR mice.

English

Superficial temporal space lies between the temporal fasciae. Abscess in the temporal and infratemporal space is very rare. They develop as a result of the extraction of infected maxillary molars. Temporal space infections or abscesses can be seen in the superficial or deep temporal regions. A 65 - year - old male patient reported with a complaint of painful swelling over the right cheek and restricted mouth opening with a history of extraction of second mandibular molar before four weeks. On examination, an ill-defined diffuse swelling was seen. Treatment was started with IV empirical antibiotics and planned for surgical drainage. Surgical drainage of the abscess in the temporal space was done along with debridement of the necrosed temporalis muscle. Infections of the maxillofacial region are of great significance to general dentists and maxillofacial surgeons. They are of clinical importance as they are commonly encountered, and are also challenging as timely intervention is needed to prevent fatal complications. The infections arising from the tooth are initially confined to the alveolar bone and surrounding periosteum. They spread along the path of the least resistance to the cortical plates. Once the infection penetrates the cortical plates, they reach the muscle plane.1 If the infection perforated is above the muscle attachments, it’s confined to an intraoral abscess. If the cortical plates are perforated below the muscular attachments, extraoral swelling develops. The next barrier is the periosteum which is strong and elastic in nature. Once the periosteum is breached, infections reach the soft tissue planes, the fascia. Most of the infections are confined to a particular space and the surrounding fascia. Based on the toxins produced by the microorganisms, the infection can spread to adjacent spaces and even retrograde. Common deep space infections are Ludwig's angina followed by peritonsillar, submandibular, and parotid abscesses. 2 Infratemporal and temporal space infections are rarely compared to other deep space infections. Many etiological factors form the base for the infections of deep spaces, dental caries, extraction of infected, non-infected tooth maxillary sinusitis, tonsillitis, maxillary sinus fracture, temporomandibular arthroscopy, drug-induced infections. Infections of odontogenic origin, spreading along infratemporal and temporal space are most common with maxillary molars followed by mandibular molars. We report a case of retrograde spread of buccal space infection into temporal space secondary to mandibular tooth extraction.

Commonalities and evolutionary divergences of mandible shape ontogenies in rodents.

In mammals, significant changes take place during postnatal growth, linked to changes in diet (from sucking to gnawing). During this period, mandible development is highly interconnected with muscle growth and the epigenetic interactions between muscle and bone control the spatialization of bone formation and remodelling in response to biomechanical strain. This mechanism contributes to postnatal developmental plasticity and may have influenced the course of evolutionary divergences between species and clades. We sought to model postnatal changes at a macroevolutionary scale by analysing ontogenetic trajectories of mandible shape across 16species belonging mainly to two suborders of Rodents, Myomorpha and Hystricomorpha, which differ in muscle attachments, tooth growth and life-history traits. Myomorpha species present a much stronger magnitude of changes over a shorter growth period. Among Hystricomorpha, part of the observed adult shape is set up prenatally, and most postnatal trajectories are genus-specific, which agrees with nonlinear developmental trajectories over longer gestational periods. Beside divergence at large scale, we find some collinearities between evolutionary and developmental trajectories. A common developmental trend was also observed, leading to enlargement of the masseter fossa during postnatal growth. The tooth growth, especially hypselodonty, seems to be a major driver of divergences of postnatal trajectories. These muscle- and tooth-related effects on postnatal trajectories suggest opportunities for developmental plasticity in the evolution of the mandible shape, opportunities that may have differed across Rodent clades.

A cadaveric analysis of anatomical variations of the anterior belly of the digastric muscle.

The anterior belly of the digastric muscle (ABDM) presents highly variable and frequent anatomical variations. Since the ABDM functions as a landmark for clinical procedures involving the submental region, it is important to have a comprehensive understanding of its variations. In this study, we sought to improve our knowledge of ABDM variations in the ethnically diverse whole-body donor population in Northern California. Specific aims were: (1) to determine the frequency of ABDM and anterior belly (AB) accessory muscle variations in cadavers donated to the UC Davis Body Donation Programme, (2) to classify these variations identified in this population using the previously proposed nomenclatures by Yamada (1935) and Zlabek (1933), and (3) to investigate the innervation and arterial supply to the representative ABDM and AB accessory muscle variations. During the 2018 and 2019 gross anatomy dissection laboratories at the UC Davis School of Medicine, the submental regions of 48 cadavers were examined and classified. Fifteen (31.2%) cadavers presented ABDM and AB accessory muscle variations. These variations were clearly categorised using the morphology of the ABDMs and attachments of the AB accessory muscles. We also identified three previously unreported types of variations, two of which presented the fusion of right and left ABDMs and one presenting an ectopic tubercle beneath the mandibular symphysis to which a pair of AB accessory muscles were attached. Anterior belly of the digastric muscle variations were found in 1 in 3 individuals in the local Northern California population. Knowledge of the prevalence and common patterns of ABDM variations in the general population would be valuable information when an operation or examination is performed in the submental region.

New theropod dinosaur from the Late Cretaceous of Brazil improves abelisaurid diversity

The Late Cretaceous Marília Formation (Bauru Group, Bauru Basin) is a geological unit that occurs on São Paulo, Minas Gerais, Goiás, and Mato Grosso do Sul states, Brazil. This formation consists predominantly of paleosols developed in a semiarid/arid environment and recent reappraisal of its formerly known members reduced its lithological composition and geographical distribution. Hence, the Marília Formation has a very sparse vertebrate fossil record without named species so far. In this contribution we describe a new abelisaurid theropod (Dinosauria) from this unit, namely Kurupi itaata gen. et sp. nov., discovery in the Municipality of Monte Alto, western São Paulo State. The holotype MPMA 27-0001/02 consists of three caudal vertebrae and the partial pelvic girdle. Kurupi itaata gen. et sp. nov. shares with other South American abelisaurids fused ischia and caudal vertebrae with long and laterodorsally oriented transverse processes, with fan-shaped distal ends. Autapomorphies of the new theropod include the variation of ∼15° of the inclination of the transverse process between the first (C1) and seventh (C7) caudal vertebra; C1 with anterolaterally projected triangular process placed below the proximodistal mid-portion of the transverse process, and a notch at the anterodistal portion of the transverse process, between a shelf-like process and the anterodistal corner of the transverse process; and anterior caudal vertebrae (present in C1 and C7, inferred in the others) with a cuneiform process, anterodorsally projected, located on the dorsal surface of the transverse process. Phylogenetic analysis recovered Kurupi itaata gen. et sp. nov. among abelisaurid theropods, but was nested in an unresolved massive polytomy of the entire clade. Taphonomic traits on the studied specimens corroborate previous proposals for the paleoenvironmental context of the Marília Formation. Kurupi itaata gen. et sp. nov. was about 5 m long, with a rigid tail, and cursorial locomotion as indicated by its a muscles attachment and bones anatomy. This new taxon contributes to the knowledge of the Maastrichtian continental fauna of Brazil and increases the diversity of medium-sized abelisaurids in western Gondwana.

Quantitative Evaluation of Palatal Lengthening After Cleft Palate Repair When a Buccal Flap Is Routinely Combined With Furlow's Z-Plasty.

The use of a buccinator myomucosal flap in combination with Furlow's Z-plasty during primary and secondary palatal repairs has been proposed by many authors to overcome some of the limitations of Furlow's technique. However, there have been no studies that quantitatively measured the effective palatal lengthening when the buccal flap is added. The buccal flap is routinely used during primary palate repair in order to fill the gap between the hard palate and reoriented palatal muscle sling. The soft palatal length was measured in the midline from the posterior edge of the hard palate to the base of the uvula. All patients were measured before starting the surgery and just after palatal closure in the standard position for cleft palate repair. Seventy-three patients with cleft palate who were candidates for primary repair were included. The mean age at the time of operation was 11.4 ± 3.5 months. The mean preoperative palatal length was 21.36 ± 3.529 mm, whereas the mean postoperative palatal length was 29.64 ± 4.171) mm. The mean palatal length change was 8.29 ± 2.514 mm (P < 0.000). The Combined use of a buccinator myomucosal flap with modified Furlow's Z-plasty in primary cleft palate repair has proven effective for palatal lengthening and achieved tensionless closure without the need for relaxing incision. It also provided a pliable soft tissue attachment of the palatal muscles to the hard palate allowing for better muscle function and mobility.

ИЗМЕНЕНИЕ ЛИНЕЙНЫХ РАЗМЕРОВ НИЖНЕЙ ЧЕЛЮСТИ ПРИ УСТРАНЕНИИ ФУНКЦИОНАЛЬНОГО БОКОВОГО СМЕЩЕНИЯ

Introduction. Facial asymmetries associated with lateral displacement of the jaw arise due to various reasons, namely, the presence of functional lateral displacement of the lower jaw, skeletal asymmetry of the maxillofacial region, and a combination of the above factors. Purpose. Identification of the etiological factor makes it possible to assess the possibility of correcting the position of the lower jaw and improving the relationship of the intra-articular structures of the temporomandibular joint. Materials and methods. Functional lateral displacement of the lower jaw is characterized by an asymmetric tone of the masticatory muscles, a change in the position of the chin, and dysfunction of the temporomandibular joint on the side of the displacement of the lower jaw. The article discusses a clinical case of a patient with pathology of the temporomandibular joint associated with functional displacement of the mandible. Comparison of the data of cone-beam computed tomography of the lower jaw at the site of attachment of the masticatory muscle before and after the elimination of the asymmetry of the maxillofacial region was carried out. Conclusion. An asymmetric change in the displacement of the condyles was obtained according to the data of electronic axiography, an improvement in the ratio of intra-articular structures, the presence of a change when comparing STL models of the lower jaw.

The toolkit of a hunter – functional morphology of larval mouthparts in a dragonfly

AbstractThe diversity of mouthpart specializations in insects is staggering. As a direct consequence thereof, the knowledge about the mouthpart geometry, muscle attachment and feeding kinematics is incomplete for the vast majority of insect taxa – as it is for dragonflies. The adult dragonflies catch their prey in flight, while the aquatic larvae prey under water – both life stages being key predators in their biotopes. To gain insights into the functional morphology of the biting‐chewing mouthparts of larval Anax imperator, we combined results from micro computed tomography (µCT), confocal laser scanning microscopy (CLSM) and high‐speed videography. Anax imperator larvae were filmed during the feeding process to describe the movement and coordination of the mouthparts. These results, together with µCT‐data, allowing for a comprehensive visualization of the 3D‐geometry and corresponding musculature of each mouthpart. The material composition of the cuticle strongly influences the strength, mobility and durability of the cuticular components of the mouthparts. With this paper, we elucidate the anatomy, geometry and material composition of A. imperator's larval mouthparts in the light of the feeding process. Furthermore, we try to lay a foundation for functional morphological comparisons of mouthparts (1) between dragonfly species belonging to different eco‐types according to their food preferences and feeding habits or even (2) between different insect groups.

Evaluating bony predictors of bite force across the order Carnivora.

In carnivorans, bite force is a critical and ecologically informative variable that has been correlated with multiple morphological, behavioral, and environmental attributes. Whereas in vivo measures of biting performance are difficult to obtain in many taxa-and impossible in extinct species-numerous osteological proxies exist for estimating masticatory muscle size and force. These proxies include both volumetric approximations of muscle dimensions and direct measurements of muscular attachment sites. In this study, we compare three cranial osteological techniques for estimating muscle size (including 2D-photographic and 3D-surface data approaches) against dissection-derived muscle weights and physiological cross-sectional area (PCSA) within the jaw adductor musculature of 40 carnivoran taxa spanning eight families, four orders of magnitude in body size, and the full dietary spectrum of the order. Our results indicate that 3D-approaches provide more accurate estimates of muscle size than do surfaces measured from 2D-lateral photographs. However, estimates of a muscle's maximum cross-sectional area are more closely correlated with muscle mass and PCSA than any estimates derived from muscle attachment areas. These findings highlight the importance of accounting for muscle thickness in osteological estimations of the masticatory musculature; as muscles become volumetrically larger, their larger cross-sectional area does not appear to be associated with a proportional increase in the attachment site area. Though volumetric approaches approximate muscle dimensions well across the order as a whole, caution should be exercised when applying any single method as a predictor across diverse phylogenies.

Calf Pain Relay - Long Distance Runner

HISTORY: A 33-year-old male, avid long-distance runner, presented with one year of right posterior calf pain exacerbated by running. The patient was initially noted to have necrotic lipomas over the medial head of gastrocnemius and underwent surgical excision with improved symptoms. Three months later, he developed pain secondary to Medial Tibial Stress Syndrome. He was advised to rest for 12 weeks and start physical therapy once improved. Upon follow-up, the patient was noted to have another palpable mass associated with tenderness to palpation preventing him from running extended distances. The pain had only improved approximately 10% despite physical therapy. The patient denied numbness, tingling, weakness or radiation into his right lower extremity. PHYSICAL EXAMINATION: On examination, the patient had full strength and intact sensation in bilateral lower extremities without atrophy or erythema. A firm mass was palpated along the insertion of soleus muscle onto proximal tibia. No bony tenderness was noted upon palpation of tibia or fibula. DIFFERENTIAL DIAGNOSIS: 1. Soleus Enthesopathy 2. Medial Tibial Stress Syndrome 3. Lipoma 4. Chronic Exertional Compartment Syndrome 5. Popliteal Artery Entrapment Syndrome TEST AND RESULTS: - Inflammatory markers: Normal - Rheumatologic studies: Negative - Compartment pressure testing: Negative - Ultrasound of right lower extremity: Focal enthesopathy at the soleus muscle attachment - MRI of right lower extremity: Interval improvement with near resolution of the mid tibial stress reaction. Enthesopathic change at the insertion of the soleus muscle on the proximal tibia and distal soleus myotendinous junction muscle strain. - CT of right tibia and fibula: Broad, cortically based ossification along the posterior tibial cortex at the level of the proximal calf. FINAL WORKING DIAGNOSIS: Soleus Enthesopathy TREATMENT AND OUTCOMES: The patient was advised to continue physical therapy for several more weeks. The patient then received ultrasound-guided trigger point injections at the attachment of the soleus on the tibia without improvement. Given no improvement with the injection, he was referred to Orthopedic Surgery who suggested elective surgical excision of the ossification. The patient will follow up after completion of the surgery.

Sexual dimorphisms in three-dimensional masticatory muscle attachment morphometry regulates temporomandibular joint mechanics

Temporomandibular joint (TMJ) disorders disproportionally affect females, with female to male prevalence varying from 3:1 to 8:1. Sexual dimorphisms in masticatory muscle attachment morphometry and association with craniofacial size, critical for understanding sex-differences in TMJ function, have not been reported. The objective of this study was to determine sex-specific differences in three-dimensional (3D) TMJ muscle attachment morphometry and craniofacial sizes and their impact on TMJ mechanics. Human cadaveric TMJ muscle attachment morphometry and craniofacial anthropometry (10Males; 11Females) were determined by previously developed 3D digitization and imaging-based methods. Sex-differences in muscle attachment morphometry and craniofacial anthropometry, and their correlation were determined, respectively using multivariate general linear and linear regression statistical models. Subject-specific musculoskeletal models of the mandible were developed to determine effects of sexual dimorphisms in mandibular size and TMJ muscle attachment morphometry on joint loading during static biting. There were significant sex-differences in craniofacial size (p = 0.024) and TMJ muscle attachment morphometry (p < 0.001). TMJ muscle attachment morphometry was significantly correlated with craniofacial size. TMJ contact forces estimated from biomechanical models were significantly, 23% on average (p < 0.001), greater for females compared to those for males when generating the same bite forces. There were significant linear correlations between TMJ contact force and both 3D mandibular length (R2 = 0.48, p < 0.001) and muscle force moment arm ratio (R2 = 0.68, p < 0.001). Sexual dimorphisms in masticatory muscle morphology and craniofacial sizes play critical roles in subject-specific TMJ biomechanics. Sex-specific differences in the TMJ mechanical environment should be further investigated concerning mechanical fatigue of TMJ discs associated with TMJ disorders.

Musculoskeletal anatomy and nomenclature of the mammalian epipubic bones.

Despite the well-established anatomy nomenclature for the marsupial skeleton, there are no names for the epipubic bone structures. Epipubic bones are paired bones articulating with the pubis and projecting cranially in the ventral body wall, present on the pelvic girdle of cynodonts, monotremes and marsupials. These bones were commonly thought to be related to pouch support in marsupials and more recently associated with locomotion. The parts of the epipubic bones have not been named and this has impeded proper morphological analysis. We analyzed the epipubic bones of 302skeletons comprising American and Australian marsupials, as well as 27monotreme skeletons, and dissected 10marsupials for myological attachments analysis. We suggest the following nomenclature for the epipubic bone structures: crest for the cranial end, shaft for the body of the bone, lateral tubercle and the medial articular process. Some markings on the epipubic bone include the oblique line, pertaining to the attachment of external abdominal oblique muscle from the opposite side. The pyramidalis line is the suggested nomenclature for the pyramidalis muscle attachment and the inguinal ligament line for the inguinal ligament attachment. Regarding myology and attachments, based on dissections and review of the literature, the muscles pyramidalis, pectineus, external and internal abdominal oblique, transversus abdominis and rectus abdominis and the structures linea alba, linea semilunaris and the inguinal ligament are connected to the epipubic bone. As has been previously noted, anatomically, epipubic bones are so named due to their position (epi-above, pubic-pubis), and the same applies to structures such as the "epipubic process" or "epipubic cartilage" in amphibians and reptiles. While testing epipubic bone homology in vertebrates is beyond the scope of this work, we believe that using "epipubic bones" or epipubic cartilage/process as standardized terms for the structures found in the most cranial part of the superior ramus of the pubis would facilitate better anatomical communication. This should be valid for other similar terms, such as "epipubes" or "prepubis", that might occur in the literature in relation to this same physiographic position, and it should also be named as epipubic. We believe that this nomenclature will help in future morphologic studies.

Fortuitous Discovery of a Bochdalek Hernia in an Adult

Bochdalek hernia is the most common type of congenital diaphragmatic hernia. It is due to a defect in the posterior attachment of the diaphragm muscle, subsequent to a failure of pleuroperitoneal membrane closure in utero. Bochdalek hernia is often asymptomatic in adults, hence, it is fortuitously discovered as an incidental finding on CT scan. Alternatively, it may be diagnosed only after complications occur, such as empyema, cardiac tamponade and gastrointestinal strangulation. CT usually demonstrates a fatty mass above the diaphragm (Figure 1: arrow), which may be associated with other organs entrapment. Coronal and sagittal reformatted images show the diaphragmatic defect (Figure 2: arrows).

Factors Involved in Morphogenesis in the Muscle-Tendon-Bone Complex.

A decline in the body’s motor functions has been linked to decreased muscle mass and function in the oral cavity and throat; however, aging of the junctions of the muscles and bones has also been identified as an associated factor. Basic and clinical studies on the muscles, tendons and bones, each considered independently, have been published. In recent years, however, research has focused on muscle attachment as the muscle–tendon–bone complex from various perspectives, and there is a growing body of knowledge on SRY-box9 (Sox9) and Mohawk(Mkx), which has been identified as a common controlling factor and a key element. Myostatin, a factor that inhibits muscle growth, has been identified as a potential key element in the mechanisms of lifetime structural maintenance of the muscle–tendon–bone complex. Findings in recent studies have also uncovered aspects of the mechanisms of motor organ complex morphostasis in the superaged society of today and will lay the groundwork for treatments to prevent motor function decline in older adults.