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Integrative Organismal Biology (Oxford,... 2020Fish perform many complex manipulation behaviors without hands or flexible muscular tongues, instead relying on more than 20 movable skeletal elements in their highly...
Fish perform many complex manipulation behaviors without hands or flexible muscular tongues, instead relying on more than 20 movable skeletal elements in their highly kinetic skulls. How fish use their skulls to accomplish these behaviors, however, remains unclear. Most previous mechanical models have represented the fish skull using one or more planar four-bar linkages, which have just a single degree of freedom (DoF). In contrast, truncated-cone hydrodynamic models have assumed up to five DoFs. In this study, we introduce and validate a 3D mechanical linkage model of a fish skull that incorporates the pectoral girdle and mandibular and hyoid arches. We validate this model using an motion dataset of suction feeding in channel catfish and then use this model to quantify the DoFs in the fish skull, to categorize the motion patterns of the cranial linkage during feeding, and to evaluate the association between these patterns and food motion. We find that the channel catfish skull functions as a 17-link, five-loop parallel mechanism. Despite having 19 potential DoFs, we find that seven DoFs are sufficient to describe most of the motion of the cranial linkage, consistent with the fish skull functioning as a multi-DoF, manipulation system. Channel catfish use this linkage to generate three different motion patterns (rostrocaudal wave, caudorostral wave, and compressive wave), each with its own associated food velocity profile. These results suggest that biomechanical manipulation systems must have a minimum number of DoFs to effectively control objects, whether in water or air.
PubMed: 33791570
DOI: 10.1093/iob/obaa031 -
Integrative Organismal Biology (Oxford,... 2020Salamanders and newts (urodeles) are often used as a model system to elucidate the evolution of tetrapod locomotion. Studies range from detailed descriptions of...
Salamanders and newts (urodeles) are often used as a model system to elucidate the evolution of tetrapod locomotion. Studies range from detailed descriptions of musculoskeletal anatomy and segment kinematics, to bone loading mechanics and inferring central pattern generators. A further area of interest has been muscle activity patterns, measured through electromyography (EMG). However, most prior EMG work has primarily focused on muscles of the forelimb or hindlimb in specific species or the axial system in others. Here we present data on forelimb, hindlimb, and epaxial muscle activity patterns in one species, , during steady state walking. The data are calibrated to limb stride cycle events (stance phase, swing phase), allowing direct comparisons to homologous muscle activation patterns recorded for other walking tetrapods (e.g., lizards, alligators, turtles, mammals). Results demonstrate that has similar walking kinematics and muscle activity patterns to other urodele species, but that interspecies variation does exist. In the forelimb, both the and are active for 80% of the forelimb swing phase, while the is active at the swing-stance phase transition and continues through 86% of the stance phase. In the hindlimb, both the and are active for 30% of the hindlimb swing phase, while the is active 65% through the swing phase and remains active for most of the stance phase. With respect to the axial system, both the anterior and posterior display two activation bursts, a pattern consistent with stabilization and rotation of the pectoral and pelvic girdles. In support of previous assertions, comparison of muscle activity timings to other walking tetrapods revealed broad-scale similarities, potentially indicating conservation of some aspects of neuromuscular function across tetrapods. Our data provide the foundation for building and testing dynamic simulations of fire salamander locomotor biomechanics to better understand musculoskeletal function. They could also be applied to future musculoskeletal simulations of extinct species to explore the evolution of tetrapod locomotion across deep-time.
PubMed: 33791558
DOI: 10.1093/iob/obaa015 -
Archives of Rheumatology Dec 2020Polymyositis (PM) is an autoimmune disease progressing in the form of a break down of the muscles that is induced by chronic inflammation in skeletal muscles. Muscle...
Polymyositis (PM) is an autoimmune disease progressing in the form of a break down of the muscles that is induced by chronic inflammation in skeletal muscles. Muscle weakness is painless and concentrates on proximal muscles, involving the pectoral and pelvic girdle. If the disease is not treated properly, it may progress and lead to a considerable decrease in the quality of life. Its conventional treatment involves drugs that suppress inflammation such as steroids, methotrexate, azathioprine, and intravenous immunoglobulin. However, conventional treatment may prove insufficient to halt the progression of the disease and offer only a limited improvement because of the adverse effects it causes in some patients. In this article, we present a 48-year-old female patient diagnosed with PM nearly 13 years ago that did not sufficiently respond to the pharmaceutical agents that were indicated for the conventional treatment of the disease and developed femoral head avascular necrosis because of the treatment and was, in the end, successfully treated with abatacept monotherapy at our clinic.
PubMed: 33758820
DOI: 10.46497/ArchRheumatol.2020.7406 -
Scientific Reports Mar 2021A new articulated postcranial specimen of an indeterminate ankylosaurid dinosaur from the Upper Cretaceous (middle-upper Campanian) Baruungoyot Formation from Hermiin...
A new articulated postcranial specimen of an indeterminate ankylosaurid dinosaur from the Upper Cretaceous (middle-upper Campanian) Baruungoyot Formation from Hermiin Tsav, southern Gobi Desert, Mongolia includes twelve dorsal vertebrae, ribs, pectoral girdles, forelimbs, pelvic girdles, hind limbs, and free osteoderms. The new specimen shows that Asian ankylosaurids evolved rigid bodies with a decreased number of pedal phalanges. It also implies that there were at least two forms of flank armor within Ankylosauridae, one with spine-like osteoderms and the other with keeled rhomboidal osteoderms. Unique anatomical features related to digging are present in Ankylosauridae, such as dorsoventrally flattened and fusiform body shapes, extensively fused series of vertebrae, anteroposteriorly broadened dorsal ribs, a robust humerus with a well-developed deltopectoral crest, a short robust ulna with a well-developed olecranon process, a trowel-like manus, and decreased numbers of pedal phalanges. Although not fossorial, ankylosaurids were likely able to dig the substrate, taking advantage of it for self-defence and survival.
PubMed: 33737515
DOI: 10.1038/s41598-021-83568-4 -
Journal of Clinical Orthopaedics and... May 2021Sprengel deformity is a rare congenital anomaly of the pectoral girdle of unknown incidence. Surgical intervention is indicated in moderate to severe cases having...
Sprengel deformity is a rare congenital anomaly of the pectoral girdle of unknown incidence. Surgical intervention is indicated in moderate to severe cases having functional and cosmetic impairment. Various surgical corrective procedures have evolved over the past decades, however the extensive magnitude of some of the surgical techniques have sometimes resulted in an unwarranted worse outcome due to associated complications like brachial plexus palsy, scapular winging, sternoclavicular joint prominence, improper scar healing and keloid formation which restrict such procedures to experienced hands at few centres. We report a case of Cavendish grade 3 Sprengel deformity in a five-year-old boy managed with a minimally aggressive modified technique of preserving the trapezius and restricting the surgery to excision of omovertebral bar and supraspinatous part of scapula by a transverse incision overlying the spine of scapula. In Sprengel deformity, the trapezius attached to the elevated scapula is underdeveloped and the technique of retraction instead of detachment of this muscle during surgery, can prevent scar adhesions and improve wound healing. In our patient, satisfactory cosmetic correction and good functional shoulder movements were achieved with minimal intervention.
PubMed: 33717937
DOI: 10.1016/j.jcot.2020.12.009 -
Journal of Anatomy Aug 2021Therizinosaurs are unusual theropods from the Upper Cretaceous of Asia and North America. North American representatives include Falcarius utahensis from central Utah,... (Comparative Study)
Comparative Study
Therizinosaurs are unusual theropods from the Upper Cretaceous of Asia and North America. North American representatives include Falcarius utahensis from central Utah, Nothronychus mckinleyi from west central New Mexico, and N. graffami from southern Utah. Nothronychus was quite large, with well-developed forelimbs and pectoral girdle. In many respects, however, these structures were typical for conventional carnivorous theropods, although therizinosaurs have been hypothesized to be herbivorous using anatomical and functional inferences. There is no indication of increased range of motion within the forelimbs, as might be predicted for derived non-avian theropods. The muscular anatomy of the pectoral girdle and forelimb of Nothronychus is reconstructed using visible muscle scars, data from extant birds and crocodilians, and models for other theropods. The osteology and inferred musculature is a mosaic of primitive and derived characters for theropods. A fossa pneumotricipitales may have been present in the proximal humerus. There was a well-developed fossa brachialis in the distal humerus. The epicleidium of the furcula is deflected, reflecting either taphonomic deformation or possibly accommodation of M. supracoracoideus in a triosseal canal, but such a development has yet to be described in any non-avian theropod. In many respects, the other muscular results were quite similar to those inferred for dromaeosaurs.
Topics: Animals; Dinosaurs; Forelimb; Muscle, Skeletal; Range of Motion, Articular
PubMed: 33665832
DOI: 10.1111/joa.13418 -
Autopsy & Case Reports Nov 2020There is scant information about the comprehensive distribution of dystrophic muscles in muscular dystrophy. Despite different clinical presentations of muscular...
There is scant information about the comprehensive distribution of dystrophic muscles in muscular dystrophy. Despite different clinical presentations of muscular dystrophy, a recent multi-center study concluded that phenotypic distribution of dystrophic muscles is independent of clinical phenotype and suggested that there is a common pattern of involved muscles. To evaluate this possibility, the present case report used cadaveric dissection to determine the whole-body distribution of fat-infiltrated, dystrophic muscles from a 72-year-old white male cadaver with adult-onset, late-stage muscular dystrophy. Severely dystrophic muscles occupied the pectoral, gluteal and pelvic regions, as well as the arm, thigh and posterior leg. In contrast, muscles of the head, neck, hands and feet largely appeared unaffected. Histopathology and a CT-scan supported these observations. This pattern of dystrophic muscles generally conformed with that described in the multi-center study, and provides prognostic insight for patients and the physicians treating them.
PubMed: 33344329
DOI: 10.4322/acr.2020.221 -
PloS One 2020A new ophthalmosaurid ichthyosaur, Thalassodraco etchesi gen. et sp. nov., from the Upper Jurassic Kimmeridge Clay Formation of Dorset, UK is described. The specimen, a...
A new ophthalmosaurid ichthyosaur, Thalassodraco etchesi gen. et sp. nov., from the Upper Jurassic Kimmeridge Clay Formation of Dorset, UK is described. The specimen, a partial, articulated skull and anterior thorax in the Etches Collection of Kimmeridge, Dorset, is exceptionally well preserved on a slab of laminated coccolith limestone and has been expertly prepared. It comprises a near complete skull in articulation with associated anterior vertebral column and dorsal ribs, complete pectoral girdle, fully exposed left forelimb, and some elements of the right forelimb. Other elements present, including an ischiopubis are preserved on separate slabs. Presumed rapid burial of the anterior portion of the specimen in the coccolith substrate has preserved a number of ossified ligaments lying across the vertebral column and associated ribs as well as stomach contents and decayed internal organs. Aspects of the dentition, skull roof bones and the forelimb configuration distinguishes the new specimen from previously described Late Jurassic ichthyosaurs. Autopmorphies for T. etchesi include a large rounded protuberance on the supratemporal bone; a thin L-shaped lachrymal, with a steeply curved posterior border; ~ 70 teeth on the upper tooth row, and deep anterior dorsal ribs. A well resolved phylogenetic analysis shows T. etchesi as a member of a basal clade within Ophthalmosauridae comprising Nannopterygius, Gengasaurus, Paraophthalmosaurus and Thalassodraco. The new specimen adds to the diversity of the Ichthyopterygia of the Kimmeridge Clay Formation and emphasises the important contribution of amateur collectors in palaeontology.
Topics: Animals; Biodiversity; Dinosaurs; Fossils; Ligaments; Phylogeny; Skull; Thorax; Tooth; United Kingdom
PubMed: 33296370
DOI: 10.1371/journal.pone.0241700 -
Molecular Ecology Jan 2021Phenotypic integration is an important metric that describes the degree of covariation among traits in a population, and is hypothesized to arise due to selection for...
Phenotypic integration is an important metric that describes the degree of covariation among traits in a population, and is hypothesized to arise due to selection for shared functional processes. Our ability to identify the genetic and/or developmental underpinnings of integration is marred by temporally overlapping cell-, tissue- and structure-level processes that serve to continually 'overwrite' the structure of covariation among traits through ontogeny. Here, we examine whether traits that are integrated at the phenotypic level also exhibit a shared genetic basis (e.g. pleiotropy). We micro-CT scanned two hard tissue traits, and two soft tissue traits (mandible, pectoral girdle, atrium and ventricle, respectively) from an F hybrid population of Lake Malawi cichlids, and used geometric morphometrics to extract 3D shape information from each trait. Given the large degree of asymmetric variation that may reflect developmental instability, we separated symmetric from asymmetric components of shape variation. We then performed quantitative trait loci (QTL) analysis to determine the degree of genetic overlap between shapes. While we found ubiquitous associations among traits at the phenotypic level, except for a handful of notable exceptions, our QTL analysis revealed few overlapping genetic regions. Taken together, this indicates developmental interactions can play a large role in determining the degree of phenotypic integration among traits, and likely obfuscate the genotype to phenotype map, limiting our ability to gain a comprehensive picture of the genetic contributors responsible for phenotypic divergence.
Topics: Animals; Cichlids; Genotype; Phenotype; Quantitative Trait Loci
PubMed: 33231336
DOI: 10.1111/mec.15748 -
Ecology and Evolution Oct 2020Frogs and toads (Lissamphibia: Anura) show a diversity of locomotor modes that allow them to inhabit a wide range of habitats. The different locomotor modes are likely...
Frogs and toads (Lissamphibia: Anura) show a diversity of locomotor modes that allow them to inhabit a wide range of habitats. The different locomotor modes are likely to be linked to anatomical specializations of the skeleton within the typical frog Bauplan. While such anatomical adaptations of the hind limbs and the pelvic girdle are comparably well understood, the pectoral girdle received much less attention in the past. We tested for locomotor-mode-related shape differences in the pectoral girdle bones of 64 anuran species by means of micro-computed-tomography-based geometric morphometrics. The pectoral girdles of selected species were analyzed with regard to the effects of shape differences on muscle moment arms across the shoulder joint and stress dissipation within the coracoid. Phylogenetic relationships, size, and locomotor behavior have an effect on the shape of the pectoral girdle in anurans, but there are differences in the relative impact of these factors between the bones of this skeletal unit. Remarkable shape diversity has been observed within locomotor groups indicating many-to-one mapping of form onto function. Significant shape differences have mainly been related to the overall pectoral girdle geometry and the shape of the coracoid. Most prominent shape differences have been found between burrowing and nonburrowing species with headfirst and backward burrowing species significantly differing from one another and from the other locomotor groups. The pectoral girdle shapes of burrowing species have generally larger moment arms for (simulated) humerus retractor muscles across the shoulder joint, which might be an adaptation to the burrowing behavior. The mechanisms of how the moment arms were enlarged differed between species and were associated with differences in the reaction of the coracoid to simulated loading by physiologically relevant forces.
PubMed: 33144978
DOI: 10.1002/ece3.6784