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Journal of Anatomy Nov 2020Birds have lost and modified the musculature joining the pectoral girdle to the skull and hyoid, called the pectoral extrinsic appendicular and infrahyoid musculature....
Birds have lost and modified the musculature joining the pectoral girdle to the skull and hyoid, called the pectoral extrinsic appendicular and infrahyoid musculature. These muscles include the levator scapulae, sternomandibularis, sternohyoideus, episternocleidomastoideus, trapezius, and omohyoideus. As non-avian theropod dinosaurs are the closest relatives to birds, it is worth investigating what conditions they may have exhibited to learn when and how these muscles were lost or modified. Using extant phylogenetic bracketing, osteological correlates and non-osteological influences of these muscles are identified and discussed. Compsognathids and basal Maniraptoriformes were found to have been the likeliest transition points of a derived avian condition of losing or modifying these muscles. Increasing needs to control the feather tracts of the neck and shoulder, for insulation, display, or tightening/readjustment of the skin after dynamic neck movements may have been the selective force that drove some of these muscles to be modified into dermo-osseous muscles. The loss and modification of shoulder protractors created a more immobile girdle that would later be advantageous for flight in birds. The loss of the infrahyoid muscles freed the hyolarynx, trachea, and esophagus which may have aided in vocal tract filtering.
Topics: Animals; Biological Evolution; Birds; Dinosaurs; Muscle, Skeletal
PubMed: 32794182
DOI: 10.1111/joa.13256 -
Journal of Anatomy 2001The pectoral girdle articulates the forelimb with the axial skeleton in all vertebrates with paired anterior appendages. The structure of the pectoral girdle and its... (Review)
Review
The pectoral girdle articulates the forelimb with the axial skeleton in all vertebrates with paired anterior appendages. The structure of the pectoral girdle and its position along the axial skeleton has changed significantly during vertebrate evolution. These morphological changes have been well described, but there is little comparative embryology to indicate how these changes may have occurred. It is equally obscure how the muscles that connect the head with the pectoral girdle have maintained appropriate attachments even though these 2 structures have become separated. Here I review the changes in the pectoral girdle across different vertebrate taxa, indicating, where known, the developmental mechanisms underlying these changes. I also suggest how the muscular connections between the head and pectoral girdle have been maintained between these once adjacent bones, displaced during vertebrate evolution.
Topics: Animals; Biological Evolution; Bone and Bones; Fossils; Humans; Neural Crest; Pectoralis Muscles; Shoulder; Vertebrates
PubMed: 11523822
DOI: 10.1046/j.1469-7580.2001.19910189.x -
ELife Mar 2022The morphology of the pectoral girdle, the skeletal structure connecting the wing to the body, is a key determinant of flight capability, but in some respects is poorly...
The morphology of the pectoral girdle, the skeletal structure connecting the wing to the body, is a key determinant of flight capability, but in some respects is poorly known among stem birds. Here, the pectoral girdles of the Early Cretaceous birds and are reconstructed for the first time based on computed tomography and three-dimensional visualization, revealing key morphological details that are important for our understanding of early-flight evolution. exhibits a double articulation system (widely present in non-enantiornithine pennaraptoran theropods including crown birds), which involves, alongside the main scapula-coracoid joint, a small subsidiary joint, though variation exists with respect to the shape and size of the main and subsidiary articular contacts in non-enantiornithine pennaraptorans. This double articulation system contrasts with in which a spatially restricted scapula-coracoid joint is formed by a single set of opposing articular surfaces, a feature also present in other members of Enantiornithines, a major clade of stem birds known only from the Cretaceous. The unique single articulation system may reflect correspondingly unique flight behavior in enantiornithine birds, but this hypothesis requires further investigation from a functional perspective. Our renderings indicate that both and had a partially closed triosseal canal (a passage for muscle tendon that plays a key role in raising the wing), and our study suggests that this type of triosseal canal occurred in all known non-euornithine birds except , representing a transitional stage in flight apparatus evolution before the appearance of a fully closed bony triosseal canal as in modern birds. Our study reveals additional lineage-specific variations in pectoral girdle anatomy, as well as significant modification of the pectoral girdle along the line to crown birds. These modifications produced diverse pectoral girdle morphologies among Mesozoic birds, which allowed a commensurate range of capability levels and styles to emerge during the early evolution of flight.
Topics: Animals; Biological Evolution; Birds; Fossils; Phylogeny; Wings, Animal
PubMed: 35356889
DOI: 10.7554/eLife.76086 -
The Journal of Chiropractic Education Oct 2022The aim of this study is to conduct a pilot survey to determine core anatomy content for chiropractic curriculum based on the perception of chiropractors and anatomy...
OBJECTIVE
The aim of this study is to conduct a pilot survey to determine core anatomy content for chiropractic curriculum based on the perception of chiropractors and anatomy educators involved in teaching in an Australian chiropractic program.
METHODS
A survey of anatomical structures previously used in a medical survey, with similar criteria for synthesizing responses, was used and classified according to whether the respondents rated an item as essential, important, acceptable, or not required in a chiropractic program. The item was scored as core if ≥60% of respondents rated it essential, recommended if 30%-59% rated it essential, not recommended if 20%-29% rated it essential, or not core if <20% rated it essential.
RESULTS
The respondents rated 81.6% of all musculoskeletal concepts as core and 18.4% as recommended, 88.8% of the vertebral column items as core, and 11.2% of the items as recommended, 69.4% upper limb and pectoral girdle items as core, 23.7% of items as recommended, 5.5% as not recommended and 1.3% as not core items for inclusion, 85.3% of all lower limb and pelvic girdle items as core, 14.4% as recommended and 0.3% not recommended.
CONCLUSION
Chiropractors and anatomists involved in teaching in an Australian chiropractic program rated most musculoskeletal items as essential for inclusion in a chiropractic teaching program to ensure adequate preparation for safe practice and to promote alignment with the standards of anatomy education delivered into the clinical professions.
PubMed: 35561322
DOI: 10.7899/JCE-21-18 -
Journal of Anatomy Mar 2017The pectoral girdle is a complex structure which varies in its morphology between species. A major component in birds is the furcula, which can be considered equivalent...
The pectoral girdle is a complex structure which varies in its morphology between species. A major component in birds is the furcula, which can be considered equivalent to a fusion of the paired clavicles found in many mammals, and the single interclavicle found in many reptiles. These elements are a remnant of the dermal skeleton and the only intramembranous bones in the trunk. Postnatally, the furcula plays important mechanical roles by stabilising the shoulder joint and acting as a mechanical spring during flight. In line with its mechanical role, previous studies indicate that, unlike many other intramembranous bones, furcula growth during development can be influenced by mechanical stimuli. This study investigated the response of individual aspects of furcula growth to both embryo immobilisation and hypermotility in the embryonic chicken. The impact of altered incubation temperature, which influences embryo motility, on crocodilian interclavicle development was also explored. We employed whole-mount bone and cartilage staining and 3D imaging by microCT to quantify the impact of rigid paralysis, flaccid paralysis and hypermobility on furcula growth in the chicken, and 3D microCT imaging to quantify the impact of reduced temperature (32-28 °C) and motility on interclavicle growth in the crocodile. This revealed that the growth rates of the clavicular and interclavicular components of the furcula differ during normal development. Total furcula area was reduced by total unloading produced by flaccid paralysis, but not by rigid paralysis which maintains static loading of embryonic bones. This suggests that dynamic loading, which is required for postnatal bone adaptation, is not a requirement for prenatal furcula growth. Embryo hypermotility also had no impact on furcula area or arm length. Furcula 3D shape did, however, differ between groups; this was marked in the interclavicular component of the furcula, the hypocleideum. Hypocleideum length was reduced by both methods of immobilisation, and interclavicle area was reduced in crocodile embryos incubated at 28 °C, which are less motile than embryos incubated at 32 °C. These data suggest that the clavicular and interclavicle components of the avian furcula respond differently to alterations in embryo movement, with the interclavicle requiring both the static and dynamic components of movement-related loading for normal growth, while static loading preserved most aspects of clavicle growth. Our data suggest that embryo movement, and the mechanical loading this produces, is important in shaping these structures during development to suit their postnatal mechanical roles.
Topics: Alligators and Crocodiles; Animals; Bone Development; Bone and Bones; Chick Embryo; Imaging, Three-Dimensional; Movement; X-Ray Microtomography
PubMed: 27921302
DOI: 10.1111/joa.12571 -
Journal of Anatomy Dec 2021Describing osteological development is of great importance for understanding vertebrate phenotypic variations, form-functional transitions and ecological adaptations....
Describing osteological development is of great importance for understanding vertebrate phenotypic variations, form-functional transitions and ecological adaptations. Anurans exhibit dramatic changes in their morphology, habitat preferences, diet and behaviour between the tadpole and frog stages. However, the anatomical details of their cranial and postcranial development have not been extensively studied, especially in Microhylidae. In this work, we studied the microhylid Microhyla fissipes, commonly known as the ornamented pygmy frog, a small-sized frog with fast metamorphosis. Its osteological development was comprehensively described based on 120 cleared and stained specimens, including six tadpoles for each stage between 28 and 45, six juveniles and six adults. Additionally, 22 osteological traits of these specimens involved in food acquisition, respiration, audition and locomotion were selected and measured to reflect the changes in tadpole ecological functions during metamorphosis. Our study provides the first detailed qualitative and quantitative developmental information about these structures. Our results have confirmed that skeletal elements (viz., neopalatines, omosternum, clavicles and procoracoids) absent in adults are not detected during development. Our data reveal that morphologically, radical transformations of the cranial structures related to feeding and breathing are completed within stages 42-45 (72 h), but the relative length and width of these skeletons have changed in earlier stages. The postcranial skeletons correlated with locomotion are well developed before stage 42 and approach the adult morphology at stage 45. Indeed, the relative length of the pectoral girdle and forelimb reaches the adult level at stage 42 and stage 45, respectively, whereas that of the vertebral column, pelvic girdle and hind limbs increases from their appearance until reaching adulthood. Based on published accounts of 19 species from Neobatrachia, Mesobatrachia and Archaeobatrachia, cranial elements are among the first ossified skeletons in most studied species, whereas sphenethmoids, neopalatines, quadratojugals, mentomeckelians, carpals and tarsals tend to ossify after metamorphosis. These results will help us to better understand the ecomorphological transformations of anurans from aquatic to terrestrial life. Meanwhile, detailed morphological and quantitative accounts of the osteological development of Microhyla fissipes will provide a foundation for further study.
Topics: Animals; Anura; Forelimb; Larva; Metamorphosis, Biological; Osteology
PubMed: 34268788
DOI: 10.1111/joa.13510 -
Scientific Reports Aug 2022The sternum is a stabilizing element in the axial skeleton of most tetrapods, closely linked with the function of the pectoral girdle of the appendicular skeleton.... (Review)
Review
The sternum is a stabilizing element in the axial skeleton of most tetrapods, closely linked with the function of the pectoral girdle of the appendicular skeleton. Modern mammals have a distinctive sternum characterized by multiple ossified segments, the origins of which are poorly understood. Although the evolution of the pectoral girdle has been extensively studied in early members of the mammalian total group (Synapsida), only limited data exist for the sternum. Ancestrally, synapsids exhibit a single sternal element and previously the earliest report of a segmental sternum in non-mammalian synapsids was in the Middle Triassic cynodont Diademodon tetragonus. Here, we describe the well-preserved sternum of a gorgonopsian, a group of sabre-toothed synapsids from the Permian. It represents an ossified, multipartite element resembling the mammalian condition. This discovery pulls back the origin of the distinctive "mammalian" sternum to the base of Theriodontia, significantly extending the temporal range of this morphology. Through a review of sternal morphology across Synapsida, we reconstruct the evolutionary history of this structure. Furthermore, we explore its role in the evolution of mammalian posture, gait, and ventilation through progressive regionalization of the postcranium as well as the posteriorization of musculature associated with mammalian breathing.
Topics: Biological Evolution; Fossils; Locomotion; Respiration; Sternum
PubMed: 35931742
DOI: 10.1038/s41598-022-17492-6 -
Journal of Ultrasound Dec 2010A thorough knowledge of the anatomy of the shoulder is essential for the assessment of its condition. The purpose of this article is to provide a useful tool for the...
A thorough knowledge of the anatomy of the shoulder is essential for the assessment of its condition. The purpose of this article is to provide a useful tool for the ultrasound (US) study of this joint. The shoulder girdle and upper arm are made up of a number of muscles and tendons: rotator cuff (supraspinatus, infraspinatus, teres minor and subscapularis), humeral biceps, deltoid and pectoral muscles, which can all be evaluated at US examination. Various and complex capsular ligamentous structures contribute to the stability of the shoulder, but only a few can be adequately evaluated by US and will therefore receive particular attention. Numerous serous bursae are situated among muscles, skin, subcutaneous tissues, joint capsule structures and bones to prevent friction and they can be evaluated by US only in the presence of pathologies. Subacromial-subdeltoid and subcoracoid bursa are most frequently involved and will therefore be described in detail. There are furthermore nerves and vessels providing the various components of the shoulder with innervation and vascularization, and they can also be studied by US. The shoulder girdle (humerus, scapula, clavicle and sternal manubrium) is situated in the deep layers; only the cortex of the bone can be seen at US as a continuous hyperechoic line. For a better understanding of the location and relationship between the structures which can be studied by US, magnetic resonance imaging (MRI) can be carried out as this method provides a wider and more complete view of the structures.
PubMed: 23396832
DOI: 10.1016/j.jus.2010.10.005 -
Nature Nov 2023The origin of vertebrate paired appendages is one of the most investigated and debated examples of evolutionary novelty. Paired appendages are widely considered as key...
The origin of vertebrate paired appendages is one of the most investigated and debated examples of evolutionary novelty. Paired appendages are widely considered as key innovations that enabled new opportunities for controlled swimming and gill ventilation and were prerequisites for the eventual transition from water to land. The past 150 years of debate has been shaped by two contentious theories: the ventrolateral fin-fold hypothesis and the archipterygium hypothesis. The latter proposes that fins and girdles evolved from an ancestral gill arch. Although studies in animal development have revived interest in this idea, it is apparently unsupported by fossil evidence. Here we present palaeontological support for a pharyngeal basis for the vertebrate shoulder girdle. We use computed tomography scanning to reveal details of the braincase of Kolymaspis sibirica, an Early Devonian placoderm fish from Siberia, that suggests a pharyngeal component of the shoulder. We combine these findings with refreshed comparative anatomy of placoderms and jawless outgroups to place the origin of the shoulder girdle on the sixth branchial arch. These findings provide a novel framework for understanding the origin of the pectoral girdle. Our evidence clarifies the location of the presumptive head-trunk interface in jawless fishes and explains the constraint on branchial arch number in gnathostomes. The results revive a key aspect of the archipterygium hypothesis and help reconcile it with the ventrolateral fin-fold model.
Topics: Animals; Animal Fins; Biological Evolution; Fishes; Fossils; Paleontology; Tomography, X-Ray Computed; Vertebrates; Siberia
PubMed: 37914937
DOI: 10.1038/s41586-023-06702-4 -
Annals of Advances in Automotive... 2012Thoracic spine flexibility affects head motion, which is critical to control in motor vehicle crashes given the frequency and severity of head injuries. The objective of...
Thoracic spine flexibility affects head motion, which is critical to control in motor vehicle crashes given the frequency and severity of head injuries. The objective of this study is to investigate the dynamic response of the human upper thoracic region. An original experimental/analytical approach, Isolated Segment Manipulation (ISM), is introduced to quantify the intact upper thoracic spine-pectoral girdle (UTS-PG) dynamic response of six adult post-mortem human subjects (PMHS). A continuous series of small displacement, frontal perturbations were applied to the human UTS-PG using fifteen combinations of speed and constraint per PMHS. The non-parametric response of the T1-T6 lumped mass segment was obtained using a system identification technique. A parametric mass-damper-spring model was used to fit the non-parametric system response. Mechanical parameters of the upper thoracic spine were determined from the experimental model and analyzed in each speed/constraint configuration. The natural frequencies of the UTS-PG were 22.9 ± 7.1 rad/sec (shear, n=58), 32.1 ± 7.4 rad/sec (axial, n=58), and 27.8 ± 7.7 rad/sec (rotation, n=65). The damping ratios were 0.25 ± 0.20 (shear), 0.42 ± 0.24 (axial), and 0.58± 0.32 (rotation). N-way analysis of variance (Type III constrained sum of squares, no interaction effects) revealed that the relative effects of test speed, pectoral girdle constraint, and PMHS anthropometry on the UTS-PG dynamic properties varied per property and direction. While more work is needed to verify accuracy in realistic crash scenarios, the UTS-PG model system dynamic properties could eventually aid in developing integrated anthropomorphic test device (ATD) thoracic spine and shoulder components to provide improved head kinematics and belt interaction.
Topics: Acceleration; Accidents, Traffic; Biomechanical Phenomena; Head; Humans; Shoulder; Spine
PubMed: 23169125
DOI: No ID Found