[Muscle-architectural and muscle spindle differentiation in the tongue of primates including man (author's transl)].
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Animals↗
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Results for “muscle architecture”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
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Comparing the Effects of Push and Hold Isometric Training on Strength and Musculotendinous Adaptations: A Within-Subject Randomized Controlled Trial.
Lum, D, Oranchuk, DJ, Chen, SE, and Kong, PW. Comparing the effects of push and hold isometric training on strength and musculotendinous adaptations: A within-subject randomized controlled trial. J Strength Cond Res 40(9): 1050-1058, 2026-Despite recent interest in delineating pushing (PIMA) and holding (HIMA) isometric muscle actions, training-induced adaptations have not been examined. As such, we compared the strength and morphological adaptations between PIMA and HIMA training. Twenty limbs across 10 adults (5 men, 5 women, age: 31.4 ± 6.5 years) were randomly assigned to PIMA or HIMA conditions and underwent 12 training sessions over 6 weeks. PIMA required subjects to exert force against a fixed lever while the HIMA limb maintained a set joint angle while resisting an isotonic lever. During each contraction, subjects had to exert force at 70% of maximal voluntary contraction for 20 seconds at an 80° knee angle, for 4-6 repetitions. Subjects completed isometric, concentric, and eccentric knee extension assessments for both limbs before and after the intervention. Pre- and postintervention ultrasound scans were performed to determine quadriceps muscle architecture and patellar tendon thickness. Increased isometric torque was found following both conditions (p < 0.05, g = 0.30-0.36), while concentric (p < 0.05, g = 0.31) and eccentric (p < 0.01, g = 0.50) torque only increased following PIMA. Both conditions increased muscle thickness (p < 0.05, g = 0.27-0.88) and vastus lateralis fascicle length (p < 0.05, g = 0.20-0.31). Only HIMA increased patellar tendon thickness (p < 0.05, g = 0.12). The increase in total quadriceps (p < 0.05, g = 0.46) and especially rectus femoris (p < 0.05, g = 1.44) thickness was greater in HIMA. The results suggest that PIMA may be more effective at improving strength, while HIMA may be superior for inducing morphological adaptations. Larger sample sizes and more ecologically valid training programs are warranted to further elucidate potential differences between different isometric types.
Humans↗
Muscle mechanical and architectural adaptations in response to different endurance training modalities in older adults.
INTRODUCTION: This study examined the effects of various cycling endurance training modalities, matched for total workload, on muscle mechanical and architectural characteristics in older adults. METHODS: Fifty healthy participants (25 females, 59-79 yrs) were randomly assigned to five age and sex matched groups: one control and four workload-matched training groups (moderate-intensity continuous, heavy-intensity continuous, high-intensity interval, and heavy-intensity continuous in eccentric cycling). Training consisted of three weekly sessions over 8 weeks, with evaluations conducted at the beginning and end of the intervention with maximal voluntary isometric contractions at five different knee angles (90, 75, 60, 45, 30°) and maximal concentric and eccentric isokinetic contractions at five different knee angular velocities (45, 90, 150, 210, 250°/s). Maximum voluntary isometric torque (Tmax) and optimal knee angle (KAopt) were obtained from the isometric contractions; eccentric torque (Tecc) and maximum concentric knee angular velocity (Vmax) were obtained from the isokinetic contractions. The muscle architecture of vastus lateralis (VL) at rest (muscle thickness, pennation angle, and fascicle length) was investigated as well. RESULTS: No statistical differences were detected between groups or time points in VL architecture, in KAopt and in Vmax. A main effect of time was observed for Tmax (p < 0.001, η2p = 0.458) and Tecc (p = 0.002, η2p = 0.191) in all the investigated training groups. The within-group comparisons indicate significant increases in Tmax in the training groups, but not in the control group. CONCLUSIONS: Commonly applied endurance exercises improve muscle mechanical capacity (Tmax and Tecc) in older adults, with no structural (architectural) muscle remodelling, when matched for workload.
Humans↗
The ultrastructural effect of distension on the neuromuscular apparatus of the urinary bladder.
The recent clinical success of distension therapy in the treatment of idiopathic detrusor hyperreflexia has prompted this ultrastructural study. The neuromuscular pathways of conduction in the rat and rabbit urinary bladder wall were examined using perfusion fixation techniques. The effects of short-term and prolonged distension were studied at frequent intervals for 4 months in treated and control animals. Prolonged distension did not alter either smooth muscle architecture or intercellular contact points. A transient phase of nerve degeneration in bladder muscle consisting of axonal swelling and lysis of organelles was observed. A quantitative estimate of nerve injury and regeneration was compiled using pooled histograms. Possible physiologic mechanisms of injury and clinical conclusions are discussed.
Animals↗
Penicillamine in the therapy of hereditary muscular dystrophy in chickens.
This was a brief 6-month study of the possible value of penicillamine in adult chickens with hereditary muscular dystrophy. Detailed histologic investigation of various parameters of muscle architecture yielded no evidence of significant therapeutic effect. Several serious toxic symptoms were noted. It is suggested that in muscular dystrophy, a disease in which the main feature is profound alteration of muscle structure, histologic studies may be the best means of documenting response to therapeutic agents.
Animals↗
Morphological and histochemical organization of the flexor carpi radialis muscle in the cat.
Most studies concerning the structure and function of skeletal muscle have utilized the hind limb of the experimental animal. However, it has been shown that the number of behavioral tasks performed by the cat's forelimb is greater than that of the hind limb. In addition, the forelimb muscles exhibit a functional complexity not observed in hind-limb musculature. The purpose of this study was to investigate the distribution of fast-twitch and slow-twitch muscle fibers and muscle spindles in the flexor carpi radialis muscle (FCR) and to correlate the distributional patterns in these structures with muscle tendon architecture and muscle function. It was found that the FCR, a wrist flexor, contains 37% slow-twitch fibers and 63% fast-twitch fibers. However, the slow-twitch fibers were concentrated in the deep region located between the tendons of origin and insertion, while the fast-twitch-glycolytic fibers were concentrated more peripherally. Muscle spindles were associated with the slow-twitch region and were never found in the region containing high concentrations of fast-twitch-glycolytic fibers. Fast-twitch-oxidative-glycolytic fibers were uniformly distributed throughout the muscle. It is proposed that the association of muscle spindles with slow-twitch fibers and the differential distribution of muscle fibers into slow-twitch and fast-twitch regions might allow these regions to function independently of one another when called upon to perform complex behavioral tasks.
Adenosine Triphosphatases↗
Neuromuscular dysfunction induced by acetylcholinesterase inhibition.
The organophosphate cholinesterase inhibitor paraoxon produces a dose-dependent necrosis in rat skeletal muscle fibers after a single administration. The pathology, which is initiated at the motor end-plate region, is evident as early as 30 minutes after paraoxon administration and is characterized by dilated mitochondria, expanded sarcoplasmic reticulum, fused and widened subsynaptic folds, and coated cleft vesicles. By 24 hours, a generalized breakdown of muscle fiber architecture is evident with an accompanying infiltration of phagocytes. Electrophysiological studies have shown that paraoxon increases neurotransmitter release and causes spontaneous and impulse-related antidromic nerve activity, both of which can be reduced significantly by reactivation of inhibited acetylcholinesterase (AChE) with pyridine-2-aldoxime methiodide. The severity of the myopathy has been found to be positively correlated to the degree and duration of AChE inhibition. It appears that 2 hours of inhibition, with a critical loss in activity, viz., 85%, is necessary to initiate severe muscle fiber necrosis. Prior nerve transection prevents myopathic development and current data support the hypothesis that the induction of skeletal muscle fiber necrosis is triggered by inhibition of a neurally regulated fraction of AChE.
Acetylcholine↗
Diagnostic value of the muscle biopsy in the neonatal period.
Muscle biopsy specimens of 20 full-term neonates (13 surgical and seven necropsy specimens) with clinical evidence of neuromuscular disease were studied to determine the diagnostic usefulness of this procedure in the newborn. Characteristic pathologic alterations were identified in specific diseases. Some findings were similar to those seen later in life, but others differed from those expected in the same diseases at older ages. Persistence of fetal muscle cells was a characteristic common to several congenital myopathies and neuropathies. Lymphocytic infiltrates, muscle fiber necrosis, and architectural alterations of the muscle fibers were not seen at birth. Extramedullary hematopoiesis may involve newborn muscle. Muscle biopsy is a safe and simple procedure in the neonatal period and has a diagnostic reliability as good as at older ages, but histochemistry and sometimes electron microscopy are essential supplements to classical histology for interpretation. Recommended indications for muscle biopsy in the neonatal period are multiple joint contractures at birth or hypotonia and weakness, of unknown origin.
Biopsy↗
Anatomic effect of distention therapy in unstable bladder: new approach.
The recent clinical success of distention therapy in the treatment of the unstable bladder is reviewed. Bladder stability and increased capacity as measured by cystometry following distention therapy as well as relief of symptoms have prompted this anatomic study. The neuromuscular pathways of conduction in rat and rabbit bladder wall were examined following short-term (two-hour) and prolonged (six-hour) distention. Treated and control animals were studied at fixed intervals for four months. Prolonged distention did not alter either smooth muscle cell architecture or intercellular junctions. It did produce a transient phase of degeneration among the unmyelinated nerve fibers in the bladder wall consisting of axonal swelling and lysis of organelles. A quantitative estimate of nerve injury was compiled using pooled histograms. These results suggest that bladder stability following distention therapy may be related to nerve degeneration in the bladder wall.
Animals↗
Mutations of Drosophila melanogaster that affect muscles.
Eight X-chromosome mutations (falling into five complementation groups) that affect the development and morphology of the indirect flight muscles of Drosophila melanogaster were investigated using histological, behavioural and genetic techniques. All of these mutations result in flightlessness, in a marked reduction in the ability of the flies to jump, and in the wings being held in abnormal positions. Mutations in each of the complementation groups have different effects on the morphology of the muscles. Two (flapwing, vertical wing) result in absence of most of the indirect flight muscle fibres, a third (upheld) is required for the gross organization of muscle structure, another (heldup) is involved in the maintenance of muscle structure once formed, and the fifth seems to be necessary for the detailed architecture of the muscle fibre (indented thorax). The analysis of flies genetically mosaic with respect to each mutation by the technique of fate-mapping suggests that three (heldup, upheld and indented thorax) of the genes concerned have their primary site of action in the musculature itself, while the other two (flapwing and vertical wing) may function primarily in the fat-body and tracheae respectively.
Animals↗
Functional heterogeneity in a multipinnate muscle.
Many mammalian muscles have a complex internal architecture. This type of structure could allow a single muscle to produce a variety of force vectors through selective regional contractions. This hypothesis was tested electromyographically in the multipinnate pig masseter by recording simultaneously from several intramuscular sites. It was found that the activity in different portions of the masseter varied systematically during the various phases of mastication. anatomical correlates of the differential activity included fasciculus orientation and length, sarcomere length in specific jaw positions, and histochemical fiber type. The usual assumptions made about muscles for biomechanical analysis, such as uniform contraction and constant line of action, are inappropriate for complex muscles such as the pig masseter.
Animals↗
Genome-wide association study of sarcopenia index reveals sex-stratified genetic architecture.
BACKGROUND: The sarcopenia index (SI), defined as the ratio of serum creatinine to cystatin C, is a proposed biomarker of muscle mass and sarcopenia, yet its genomic basis and genetic architecture remain largely unexplored. METHODS: We performed combined-sex and sex-stratified genome-wide association studies of SI in the UK Biobank. We examined the overlap between SI-associated loci and loci previously reported for sarcopenia-related traits. We assessed sexually dimorphic effects and gene-sex interactions, performed fine-mapping, and conducted credible gene prioritization, motif and transcription factor binding enrichment, gene-set enrichment, linkage disequilibrium score regression, and cross-phenotype colocalization. RESULTS: We identified 774 unique independent SI-associated loci across all analyses, with 747 detected in the combined-sex GWAS, 283 in the male-stratified GWAS, and 311 in the female-stratified GWAS; 367 of these loci had not been previously reported for conventional sarcopenia-related traits. Sex-stratified analyses highlighted the rs1145093-chr15q21.1-GATM region, where CARMA identified sex-differentiated causal variants. We prioritized 17 male-biased and 11 female-biased credible genes. Enrichment analyses implicated androgen receptor and GATA4 in males, and ESR1 and MYOD1 in females. Enrichment revealed shared pathways involving inflammation, cellular stress, and aging-related processes. LDSC showed inverse genetic correlations between SI and heart failure (rg = -0.19, p = 2.30 × 10- 9) and metabolic syndrome (rg = -0.12, p = 8.49 × 10- 8), and a positive correlation with chronic kidney disease. Compared with female SI, male SI exhibited two additional loci showing colocalization with four metabolic traits. CONCLUSIONS: These findings clarify the genetic architecture of SI and reveal sex-dependent mechanisms underlying sarcopenia, supporting precision risk assessment and targeted interventions.
Humans↗
Bumps, grinds take toll on bones, muscles, mind.
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Animals↗
Muscular equivalent of the lower esophageal sphincter.
In order to measure muscle thickness and to define the muscular architecture at the gastroesophageal function, both en bloc fixation and a new method of preparing dried fiber specimens were used. Specimens were obtained from 32 kidney donors and human cadavers. Wall thickness was measured at 32 identical locations in the esophagus and stomach. The oblique gastroesophageal ring (GER) was the site of greatest muscular thickness and served as a reference point. From the GER the muscle thickness tapered (P less than 0.05 to P less than 0.001) in both a cephalic (esophageal) and caudal (gastric) direction for a length of 31 mm +/- 2.5 SD. The increase in thickness was due to an increase in the muscle mass (fiber aggregation) of the inner muscle coat. The muscle bundles of this coat split up 10.2 mm +/- 3.0 SD above the GER (fixed specimen) and for a length of 25 mm +/- 8 SD formed short transverse muscle clasps on the lesser curve side. Those muscle bundles on the greater curve side formed long oblique gastric fiber loops. The angle of His was inconstant in location and distal to the uppermost gastric oblique fibers (18 mm +/- 7 SD) and to the GER (9 mm +/- 6 SD).
Adolescent↗
Macrophage regulation of extracellular matrix remodeling in aging skeletal muscle.
The extracellular matrix (ECM) is a dynamic structural network that supports tissue architecture and regulates cell function. It is primarily composed of collagens, elastin, proteoglycans, and glycoproteins, which are synthesized by canonical and non-canonical ECM-producing cells. During aging, the ECM undergoes progressive changes in structure and composition, a process recently recognized as the 13th hallmark of aging. In skeletal muscle (SKM), age-associated ECM remodeling, largely regulated by immune system-ECM crosstalk, contributes to sarcopenia and impaired regeneration. Macrophages (MΦs), as key innate immune cells, regulate ECM dynamics both indirectly by activating canonical ECM-producing cells and directly by synthesizing ECM components. Notably, a distinct subset of ECM-producing MΦs that express collagen (COL+ MΦs) has been identified across multiple tissues, although their function in SKM homeostasis and aging remains poorly understood. Here, we review current knowledge of ECM production and remodeling, with special emphasis on MΦ involvement, including COL+ MΦs, as critical regulators of fibrogenesis, especially during SKM aging and regeneration.
Extracellular Matrix↗
Facial rehabilitation with temporal muscle. New concepts.
Facial rehabilitation, utilizing the transposed temporalis muscle, was performed. Three new innovations of this technique include: (1) The whole muscle is transposed into the face to accomplish augmentation, support, protection for the eye, and movement. (2) Following transposition of the temporalis muscle, its nerve supply is lysed at the foramen ovale. Nerve substitution by a free, autogenous graft from the proximal segment of the ipsilateral facial nerve or crossfacial sural nerve is accomplished. This technique substitutes the facial nerve axons and nuclei for the trigeminal nerve in this muscle and thus eliminates movement on mastication and facilitates the possibility for expression. (3) This muscle may be transposed with a portion of the temporal and parietal bones to add bony architecture to the cheek and orbit.
Facial Muscles↗
Exploring the shared genetic architecture of sarcopenia using genomic structural equation modeling.
Sarcopenia is a common age-associated condition characterized by the progressive loss of skeletal muscle mass, strength, and physical functionality. While large-scale genome-wide association studies (GWAS) have previously addressed isolated traits of sarcopenia, the multifactorial genetic architecture underlying this condition remains largely undefined. To characterize the common genetic basis of sarcopenia-related traits, genomic structural equation modeling (Genomic-SEM) was implemented. Multiple post-GWAS analytic approaches were integrated to pinpoint susceptibility loci. These analyses encompassed identifying enriched genetic pathways and relevant genomic elements, as well as cell-type-specific enrichment in skeletal muscle satellite stem cells, mesenchymal stem cells, and skeletal muscle satellite cells in limb muscle. Furthermore, based on the integrated GWAS data of sarcopenia-related traits, polygenic risk score (PRS) analysis was conducted to evaluate risk associations at the chromosomal level. A well-fitted Genomic-SEM successfully integrated the GWAS data, revealing the shared genetic architecture of sarcopenia-related traits. We identified 110 single nucleotide polymorphisms (SNPs) reaching genome-wide significance (p < 5 × 10-8), of which 9 represent novel discoveries. Subsequent fine-mapping procedures and gene-set analyses identified 15 causal variants alongside 77 candidate susceptibility genes. This study provides a comprehensive genetic characterization of sarcopenia via Genomic-SEM, offering new insights into the etiological pathways underlying sarcopenia.
Sarcopenia↗
Split-line patterns of the mandible following masseterectomy in adult and growing monkeys.
Architectural changes of the mandibular ramus following masseterectomy were analyzed by means of the split-line technique in both adult and growing monkeys. The right masseter muscle was resected in ten tufted capuchin monkeys (Cebus apella) and they were sacrificed following a 12-month period. Along with modifications in the shape of the mandible, the masseterectomy induced structural changes as revealed by alterations in the split-line patterns. These changes were much more evident in the adult animals. In growing monkeys, intrinsic forces determine an architecture of mandibular growth, represented by the direction of the splits. This is not influenced by the lack of mechanical factors like muscle action. Conversely, the final fibrous architecture of the bone in the adult monkey may be modified by extrinsic mechanical factors.
Age Factors↗