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Functional Anatomy
Published in James Crossley, Functional Exercise and Rehabilitation, 2021
Skeletal muscle is composed of many individual muscle fibers wrapped together in bundles. Connective tissue known as fascia covers each of these bundles. The outer layer that covers the whole muscle is called the epimysium. The epimysium runs into tendon of the muscle that attaches and transmits force to the bone. Muscles attach to bone proximally (origin) and distally (insertion). Origin – muscle attachment that is generally more proximal and moves the leastInsertion – muscle attachment that is generally more distal and moves the most Under the epimysium we see bundles of muscle fibers known as the fascicles, wrapped in fascia called the perimysium. Each muscle fiber is wrapped in a connective tissue called the endomysium. Each muscle fiber forms the building blocks of muscle called myofibrils.
Muscle and Nerve Histology
Published in Maher Kurdi, Neuromuscular Pathology Made Easy, 2021
Muscle tissue is differentiated into smooth, cardiac, and skeletal muscles. This differentiation embryonically starts to develop from mesoderm during the 7th week of gestation and it completely forms by the 28th week of gestation. The nuclei take their peripheral positions after 20 weeks of gestation. Skeletal muscle is elongated on longitudinal sections and striated in cross section. The entire portion is enclosed in a connective tissue sheath called epimysium, which is composed of extracellular matrix and irregular collagens. The epimysium connects into the tendon sheath and divides the muscle into groups of bundles, or fascicles, separated from each other by perimysium (Figure 1.1). The myotendinous junction area sometimes mimics dystrophy (pseudomyopathy), as it may show alternative features of hypertrophic and atrophic fibers, excess fibrous tissue, and multiple internal nuclei (Figure 1.2).
Skeletal Muscle
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
The endomysium, perimysium, and epimysium are made up mostly of the protein collagen, with some elastic connective tissue fibers consisting of the protein elastin, both proteins being made by cells referred to as fibroblasts. The endomysium conveys blood capillaries and nerve terminals to the muscle fibers and encloses fibroblasts and satellite cells involved in the repair of muscle tissue and in the formation of new muscle fibers to replace those that are irreversibly damaged. The epimysium separates the muscle from adjacent tissues and organs and reduces friction with other muscles and with bone.
The size and echogenicity of the tibialis anterior muscle is preserved in both limbs in young children with unilateral spastic cerebral palsy
Published in Disability and Rehabilitation, 2022
Steven J. Obst, Reuben Bickell, Kaysie Florance, Roslyn N. Boyd, Felicity Read, Lee Barber
Manual muscle segmentation was completed using the B-mode ultrasound images at ∼10% intervals, with the outer hyperechoic boundary representing the epimysium excluded from analysis (Figure 1). MG segmentation was from the distal myotendinous junction to the proximal muscle cross-section adjacent to the most distal aspect of medial femoral condyle. TA segmentation was from the proximal myotendinous junction to the distal muscle-tendon junction. A shape-based interpolation was used to create a 3D volumetric muscle reconstruction from the segmented muscle cross-sections [20]. Previous studies have confirmed the accuracy and reliability of our 3DUS system for in vivo measures of muscle size and echo intensity [21–23]. MG and TA volumes were expressed as an absolute (ml) and body-weight normalised value (ml/kg). MG and TA muscle lengths were defined as the linear distance between the centroid of the most proximal and distal muscle cross-sections. Muscle length was expressed as an absolute (mm) and tibial-length normalised value (mm/mm). All images that comprised the reconstructed muscle volume were cropped and masked to exclude image data outside the muscle region of interest, and then exported as a jpeg (lossy) for image analysis in Matlab (R2018b, The MathWorks, Natick, MA).
Modeling of muscular activation of the muscle-tendon complex using discrete element method
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Anthony Roux, Jennyfer Lecompte, Ivan Iordanoff, Sébastien Laporte
The mechanical properties and structures of the MTC model were described in Roux et al. (2016) (Figure 5). Numerical model was complete in DEM using GranOO software (www.granoo.org). Mechanical properties of MTC were based on values from the literature (Matschke et al. 2013, Regev et al. 2011). Fibers were built with spherical discrete elements, to model the inertia effects, linked by springs, to model the rheological behavior (stiffness was related to Young’s modulus: fiber’s Young’s modulus = 37.44 kPa). Tendon fibers were built in accordance with the arrangement of finger-like muscle fibers, inserted into the muscle to represent the myo-tendinous junction (MTJ) (Roux et al. 2016) (tendon’s Young’s modulus = 800 MPa, MTJ’s Young’s modulus = 400 MPa). Links are also created between fibers themselves and between tendon’s fibers and the epimysium (same Young’s modulus as tendon’s fibers) in order to simulate sliding between these two entities. The extracellular matrix (ECM) was computed using springs between fibers in all directions (ECM’s Young’s modulus = 0.1 MPa). For further information, the reader can refer to Roux et al. 2016.
Superficial CD34-Positive Fibroblastic Tumor on the Chest Wall of an 8-Year-Old Girl: A Case Report and Literature Review
Published in Pediatric Hematology and Oncology, 2021
Si Ying Li, Hai Lan Zhang, Yu Zuo Bai
An 8-year-old girl was admitted to our hospital 4 months after a tumor was detected on her left chest wall. The patient’s symptoms had started 4 months earlier with a mild tenderness mass on the left chest wall without irritation or inflammatory manifestations such as redness, swelling, or fever. The tumor was approximately the size of a fingernail and grew slowly. During physical examination, an enclosed solid mass with size of 1.5 × 1.0 × 1.0 cm was detected on the left chest wall, at approximately the level of the 8th to 9th rib, with a clear border. Imaging examination by ultrasonography showed a hypoechoic enclosed mass on the epimysium layer of left chest wall. The mass was 0.9 × 0.7 × 0.6 cm in size. No obvious blood flow signal was detected by Color Doppler Flow Imaging (CDFI) (Figure 1A).