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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.
Inflammatory Myopathy
Published in Maher Kurdi, Neuromuscular Pathology Made Easy, 2021
The diagnosis of polymyositis (PM) is probably obsolete, because it may encompass many different diseases. It is the rarest form of myositis, and some authors even question its existence. It is generally accepted that none of the reported antibodies of PM were actually associated with the disease spectrum. PM as a separate entity is undoubtedly non-existent and should be considered only if other well-defined diseases have been excluded. However, the disease should be re-classified as overlap myositis or adermatopathic myositis. Patients present clinically with a subacute proximal rather symmetric myopathy without skin symptoms, no family history of muscle disease, and after having ruled out toxic, viral, and muscular dystrophy conditions. The usual feature of the diseases is necrotizing myopathy with very minimal endomysial T-cell inflammation invading non-necrotic muscle fibers (Figure 20.6). There is a widespread expression of MHC class-I in the entire fiber. No cytological vacuolations, mitochondrial aggregation, or perifascicular pathology have been reported. The majority of reported cases in the literature support that anti-SRP and anti-PML-SCL autoantibodies are closely related to PM and associated with treatment-resistant forms.
Muscle Disorders
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Kourosh Rezania, Peter Pytel, Betty Soliven
Muscular dystrophies: Endomysial inflammatory infiltrate is often seen in facioscapulohumeral dystrophy, dysferlinopathy, calpainopathy, and some congenital myopathies.Myotonic dystrophy type 2 typically presents with proximal > distal weakness.
Histological and immunohistochemical study of the effect of ozone versus erythropoietin on induced skeletal muscle ischemia-reperfusion injury in adult male rats
Published in Ultrastructural Pathology, 2022
Magdy F. Gawish, Sally A. Selim, Alyaa A. Abd El-Star, Samah M. Ahmed
Control group showed long cylindrical non-branched muscle fibers with acidophilic cytoplasm, transverse striations, and multiple peripheral elongated nuclei. Muscle fibers were separated by delicate connective tissue called the endomysium and muscle bundles were separated by perimysium (Figure 3a). IR group exhibited disrupted muscle fibers with loss of striation, increased endomysial spaces, and central dark stained nuclei. Edema was observed as wide separation of the muscle bundles (Figure 3b). Degenerative changes were observed as some muscle fibers showed hyalinization of the sarcoplasm and nuclear clumps (Figure 3c). Extravasation and congested blood vessels between the damaged skeletal muscle fibers were also detected (Figure 3d). Post-reperfusion ozone-treated group revealed most of the muscle fibers appeared relatively normal with peripheral flat nuclei, cross-striations, narrow endomysial spaces, and blood vessel in the perimysium while some fibers with central nuclei were present (Figure 3e). Post-reperfusion EPO-treated group showed most of muscle fibers appeared regular with narrow endomysial spaces, cross-striations, and peripheral flat nuclei (Figure 3f). The recovering post-reperfusion without treatment showed muscle fibers were disarranged with central nuclei and widely separated (Figure 3g). Also, waviness of muscle fibers with numerous vesicular nuclei was observed in other sections (Figure 3h).
Leptin receptor defect with diabetes causes skeletal muscle atrophy in female obese Zucker rats where peculiar depots networked with mitochondrial damages
Published in Ultrastructural Pathology, 2021
Jacques Gilloteaux, Charles Nicaise, Lindsay Sprimont, John Bissler, Judith A Finkelstein, Warren R Payne
The LM surveys of the semi-thin sections, stained by toluidine blue, the muscle fiber profiles displayed diverse aspects of staining characteristics, allowing to recognized them as 3 main types, with their specific staining topography. A brief qualitative survey allowed to recognize that the whitish-stained were always the widest fiber profiles, likely being the fast glycolytic fibers, displaying an almost transparent orthochromatic aspect compared with oxidative fibers that were narrower than the first ones. Moreover, the strongest with toluidine stain ones were the thinnest, matching the SO type with histochemistry (see 1.b) and all FOG revealed outskirts whose qualitative profiles revealed many longitudinally-oriented, elongated, narrow intermyofibrillar masses and thick subsarcolemmal (and perikaryal) accumulations of admixed orthochromatic and metachromatic contrast. This morphology aspects made the fibers to appear more of less serrated, seemingly ‘ragged’ according to the randomness plane of thin sectioning. All semi-thin sections revealed their fine muscle cross-striations. The endomysium, made of intercellular loose connective elements, is displayed as narrow gaps between muscle fibers where small blood vessels, mainly capillaries, can be revealed. (Figure 1(a-d)).
Bacopa Monnieri Protects the Directly Affected Organ as Well as Distant Organs Against I/R Injury by Modulating Anti-Inflammatory and Anti-Nitrosative Pathways in A Rat Model for Infra-Renal Aortic Occlusion
Published in Journal of Investigative Surgery, 2021
Hilal Ozlu, Ayse Cakir Gundogdu, Zubeyir Elmazoglu, Gulnur Take Kaplanoglu, Levent Oktar, Cimen Karasu
In the H&E staining of the sham control and B. monnieri-treated groups, the skeletal muscle was normal in appearance with the nuclei located on the periphery directly under the sarcolemma and regular striations. The blood vessels were clear in the endomysium which surrounded muscle fibers (Figure 3). In I/R group, the most striking findings were nuclear migration to the central position and amitotic nuclear division. Myofibril organization was disrupted and there were no striations, particularly in the fibers with nuclear migration (Figure 3). No change in endomysium was observed. Nuclear migration and amitotic division were also detected in the B. monnieri-treated I/R group. However, myofibril organization and striations were more regular than in I/R group (Figure 3). Histological scores for severity of injury from muscle tissues are shown in Table 1.