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A Review of the Technologies and Methodologies Used to Quantify Muscle-Tendon Structure and Function
Published in Cornelius Leondes, Musculoskeletal Models and Techniques, 2001
The extensive membrane network of muscle cells performs several functions. The endomysium provides structural support for the muscle fiber and the neural and vascular tissues interacting with it. The basal lamina appears to play a role in injury repair. Complete repair can occur rapidly if the basal lamina is intact to provide a scaffold for regeneration.26,54,88 The basal lamina also communicates with the nerve to signal it where to innervate the muscle fiber if denervation has occurred. The plasmalemma, T-system, and SR function as semi-permeable barriers, conduits for electrical signal propagation, filters, and calcium storage centers. The plasmalemma acts as a filter by requiring a certain number of receptors on its surface to be stimulated before changing its membrane permeability and conducting the electrical signal of the nerve into the cell. The T-system provides the conduit for rapid transmission of electrical activity to the inner regions of the cell. The SR stores and releases calcium ions which are essential for force production and relaxation.
Muscle Physiology and Electromyography
Published in Verna Wright, Eric L. Radin, Mechanics of Human Joints, 2020
Figure 2 shows the gross structure of a muscle. The muscle belly is composed of a large number of fasciculi, bundles of individual muscle fibers held together by a connective tissue sheath (perimysium). A softer connective tissue, endomysium, fills the spaces between the muscle fibers. The fasciculi are enclosed in the epimysium, a tougher connective tissue sheath, which is continuous with the perimysium of the individual fasciculi internally and with adjacent structures externally. At the ends of the muscle, the epimysium is extended into the tendon or aponeurosis.
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.
Aponeurosis behaviour during muscular contraction: A narrative review
Published in European Journal of Sport Science, 2018
The aponeurosis and tendon are seamlessly connected within and outside the muscle belly through a connective tissue network, which surrounds muscle fibres (endomysium), groups of muscle fibres (perimysium) and whole muscles (epimysium) (Purslow, 2010). The means by which transverse forces are transmitted to the aponeurosis and surrounding muscles (Maas & Finni, 2018) are presumably through this connective tissue network (Street, 1983), which is stressed as muscle fibres are activated and fluid pressures within and outside the muscle’s fascial compartment increase during contraction (Aratow et al., 1993; Ateş et al., 2018; Reinhardt, Siebert, Leichsenring, Blickhan, & Böl, 2016). Longitudinal force transmission seemingly occurs through the same network and mechanism, as increasing muscle fluid volume has been shown to increase passive force by interacting with surrounding collagen fibres (Sleboda & Roberts, 2017). It has been shown that the arrangement of the collagen fibres within the endomysium and perimysium allows their geometry to vary as a function of muscle length, such that radial expansion of muscle fibres can be resisted at short lengths (Azizi, Deslauriers, Holt, & Eaton, 2017; Gindre, Takaza, Moerman, & Simms, 2013) and longitudinal stretch of the muscle fibres can be resisted at long lengths (Gindre et al., 2013; Purslow, 1989; Purslow & Trotter, 1994). Collagen fibres of the endomysium are connected to collagen fibres of the perimysium and are expected to be constituents of the tendon (Huijing, 1999), which emphasises the continuity of the connective tissue network and force transmission pathways from the muscle fibres to the tendon. Collagen fibres at the ends of muscle fibres can also transmit force to the tendon through the myotendinous junction, whereby the sarcolemma folds extensively in the direction of muscle fibres (Huijing, 1999) and collagen fibres from both the muscle fibres and aponeurosis are linked in an interdigitated fashion (Huijing, 1999; Maas & Finni, 2018).