Читать книгу Musculoskeletal Disorders - Sean Gallagher - Страница 78

As previously mentioned and depicted (Figures 3.3 and 3.6), individual muscle fibers are bound together by a complex system of collagenous supporting tissue that link individual myofibers into a fascicle in order to form a single functional mass (Gillies & Lieber, 2011). The size of the fasciculi reflects the function of a muscle. Muscles responsible for fine controlled movements, like those of the hand, have small fasciculi and a relatively greater proportion of perimysial supporting tissue. Larger muscles responsible for gross movements have large fascicles and relatively little perimysial tissue. Muscle fibers are also anchored by these fascial connective tissues. The external lamina transmits the contractile forces developed by the internal contractile proteins. The connective tissue framework becomes continuous with those of tendons, as well as bone or skin when muscles are directly attached to these latter structures. The extracellular matrix also serves as a biological reservoir of muscle stem cells. In both injured and diseased states, the extracellular matrix adapts dramatically, a property that has clinical manifestations for muscle function.

Figure 3.11 The neuromuscular junction. Adult skeletal muscle is highly organized with one neuronal branch innervating each myofiber at the neuromuscular junction, which exhibits a mature, pretzel morphology with direct overlap between the presynaptic nerve terminal bouton and the postsynaptic acetylcholine receptor clusters.

Gilbert‐Honick, J. & Grayson, W. (2020). Vascularized and innervated skeletal muscle tissue engineering. Advanced Healthcare Materials 9(1): e1900626. Wiley.