The Structure and Role of Intramuscular Connective Tissue in Muscle Function

The Structure and Role of Intramuscular Connective Tissue in Muscle Function — The Fascia Guide

Key takeaways

01Connective tissue transmits muscle force laterally between fibers through specialized protein links
02Many muscle fibers insert into connective tissue rather than spanning from tendon to tendon
03Muscles and their internal fascia function as an integrated unit for force production
04Intramuscular layers connect individual muscles to the body's global deep fascial system

Intramuscular connective tissue is essential for lateral force transmission and coordinating movement through the broader fascial network.

Abstract

Extracellular matrix (ECM) structures within skeletal muscle play an important, but underappreciated, role in muscle development, function and adaptation. Each individual muscle is surrounded by epimysial connective tissue and within the muscle there are two distinct extracellular matrix (ECM) structures, the perimysium and endomysium. Together, these three ECM structures make up the intramuscular connective tissue (IMCT). There are large variations in the amount and composition of IMCT between functionally different muscles. Although IMCT acts as a scaffold for muscle fiber development and growth and acts as a carrier for blood vessels and nerves to the muscle cells, the variability in IMCT between different muscles points to a role in the variations in active and passive mechanical properties of muscles. Some traditional measures of the contribution of endomysial IMCT to passive muscle elasticity relied upon tensile measurements on single fiber preparations. These types of measurements may now be thought to be missing the important point that endomysial IMCT networks within a muscle fascicle coordinate forces and displacements between adjacent muscle cells by shear and that active contractile forces can be transmitted by this route (myofascial force transmission). The amount and geometry of the perimysial ECM network separating muscle fascicles varies more between different muscle than does the amount of endomysium. While there is some evidence for myofascial force transmission between fascicles via the perimysium, the variations in this ECM network appears to be linked to the amount of shear displacements between fascicles that must necessarily occur when the whole muscle contracts and changes shape. Fast growth of muscle by fiber hypertrophy is not always associated with a high turnover of ECM components, but slower rates of growth and muscle wasting may be associated with IMCT remodeling. A hypothesis arising from this observation is that the level of cell signaling via shear between integrin and dystroglycan linkages on the surface of the muscle cells and the overlying endomysium may be the controlling factor for IMCT turnover, although this idea is yet to be tested.

Cite this study

APA: Peter P Purslow (2020). The Structure and Role of Intramuscular Connective Tissue in Muscle Function. https://fasciaresearchdatabase.com/the-structure-and-role-of-intramuscular-connective-tissue-in-muscle-function/
MLA: Peter P Purslow. "The Structure and Role of Intramuscular Connective Tissue in Muscle Function." 2020, https://fasciaresearchdatabase.com/the-structure-and-role-of-intramuscular-connective-tissue-in-muscle-function/.
Chicago: Peter P Purslow. 2020. "The Structure and Role of Intramuscular Connective Tissue in Muscle Function.". https://fasciaresearchdatabase.com/the-structure-and-role-of-intramuscular-connective-tissue-in-muscle-function/