Force Transmission between Synergistic Skeletal Muscles through Connective Tissue Linkages

Huub Maas,Thomas G Sandercock

doi:10.1155/2010/575672

Abstract

The classic view of skeletal muscle is that force is generated within its muscle fibers and then directly transmitted in-series, usually via tendon, onto the skeleton. In contrast, recent results suggest that muscles are mechanically connected to surrounding structures and cannot be considered as independent actuators. This article will review experiments on mechanical interactions between muscles mediated by such epimuscular myofascial force transmission in physiological and pathological muscle conditions. In a reduced preparation, involving supraphysiological muscle conditions, it is shown that connective tissues surrounding muscles are capable of transmitting substantial force. In more physiologically relevant conditions of intact muscles, however, it appears that the role of this myofascial pathway is small. In addition, it is hypothesized that connective tissues can serve as a safety net for traumatic events in muscle or tendon. Future studies are needed to investigate the importance of intermuscular force transmission during movement in health and disease.

Highlights

When skeletal muscle fibers are excited, a cascade of events is triggered, which leads to forces exerted on the skeleton
The present review focuses on the connective tissues that are found in the direct environment of skeletal muscles and their potential effects in muscle function during movement
It has long been common to view muscles as mechanically independent actuators. This is readily apparent from biomechanical models of the musculoskeletal system in which muscles are connected to the skeleton at their origin and insertion [2, 3]

Summary

Introduction

When skeletal muscle fibers are excited, a cascade of events is triggered, which leads to forces exerted on the skeleton. It has long been common to view muscles as mechanically independent actuators This is readily apparent from biomechanical models of the musculoskeletal system in which muscles are connected to the skeleton at their origin and insertion [2, 3]. Journal of Biomedicine and Biotechnology observed after pharmacological block of heterogenic reflexes.” Note that in these experiments the tendons are severed from their insertion site and individually connected to force transducers. This means that the mechanical linkage was provided by structures at the muscle belly boundary (i.e., the epimysium). The purpose of this article is first to review the initial series of systematic experiments on mechanical interactions between synergistic muscles (i.e., neighboring muscles which produce the same movement at the joint) via connective tissue linkages (named epimuscular myofascial pathways) that revealed the presence and capacity of this phenomenon (mechanical interactions between antagonistic muscles have been reviewed elsewhere; see [7]); second, to discuss the current debate on the importance of epimuscular myofascial force transmission during normal movements; and third, to discuss the potential functions of inter- and extramuscular connective tissues for pathological muscle-tendon conditions

Mechanical Interaction between Muscles through Connective Tissue Structures

Intramuscular connective tissue

Findings

Conclusions