Sarcomere

Two of the study’s lead researchers, David Warshaw, Ph.D., Michael Previs, Ph.D., both molecular physiologists from the University of Vermont’s Cardiovascular Research Institute, used powerful microscopes to look inside a part of heart muscle tissue called the sarcomere.

Source: tatoeba (12115777)

1997, Kenneth Axen, Kathleen Vermitsky Axen, The Princeton Review Physiology Coloring Workbook, Princeton Review Publishing, Random House, page 51, The sarcomere determines the amount of overlap between the actin and myosin filaments and thus, the number of cross-bridges that participate in a given contraction. Since each cross bridge contributes to the contraction, sarcomeres generate their maximal force when their contraction employs the maximal number of cross-bridges between the actin and myosin filaments.

Source: wiktionary

Specific proteins are responsible for the bands and zones within each sarcomere.

Source: wiktionary

Of particular importance was the confirmation that the sarcomere lengths are instantaneously unstable for any reasonable assignment of parameters and number of sarcomeres, even as low as 100.

Source: wiktionary