Sarcomere

Sarcomere is the fundamental contractile unit of a muscle fiber, bounded by Z-discs and comprising interconnecting thin (actin) and thick (myosin) filaments. It shortens during contraction, producing muscle force, and is the repeating structural unit that gives striated muscle its organized, banded appearance. In anatomy and physiology, it’s the smallest functional unit of the myofibril responsible for sarcomeric contraction.