Question

What causes your muscles to move?

Answer 1

Muscle is formed of long muscle fibers . Muscle fiber is formed of many smaller units. These smaller units contract. This makes muscle to contract.

Explanation:

As explained in short answer, smaller units of muscle fiber is a myoneme.
Each my one me is with two muscle protein molecules. These proteins are actin and myocin.
In presence of calcium ions actin and myocin filaments interact.
Interaction of actin and myocin makes myoneme to contract.
Initially contraction of myoneme contracts muscle fibre to contract. And muscle to contract.

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