What mineral is released within muscle cells to trigger contractions?

Calcium ions are the mineral released within muscle cells to trigger contractions. When a muscle is stimulated by a nerve impulse, calcium is released from the sarcoplasmic reticulum into the cytoplasm. This increase in calcium concentration allows the interaction of actin and myosin filaments, facilitating muscle contraction. After contraction, calcium is reabsorbed, leading to muscle relaxation.