Question

The calcium that triggers muscle contraction is stored in synaptic vesicles. the motor neuron. the mitochondria. the endoplasmic reticulum.

Answer 1

The calcium that triggers muscle contraction is stored in synaptic vesicles called endoplastic reticulum. that is not the only function of  the endoplastic reticulum it is also a network of a membranous tubules within the cytoplasm of a eucryotic cell continuous with the nuclear membrane.