Sarcoplasmic reticulum (SR)

Endoplasmic reticulum of striated muscle specialised for the sequestration of calcium ions that are released upon receipt of a signal relayed by the T tubules from the neuromuscular junction (an area of membrane between a motoneuron and the muscle cell membrane forming a synapse between them)

. See Endoplasmic reticulum (ER), Motoneuron, Striated muscle, Synapse