Terminal cisternae

[1] Terminal cisternae are discrete regions within the muscle cell.

They store calcium (increasing the capacity of the sarcoplasmic reticulum to release calcium) and release it when an action potential courses down the transverse tubules, eliciting muscle contraction.

This releases tropomyosin, exposing active sites of the thin filament, actin.

There are several mechanisms directly linked to the terminal cisternae which facilitate excitation-contraction coupling.

The terminal cisternae, along with the transverse tubules, are the mechanisms of transduction from a nervous impulse to an actual muscle contraction.