Transverse Muscle Cells

What is the role of the transverse tubules?
Transverse tubules is to conduct impulses from surface of the cell down to the cell. In response to stimulation of muscle, calcium channels in t-tubules open and allow calcium to flow down its electro-chemical gradient into cell. The purpose of t-tubules is allow depolarization to quickly penetrate to the interior of the cell. The t-tubules help bring the extracellular environment to all parts of the muscle cell more quickly and which better coordinates muscle contraction.

http://medical-dictionary.thefreedictionary.com/T+tubule+system
http://people.eku.edu/ritchisong/301notes3.htm