T-tubules, also known as transverse tubules, are narrow tubes that are continuous with the sarcolemma (i.e., the cell membrane of striated muscle cells). In skeletal/cardiac muscle cells, T-tubules form invaginations of the sarcolemma that contain many ion channels involved in excitation-contraction (e-c) coupling of muscle cells. Thus, transverse tubules function to conduct the action potential from the cell membrane (sarcolemma) to the interior of the muscle cell.
A nerve is actually a long threadlike bundle of dendrites that conduct electrical impulses. Dendrite word derived from the Greek word 'dendron' which means tree. They carry messages in the form of electrical impulses to cell body, there are also wire like nerves called axon.
