Another trip into the microworld

Our skeletal muscles, those over which we have conscious control, are made up of fine fibres. Under the microscope the fibres have a distinct striated appearance with cross bands of different thickness. We need to signal to the muscle fibres when we wish them to contract, or to relax. The messages are sent from the central nervous system via nerves. The  photograph shows a section through a few muscle fibres together with the end of a nerve fibre.