the basics - the sarcomere
The sarcomere is the minimal unit of the contractile apparatus in all cross-striated muscle cells (heart and skeletal muscle). It consists of three filament systems: the actin (thin) filaments and myosin (thick) filaments, whose interaction leads to muscle contraction, and the elastic filament consisting of the giant titin protein. These filament systems are crosslinked through sarcomeric alpha-actinin at the Z-discs and myomesin at the sarcomeric M-band.
Move your mouse over the image above to see the names and locations of the filament systems, the crosslinkers and the Z-disc and M-band. For more information on components of the sarcomere and their function read the review "From A to Z and back?" available online here.