Book excerpt: The past 70 years of muscle research have profoundly shaped our current understanding of the structure and function of muscle. X-ray diffraction became a key method in its structural analysis and yielded valuable insights into the molecular arrangement of the contraction apparatus. This work employs an extension of the X-ray diffraction methodology, scanning X-ray diffraction, for structural imaging of biological cells and tissue. With this technique periodicites in a structure on the order of several nanometers can be detected and, by raster scanning of the X-ray beam over the sample, imag...