Anyone looking for good, clear, information about the structure and terminology of the German Shepherd Dog would do well to start with Louis Donald’s site and blog on the GSD.
Whether your passion is conformation, or you would just like to be able to discuss structure knowledgeably – you will find a wealth of information – 
from the effects of Photoshop on breeding programs to the basics of anatomy. There is plenty to read and see and learn here. (Pop quiz – where is the Metatarsus?)
Link and image used with permission.
Ontario Region - GSSCC 