1 Institute of Anatomy, Medical Faculty "Carl Gustav Carus", Technical University Dresden, Fetscherstr. 74, 01307, Dresden, Germany.
2 San Francisco VA Medical Center, University of California, San Francisco, 4150 Clement St, Box 111D, San Francisco, CA, 94121, USA.
3 Institute of Anatomy, Medical Faculty "Carl Gustav Carus", Technical University Dresden, Fetscherstr. 74, 01307, Dresden, Germany. michael.kasper@tu-dresden.de.