Figure 1.

Transverse section of an octopus arm (modified from [2]) with the ventral (V), dorsal (D), and lateral (LT) aspects of the arm marked. The l axial nerve cord (N) runs along the longitudinal axis of each arm and is surrounded by transverse muscles (T). Oblique muscles (O) are arranged in thin external layers. Longitudinal muscles (L) are organized in four groups located at each side of the arm. The trabecula (TR) are small transverse muscle strips located within the longitudinal muscles.