Fig. 2.

Schematic presentation of embryonic origin of cranial muscles in gnathostomes based on Edgeworth's (1902, 1911, 1923, 1926a,b,c, 1928, 1935) works: premyogenic cells originate from the paraxial mesoderm (hatched areas) and several somites (areas with vertical bars); large arrows indicate a contribution of cells in segments of the mesoderm to muscle formation of different cranial arches. For more details, see text (modified from Miyake et al., 1992; the nomenclature of the structures illustrated follows that of these authors).