Figure 6 : Evolution of pectoral innervation.

From: Ancestry of motor innervation to pectoral fin and forelimb

Figure 6

(a) Cladogram of living jawed vertebrates8, with vignettes showing innervation patterns of pectoral appendages. Occipital (pectoral, red; hypobranchial, grey) and spinal (blue) nerves are illustrated schematically. (b) Summary of key Hox genes expressed in neuronal (top) and mesodermal (bottom) compartments along the anterior–posterior axis in fish and tetrapods43,46,47,49,51.