Figure 8.

(a) The reptilian body undergoes distinct morphological changes including elongation of the neck and dropping of the shoulder girdles creating the neck transition region. (b) The formation of the neck region may explain the peculiar behavior of the fibers of von Lenhossek, which represent the reptilian spinal accessory nerve. More investigation is necessary to confidently provide a definitive explanation. Cell bodies of the accessory nerve in reptiles are located within the ventral horn of the cervical spinal cord. The axons project intraspinally to exit via the dorsal root. These fibers originally described by von Lenhossek remain poorly understood.