The origins of the sympathetic nervous system from Vesalius to Riolan.

VESALIUS' ILLUSTRATION of the 'sixth pair' of cranial nerves in the De Humani Corporis Fabrica shows the sympathetic trunk arising as a branch of the vagus in a position corresponding to the top of the thorax (see fig. 1). The text is the verbal equivalent of the illustration. Although of all Vesalius' work, the cranial nerves are perhaps the most open to criticism,' this error remained uncorrected for half a century. Some reasons are suggested in this paper for Vesalius' mistake, and an attempt is made to follow its subsequent history.