Pupillomotor Pathways In the Spinal Cord

Abstract

In 1851 Budge and Waller showed that pupillodilator fibers descended as far as the upper thoracic segments of the cord before running to the cervical sympathetic chain. They noted that a nucleus appeared to exist in the T-2 and T-3 segments and referred to it as the ciliospinal center. The location of this descending pupillomotor pathway has, however, remained largely conjectural. Foerster and associates, on the basis of anterolateral cordotomies performed at a high cervical level, were able to state that it must lie in the ventral quadrant of the cord since in their hands an ipsilateral Horner's syndrome was an almost invariable result of this operation; and all neurosurgeons who perform high cervical cordotomies are familiar with this minor postoperative deficit. In addition to the descending pupillodilator pathway, an ascending fiber system is known to exist which also produces pupillodiatation. Thus, painful stimulation results in mydriasis, which was attributed