The ascending projections of the dorsolateral funiculus of the spinal cord in the primate.

The ascending projections of the dorsolateral funiculus of the spinal cord to the brain stem have been determined in five macaque monkeys. Connections to the lateral cervical nucleus and to the reticular nucleus of the cord in the C1 and C2 segments are present. In the medulla the most prominent connections are to the nuclei "Z" and "x" of Brodal and Pompeiano, to the rostral portion of n. gracilis and to the n. proprius of the restiform body. Minor projections reach the rostral part of the medial and lateral cuneate nuclei, the reticular nucleus, the n. centralis dorsalis and the periependymal gray. There were no projections to planes rostral to the medulla. In view of the connections established it is concluded that ascending systems in the DLF to the brain stem of primates are concerned with transmission of mechanoreceptor input to the cerebellum and thalamus and that nociceptive relay appears very unlikely.