Projections of the dorsal column nuclei and the spinal cord on the inferior olive in the cat

This study demonstrates partially overlapping fiber termination areas in the inferior olive originating from the dorsal column nuclei and the spinal cord. Based on the distribution of the terminations the dorsal accessory olive can be divided into a rostral and a caudal part. In the caudal part terminations are found of fibers originating in the contralateral gracile nucleus and in the lumbar and cervical spinal cord. Terminations in the rostro‐medial part of the dorsal accessory olive arise from the contralateral internal cuneate nucleus and from the opposite intermediate grey at C.1. Fibers from more caudal regions of the internal cuneate nucleus terminate in the dorsal accessory olive caudal to those originating from more rostral regions of this nucleus. The gracile nucleus and the lumbar spinal cord project to the rostro‐lateral portion of the dorsal accessory olive. The terminations in the medial accessory olive from the lumbar spino‐olivary fibers are found in a laterally located zone in the caudal one‐third of the nucleus. This spino‐olivary termination area extends more rostrally and medially after interruption of the cervical spino‐olivary fibers. Fibers from the contralateral gracile nucleus terminate in a medial zone in the caudal half of the medial accessory olive, while terminations of the contralateral internal cuneate nucleus are found at a more rostral level in the medial part of the medial accessory olive. Connections between the inferior olive and the caudal part of the spinal trigeminal nucleus, the lateral cervical nucleus and the cervical dorsal horn could not be demonstrated.