A folded band of gray matter that encloses a white core (hilum nuclei olivaris inferioris) and that produces the elevation called the oliva on the medulla oblongata. It is a nuclear complex that receives heavy projections from the spinal cord, mesencephalon, and cerebral cortex and projects fibers via the contralateral inferior cerebellar peduncle, mostly to the neocerebellum, with a few going to the vermis.