Ascending and descending propriospinal pathways between lumbar and cervical segments in the rat: Evidence for a substantial ascending excitatory pathway

► Propriospinal systems between cervical and lumbar segments were investigated. ► Descending systems formed crossed and uncrossed pathways projecting to the rostral lumbar cord. ► Some descending cells contain calretinin and calbindin. ► An ascending excitatory pathway exists that terminates in the C7-C8 ventrolateral motor nucleus. ► This pathway will influence muscles of the axilla and may couple activity of hind- and forelimbs.