Highlights d Brainstem V2a neurons control orienting movements, locomotor speed, and trajectory d Distinct V2a subsets contact the cervical and lumbar spinal segments d Cervical-projecting V2a neurons govern the head orientation and the path trajectory d Lumbar-projecting V2a neurons are dedicated to control locomotor velocity

Highlights d Afadin elimination from motor neuron progenitors causes hopping phenotype d Afadin function at the neuroepithelium controls organization of spinal midline d Miswiring of dI4-5, V0, and V2a premotor interneurons in afadin mutant mice