The term brainstem tracts (bst) refers to bundles of extrapyramidal axons in the brainstem (BST), such as the motor pathways connecting the hypothalamus (HYP) through the periaqueductal gray (PAG) and other brainstem nuclei to motor units in the anterior gray column (AGC) of the spinal cord (SPC). They are found in the human, macaque, rat and mouse ( NeuroNames ).