It is responsible for motor impulses that arise from one side of the midbrain to muscles on the opposite side of the body.
The portion of the midbrain from where this tract originates is the superior colliculus, which receives afferents from the visual nuclei (primarily the oculomotor nuclei complex), then projects to the contralateral portion of the spinal cord.
The tract descends to the cervical spinal cord to terminate in Rexed laminae VI, VII, and VIII to coordinate head, neck, and eye movements, primarily in response to visual stimuli.