Rubrospinal tract

The rubrospinal tract is an example of a descending motor tract. It comprises of upper motor neurons which facilitate the activity of the flexor muscles and inhibit the activity of the extensor or antigravity muscles of the body. The rubrospinal tract extends from the mid-brain, all the way down, to the anterior gray column of the spinal cord.

The rubrospinal tract originates from the red nucleus, which is located in the mid-brain, at the level of the superior colliculus. The tract decussates (or crosses the midline) at the same level, following which it descends in the lateral funiculus (or the lateral white column). The rubrospinal tract terminates at the alpha and gamma motor neuronal cell bodies in the anterior horns of the spinal cord.

Since, the red nucleus receives afferents from both cerebral cortex and the cerebellum, therefore the rubrospinal tract serves as an important indirect pathway through which cerebral cortex and cerebellum can modulate the activity of alpha and gamma lower motor neurons.