See Nucleus rubber.

a structure of the midbrain, connects the cerebellum to the thalamus and spinal cord

A brainstem motor control nucleus that gives rise to the rubrospinal tract. Activation of the rubrospinal tract promotes limb flexion.

The red nucleus (nucleus ruber) is a structure in the rostral midbrain involved in motor coordination. In animals without a significant corticospinal tract, gait is mainly controlled by the red nucleus. In humans, the red nucleus mainly controls the muscles of the shoulder and upper arm, but it has some control over the lower arm and hand as well.