Point 22 Intro Pathway Deficit Overview Problems Contents Anatomy

The most important efferent projection of the red nucleus is to the contralateral spinal cord i.e., the RUBROSPINAL projection. Thus red nucleus neurons possess axons that cross just ventral to the nucleus and descend in the midbrain, pons and medulla (we can not identify this pathway in our brain stem series of cross sections) to reach the spinal cord. In the spinal cord the rubrospinal tract courses within the LATERAL FUNICULUS JUST VENTRAL TO THE LATERAL CORTICOSPINAL TRACT. The rubrospinal tract is thought to be involved in the control of both the flexor and extensor muscles, but even this is debated. This tract courses adjacent to the lateral corticospinal tract and terminates in roughly the same region (laminae) of the spinal cord gray. These two pathways are therefore thought to act somewhat in concert. This close association (rubrospinal/corticospinal) is further exemplified by the fact that the motor cortex also projects to the red nucleus. This means that the corticospinal tract is paralleled by an "indirect corticospinal tract" with a relay in the red nucleus, i.e., the corticorubrospinal tract. The rubrospinal projection is also, of course, influenced by the motor information coming out of the cerebellum, as well as from the motor cortex.