Rubrospinal Tract

The rubrospinal tract is a descending motor pathway that originates in the red nucleus of the midbrain and plays a role in facilitating flexor muscle tone, particularly in the upper limbs. Though prominent in quadrupeds, its role in humans is limited and partially redundant with the corticospinal tract.

- Red nucleus (nucleus ruber), specifically its magnocellular part, located in the midbrain tegmentum.

- Fibers decussate immediately in the ventral tegmental decussation. - Descend contralaterally through the lateral funiculus of the spinal cord, anterior to the lateral corticospinal tract. - Most projections are to cervical and upper thoracic levels.

- Synapses primarily in laminae V–VII of the spinal cord gray matter. - Influences interneurons and motor neurons controlling flexor muscles of the upper extremity.

- Facilitates flexor tone and inhibits extensor tone (especially in upper limbs). - Involved in fine motor control, though minimal in humans. - May contribute to motor recovery post-stroke via plastic reorganization.

- Redundant with corticospinal tract in humans. - Its function may become more relevant in compensatory plasticity after corticospinal damage. - Damage rarely produces isolated clinical signs but may be involved in decorticate rigidity.

- Highly developed in quadrupeds, contributing to limb coordination in locomotion. - In humans, vestigial but potentially important in motor plasticity.

• Lateral Corticospinal Tract
• Vestibulospinal Tract
• Reticulospinal Tract