The Rubrospinal Tract Runs in the Lateral Column of the Spinal Cord
The rubrospinal tract runs in the lateral column (lateral funiculus) of the spinal cord, specifically in the dorsal portion of the lateral funiculus. 1, 2, 3
Anatomical Course of the Rubrospinal Tract
The rubrospinal tract follows a specific path from the brain to the spinal cord:
- Originates from the red nucleus, primarily from the parvicellular region 3
- Crosses the midline via the ventral tegmental decussation 1
- Descends through the lateral funiculus of the contralateral spinal cord 1, 2, 3
- Specifically travels in the dorsal portion of the lateral funiculus, positioned between the lateral spinal nucleus and calretinin-positive fibers 3
Termination and Function
The rubrospinal tract has specific termination patterns in the spinal cord:
- Terminates primarily in contralateral laminae 5,6, and the dorsal part of lamina 7 at all spinal cord levels 3
- Some fibers extend to the dorsolateral part of lamina 9 at cervical (C8-T1) and lumbar (L5-L6) levels, corresponding to hand and foot motor neurons respectively 3
- Functionally involved in the control of distal limb movements, particularly skilled movements 4, 5, 3
- Shows preferential connections to motor neurons controlling distal and intermediate forelimb muscles rather than proximal muscles 4
Clinical Significance
Understanding the location of the rubrospinal tract has important clinical implications:
- Lesions affecting the lateral funiculus, even small ones, can impair skilled movements, particularly the "arpeggio" movement (rotatory hand movements) 5
- The rubrospinal tract appears to be more involved in hand rotation than in digit use 5
- Microstimulation of the red nucleus produces shorter latency responses in distal forelimb muscles compared to proximal muscles, supporting its role in distal limb control 4
Somatotopic Organization
The rubrospinal tract shows somatotopic organization:
- Neurons projecting to the cervical spinal cord (controlling upper limbs) are predominantly located dorsomedially in the red nucleus 3
- Neurons projecting to the lumbar spinal cord (controlling lower limbs) are predominantly located ventrolaterally in the red nucleus 3
- Approximately 60% of SMI-32-positive neurons in the red nucleus project to the cervical cord, while 24% project to the lumbar cord 3