The rubrospinal tract arises from the red nucleus, crosses immediately in the ventral tegmental decussation, and descends in the lateral funiculus. Its principal functional role in humans is best described as:
- A Facilitation of extensor antigravity muscles of the trunk
- B Facilitation of flexor muscles of the upper limb ✓
- C Modulation of nociceptive transmission in the dorsal horn
- D Coordination of conjugate horizontal gaze
Correct answer: B. Facilitation of flexor muscles of the upper limb
Explanation
Rubrospinal fibres excite flexor motor neurons of the contralateral upper limb and inhibit extensors, acting as a flexor bias system that complements the corticospinal tract. In humans the tract is small and largely replaced by the corticospinal tract, ending at cervical levels. Extensor tone is driven mainly by the vestibulospinal and reticulospinal systems, descending pain modulation uses the raphespinal tract, and gaze coordination depends on the MLF and cortical eye fields.
Reference: Gray's Anatomy, 42nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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