Final answer:
The assertion that the vestibular system is the only sensory system projecting directly to the cerebellum is false. Both vestibular system fibers and proprioceptive information from the dorsal column system project to the cerebellum, which is crucial for balance and coordinated movement.
Step-by-step explanation:
The statement that the vestibular system is the only sensory system to send projection fibers directly to the cerebellum is false. While the vestibular system does project fibers directly to the cerebellum to assist in balance and coordination, it is not the only system to do so. Other neural pathways, such as the proprioceptive pathways of the dorsal column system, also have a collateral projection to the medulla that projects to the cerebellum. Additionally, the corticospinal fibers that project to the ventral horn of the spinal cord branch off to synapse in the pons before projecting to the cerebellum.
These various streams of information, including the ones from the vestibular system and proprioceptive feedback, are compared in the cerebellar cortex. The cerebellum then integrates this information to help maintain balance and coordinate movements, such as stimulating the red nucleus of the midbrain, which results in corrective commands via the rubrospinal tract to adjust the muscles accordingly.