Final answer:
The corticospinal tract is the white matter tract that carries motor signals from the cortex to the spinal cord and permits voluntary muscle movement.
Step-by-step explanation:
The white matter tract responsible for conveying motor signals from the cortex to the spinal cord is known as the corticospinal tract. This tract is crucial for the initiation of voluntary muscle movement. It originates in the primary motor cortex, where neurons known as Betz cells send their axons through the corticospinal tract to synapse on lower motor neurons in the spinal cord. Most of the fibers in this tract cross over to the opposite side of the body at the pyramidal decussation, which means that the right motor cortex controls muscles on the left side of the body, and vice versa. The corticospinal tract descends through various structures, including the internal capsule, cerebral peduncles, pons, and the medullary pyramids before entering the spinal cord and synapsing with lower motor neurons in the ventral horn.