Question

Two terms for the massive motor tracts serving voluntary movement are ________?

1) pyramidal and corticospinal
2) extrapyramidal and rubrospinal
3) segmental and nigrostriatal
4) supplementary and cerebellar-pontine

Answer 1

The correct terms for the massive motor tracts serving voluntary movement are pyramidal and corticospinal. These tracts facilitate voluntary control over skeletal muscles through a two-neuron connection involving upper and lower motor neurons, with a crossing over at the pyramidal decussation (option 1).

Step-by-step explanation:

The two terms for the massive motor tracts serving voluntary movement are pyramidal and corticospinal. These tracts are integral parts of the skeletomotor system that enable conscious control over skeletal muscles. Voluntary movements are facilitated by a two-cell projection from the precentral gyrus of the frontal lobe to the skeletal muscles. The corticospinal tract is specifically composed of upper motor neurons, with their cell bodies in the primary motor cortex, and lower motor neurons in the ventral horn of the spinal cord that project to the skeletal muscles. Motor commands travel down these tracts, which involve a crossing over at the medullary-spinal border, known as the pyramidal decussation. This ensures that the brain hemisphere controls the opposite side of the body.

Hence, the answer is option 1.