Final answer:
The corticospinal tract is the descending tract that controls motor impulses to skeletal muscles, consisting of upper and lower motor neurons that originate in the brain and synapse in the spinal cord.
Step-by-step explanation:
The descending tract whose fibers conduct motor impulses to skeletal muscles is the corticospinal tract. This major tract controls skeletal muscle movements and connects the brain to the body's muscles. It is composed of two neurons: the upper motor neuron and the lower motor neuron.
The upper motor neuron has its cell body in the primary motor cortex of the frontal lobe. It then synapses on the lower motor neuron, which is located in the ventral horn of the spinal cord. From there, the lower motor neuron projects to the skeletal muscle in the periphery, facilitating voluntary movement.
The corticospinal tract is mostly contralateral, meaning that neurons originating from one side of the brain influence muscles on the opposite side of the body. However, in the anterior corticospinal tract, some axons may not decussate and instead influence muscles on the same side, which is important for coordinating postural muscles and broad movements of the body's trunk.