Final answer:
The features of the descending projection tracts of motor pathways include bilateral coordination, the corticospinal tract controlling skeletal muscle movements, and the presence of the corticobulbar and corticospinal tracts.
Step-by-step explanation:
The descending projection tracts of motor pathways have several features. First, the anterior corticospinal tract is not entirely contralateral because it involves movements of the body trunk which require both sides of the body. Some branches of this tract project into the ipsilateral ventral horn to control synergistic muscles or inhibit antagonistic muscles. These coordinating axons are considered bilateral as they are both ipsilateral and contralateral.
The corticospinal tract is the major descending tract that controls skeletal muscle movements. It is composed of the upper motor neuron and the lower motor neuron. The upper motor neuron originates in the primary motor cortex of the frontal lobe and synapses on the lower motor neuron in the ventral horn of the spinal cord, which then projects to the skeletal muscle in the periphery.
The descending motor pathways for the somatic nervous system include two divisions: the corticobulbar tract and the corticospinal tract. The corticobulbar tract originates in the primary motor cortex and projects to the motor nuclei in the brain stem, controlling voluntary movements of the cranial muscles. The corticospinal tract, on the other hand, originates in the primary motor cortex and crosses the midline of the brain stem or spinal cord to control voluntary movements of the limbs on the opposite side of the body.