Final answer:
The efferent pathways from the motor cortex consist of the corticobulbar and corticospinal tracts, which are responsible for transmitting voluntary motor commands to the head, neck, trunk, and limb muscles. The right motor cortex controls the left side of the body and vice versa, due to the largely contralateral organization of the motor pathways.
Step-by-step explanation:
The efferent pathways (outgoing pathways) from the motor cortex are chiefly composed of the corticobulbar and corticospinal tracts. The primary motor cortex is responsible for initiating voluntary motor commands that are then relayed to different parts of the body to control movement. The two main types of neurons involved in this process are the upper motor neurons, which have their cell bodies located in the motor cortex, and the lower motor neurons, found in the brain stem or spinal cord.
The corticobulbar tract contains axons that project ipsilaterally from the cortex to cranial motor nuclei in the brain stem. This pathway mainly controls the muscles of the head and neck. On the other hand, the corticospinal tract is largely contralateral, with axons that cross the midline in the brain stem or spinal cord to synapse on the opposite side, controlling muscles of the trunk and limbs.
This organization enables the right motor cortex to control muscles on the left side of the body and the left motor cortex to control muscles on the right side. The corticospinal tract further descends through the pons and projects into the cerebellar cortex, while the cerebellar cortex continuously adjusts motor commands based on sensory feedback to ensure smooth and coordinated movements.