Final answer:
Alpha and gamma motoneurons that innervate extensors are located more ventrally in the ventral horn of the spinal cord. The ventral horn contains large, multipolar neurons that command muscle contractions, including those of the extensors, making the correct answer to the question 'Ventrally'.
Step-by-step explanation:
The location of alpha and gamma motoneurons within the ventral horn of the spinal cord that innervate extensors, like the axial muscles of the trunk and the muscles of the limbs, is directly related to the type of muscle they control. For these particular motoneurons that innervate extensors, they are located more ventrally within the ventral horn. It is important to note that while the anterior corticospinal tract axons — responsible for controlling the muscles of the body trunk — synapse with lower motor neurons in the medial regions of the ventral horn, the question specifically asks about the neurons innervating extensors, which are said to be ventrally located. Therefore, the correct answer to the question is option 3) Ventrally.