Objection 1. It would seem that Christ's soul had omnipotence with regard to His own body. For Damascene says (De Fide Orth. iii, 20,23) that "all natural things were voluntary to Christ; He willed to hunger, He willed to thirst, He willed to fear, He willed to die." Now God is called omnipotent because "He hath done all things whatsoever He would" (Psalm 113:11). Therefore it seems that Christ's soul had omnipotence with regard to the natural operations of the body.
Objection 2. Further, human nature was more perfect in Christ than in Adam, who had a body entirely subject to the soul, so that nothing could happen to the body against the will of the soul--and this on account of the original justice which it had in the state of innocence. Much more, therefore, had Christ's soul omnipotence with regard to His body.
Objection 3. Further, the body is naturally changed by the imaginations of the soul; and so much more changed, the stronger the soul's imagination, as was said in I, 117, 3, ad 3. Now the soul of Christ had most perfect strength as regards both the imagination and the other powers. Therefore the soul of Christ was omnipotent with regard to His own body.
On the contrary, It is written (Hebrews 2:17) that "it behooved Him in all things to be made like unto His brethren," and especially as regards what belongs to the condition of human nature. But it belongs to the condition of human nature that the health of the body and its nourishment and growth are not subject to the bidding of reason or will, since natural things are subject to God alone Who is the author of nature. Therefore they were not subject in Christ. Therefore Christ's soul was not omnipotent with regard to His own body.
I answer that, As stated above (Article 2), Christ's soul may be viewed in two ways. First, in its proper nature and power; and in this way, as it was incapable of making exterior bodies swerve from the course and order of nature, so, too, was it incapable of changing its own body from its natural disposition, since the soul, of its own nature, has a determinate relation to its body. Secondly, Christ's soul may be viewed as an instrument united in person to God's Word; and thus every disposition of His own body was wholly subject to His power. Nevertheless, since the power of an action is not properly attributed to the instrument, but to the principal agent, this omnipotence is attributed to the Word of God rather than to Christ's soul.
Reply to Objection 1. This saving of Damascene refers to the Divine will of Christ, since, as he says in the preceding chapter (De Fide Orth. xix, 14,15), it was by the consent of the Divine will that the flesh was allowed to suffer and do what was proper to it.
Reply to Objection 2. It was no part of the original justice which Adam had in the state of innocence that a man's soul should have the power of changing his own body to any form, but that it should keep it from any hurt. Yet Christ could have assumed even this power if He had wished. But since man has three states--viz. innocence, sin, and glory, even as from the state of glory He assumed comprehension and from the state of innocence, freedom from sin--so also from the state of sin did He assume the necessity of being under the penalties of this life, as will be said (14, 2).
Reply to Objection 3. If the imagination be strong, the body obeys naturally in some things, e.g. as regards falling from a beam set on high, since the imagination was formed to be a principle of local motion, as is said De Anima iii, 9,10. So, too, as regards alteration in heat and cold, and their consequences; for the passions of the soul, wherewith the heart is moved, naturally follow the imagination, and thus by commotion of the spirits the whole body is altered. But the other corporeal dispositions which have no natural relation to the imagination are not transmuted by the imagination, however strong it is, e.g. the shape of the hand, or foot, or such like.
Source: Summa Theologica (New Advent)