42 It is an undoubted fact that it was to Peter alone and to his successors, the Roman Pontiffs, that Jesus Christ entrusted the entirety of his flock: "Feed my lambs; feed my sheep." But even though each bishop is the pastor of that portion only of the Lord's flock entrusted to him, nevertheless as lawful successor of the Apostles by God's institution and commandment he is also responsible, together with all the other bishops, for the Apostolic task of the Church, according to the words of Christ to the Apostles: "As the Father has sent me, I also send you."
Source: Fidei Donum (Vatican.va)