A bone anchor is provided, comprisinga shank (2, 2', 2") having a free end (3),a channel (6, 6', 6") extending through the shank (2, 2', 2") to the free end (3) and having a longitudinal axis (C) and at least one opening (9) in a wall of the shank which connect the channel with the outside；whereina narrowing member (10, 10', 10") is provided in the channel (6, 6', 6") in a region at or close to the free end (3) that narrows a cross-section of the channel without closing the channel in such a manner that bone cement or another substance which is introduced into the channel is prevented from exiting through the free end (3).
