The invention relates to a device for joining a bone fixation element to a longitudinal rod. Said device comprises: A) a plate-shaped transversal connector (3) with a plate top side (5) for placing against a longitudinal rod (1) and with a cavity (7) that passes through said transversal connector (3); B) a clamping jaw (10), which can be resiliently compressed and which can be accommodated inside the cavity (7), and; C) a tightening means (12), which is provided for radially spreading the clamping jaw (10) inside the cavity (7), whereby; D) the transversal connector (3) comprises a boring (19), which passes through the transversal connector (3) from the plate top side (5) to the plate bottom side (6) and which is located at a distance (31) from the cavity (7). The inventive device also comprises: E) a longitudinal rod connector (13), which can be accommodated inside the boring (19) and which is provided with a channel (17) for accommodating a longitudinal rod (1), and; F) fixing means (33) for detachably fixing a longitudinal rod (1) that can be inserted into the channel (17), and for detachably fixing the longitudinal rod connector (13) with regard to the transversal connector (3), and such that; G) when the fixing means (33) is loosened, the transversal connector (3) is arranged in a manner that permits it to rotate with the longitudinal rod connector (13) about the central axis (14).