A coupling assembly is provided for coupling a rod to a bone anchoring element, the coupling assembly including: a receiving part (5, 5', 5") with a top end (5a) and an opposite bottom end (5b)； a section (52) for receiving the rod； and an accommodation space (55, 56) for accommodating a head (3) of the bone anchoring element, the accommodation space being in communication with the top end of the receiving part through a passage (51； 120) and being in communication with the bottom end through an opening (57) at the bottom end for inserting the head； and a pressure element (7, 7', 7") located at least partially in the accommodation space, the pressure element having a cap portion (72) configured to encompass the head； wherein the pressure element (7, 7', 7") can assume in the receiving part an inserting position in which inserting of the head into the receiving part is permitted, a locking position in which the head can be locked in the receiving part and a pre-locking position in which the pressure element is pivotable in the receiving part and wherein the pressure element is arranged such that the cap portion (72) narrows the opening (57) at the bottom end (5b) to prevent removal of the head (3), wherein a first retaining element (8a, 8b) is provided that prevents the pressure element from moving further towards the top end (5a) in the insertion position and wherein a second retaining element (11, 60, 60") different from the first retaining element is provided that prevents the pressure element from moving further towards the top end (5a) in the pre-locking position.本案提供一種聯結總成，供桿件聯結於骨骼固定元件，聯結總成包含：容納件(5,5',5")，有頂端(5a)和對立之底端(5b)；容納桿件用之一段(52)；包容空間(55,56)，供包容骨骼固定元件之頭部(3)，包容空間係透過通道(51；120)與容納件頂端相通，並透過底端之開口(57)與底端相通，供頭部插入；壓力元件(7,7',7")，至少部份位在包容空間內，壓力元件具有帽部(72)，構成包圍頭部；其中壓力元件(7,7',7")在容納件內可呈容許頭部插入容納件內之插入位置，可把頭部鎖定於容納件內之鎖定位置，和壓力元件可在容納件內樞動之預鎖定位置，其中壓力元件之配置，致帽部(72)使開口(57)在底端(5b)變窄，以防頭部(3)脫出；其中設有第一扣件(8a,8b)，防止壓力元件在插入位置繼續朝頂端(5a)運動；又其中設有與第一扣件不同之第二扣件(11,60,60")，防止壓力元件在預鎖定位置繼續朝頂
