A polyaxial bone anchoring device is provided including a bone anchoring element (1) having a shank (2) for anchoring in the bone and a head (3) a receiving part (5) for coupling a rod (6) to the bone anchoring element (1) the receiving part including a rod receiving portion (9, 9’, 9”) having a first end (9a) and a second end (9b) and a recess (12) with a bottom for receiving the rod (6) therein, a head receiving portion (19, 19’, 19”) having a first end (19a) and an open second end (19b) with a bounding edge and a hollow interior portion (23) in communication with the open second end (19b) for introduction of the head (3), the head receiving portion being flexible so as to allow introduction and clamping of the head (83) a locking ring (8) mounted around the head receiving portion (19, 19’, 19”) wherein the head (3) is pivotable in the head receiving portion (19, 19’, 19”) and can be locked at an angle by compressing the head receiving portion (19) by means of the locking ring (8) wherein the bounding edge is configured to permit the anchoring element to pivot at a larger pivot angle at a first location of the bounding edge than at a second location of the bounding edge and wherein the head receiving portion (19) is rotatably connected to the rod receiving portion (9, 9’, 9”).本案提供一種多軸式骨骼固定裝置,包含:骨骼固定元件(1),有固定於骨骼之軸部(2),和頭部(3);容納件(5),把桿件(6)聯結於骨骼固定元件(1);容納件含有:桿件容納部(9,9’,9”),有第一端(9a)和第二端(9b),以及凹部(12),有底部可容納桿件(6);頭部容納部(19,19’,19”),有第一端(19a)和具限界邊緣的開口第二端(19b),以及空心內部(23),與開口第二端(19b)相通,以引進頭部(3),頭部容納部具撓性,可引進並夾持頭部(83);鎖環(8),安裝在頭部容納部(19,19’,19”)周圍;其中頭部(3)可在頭部容納部(19,19’,19”)內樞動,利用鎖環(8)壓縮頭部容納部(19),即可鎖定在一角度;其中限界邊緣之構成,容許固定元件在限界邊緣的第一位置,比在限界邊緣的第二位置,以更大樞動角度樞動;又其中頭部容納部(19)係轉動自如連接於桿件容納部(9,9’,9”)。1‧‧‧骨骼固定元件2‧‧‧螺紋軸部3‧‧‧頭部5‧‧‧容納件6‧‧‧桿件7‧‧‧封閉元件8‧‧‧鎖環9‧‧‧桿件容納部9a‧‧‧桿件容納部第一端9b‧‧‧桿件容納部第二端12‧‧‧U形凹部13‧‧‧陰螺紋15‧‧‧缺口16‧‧‧銷孔18‧‧‧插銷19‧‧‧頭部容納部19a‧‧‧頭部容納部第一端19b‧‧‧頭部容納部第二端21‧‧‧凹溝22‧‧‧錐形外表面部81‧‧‧鎖環凸部82‧‧‧鎖環凸部自由端C‧‧‧對稱中央軸線L‧‧‧槽溝縱軸線
