Housing piece to accommodate a rod (6) in order to couple the rod with a bone anchoring element (1), the housing piece including a housing piece body (5) with a channel to accommodate the rod (6 ), and an accommodation space (9, 15) to accommodate a head (3) of the bone anchoring element, the accommodation space having an opening (14) to introduce the head； and a pressure element (8, 8 ') located at least partially in the housing space, the pressure element having a flexible part (82) to immobilize the head and a recess (89) to accommodate the rod； said pressure element being sized so that it can be inserted from the opening (14)； and the housing part body having a first end (5a) and a second end (5b), an essentially U-shaped recess (10) at the first end forming the rod channel and a bore (9) that extends from the first end (5a) to the second end (5b), the bore (9) having a smaller diameter approximately in its middle section (91) or next to it in a central area of the housing part body, and the opening (14) being provided at the second end (5b), characterized in that the pressure element has a first section (81) that includes the recess to accommodate the rod and has a first diameter that is smaller than the diameter of the opening (14) and a second section (82) which is the flexible part having a second diameter that is larger than the diameter of the opening (14).Pieza de alojamiento para alojar una varilla (6) con el fin de acoplar la varilla con un elemento de anclaje óseo (1), incluyendo la pieza de alojamiento un cuerpo de pieza de alojamiento (5) con un canal para alojar la varilla (6), y un espacio de acomodación (9, 15) para acomodar una cabeza (3) del elemento de anclaje óseo, teniendo el espacio de acomodación una abertura (14) para introducir la cabeza； y un elemento de presión (8, 8') situado al menos parcialmente en el espacio de alojamiento, teniendo el elemento de presión una parte flexible (82) para inmovilizar la cabeza y un entrante (89) para alo
