US Patent 9277942 Polyaxial bone anchoring device with enlarged pivot angle

A polyaxial bone anchoring device includes a receiving part to receive a rod for coupling the rod to a bone anchoring element, the receiving part having a top end and a bottom end, a first passage at the bottom end with a first longitudinal axis, and a second passage at the top end with a second longitudinal axis that intersects the first longitudinal axis, and a compression element, wherein at least one of the receiving part or the compression element has a seat with an opening facing the bottom end, and wherein the compression element is movable relative to the receiving part along the first longitudinal axis between a first position wherein the seat is expandable and configured for insertion of a head of a bone anchoring element and pivoting of the head, and a second position wherein the seat is compressed to lock an inserted head therein.