A cervical polyaxial bone anchor includes a shank having an integral spherical head and a receiver having an upper channel for receiving a rod and a lower seat near a lower opening for receiving a closed retainer that includes a compressible upper portion engaged with the receiver seat and an expandable lower portion capturing the shank head. An outer sleeve slidable with the receiver prohibits expansion of the retainer lower portion during operation. A compression insert engages the retainer upper portion and is in friction fit with the shank head prior to fixing of an angle of the shank with respect to the receiver.
