A surgical device which is a posterior pedicle screw having a taper lock and which comprises: a coupling having an opening extending therethrough; a collet receivable in the opening of the coupling; and a pedicle screw having a head receivable in an opening of the collet, the pedicle screw comprising a shank with a helical thread, a head having a top and a bottom surface, and a neck between the bottom of the head and the shank, the head receivable in an opening of the collet, such that the pedicle screw is movable throughout a plurality of positions and is substantially free from interference between the neck and the collet and between the neck and the coupling, and characterised in that: the collet has a bottom edge having an annular beveled lip extending upwards and inwards from the bottom outer edge of the collet; the coupling has a bottom edge having an annular beveled lip extending upwards and inwards from the outer edge of the coupling, and the neck has a diameter less than the diameter of the bottom of the head and the diameter of the helical thread of the shank and has a length and a diameter that co-operate with the beveled lips (55, 79) for reducing interaction therebetween, thereby to maximize annular motion of the pedicle screw relative to the collet and the coupling such that the pedicle screw has a conical range of motion of at least 70 degrees. a coupling having an opening extending therethrough; a collet receivable in the opening of the coupling; and a pedicle screw having a head receivable in an opening of the collet, the pedicle screw comprising a shank with a helical thread, a head having a top and a bottom surface, and a neck between the bottom of the head and the shank, the head receivable in an opening of the collet, such that the pedicle screw is movable throughout a plurality of positions and is substantially free from interference between the neck and the collet and between the neck and the coupling, and characterised in that: the collet has a bottom edge having an annular beveled lip extending upwards and inwards from the bottom outer edge of the collet; the coupling has a bottom edge having an annular beveled lip extending upwards and inwards from the outer edge of the coupling, and the neck has a diameter less than the diameter of the bottom of the head and the diameter of the helical thread of the shank and has a length and a diameter that co-operate with the beveled lips (55, 79) for reducing interaction therebetween, thereby to maximize annular motion of the pedicle screw relative to the collet and the coupling such that the pedicle screw has a conical range of motion of at least 70 degrees. the collet has a bottom edge having an annular beveled lip extending upwards and inwards from the bottom outer edge of the collet; the coupling has a bottom edge having an annular beveled lip extending upwards and inwards from the outer edge of the coupling, and the neck has a diameter less than the diameter of the bottom of the head and the diameter of the helical thread of the shank and has a length and a diameter that co-operate with the beveled lips (55, 79) for reducing interaction therebetween, thereby to maximize annular motion of the pedicle screw relative to the collet and the coupling such that the pedicle screw has a conical range of motion of at least 70 degrees.