A connector assembly, comprising: a connector (230; 330) having a proximal end and a distal end that define a proximal-distal axis, the connector (230; 330) including: a coupling portion (240; 340) having an opening (242; 342) configured to mate the connector (230; 330) to a receiver member (204; 304) of a bone anchor assembly, the bone anchor assembly having a first rod-receiving recess for receiving a first rod, and a receiving portion in which a second rod-receiving recess is formed, the second rod-receiving recess being configured to receive a second rod; a first fastener having a distal end configured to engage the receiver member (204; 304) to lock the first rod to the receiver member (204; 304) and a proximal end configured to engage the coupling portion (240; 340); a second fastener engaged with the receiving portion of the connector (230; 330) to lock the second rod to the connector (230; 330), and a locking nut (260; 360) mateable to the first fastener to secure the connector (230; 330) to the receiver member (204; 304), characterized in that the locking nut (260; 360) is configured to be received within the opening (242; 342) of the coupling portion (240; 340), wherein the opening (242; 342) of the coupling portion (240; 340) includes an inner articulation surface that interfaces with an outer articulation surface formed in the locking nut (260; 360), and wherein the inner articulation surface is complementary to the outer articulation surface such that in an unlocked configuration of the locking nut (260; 360) the locking nut (260; 360) is polyaxially movable within the opening (242; 342) relative to the connector (230; 330) wherein the locking nut is capable of expanding or contracting in a radial direction, wherein the locking nut further comprises slits formed therein that allows for expansion or contraction in the radial direction, wherein the slits comprise first and second slits (266p, 266d) that are diametrically opposed, and wherein the first slits are formed in a proximal surface of the locking nut being capable of receiving a driver instrument for rotating the locking nut and the second, diametrically opposed slits are formed in the distal surface of the locking nut being capable of allowing contraction and expansion of the locking nut in the radial direction. a coupling portion (240; 340) having an opening (242; 342) configured to mate the connector (230; 330) to a receiver member (204; 304) of a bone anchor assembly, the bone anchor assembly having a first rod-receiving recess for receiving a first rod, and a receiving portion in which a second rod-receiving recess is formed, the second rod-receiving recess being configured to receive a second rod; a first fastener having a distal end configured to engage the receiver member (204; 304) to lock the first rod to the receiver member (204; 304) and a proximal end configured to engage the coupling portion (240; 340); a second fastener engaged with the receiving portion of the connector (230; 330) to lock the second rod to the connector (230; 330), and a locking nut (260; 360) mateable to the first fastener to secure the connector (230; 330) to the receiver member (204; 304), characterized in that the locking nut (260; 360) is configured to be received within the opening (242; 342) of the coupling portion (240; 340), wherein the opening (242; 342) of the coupling portion (240; 340) includes an inner articulation surface that interfaces with an outer articulation surface formed in the locking nut (260; 360), and wherein the inner articulation surface is complementary to the outer articulation surface such that in an unlocked configuration of the locking nut (260; 360) the locking nut (260; 360) is polyaxially movable within the opening (242; 342) relative to the connector (230; 330) wherein the locking nut is capable of expanding or contracting in a radial direction, wherein the locking nut further comprises slits formed therein that allows for expansion or contraction in the radial direction, wherein the slits comprise first and second slits (266p, 266d) that are diametrically opposed, and wherein the first slits are formed in a proximal surface of the locking nut being capable of receiving a driver instrument for rotating the locking nut and the second, diametrically opposed slits are formed in the distal surface of the locking nut being capable of allowing contraction and expansion of the locking nut in the radial direction.