Abstract: A surgical retractor assembly for providing a generally constant retracting force at a fixation site on a patient despite possible movements of the fixation site during application of the retracting force. The retractor assembly comprises a support structure engaging element for providing communication between the surgical retractor assembly and a support structure; a retractor guide for receiving a first end of a retracting member, the retractor guide being coupled to the support structure engaging element, wherein the retractor guide is displaceable relative to the support structure engaging element; and a biasing structure that provides the retracting force.

Abstract: An articulated arm for holding surgical instruments, having elongated arm members; rotational joints connecting the arm members end to end, such that members are pivotable about the joints and at least one of the joints is selectively lockable by fluid pressure; and a plurality of tubes communicating fluid pressure between two adjacent joints. When two adjacent members are pivoted relative to one another, the tubes connecting a particular pair of joints remains substantially stationary with respect to the arm member connecting that pair of joints.