Surgical treatment of tissue includes electrocauterization of blood vessels interposed between spaced sets of electrodes of opposite polarity, and includes transection of such tissue by a cutter that is mounted between the spaced sets of electrodes for translational and lateral movement relative to the sets of electrodes. Orientations of the sets of electrodes within a range of angles about an elongated axis of a supporting body are controlled by manual movement of an actuator mounted near a proximal end of the body for movement through a smaller range of angles via linkage connecting the actuator to the electrodes. Tissue dissection with gas insufflation to form an anatomical space in tissue is facilitated by a fluid outlet port located near the tissue-dissecting tip at the distal end of the elongated body that delivers through the tissue-dissecting tip to the dissected tissue a fluid under pressure that is supplied along a lumen within the elongated body.