Patent ID: 8142355

Claim:
A retractor blade assembly, comprising: (a) a first blade having attached thereto a first barrel, the first barrel having a wall circling a first axis and defining a first lumen, a first channel in the wall having a first angle with respect to the first axis and a second channel in the wall having a second angle with respect to the first axis and the second angle being symmetric about the first axis with respect to the first angle, (b) a second blade having attached thereto a second barrel, the second barrel having a wall circling a second axis and defining a second lumen, a third channel in the second wall having a third angle with respect to the second axis, and a fourth channel in the second wall having a fourth angle with respect to the second axis, a slope of the third angle being opposite in sign with respect to the second axis to that of the first angle and the fourth channel being symmetric about the second axis with respect to the third channel, wherein the first barrel fits within the second lumen of the second barrel such that the first and third channels intersect to form a first gap and the second an fourth channels intersect to form a second gap, and wherein the first axis is substantially collinear with the second axis; (c) a cylindrical plunger having a third axis, an outer surface, a first end and a second end, the first end having a hole through and at a right angle to the third axis, and the second end having a screw thread cut into the surface of the plunger, the cylindrical plunger fitting within the first lumen of the first barrel such that said hole aligns with the first gap and the second gap and the hole, first gap and second gap forming a passage, and wherein the third axis is substantially collinear with the first and second axes; (d) a rod fitting through the passage such that movement of the plunger along the third axis causes the first barrel to rotate in a first direction and the second barrel to rotate in a second direction opposite the first direction; (e) a holder possessing a third lumen, wherein the second barrel fits within the third lumen; and (f) a nut having an internal screw thread and fitting over the end of the plunger; whereby rotation of the nut causes the internal screw thread of the nut to engage the plunger screw thread and causes the plunger to move along the third axis, thereby causing the first and second barrels to rotate about the first and second axes, respectively, in opposite directions.