Patent ID: 7465310

Claim:
A medical knife having a blade, the blade including: a distal end and a proximal end; a pair of opposed, first and second sides extending from the distal end to the proximal end; a pair of cutting edges formed between the first and second sides and extending from the distal end to the proximal end; a pair of boundary lines defined on the first side and extending from the distal end to the proximal end; and a pair of cutting surfaces formed on the first side, each of the cutting surfaces being defined between one of the cutting edges and a corresponding one of the boundary lines, wherein each of the cutting surfaces includes an outer cutting surface formed continuously with a corresponding one of the cutting edges and an inner cutting surface formed continuously with a corresponding one of the boundary lines, wherein an angle of each of the inner cutting surfaces with respect to a first hypothetical plane is larger than an angle of the outer cutting surfaces with respect to the first hypothetical plane, and wherein the first hypothetical plane includes the first and second sides, wherein the inner cutting surfaces are connected to each other at a connecting portion in the vicinity of the distal end, wherein a width of each of the outer cutting surfaces between a corresponding one of the cutting edges and the corresponding inner cutting surface is gradually increased from the distal end to the proximal end, and a width of each of the inner cutting surfaces between a corresponding one of the boundary lines and a corresponding one of the outer cutting surfaces is gradually decreased from the connecting portion to the proximal end, and wherein an intermediate surface is formed on the first side between the inner cutting surfaces, the pair of boundary lines being located between the intermediate surface and the inner cutting surfaces, the intermediate surface having an arch-shaped recessed surface with respect to a second hypothetical plane, the second hypothetical plane including the pair of boundary lines.