A vertical line is drawn the width of two fingers to the right of the nipple, as shown in [Fig. 389], the length of the line being obvious.
Fig. 389.—Method of Locating Strip of Cartilage.
Where the vertical crosses the eighth costal cartilage an incision is made downward over and not under the border of the cartilage.
The incision extends downward for a distance of eight centimeters, where it is turned upward at an angle, as shown, to a distance of three centimeters.
By separating the muscular aponeurosis made visible by this incision the lower edge of the eighth costal cartilage is exposed. The knife is moved along the lower edge of the cartilage, dividing the fibers of the insertion of the transverse muscle from without inward. The cartilage can now be grasped between the thumb and forefinger and be forced out of its normal position after a slight anterior dissection.
The union between cartilage and bone is exposed. The chisel is used to divide the cartilage about one centimeter from the rib, after the costal or inner extremity has been made.
The position of the hands and the exposed cartilage is shown in [Fig. 390].
Fig. 390.—Excising Strip of Costal Cartilage.