An incision is no more than a cut, but in medical usage it has come to mean a deliberate cut made by the surgeon, as opposed to an accidental cut which in “doctorspeak” is called a laceration.
The superficial incision is made to alter the position or shape of superficial structures, and the surgeon’s usual major concern is that the ultimate result should not be unsightly as the result of the scar, for all incisions when they heal will leave a scar. This may be almost invisible, or according to the nature of the skin and the placing of the incision, may be heaped up and thickened, known as a keloid.
The deep incision is made in order to expose the tissue deep to the skin, that requires the surgeon’s attention; it is therefore “planned,” not haphazardly performed, and planned not only to expose the tissue that needs attention, but also to avoid other tissues which lie between the skin and the target structure and might be damaged in the exploration. It is further planned in such a way that should a larger incision be required it will be facilitated by the choice of the initial positioning of the cut – known as extensile exposure and illustrated books are written on this subject – another reason why the surgeon is expected to know his anatomy.
There was a time when the maxim was, “Big incision means big surgeon” with the intended corollary. But times have changed, and although we have not yet reached, “Little incision equals big surgeon” the patient values a small scar and “keyhole surgery” has become the norm, in particular with so much surgery now performed with the aid of the endoscope or even the robot.
Another issue in the placing of the incision is the structure of the skin which folds readily in one plane but not in another; an incision made across the fold will produce in general a less slightly scar than the ones made along it; such incisions can in fact be hidden quite often within the fold.