Fig. 18.—Oblique Exit Gutter.
Diagram enlarged to actual size from case shown in fig. 24, p. 64.
With increasing degrees of obliquity of impact more and more pronounced oval openings of entry result, culminating in an actual gutter such as is seen in fig. 17.
In all oval openings the loss of substance is more pronounced at the proximal margin, while the wound is liable to undergo secondary enlargement at the distal margin, since in the former the epidermis is mainly affected, while in the latter the epidermis is spared as an ill-nourished bridge, the deeper layers of the skin suffering the more severely. When the wound occurs in regions, such as the chest-wall or over the sacrum, where the skin is firmly supported, the oval openings are often very considerable in size, reaching a diameter at least double that of the circular ones. In the case of the oval openings the depression of the margins is not such a well-marked feature as in wounds resulting from rectangular impact of the bullet, since the distal margin is really lifted.
Fig. 19.
Oval Entry Wound over third sacral vertebra. Exit wound, anterior abdominal wall. Slightly starred variety. Diagram made on second day
Aperture of exit.—The wound of exit in normal cases offers far more variation in appearance than that of entry, this variation depending on several circumstances: first, the want of support to the skin from without, and such other factors as the degree of velocity retained by the travelling bullet, the locality of the opening, and the density, tension, and resistance offered by the particular area of skin implicated.
When the range has been short and the velocity high, it is often difficult to discriminate between the two apertures. Both may be circular and of approximately the same size, and the only distinguishing characteristic, the slight depression of the margin of the wound of entrance, may be absent if any time has elapsed between the infliction of the injury and examination by the surgeon. One very strong characteristic if present is the general tendency of the margins, and even the area surrounding the exit wound itself, to be somewhat prominent. Fig. 16 shows this point, although the wound from which it was drawn had been produced thirty-six hours before death. The specimen was then hardened in formalin and still preserves its original aspect. This character is, however, more frequently displayed in wounds received at mean, or longer, ranges. In wounds produced by bullets travelling at the highest degrees of velocity it is often absent.
