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gunshot wound

Monday 23 March 2009

Digital slides

- UI:986 - Gunshot wound

Injuries of this nature fall largely into the domain of forensic pathology, a specialty dealing with trauma and medicolegal issues. The character of a gunshot wound at entry and exit and the extent of injury depend on the type of gun used (handgun or rifle) and on a large number of variables, including the caliber of the bullet, the type of ammunition, the distance of the firearm from the body, the locus of the injury, the trajectory of the missile (at right angles to the skin or oblique), and the gyroscopic stability of the bullet (the presence or absence of wobbling or tumbling).

With handguns held at close range (within a foot of the skin surface), there is a gray-black discoloration about the wound of entrance (fouling) produced by the heat, smoke, and burned powder deposits exiting with the bullet from the muzzle. In addition, there may be discrete, larger particles of unburned powder producing a halo of stippling about the entrance wound, the diameter of which depends on the distance of the gun from the body. When firearms are held more than a foot away, but within 3 feet, there may be only stippling without fouling. At greater distances, neither is present.

In general, the perforating cutaneous wound is slightly smaller than the diameter of the bullet and has a narrow enclosing rim of abrasion. When the trajectory of the bullet is angled into the skin, the abrasion is asymmetric, having its greatest width at the margin closest to the origin of the bullet.

Depending on the size and velocity of the bullet and the distance between the target and the muzzle to the firearm, when the skin is closely applied to underlying bone as in the scalp, entering gas may elevate the overlying skin and, in some instances, produce stellate lacerations about the perforating wound.

Similarly, large-caliber, high-velocity missiles, after penetrating the skin and subcutaneous tissues, may traverse internal organs and, by their mass and velocity, cause extending massive lacerations through the liver or other viscera. In contrast, smaller, low-velocity bullets, even though they penetrate the organ, may produce only fairly restricted burrowing or through-and-through tracts with limited surrounding injury.

Cutaneous exit wounds are generally more irregular than are wounds of entrance, because in passing through the tissues, the bullet almost inevitably develops a wobbling trajectory. In fact, with high-velocity rifle bullets, the exit wound may be considerably larger than the entrance wound. The margins of the wound may be everted, and there is no fouling or stippling and often little surrounding abrasion. To the experienced eye, it is evident that gunshot wounds tell a story.