Temporary cavity formation is a critical concept in high-velocity rifle wound ballistics. It differs from the permanent cavity in that:

• A The temporary cavity is the actual tissue defect visible at autopsy; the permanent cavity is invisible
• B The temporary cavity is a momentary radial displacement of tissue caused by the sonic pressure wave; it is far larger than the permanent track and causes stretch injury beyond the bullet path in non-elastic organs ✓
• C Both cavities have identical dimensions in elastic tissues like lung
• D Temporary cavity formation occurs only in shotgun injuries due to multiple pellet pressure waves

Explanation

When a high-velocity bullet (>600 m/s) passes through tissue, it transfers enormous kinetic energy radially. The temporary cavity is the momentary, pulsating expansion of tissue around the bullet track — far larger than the bullet diameter and the permanent cavity. This creates enormous stretch forces lasting milliseconds. In elastic tissue (lung, muscle), tissues can partially recoil and the permanent cavity is smaller than temporary. In non-elastic tissues (brain, liver), the temporary cavity causes fracturing and shattering beyond the permanent track, explaining the massive destruction of high-velocity wounds. Handguns (low velocity) produce primarily permanent cavity injury.

Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.

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Written and medically reviewed by the StethoPrep medical team.