Cadaveric spasm is –
**Core Concept**
Cadaveric spasm, also known as instantaneous rigor or cataleptic rigidity, is a rare phenomenon where a muscle contracts immediately after death, leading to the preservation of the last action or posture of the individual. This condition is thought to be caused by an abrupt cessation of neural activity, resulting in the maintenance of the muscle tone at the time of death.
**Why the Correct Answer is Right**
The exact mechanism of cadaveric spasm is not fully understood, but it is believed to occur due to an instantaneous loss of adenosine triphosphate (ATP) in the muscle cells, leading to a rapid contraction of the muscles. This is in contrast to the more common rigor mortis, which develops several hours after death due to the breakdown of ATP and the accumulation of lactic acid in the muscles.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because instantaneous rigor is a distinct entity from rigor mortis, which is a more common and widespread phenomenon.
**Option B:** Incorrect because cataleptic rigidity is not a synonym for cadaveric spasm; it is a broader term that can refer to various conditions.
**Option C:** Incorrect because this option does not accurately describe the characteristics of cadaveric spasm.
**Clinical Pearl / High-Yield Fact**
One of the key distinguishing features of cadaveric spasm is its instantaneous onset, which can be a valuable clue in forensic pathology. This phenomenon can also provide important information about the circumstances surrounding the death.
**Correct Answer: C. Instantaneous rigor.