Firearm injuries: keyhole defect: practice question

A Forensic Medicine question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Forensic Medicine · Firearm injuries: keyhole defect

Sample item

A shooting victim's skull shows a single bony defect that is bevelled internally at one end and externally at the other, shaped like a keyhole. What is the correct interpretation?

AA contact wound with gas expansion under the scalpBA shotgun wad injury at close rangeCTwo bullets entered at the same pointDA bullet struck the skull tangentially, producing a combined entry and exit defect

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. A bullet struck the skull tangentially, producing a combined entry and exit defect

When a bullet strikes the skull at a very acute angle it glances along the surface, producing a keyhole defect that has the internal bevel of an entry at one end and the external bevel of an exit at the other. It indicates a tangential strike and helps give the bullet direction.

Option by option

A. A contact wound with gas expansion under the scalp
Contact wounds show a stellate or ragged entry with soot, not opposite bevelling.
B. A shotgun wad injury at close range
A wad injury would show a wad impression and pellets, not a keyhole defect.
C. Two bullets entered at the same point
Two bullets at the same point would not give a single defect with opposite bevelling at each end.
D. A bullet struck the skull tangentially, producing a combined entry and exit defect (correct)
Correct. A tangential strike produces a combined entry-exit keyhole lesion.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is D, A bullet struck the skull tangentially, producing a combined entry and exit defect. When a bullet strikes the skull at a very acute angle it glances along the surface, producing a keyhole defect that has the internal bevel of an entry at one end and the external bevel of an exit at the other.

Why is "A contact wound with gas expansion under the scalp" not the answer?

Contact wounds show a stellate or ragged entry with soot, not opposite bevelling.

Why is "A shotgun wad injury at close range" not the answer?

A wad injury would show a wad impression and pellets, not a keyhole defect.

Why is "Two bullets entered at the same point" not the answer?

Two bullets at the same point would not give a single defect with opposite bevelling at each end.

What concept does this question test?

It tests Firearm injuries: keyhole defect in Forensic Medicine. It indicates a tangential strike and helps give the bullet direction.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Firearm injuries: keyhole defect?

Learn postmortem changes with their timelines, and toxicology as poison, sign, test and antidote. Then use the flashcards and the other Forensic Medicine questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.