Peripheral nerve injuries: ape hand thumb posture: practice question

A Orthopaedics 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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Orthopaedics · Peripheral nerve injuries: ape hand thumb posture

Sample item

A man has a deep laceration at the wrist with thenar flattening, and the thumb lies adducted and extended in the plane of the palm. Which explains the thumb posture?

ARadial nerve palsy at the wristBLoss of the adductor pollicis aloneCParalysis of the extensor pollicis longusDLoss of the median-supplied thenar muscles with unopposed adductor pollicis and long extensor

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

The answer and the reasoning

D. Loss of the median-supplied thenar muscles with unopposed adductor pollicis and long extensor

In low median nerve palsy abductor pollicis brevis, opponens pollicis and the superficial head of flexor pollicis brevis are paralysed, so the thumb cannot abduct or oppose and sits in the plane of the palm, called ape hand. The ulnar-supplied adductor and the extensor tendons then pull the thumb back. Sensation is lost over the lateral three and a half digits.

Option by option

A. Radial nerve palsy at the wrist
A radial lesion does not flatten the thenar eminence.
B. Loss of the adductor pollicis alone
The adductor pollicis is ulnar and is preserved in a median lesion.
C. Paralysis of the extensor pollicis longus
The extensor pollicis longus is radial and is working here.
D. Loss of the median-supplied thenar muscles with unopposed adductor pollicis and long extensor (correct)
Correct. Thenar paralysis leaves the thumb adducted and extended.

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 Orthopaedics question

What is the answer to this Orthopaedics question?

The best answer is D, Loss of the median-supplied thenar muscles with unopposed adductor pollicis and long extensor. In low median nerve palsy abductor pollicis brevis, opponens pollicis and the superficial head of flexor pollicis brevis are paralysed, so the thumb cannot abduct or oppose and sits in the plane of the palm, called ape hand.

Why is "Radial nerve palsy at the wrist" not the answer?

A radial lesion does not flatten the thenar eminence.

Why is "Loss of the adductor pollicis alone" not the answer?

The adductor pollicis is ulnar and is preserved in a median lesion.

Why is "Paralysis of the extensor pollicis longus" not the answer?

The extensor pollicis longus is radial and is working here.

What concept does this question test?

It tests Peripheral nerve injuries: ape hand thumb posture in Orthopaedics. The ulnar-supplied adductor and the extensor tendons then pull the thumb back. Sensation is lost over the lateral three and a half digits.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 Peripheral nerve injuries: ape hand thumb posture?

Pair each fracture with its classic complication and nerve injured. Then use the flashcards and the other Orthopaedics 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.