'Ape hand' deformity is due to compression of which nerve?

AIIMS CRE 2025

Applied Anatomy

Easy

Appeared in: AIIMS CRE 2025

Explanation

Ape hand deformity is caused by damage to the median nerve, which leads to paralysis and atrophy of the thenar muscles.
The thenar muscles (opponens pollicis, abductor pollicis brevis, flexor pollicis brevis) are responsible for the opposition of the thumb.
Without the function of these muscles, the thumb cannot be brought forward to touch the other fingers and lies flat in the plane of the palm, a condition known as ape hand.
This is a classic sign of median nerve palsy, often resulting from compression in the carpal tunnel or injury in the forearm.

Option A: Injury to the radial nerve does not cause ape hand. It classically leads to 'wrist drop' because it innervates the extensor muscles of the wrist and fingers.
Option C: Injury to the ulnar nerve results in a 'claw hand' deformity, which primarily affects the ring and little fingers, causing them to curl up. It does not cause the thumb-related changes seen in ape hand.
Option D: Damage to the axillary nerve affects the shoulder, not the hand. It causes paralysis of the deltoid muscle, leading to a flattened shoulder appearance and difficulty in abducting the arm.

Visual 1: Infographic - A comparative chart showing the hand deformities (Ape Hand, Claw Hand, Wrist Drop) side-by-side, with arrows pointing to the affected nerve (Median, Ulnar, Radial) and a list of the paralyzed muscles for each.
Visual 2: Anatomical Diagram - A diagram of the arm and hand showing the course of the median nerve and highlighting the thenar muscles it innervates.
Visual 3: Clinical Photo - A clear photograph of a hand with ape hand deformity, with labels pointing to the atrophied thenar eminence and the adducted thumb.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Peripheral Nerve Injury and Associated Hand Deformities as background academic context rather than a clinical decision trigger.
Recognizing specific hand deformities like ape hand is a crucial diagnostic skill for nurses, as it points directly to the location of a neurological lesion (the median nerve).
A nurse's assessment would include testing for thumb opposition (e.g., asking the patient to touch the tip of their thumb to the tip of their little finger) and inspecting the thenar eminence for wasting.
Patient education is vital. For a patient with median nerve palsy, nurses teach protective strategies to prevent injury to the thumb and fingers, which have diminished sensation, and exercises to maintain joint mobility.

How to Approach the Question

First, identify the key term in the question: 'Ape hand' deformity. This is a specific clinical sign.
Access your knowledge of peripheral nerve injuries and their classic presentations. Try to recall which nerve is associated with which deformity.
If an image is provided, analyze it carefully. The image here directly links 'Ape Hand' to 'Median Nerve Palsy', providing a strong clue.
Evaluate each option: a) Radial nerve -> Wrist Drop, b) Median nerve -> Ape Hand, c) Ulnar nerve -> Claw Hand, d) Axillary nerve -> Shoulder issues.
Based on this systematic association, select the option that correctly links the deformity to the nerve. The median nerve is the correct answer for ape hand deformity.

Concept Tested & Keywords

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