**Core Concept**
The thenar eminence is a muscle group located on the palmar surface of the thumb, consisting of three muscles: abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis. The median nerve supplies these muscles, except for one, which has a different innervation.

**Why the Correct Answer is Right**
The abductor pollicis longus muscle is the one that does not receive its innervation from the median nerve. Instead, it is innervated by the posterior interosseous nerve, a branch of the radial nerve. This is because the abductor pollicis longus muscle is involved in the abduction of the thumb at the metacarpophalangeal joint, which is a movement that requires a different nerve supply compared to the other muscles in the thenar eminence.

**Why Each Wrong Option is Incorrect**
**Option A:** The abductor pollicis brevis muscle is supplied by the median nerve, so it is not the correct answer. The median nerve innervates this muscle, which is involved in the abduction of the thumb at the carpometacarpal joint.
**Option B:** The flexor pollicis brevis muscle is also supplied by the median nerve, making it an incorrect answer. This muscle is involved in the flexion of the thumb at the interphalangeal joint.
**Option C:** The opponens pollicis muscle is supplied by the median nerve, so it is not the correct answer. This muscle is involved in the opposition of the thumb, which is a movement that requires innervation by the median nerve.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that the median nerve supplies most of the muscles in the thenar eminence, except for the abductor pollicis longus muscle, which is innervated by the posterior interosseous nerve. This is a critical piece of information for any medical professional, especially in the context of nerve injuries or surgical procedures involving the hand.

**Correct Answer:** D.