**Core Concept:** Lunate dislocation is a disruption of the lunotriquetral ligament, leading to instability of the wrist joint and compression of the superficial radial nerve. The superficial radial nerve, also known as the posterior interosseous nerve, is a branch of the radial nerve and innervates the muscles of the posterior aspect of the forearm and hand, including the extensor muscles and the dorsal cutaneous branch to the thumb, index, and middle fingers.

**Why the Correct Answer is Right:** The correct answer, D, is the superficial radial nerve because it is the major nerve affected by lunate dislocation. The injury to the superficial radial nerve results from compression of the nerve as it passes over the lunate bone, causing pain, paraesthesia, and weakness in the radial half of the hand and forearm.

**Why Each Wrong Option is Incorrect:**

A. The median nerve, while it may be affected in carpal tunnel syndrome, is not directly related to lunate dislocation.
B. The ulnar nerve is not the correct answer because lunate dislocation primarily affects the radial nerve.
C. The ulnar nerve is not affected by lunate dislocation, as it is the posterior interosseous nerve that is the target of the question, not the ulnar nerve.

**Clinical Pearl:** Recognizing and treating lunate dislocation promptly is essential to prevent long-term complications such as cubital tunnel syndrome and radial nerve palsy due to the prolonged compression of the affected nerves.

**Correct Answer:** D. Superficial Radial Nerve