**Question:** All of the following show ulnar nerve injury EXCEPT:

A. Cubital Tunnel Syndrome
B. Median Nerve Injury
C. Radial Nerve Injury
D. Carpal Tunnel Syndrome

**Core Concept:** Ulnar nerve is a mixed motor and sensory nerve that originates from the brachial plexus and supplies various muscles, sensory distribution to the ulnar half of the hand, and provides sensation to the medial two-thirds of the ring and little fingers. Different types of ulnar nerve injuries can occur due to trauma, compression, or inflammation.

**Why the Correct Answer is Right:** The correct answer, **Option D: Carpal Tunnel Syndrome**, is not an ulnar nerve injury but a compression neuropathy involving the median nerve. The carpal tunnel is a narrow passage in the wrist where the median nerve and nine digital nerves pass through. Injury to the median nerve is more common than the ulnar nerve, and it is associated with symptoms like numbness, pain, and weakness in the distribution of the median nerve.

**Why Each Wrong Option is Incorrect:**

**Option A: Cubital Tunnel Syndrome** is a compression neuropathy involving the ulnar nerve as it passes through the cubital tunnel (elbow) and results in symptoms such as sensory loss, paresthesia, and ulnar nerve weakness. This is an ulnar nerve injury, not a median or radial nerve injury.

**Option B: Median Nerve Injury** is a separate compression neuropathy involving the median nerve, which is different from the ulnar nerve. It presents with similar symptoms to cubital tunnel syndrome but in the distribution of the median nerve.

**Option C: Radial Nerve Injury** is another compression neuropathy involving the radial nerve, which is distinct from the ulnar nerve and median nerve. Injuries to the radial nerve lead to weakness in the muscles innervated by the radial nerve and do not affect the ulnar nerve.

**Core Concept:** The correct answer, **Option D: Carpal Tunnel Syndrome**, is a compression neuropathy involving the median nerve, while the wrong options involve ulnar nerve compression neuropathies (A and C) or radial nerve injuries (B and C).

**Clinical Pearls:**

- Understanding the difference between compression neuropathies involving the median, ulnar, and radial nerves is crucial for accurate diagnosis and management of nerve injuries.
- Differential diagnosis of ulnar nerve injuries includes cubital tunnel syndrome and radial nerve injuries, while carpal tunnel syndrome should be ruled out in cases of median nerve compression neuropathy.

**Why Each Wrong Option is Incorrect:**

1. Cubital Tunnel Syndrome (Option A) - This is a compression neuropathy involving the ulnar nerve, leading to symptoms similar to carpal tunnel syndrome but affecting the ulnar nerve.
2. Radial Nerve Injury (Option C) - This is a compression neuropathy involving the radial nerve, resulting in weakness in the muscles innervated by the radial nerve but not affecting the ulnar nerve.
3. Median Nerve Injury (Option B) - This is a compression neuropathy