**Question:** Ulnar nerve injury at wrist involves following except -

A. Radial nerve
B. Sural nerve
C. Deep branch of the ulnar nerve
D. Superficial branch of the radial nerve

**Core Concept:**

The ulnar nerve is a major peripheral nerve in the human body, responsible for sensory, motor, and proprioceptive functions in the hand. Injuries to the ulnar nerve can occur at various sites, including the wrist, where it passes through the Guyon canal (also known as the osseous canal of Hamate). The Guyon canal is a tunnel formed by the triquetral and pisiform bones, in which the deep and superficial branches of the ulnar nerve pass through.

**Why the Correct Answer is Right:**

Ulnar nerve injury at the wrist typically involves the deep branch of the ulnar nerve, as it is the branch that passes through the Guyon canal. When the deep branch of the ulnar nerve is injured, patients may experience symptoms such as sensory loss, muscle weakness, and atrophy in the ulnar nerve distribution (palmar side of ring finger, little finger, and the ulnar half of the little finger).

**Why Each Wrong Option is Incorrect:**

A) Radial nerve: The radial nerve is a separate nerve, providing motor and sensory innervation to the forearm and hand. It is not involved in ulnar nerve injuries at the wrist.

B) Sural nerve: The sural nerve is another peripheral nerve that does not pass through the Guyon canal and is not involved in ulnar nerve injuries at the wrist. It is a sensory nerve that supplies sensation to the posterior leg and foot.

C) Deep branch of the radial nerve: This is incorrect because the deep branch of the radial nerve does not pass through the Guyon canal. It provides sensory innervation to the dorsum of the hand, not the ulnar nerve distribution.

D) Superficial branch of the radial nerve: Similarly, the superficial branch of the radial nerve does not pass through the Guyon canal and is not involved in ulnar nerve injuries at the wrist. It provides sensory innervation to the dorsum of the hand, not the ulnar nerve distribution.

E) Simultaneous injury to both the ulnar nerve and the deep branch of the radial nerve: This combination is incorrect because the deep branch of the radial nerve does not pass through the Guyon canal and is not affected in ulnar nerve injuries at the wrist.

**Clinical Pearl:**
Understanding the anatomy and distribution of peripheral nerves is crucial for diagnosing and treating nerve injuries. The Guyon canal is a crucial landmark in identifying ulnar nerve injuries, as it is the site of passage for the deep and superficial branches of the ulnar nerve.