**Question:** Superficial branch of ulnar nerve supplies to the following muscle

**Core Concept:** The ulnar nerve is a major nerve in the upper limb that plays a crucial role in motor and sensory functions. It originates from the spinal cord and consists of both sensory and motor components. The ulnar nerve has several branches that supply specific muscles and organs.

**Why the Correct Answer is Right:** The correct answer, D - **Supinator muscle**, is a key muscle of the forearm that is innervated by the superficial branch of the ulnar nerve. The superficial branch of the ulnar nerve, also known as the "little finger nerve", primarily supplies the motor innervation to the supinator muscle, which is responsible for supination (palm down) movement of the forearm.

**Why Each Wrong Option is Incorrect:**

A. **Anconaeus muscle**: This muscle is innervated by the deep branch of the radial nerve, not the ulnar nerve.
B. **Long flexor of the forearm**: The long flexor of the forearm is supplied by the median nerve, not the ulnar nerve.
C. **Short flexor of the forearm**: The short flexor of the forearm is supplied by the median nerve, not the ulnar nerve.

**Clinical Pearl:** Understanding the anatomy and innervation of various muscles helps in diagnosing and treating nerve injuries or palsies. Proper knowledge of these nerves can aid in interpreting clinical findings and formulating a differential diagnosis for upper limb neuropathies.

**Correct Answer:** **Supinator muscle** (D) is innervated by the superficial branch of the ulnar nerve, which is essential for understanding the anatomy and clinical implications of nerve injuries in the upper limb.