**Core Concept**
Most muscles in the human body have a single nerve supply; however, some muscles are known to have dual nerve supply, which can be crucial in clinical scenarios, especially in assessing motor function and nerve damage.

**Why the Correct Answer is Right**
The pronator teres muscle is supplied by the median nerve for its lateral head and the anterior interosseous nerve (a branch of the median nerve) for its medial head. However, the medial head of the pronator teres is also supplied by the anterior interosseous nerve, which is a branch of the median nerve, and not by a separate nerve. This makes the pronator teres muscle unique in having a dual nerve supply through a single nerve (the median nerve) and a branch of that nerve (the anterior interosseous nerve).

**Why Each Wrong Option is Incorrect**
**Option A:** The subscapularis muscle has dual nerve supply, receiving innervation from the upper and lower subscapular nerves (both branches of the brachial plexus).

**Option B:** The pectoralis major muscle has dual nerve supply, receiving innervation from the lateral pectoral nerve (C5-C7) and the medial pectoral nerve (C8-T1).

**Option D:** The flexor digitorum profundus muscle has dual nerve supply, receiving innervation from the anterior interosseous nerve (a branch of the median nerve) and the ulnar nerve.

**Clinical Pearl / High-Yield Fact**
When assessing motor function in the upper limb, particularly in the context of nerve damage or palsy, it is essential to remember that some muscles, like the pronator teres, have dual nerve supply. This can lead to an atypical presentation of motor weakness or paralysis.

**✓ Correct Answer: C. Pronator teres**