**Core Concept**
The question is testing the anatomical relationship between the wrist and the muscles of the hand, specifically those innervated by the median, ulnar, and radial nerves. The patient's symptoms and x-ray findings are likely related to a fracture or dislocation affecting the wrist joint.

**Why the Correct Answer is Right**
The muscles of the hand are primarily innervated by the median (C8-T1), ulnar (C8-T1), and radial (C5-C7) nerves. The wrist joint is a complex structure that includes bones, ligaments, and tendons. A fracture or dislocation in the wrist region can affect the surrounding muscles. However, the **extensor pollicis longus** (EPL) muscle is innervated by the posterior interosseous nerve (PIN), a branch of the radial nerve, which is not directly related to the wrist joint. Therefore, in a condition affecting the wrist, the EPL muscle would likely be spared.

**Why Each Wrong Option is Incorrect**
* **Option A:** The **flexor carpi radialis** muscle is innervated by the median nerve, which could be affected in a wrist injury.
* **Option B:** The **palmaris longus** muscle is also innervated by the median nerve and could be affected in a wrist injury.
* **Option C:** The **extensor digitorum** muscle is innervated by the posterior interosseous nerve (PIN), but its function and innervation can be affected by wrist injuries.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that wrist injuries can have a wide range of consequences, including nerve damage, tendon rupture, and fractures. The specific muscles and nerves involved can vary depending on the type and severity of the injury.

**Correct Answer:** C.