A 40-year-old man was repairing his wooden shed on Sunday morning. By afternoon, he felt that the hammer was becoming heavier and heavier. He felt pain in the lateral side of the elbow and also found that squeezing water out of sponge hurt his elbow. Which of the muscles are most likely involved-

**Core Concept**
The question describes a scenario of lateral elbow pain and weakness in activities that require gripping or wrist extension, such as squeezing a sponge or holding a hammer. This clinical presentation is characteristic of lateral epicondylitis, also known as tennis elbow, which is an overuse injury of the extensor muscles of the forearm.

**Why the Correct Answer is Right**
Lateral epicondylitis is caused by inflammation of the tendons that attach to the lateral epicondyle of the humerus. The primary muscles involved are the extensor carpi radialis brevis (ECRB) and the extensor digitorum (ED). The ECRB is responsible for wrist extension and radial deviation, while the ED assists in finger extension. The pain and weakness described in the scenario are consistent with overuse of these muscles, particularly in activities that require repetitive gripping or wrist extension.

**Why Each Wrong Option is Incorrect**
**Option A:** The flexor carpi radialis (FCR) is a muscle involved in wrist flexion and radial deviation, which is not consistent with the clinical presentation of lateral epicondylitis.

**Option B:** The pronator teres (PT) is a muscle involved in forearm pronation, which is not directly related to the symptoms described in the scenario.

**Option C:** The supinator muscle is involved in forearm supination and is not typically associated with lateral epicondylitis.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that lateral epicondylitis is often caused by overuse of the forearm extensors, particularly in activities that involve repetitive gripping or wrist extension. This can be prevented by incorporating exercises that strengthen the forearm flexors and improving grip strength.

**Correct Answer:** C. Supinator

✓ Correct Answer: C. Extensor carpi radialis longus and brevis