Which muscle paralysis can cause ‘Winging of scapula’?
**Core Concept**
The question tests the understanding of muscle function and anatomy, specifically the muscles that stabilize the scapula. **Winging of the scapula** is a condition where the scapula protrudes outward, resembling a wing. This occurs due to the weakness of the muscles that hold the scapula in place.
**Why the Correct Answer is Right**
The correct answer is related to the paralysis of the **Serratus anterior** muscle, which is primarily responsible for holding the scapula against the thoracic wall and rotating it upward. When this muscle is weakened or paralyzed, the scapula can no longer be properly stabilized, leading to the characteristic 'winging' appearance.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it does not relate to the specific muscle responsible for scapular stabilization.
**Option B:** Incorrect as it is not directly associated with the primary function of holding the scapula against the thoracic wall.
**Option C:** Incorrect because, although it involves muscles of the shoulder, it is not the primary cause of winging of the scapula.
**Clinical Pearl / High-Yield Fact**
Remember, **Serratus anterior** paralysis is a common cause of winging of the scapula, often due to injury of the **Long thoracic nerve**. This condition can significantly impair shoulder movement and function.
**Correct Answer:** D. Serratus anterior.