Winging of scapula is seen in paralysis of which muscle?
**Core Concept**
Winging of the scapula is a clinical sign characterized by the protrusion of the scapula from the posterior chest wall, typically due to weakness or paralysis of the muscles that stabilize the scapula. The primary muscles responsible for scapular stability are the serratus anterior and the trapezius.
**Why the Correct Answer is Right**
The serratus anterior muscle plays a crucial role in rotating the scapula upward and around the thorax, preventing the scapula from protruding. When the serratus anterior muscle is paralyzed, the scapula loses its stability, leading to winging of the scapula. This is often seen in patients with long thoracic nerve palsy, which innervates the serratus anterior muscle. The long thoracic nerve arises from the spinal cord between C5 and C7 and travels down to innervate the serratus anterior muscle.
**Why Each Wrong Option is Incorrect**
* **Option A:** The latissimus dorsi muscle is involved in adduction, extension, and internal rotation of the shoulder joint. Its paralysis would not lead to winging of the scapula.
* **Option B:** The rhomboids are a group of muscles that stabilize the scapula against the thoracic wall. While their paralysis can cause scapular winging, it is less common than serratus anterior paralysis.
* **Option C:** The levator scapulae muscle assists in elevating the scapula and rotating it downward. Its paralysis would not lead to winging of the scapula.
**Clinical Pearl / High-Yield Fact**
Winging of the scapula can be a sign of a serious underlying condition, such as long thoracic nerve palsy or muscular dystrophy. It is essential to investigate the cause of scapular winging to prevent further muscle damage and improve patient outcomes.
**Correct Answer:** D. Serratus anterior muscle.