Winging of scapula is due to paralysis of –
**Core Concept**
Winging of the scapula is a clinical condition characterized by the medial border of the scapula protruding laterally, leading to an abnormal appearance. This occurs due to weakness or paralysis of the muscles that stabilize the scapula against the thoracic wall.
**Why the Correct Answer is Right**
The primary muscles responsible for scapular stabilization are the serratus anterior and trapezius. The serratus anterior muscle, specifically, plays a crucial role in upward rotation and medial rotation of the scapula. Paralysis of the long thoracic nerve, which innervates the serratus anterior muscle, leads to winging of the scapula. This is because the affected muscle is unable to contract and maintain its normal position, resulting in the scapula protruding laterally.
**Why Each Wrong Option is Incorrect**
* **Option A:** While the trapezius muscle also contributes to scapular stabilization, its paralysis primarily affects scapular elevation and downward rotation, rather than winging.
* **Option B:** The rhomboid muscles, primarily involved in scapular adduction and downward rotation, are not directly responsible for winging of the scapula.
* **Option C:** The latissimus dorsi muscle, primarily involved in arm adduction and extension, is not directly involved in scapular stabilization.
**Clinical Pearl / High-Yield Fact**
It's essential to note that winging of the scapula can also be caused by other factors, such as muscle imbalances, scoliosis, or congenital conditions. A thorough clinical examination and imaging studies are necessary to determine the underlying cause.
**Correct Answer:** D. Serratus anterior paralysis due to long thoracic nerve injury.