A 39-year-old woman complains of an inability to reach the top of her head to brush her hair. History reveals that she had undergone a bilateral mastectomy procedure 2 months earlier. Physical examination demonstrates winging of both of her scapulae. Which nerves were most likely damaged during surgery?

**Core Concept**
The question tests the understanding of anatomical structures involved in shoulder movement and the potential complications of surgical procedures. The **long thoracic nerve** and **spinal accessory nerve** are crucial for scapular stability and movement.

**Why the Correct Answer is Right**
Damage to the **long thoracic nerve**, which innervates the **serratus anterior muscle**, would lead to winging of the scapula, as this muscle helps in stabilizing and rotating the scapula. The symptoms described, such as difficulty in raising the arm above the head and winging of the scapula, are consistent with damage to this nerve, particularly in the context of a recent surgical procedure like mastectomy, where this nerve can be at risk.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because, while the spinal accessory nerve is involved in shoulder movement, its primary role is in controlling the sternocleidomastoid and trapezius muscles, not directly related to the symptom of scapular winging as described.
**Option B:** Incorrect as it is not specified, but typically, damage to other nerves would not result in the specific symptom of bilateral scapular winging post-mastectomy.
**Option D:** Incorrect for similar reasons as Option A, focusing on a different aspect of shoulder function not directly related to the described symptoms.

**Clinical Pearl / High-Yield Fact**
It's crucial to recognize that surgical procedures, especially those involving the chest and axilla like mastectomies, can put nerves at risk. The **long thoracic nerve** is particularly vulnerable due to its long, superficial course along the thoracic wall, making it prone to injury during such surgeries.

**Correct Answer:** D. Long thoracic nerve.

✓ Correct Answer: C. Long thoracic