**Question:** Following surgical removal of a firm nodular cancer swelling in the right breast and exploration of the right axilla, on examination the patient was found to have a winged right scapula. Most likely this could have occurred due to injury to the:

A. T-Spine
B. Brachial Plexus
C. Subclavian Artery
D. Thoracic Wall

**Correct Answer:** B. Brachial Plexus

**Core Concept:**
The brachial plexus is a network of nerves that originate from the cervical spinal cord and innervate the upper limb muscles, skin, and sensory receptors. It consists of five roots: C5, C6, C7, C8, and T1. Injuries to any of these roots can lead to various clinical presentations depending on the affected nerves' function.

**Why the Correct Answer is Right:**
The winged scapula is a clinical sign resulting from injury to the brachial plexus roots C5, C6, C7, and T1. These roots contribute to the innervation of the muscles responsible for scapular stabilization and elevation, particularly the serratus anterior and rhomboid muscles. Injuries to these nerves can cause winged scapula due to paralysis of these muscles, leading to a winged appearance of the scapula on the chest wall.

**Why Each Wrong Option is Incorrect:**

A. T-Spine (Thoracic Spine): Injuries to the T-spine are less likely to cause winged scapula as the thoracic wall muscles are supplied by different nerves (costovertebral, costoclavicular, and supraclavicular nerves) and are not directly affected by brachial plexus injuries.

B. Thoracic Wall: Similar to T-spine, injuries to the thoracic wall are not directly related to brachial plexus injuries and would not cause the clinical presentation of a winged scapula.

C. Subclavian Artery: This option focuses on the blood vessel rather than the nerves that innervate the upper limb muscles, making it irrelevant to the winged scapula clinical sign.

D. Thoracic Wall: As mentioned before, injuries to the thoracic wall are not directly related to brachial plexus injuries and would not cause the clinical presentation of a winged scapula.

**Clinical Pearl:**

The winged scapula is a rare clinical sign, but it is important to recognize as it can indicate a significant brachial plexus injury, which requires further evaluation and management. In such cases, investigations like electromyography (EMG) and nerve conduction studies (NCS) can help confirm the diagnosis and guide management decisions.