**Core Concept:**
The mid-axillary line is a line that runs along the lateral border of the rib cage, passing through the intercostal spaces. When performing a pleural tap (also known as a thoracentesis), the physician needs to identify the appropriate intercostal space and pierce the parietal pleura to access the pleural cavity.

**Why the Correct Answer is Right:**
When performing a thoracentesis, the physician should pierce the skin, subcutaneous tissue, and intercostal muscles in order to reach the pleural space. The correct answer is **D**, which states that the **serratus anterior muscle** is NOT pierced.

The serratus anterior muscle is a long, fan-shaped muscle that extends from the seventh cervical vertebra to the costal cartilages of ribs II-V. It is involved in elevating the rib cage and protecting the intercostal nerves, thus preventing them from being damaged during the procedure.

**Why Each Wrong Option is Incorrect:**
Option A refers to the **pectoralis major muscle**, which is not involved in protecting the intercostal nerves and therefore should not be pierced during the procedure.

Option B refers to the **pectoralis minor muscle**, which is also not involved in protecting the intercostal nerves and should not be pierced.

Option C refers to the **pectoralis minor muscle**, which is not the primary muscle protecting the intercostal nerves and should not be pierced.

**Why the Correct Answer is Right:**
The correct answer, **D**, explains that the serratus anterior muscle should not be pierced as it plays a crucial role in protecting the intercostal nerves during the procedure. Piercing this muscle could result in damaging the intercostal nerves, causing pain or neurological complications post-procedure.

**Clinical Pearl:**
When performing a thoracentesis, the physician should identify the correct intercostal space and pierce the skin and subcutaneous tissue, but not the underlying muscles, specifically the serratus anterior muscle, to avoid complications and ensure a successful procedure.