**Core Concept**
The **latissimus dorsi** muscle is a large, flat muscle on the back that extends, adducts, and medially rotates the shoulder joint. Its nerve supply is crucial for its function. The **thoracodorsal nerve** is responsible for innervating this muscle.

**Why the Correct Answer is Right**
The **thoracodorsal nerve**, which arises from the **posterior cord of the brachial plexus**, specifically supplies the **latissimus dorsi**. This nerve is essential for the muscle's actions, including extension, adduction, and medial rotation of the shoulder joint. The thoracodorsal nerve carries motor fibers that control the contraction of the latissimus dorsi.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it does not specifically relate to the latissimus dorsi's nerve supply.
**Option B:** Incorrect as it is not the nerve responsible for the latissimus dorsi.
**Option C:** Incorrect because, although related to the brachial plexus, it is not the specific nerve for the latissimus dorsi.

**Clinical Pearl / High-Yield Fact**
Remembering that the **thoracodorsal nerve** supplies the **latissimus dorsi** is crucial for understanding the muscle's function and potential deficits if the nerve is damaged. This knowledge is key in clinical examinations and surgical procedures.

**Correct Answer:** D. Thoracodorsal nerve