## **Core Concept**
The prostatic venous plexus plays a significant role in the drainage of the prostate gland. It is part of the pelvic venous system and is closely related to the prostate gland, facilitating its drainage.

## **Why the Correct Answer is Right**
The prostatic venous plexus is closely related to the **inferior vesical vein**, **internal iliac vein**, and **deep dorsal vein of the penis**. These veins are directly involved in the venous drainage of the prostate. The **inferior vesical vein** and **internal iliac vein** are key components of this drainage system. The **deep dorsal vein of the penis** also communicates with the prostatic venous plexus.

## **Why Each Wrong Option is Incorrect**
- **Option A:** The **inferior vesical vein** is indeed related to the prostatic venous plexus as it is one of the veins that drain into it.
- **Option B:** The **internal iliac vein** receives blood from the prostatic venous plexus, making it related.
- **Option C:** The **deep dorsal vein of the penis** communicates with the prostatic venous plexus, thus it is related.
- **Option D:** The **azygos vein** primarily deals with the drainage of the thoracic wall and is not directly related to the prostatic venous plexus.

## **Clinical Pearl / High-Yield Fact**
A key clinical point to remember is that the prostatic venous plexus is valveless, which can have implications for the spread of cancer cells. Also, the rich communication between the prostatic venous plexus and other pelvic veins is significant for understanding potential pathways for metastasis.

## **Correct Answer:** D. azygos vein