## **Core Concept**
The deep perineal pouch, also known as the deep perineal space, is a fascial space in the perineum that contains vital structures. It is located between the superior and inferior layers of the urogenital diaphragm. Understanding its contents is crucial for diagnosing and managing pelvic injuries and conditions.

## **Why the Correct Answer is Right**
The deep perineal pouch contains several key structures, including the **internal urethral sphincter**, **transverse perineal muscles**, **bulbourethral glands** (also known as Cowper's glands), and the **dorsal neurovascular bundle** of the penis or clitoris. The **external urethral sphincter** is actually considered part of the superficial perineal pouch.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is not provided, but typically, structures like the internal urethral sphincter, bulbourethral glands, and the dorsal neurovascular bundle are included in the deep perineal pouch.
- **Option B:** Similarly, this option is not specified, but if it refers to a structure within the deep perineal pouch, it would be correct.
- **Option C:** Without specifics, we assume it could relate to contents of the deep perineal pouch.
- **Option D: External urethral sphincter** - This is the correct answer because the **external urethral sphincter** is actually located in the superficial perineal pouch, not the deep perineal pouch.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that the **deep perineal pouch** contains structures critical for urethral support and continence, such as the internal urethral sphincter (in males) and the **bulbourethral glands**. Damage to these structures can lead to urinary incontinence or difficulties with ejaculation.

## **Correct Answer:** D. External urethral sphincter.