**Core Concept**
The ischiorectal fossa, also known as the ischioanal fossa, is a **fat-filled space** located on either side of the **anal canal**. It is bounded by several key anatomical structures. Understanding the boundaries of this space is crucial for diagnosing and treating conditions such as **abscesses** and **fistulas**.

**Why the Correct Answer is Right**
The correct boundaries of the ischiorectal fossa include the **inferior fascia of the urogenital diaphragm** (perineal membrane) inferiorly, the **sacrospinous ligament** and **tuber ischii** laterally, the **levator ani muscle** medially, and the **gluteus maximus muscle** and **fascia** superiorly. These boundaries enclose a space that contains **loose connective tissue**, **blood vessels**, and **nerves**.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it does not accurately describe the lateral boundary.
**Option B:** Incorrect as it fails to account for the superior boundary.
**Option C:** Incorrect because the description of the medial boundary is inaccurate.

**Clinical Pearl / High-Yield Fact**
The ischiorectal fossa is a significant anatomical location for **surgical drainage of abscesses** and understanding its boundaries is essential for **perianal surgery**. Remembering the boundaries can help in identifying the extent of disease spread.

**Correct Answer:** D. The boundaries of the ischiorectal fossa are the inferior fascia of the urogenital diaphragm inferiorly, the sacrospinous ligament and tuber ischii laterally, the levator ani muscle medially, and the gluteus maximus muscle and fascia superiorly.