**Core Concept**
The hiatus semilunaris is a crescent-shaped opening in the lateral wall of the nasal cavity, specifically within the middle meatus. It serves as a passage for the semilunar hiatus, allowing the drainage of mucus from the anterior ethmoidal air cells and the frontal sinus into the nasal cavity.

**Why the Correct Answer is Right**
The hiatus semilunaris is located in the middle meatus due to its embryological origin. During fetal development, the nasal cavity and paranasal sinuses form from a common precursor, the nasal placode. The middle meatus is a result of the downward growth of the nasal septum, which creates a groove that eventually forms the hiatus semilunaris. This anatomical structure is crucial for the drainage of the anterior ethmoidal air cells and the frontal sinus. The semilunar hiatus is lined by ciliated pseudostratified columnar epithelium, which helps to clear mucus from the nasal cavity.

**Why Each Wrong Option is Incorrect**
**Option A:** The superior meatus is located above the middle meatus and is not associated with the hiatus semilunaris.
**Option C:** The inferior meatus is located below the inferior turbinate and does not contain the hiatus semilunaris.
**Option D:** The sphenoethmoidal recess is a small opening located above the superior concha and is not related to the hiatus semilunaris.

**Clinical Pearl / High-Yield Fact**
The hiatus semilunaris is an important landmark in endoscopic sinus surgery, as it serves as a reference point for the location of the anterior ethmoidal air cells and the frontal sinus.

**✓ Correct Answer: B. Middle meatus**