The adult maxillary air sinus always lies directly above the following teeth:
**Core Concept**
The maxillary air sinus, also known as the **antrum of Highmore**, is a large pyramid-shaped cavity in the maxillary bone. It is closely related to the roots of the upper teeth. The **maxillary sinus** is the largest of the paranasal sinuses and plays a crucial role in the drainage and aeration of the nasal cavity.
**Why the Correct Answer is Right**
The correct answer is related to the anatomical position of the maxillary sinus in relation to the upper teeth. The maxillary sinus is located above the **premolars** and **molars**, extending from the **lateral wall of the nasal cavity** to the **zygomatic process** of the maxilla.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the sinus does not lie above the incisors.
**Option B:** This option is incorrect because the sinus does not lie above the canines.
**Option C:** This option might seem plausible but is not entirely accurate in describing the relationship.
**Option D:** This is the correct relationship, with the maxillary sinus lying above the **premolars and molars**.
**Clinical Pearl / High-Yield Fact**
It is crucial to remember that the maxillary sinus floor is closely related to the **apices of the upper molars**, which can be relevant in dental procedures to avoid sinus penetration.
**Correct Answer:** D. premolars and molars.