Sinus least involved in children is:
**Core Concept**
The question is testing the knowledge of the common sinus involved in pediatric population and the ones that are less common or rarely affected. Sinusitis is a common condition in children, and understanding the anatomy and epidemiology of sinus involvement is crucial for diagnosis and management.
**Why the Correct Answer is Right**
The maxillary sinus is the most commonly involved sinus in children, followed by the ethmoid and frontal sinuses. The sphenoid sinus, being the least developed and smallest of the paranasal sinuses, is less likely to be involved in children. This is due to its smaller size and less developed drainage pathway, making it less susceptible to infection and inflammation.
**Why Each Wrong Option is Incorrect**
**Option A:** Maxillary sinus - This is the most commonly involved sinus in children, making it an incorrect answer.
**Option B:** Ethmoid sinus - While ethmoid sinusitis is common in children, it is not the least involved sinus.
**Option C:** Frontal sinus - Frontal sinusitis is also common in children, especially in older children and adolescents, making it an incorrect answer.
**Clinical Pearl / High-Yield Fact**
The sphenoid sinus is not typically visible on a plain radiograph until the age of 6-7 years, making it a less likely candidate for sinusitis in younger children.
**Correct Answer:** D. Sphenoid sinus