## **Core Concept**
The volume of the orbit refers to the total space within the bony cavity that houses the eyeball and its associated muscles, vessels, and nerves. Understanding orbital volume is essential in ophthalmology and oculoplastic surgery, particularly in assessing and managing conditions like orbital tumors, fractures, and thyroid eye disease.

## **Why the Correct Answer is Right**
The correct volume of each orbit is approximately **30 mL**. This space is occupied by the eyeball itself (about 6.5 mL), extraocular muscles, nerves, vessels, and orbital fat. The orbital volume is crucial for maintaining the position and function of the eyeball and its associated structures.

## **Why Each Wrong Option is Incorrect**
- **Option A:** . This option is incorrect because it does not accurately represent the volume of the orbit.
- **Option B:** . This option is incorrect as it underestimates or overestimates the actual orbital volume.
- **Option D:** . This option is incorrect for similar reasons, not accurately reflecting the known volume of the human orbit.

## **Clinical Pearl / High-Yield Fact**
A key clinical point to remember is that changes in orbital volume, whether due to disease or trauma, can significantly affect the position of the eyeball and lead to clinical issues like proptosis (bulging of the eye) or enophthalmos (sunken appearance of the eye). Accurate assessment of orbital volume is therefore critical in the diagnosis and management of orbital disorders.

## **Correct Answer Line**
**Correct Answer: C. 30 mL.**