This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anatomy, Development and clinical examination, Subject name: Ophthalmology
The optic canal is a pa of 
Select and explain. 
A. Lesser wing of sphenoid, B. Greater wing of sphenoid, C. Ethmoid, D. Pterygium
A: Lesser wing of sphenoid
Answer: A: Lesser wing of sphenoid 
Explanation: *The optic nerve leaves the orbit is the optic canal to enter the cranial vault *The optic canal is the most posterior landmark of the orbit. It measures 10mm in length *The thin piece of bone separating the optic canal from the superior orbital fissure is the optic strut *The optic strut and optic canal are a pa of the lesser wing of the sphenoid bone Fig - Foramina and bony landmarks of the sphenoid wings and pterygoid process. Reference : AK Khurana Comprehensive Ophthalmology, 6th edition, pg no. 310