This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Thinnest bone is a pa of which bone 
Select and explain. 
A. Frontal, B. Ethmoid, C. Sphenoid, D. Temporal
B: Ethmoid
Answer: B: Ethmoid 
Explanation: The lamina papyracea (or orbital lamina) is a smooth, oblong bone plate which forms the lateral surface of the labyrinth of the ethmoid bone in the skull. The plate covers in the middle and posterior ethmoidal cells and forms a large pa of the medial wall of the orbit. The ethmoid bone is an anterior cranial bone located between the eyes.] It contributes to the medial wall of the orbit, the nasal cavity, and the nasal septum. The ethmoid has three pas: cribriform plate, ethmoidal labyrinth, and perpendicular plate.