This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
Sphenopalatine foramen opens into which wall of pterygopalatine fossa? 
Select and explain. 
A. Lateral wall, B. Medial wall, C. Superior wall, D. Inferior wall
B: Medial wall
Answer: B: Medial wall 
Explanation: Sphenopalatine foramen opens into the medial wall of pterygopalatine fossa. It opens into the nasal cavity and transmits sphenopalatine aery and nasopalatine nerve.Pterygopalatine fossa boundaries:Anterior wall: posterior surface of maxilla posterior wall of maxillary sinus.Posterior wall: formed by pterygoid process and greater wing of sphenoid. Openings in it are foramen rotundum, pterygoid canal and pterygopalatine canal.Medial wall: formed by perpendicular plate of the palatine.Lateral wall is open.Roof: greater wing and body of the sphenoid. Opening is inferior orbital fissure.Floor: fusion of the maxilla and pterygoid process of the sphenoid. Opening is greater palatine foramen.