Questions about Ravenclaw

[Missy]

No: HPFGUIDX 68090

Can someone please tell me if I've missed something?  I don't seem to 
remember ever really being told about Ravenclaw.  I mean, I know 
they're the smart ones, and we've met quite a few from the house.  
But who is Ravenclaw's head of house?  Does Ravenclaw have a ghost?  
The books make such a deal about telling us that Snape is HoH for 
Slytherin, and the ghost is te Bloody Baron.  Professor Sprout and 
the Fat Friar for Hufflepuff.  But what about Ravenclaw?  Did I just 
overlook that sentence?

Thanks for any replies.

Missy