Crankcase breather question

I just want some clarification, im running stock valve covers on my 340. On the drivers valve cover i have my pcv valve and the hose routed to the carb. On the pass side valve cover i have a edelbrock breather with a hose going to the air cleaner. Now in theory the pcv valve opens with a vacuum from the carb and by doing that then draws clean air through the pass side breather? I thought the pcv valve vented the crankcase and the other breather vented into the engine? How does the pcv valve allow air to flow through the other breather into the engine with air going into the carb at the same time?