|The first question for you to address is why your manager feels that it is perfectly acceptable to take a corporate detour around your desk.|
In many cases, this type of behavior is an indicator of managerial incompetence. And, this is not just garden variety incompetence, but something that has far nicer packaging. Side-stepping managers often claim that they engage in this behavior in order to facilitate communication, take faster action on important problems, deal with the troops on a one-on-one basis, and even provide better support to the person being bypassed. Such motives sound lofty, but they are typically voiced by managers who have spent too much of their time reading management books that have more pictures than text.
At the same time, some managers bypass those who report to them if the bypassed individuals are failing to perform satisfactorily. If this is the case, your manager is by-passing you as a short-term solution, and you know what the long-term solution is.
Either way, your next step is to approach him and discuss the situation. Be sure to express yourself with words that have extra significance to him as a manager. Show him specific cases where his behavior actually undermined productivity, communication, coordination, or teamwork, and then emphasize the point that the department will operate more effectively, and he will save a good deal of his own time, if he will deal directly with you, rather than with your troops.
If he still insists on taking a detour around your desk, remember that you can take one around his.