Determine the bony walls of the Maxillary sinus:

The Anterior wall of the sinus has thin compact bone above the apex of the canine teeth which may extend to the lateral piriform of the nose. The infraorbital neurovascular bundle lies directly in the bone and within the sinus mucosa which should be not be injured during surgery. The Superior wall represents the thin orbital floor. The infraorbital neurovascular bundle run in the infraorbital  canaltraversing this wall. Manipulation of this wall is not indicated during the sinus graft procedure.