One-Piece OZ Craniotomy. G, Anterior view of the left orbit in a cadaveric dissection. The periorbita has been retracted inferiorly to expose the orbital surface of the keyhole as seen between the periorbita and the osseous orbital roof. The inset shows the direction of the cuts extending into the keyhole. H, The fourth cut of the one-piece OZ craniotomy (Cut 4) has been extended intraorbital along the orbital roof from the orbital compartment of the key-hole and through the supraorbital rim. The position of Cut 4 determines how much of the roof is elevated with the bone flap during the one-piece OZ craniotomy. I, A frontotemporal scalp flap has been reflected and the periorbita has been separated from the orbital roof and lateral wall. The one-piece OZ craniotomy has been completed using the six cuts described in A and the bone flap is being elevated. The frontal dura has been elevated from the remaining orbital roof and lateral wall. J, Right one-piece orbitozygomatic bone flap. Note that only a small part of the roof and lateral wall of the orbit has been elevated. (Images courtesy of AL Rhoton, Jr.)