Vascular Anatomy of the Anteriorly Based Frontal Pericranial Flap. A, Left supraorbital region. The galea-frontalis muscle has been separated from the pericranium down to the level of the orbital rim. The supraorbital and supratrochlear arteries divide into superficial branch and deep branches at or below the level of orbital rim. Note the tiny anastomoses between the superficial branches and deep branches. The transverse supraorbital vein, into which the pericranial veins empty, courses along the lower edge of the orbital rim. The deep branch of supraorbital nerve runs superiorly on the pericranium, usually accompanying the deep branches of the supraorbital artery. B, Right supraorbital region. The pericranium was separated from the bone and reflected forward to expose its deep side. The transverse supraorbital vein coursed superficially on the pericranium 11 mm above the supraorbital rim. C, Same supraorbital region shown in B. The pericranium has been reflected back against the bone to expose the superficial side. The transverse supraorbital vein was preserved during separation of the galea-frontalis layer from the pericranial layer. The pericranial veins did not fill with colored latex in this case. D, Right supraorbital region with a supraorbital foramen. The pericranium has been removed. The deep branch and small part of superficial branch of the supraorbital nerve and a tiny accompanying deep artery pass through the foramen. The main trunk of the supraorbital artery passes around the orbital rim and not through the supraorbital foramen. E, Left supraorbital region. The pericranium has been separated from galea-frontalis layer down to the level the supraorbital rim. A deep (pericranial) branch (white arrow) arises in the galea-frontalis layer 15 mm above the supraorbital rim and crosses to the pericranium. F, Same supraorbital region in E. Separating the pericranium from galea-frontalis layer down to the orbital rim results in transection of the deep branch (white arrow) that arises in the superficial layer above the orbital rim. G, Right supraorbital region. Separation of the pericranium from the galea-frontalis layer down to the level of the orbital rim exposes a deep branch (white arrow) that separates from the superficial branch of the supraorbital artery 8 mm above the orbital rim. H, Right supraorbital region. A deep branch (white arrow) separates from the superficial branch of the supraorbital artery 8 mm above the orbital rim. (Images courtesy of AL Rhoton, Jr.)