Review Article

Microsurgical Anatomy of the Orbit: The Rule of Seven

Figure 5

(a)–(d) Dissections of the left cranial base and orbit. The ophthalmic artery also sends dural branches and may thus become involved in the supply of dural based lesions. In this role, two sets of branches can be recognized: the lateral and medial branches of the ophthalmic system. (a) The lateral branches include the lacrimal, recurrent meningeal, and sphenoidal branches which establish connections with external carotid branches (middle and accessory meningeal artery) along the dura over the greater sphenoid wing. (b) The medial division includes the anterior and posterior ethmoidal branches that reach the anterior fossa and frontal pole after coursing through the ethmoidal canals. The continuation of the anterior ethmoidal artery along the falx is named falcine artery and is involved in the supply of the falx and dura over the frontal pole. (c) The main orbital drainage pathway is the superior ophthalmic vein. This vein forms by gathering of several tributaries on the medial orbital corner. (d) From the medial orbital corner, the superior ophthalmic vein crosses above the optic nerve, collecting, on occasions, the smaller inferior ophthalmic vein. In this specimen, the superior ophthalmic vein passes outside the annulus to end up into the cavernous sinus.
468727.fig.005a
(a)
468727.fig.005b
(b)
468727.fig.005c
(c)
468727.fig.005d
(d)