BLOOD-SUPPLY OF THE OLFACTORY NERVE - MENINGEAL RELATIONSHIPS AND SURGICAL RELEVANCE

The authors report the results of a series of dissections and anatomic sections of the fronto-basal region of the brain and of the anterior cranial fossa in human cadavers. The constant presence of an arachnoid al cistern above the olfactory nerve was verified. The arachnoid separ ates from the pial membrane and forms a bridge with the ventral part o f the olfactory bulb and tract, from the lateral edge of the olfactory sulcus to the medial edge of the gyrus rectus. The cistern is wide in its anterior portion, between the gyrus rectus and the olfactory bulb , and is reduced to a virtual slit in its posterior portion where the tract is lodged in the olfactory sulcus. The olfactory nerve can be se parated without damaging fronto-basal arachnoidial adhesions over seve ral centimeters. Dissection of this region after intravascular injecti on of colored media shows the constant presence of an artery destined to the olfactory bulb and tract. It originates either from the lateral surface of the anterior cerebral a. (segment A2), or from the medial fronto-basal a., and consistently provides terminal branches in front of the olfactory trigone in the medial olfactory sulcus. At their vent ral extremity, the olfactory structures are therefore vascularised ind ependently for several centimeters, from the lower face of the frontal lobe. The independent vascularisation of the olfactory nerve, the ten uous and easily detachable adhesions, and the actual presence of a tru e arachnoidal cistern all contribute to enabling surgical techniques w hich conserve olfactory function during anterior approaches.