Blood supply of the olfactory nerve

Abstract

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 arachnoidal cistern above the olfactory nerve was verified. The arachnoid separates from the pial membrane and forms a bridge with the ventral part of 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 separated without damaging fronto-basal arachnoidial adhesions over several centimeters. Dissection of this region after intravascular injection 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 ventral extremity, the olfactory structures are therefore vascularised independently for several centimeters, from the lower face of the frontal lobe. The independent vascularisation of the olfactory nerve, the tenuous and easily detachable adhesions, and the actual presence of a true arachnoidal cistern all contribute to enabling surgical techniques which conserve olfactory function during anterior approaches.

Anatomy of the olfactory nerve: A comprehensive review with cadaveric dissection

“…They penetrate the cranial cavity, pass through the subarachnoid space, and immediately enter the olfactory bulbs through its ventral surface; there they synapse with the second‐order bulbar neurons (Walker, ; Levine and Marcillo, ; Giessel and Datta, ). The fila olfactoria emerge from the cribriform plate surrounded by a meningeal covering (arachnoid) (Favre et al, ). They also acquire a Schwann cell hedge approximately 0.5 mm beyond the olfactory bulb (Figueiredo et al, ).…”

“…Each olfactory nerve comprises the olfactory bulb and the olfactory tract and is actually an extension of the telencephalon, lacking Schwann cells (Fig. ) (Favre et al, ; Figueiredo et al, ). The olfactory bulb is the primary center of the system and serves as a relay station for all impulses that pass between the olfactory mucosa and upper olfactory centers (Walker, ; Shipley and Ennis, ; Levine and Marcillo, ).…”

“…It has an average volume of 125 mm 3 (Abolmaali et al, ). Its rostral edge is located approximately 22 mm from the frontomarginal sulcus and 26 mm from the anterior wall of the frontal sinus (Favre et al, ; Shipley and Ennis, ; Cömert et al, ). Its dorsal surface is in contact with the orbital and rectus gyri (the inferior surface of the frontal lobes), separated by a double layer of arachnoid membrane.…”

“…Two grooves called the “olfactory ethmoidal canals” are formed on each side of the crista galli, where the olfactory tract is housed. The cribriform plate gives rise to the roof of the nasal cavity, with which it communicates through 18–22 foramina on each side (Walker, ; Favre et al, ; Levine and Marcillo, ). Each perforation has a diameter <1 mm (Vasvári et al, ).…”

“…A). They are especially important in anterior and middle cranial fossa approaches, where some measure of olfactory injury is a common sequela (Favre et al, ; Cardali et al, ; Wang et al, ; Cömert et al, ).…”