Dissection‐Based Investigation of Variations in Major Gross Arterial Supply to the Trigeminal Ganglion

Abstract

Introduction & Objective The trigeminal nerve (CN V) primarily conveys afferent sensory input from the anterolateral aspect of the face and scalp via its three main branches – the ophthalmic nerve (CN V1), maxillary nerve (CN V2), and mandibular nerve (CN V3). The 20,000-35,000 primary afferent pseudounipolar neurons of CN V1-3 converge at the trigeminal ganglion (TG) where the neurons’ cell bodies are positioned. The TG is located in Meckel's cave (cavum trigeminale), an intracranial area along the sphenoid bone deep to the meningeal layer of dura mater just anterior to the petrous apex. Four main arterial sources have been reported to perfuse the TG – the accessory meningeal artery (AMA), a branch of middle meningeal artery (MMA), a branch of internal carotid artery (ICA), and a tentorial branch of the superior cerebellar artery (SCA). The reported rate for each potential arterial supply remains variable. The objective of this study was to identify the arterial source of the TG via human cadaveric dissection and quantify the rate of occurrence. Materials & Methods Right and left trigeminal ganglia were examined on 29 embalmed human cadavers. Origins of gross arterial supply traversing the deep surface of the ganglia were identified and recorded. Arterial supply was photographed (iPad Pro, Apple Inc.) and image color contrast was utilized to aide structure identification (Adobe Photoshop 20.0.9). TG tissue samples including the major vessel(s) were collected, paraffin embedded, sectioned at 5 μm, and stained with hematoxylin and eosin (H&E). Major arteries and normal microvasculature were verified with light microscopy (Zeiss Axioskop, Model 45 14 85) and photographed (AmScope Digital Camera, Model MU1003). Results Blood supply to 28 TG was inconclusive due to compromised vessel integrity from a previous course dissection. Of the remaining 30 TG, 56.6% were supplied by a branch of ICA, 16.7% by AMA, and 10.0% by a branch of MMA. No TG were supplied by the tentorial branch of SCA. Anastomotic connections were discovered between MMA/ICA and AMA/ICA for 10.0% and 6.7% of TG supply, respectively. Three of the five AMAs were noted to course through separate foramen in the basicranium instead of the foramen ovale as expected. H&E histological examination confirmed artery structure and verified expected arteriole and capillary microvasculature throughout the TG. Conclusions & Significance In both exclusive and anastomotic form, the majority of TG arterial supply originated from the ICA. Supply from the AMA, MMA, and SCA occurred less often but still merit significance. The results of this study reflect known rates of TG arterial supply. Gross imaging from this study may supply medical educators with new resources to facilitate TG dissection in gross dissection laboratories and may also provide diagnosticians and cardiovascular surgeons with better understanding of TG arterial supply variations that could benefit diagnosis, surgical approaches, and outcomes. In case of blockage, stenosis, or ligation, anastomotic supply would provide anatomical insurance to the TG but warrants further study.