Anastomotic patterns of the facial parotid plexus (PP): A human cadaver study

Details of the human facial parotid plexus (PP) are not readily accessible during ordinary anatomical teaching because of insufficient time and difficulties encountered in the preparation. For parotid and facial nerve surgery however, precise knowledge of PP is of crucial importance. The aim of this study was therefore to provide more details of PP in anatomic specimens. Following anatomical dissection, its location, syntopy and morphology were analyzed in 158 cervico-facial halves of 95 cadavers. The facial nerve (FN) divides into a larger temporo-facial and a smaller cervico-facial trunk. Both trunks branch, form PP, and thus form connections along six distinctive anastomotic types. These anastomoses may explain why accidental or essential severance of a supposed terminal facial branch fails to result in the expected muscle weakness. However, whereas earlier anatomical and clinical studies report connections between both trunks in 67-90% of the cases, our data indicate the presence of anastomoses only in 44%. One reason for this difference may be found in our microscope-assisted dissection in infratemporal regions from which the parotid gland has been removed. Thereby we tracked both FN-trunks in both directions - distally and proximally - and determined the exact origin of all terminal FN branches. This lower rate of occurrence of connections between both trunks reduces the chances of luckily preserved muscle innervation and enhances the risk of facial palsy after transection of a terminal branch. Accordingly, precise anatomical knowledge on PP should be renewed and transection of facial nerve branches avoided.