Fig. 1
From: Correlation between preoperative predictions and surgical findings in the parotid surgery for tumors
a The facial nerve line (FNL) is the line between the lateral surface of the posterior belly of m. digastricus and the lateral surface of the cortex of the ramus part of the mandible as seen at CT scan image. b The Utrecht line (UL) runs from the most dorsal point of the ipsilateral half of the first vertebra to the most dorsal point of the retromandibular vein as seen at CT scan image. c The Conn’s arc (CA) is a 8.5 mm radius semicircle with the center on the most distant point of the posterior edge of the ramus as seen at CT scan image. d The retromandibular vein line (RV) as seen at CT scan image