Microsurgical anatomy and surgical exposure of the petrous segment of the internal carotid artery.
The petrous segment of the internal carotid artery has been exposed in the transpetrosal, subtemporal, infratemporal, transnasal, transmaxillary, transfacial, and a variety of transcranial approaches. The objective of the current study was to examine anatomic features of the petrous carotid and its branches as related to the variety of approaches currently being used for its exposure. Twenty middle fossae from adult cadaveric specimens were examined using magnification of x3 to x 40 after injection of the arteries and veins with colored silicone. The petrous carotid extends from the entrance into the carotid canal of the petrous part of the temporal bone to its termination at the level of the petrolingual ligament laterally and the lateral wall of the sphenoid sinus medially. The petrous carotid from caudal to rostral was divided into 5 segments: posterior vertical, posterior genu, horizontal, anterior genu, and anterior vertical. Fourteen (70%) of the 20 petrous carotids had branches. The branch that arose from the petrous carotid was either a vidian or periosteal artery or a common trunk that gave rise to both a vidian and 1 or more periosteal arteries. The most frequent branch was a periosteal artery. An understanding of the complex relationships of the petrous carotid provides the basis for surgically accessing any 1 or more of its 5 segments.