Anatomy of the sympathetic pathways in the carotid canal

The sympathetic fibers in the carotid canal were studied in 30 unfixed specimens from human cadavers. Thirty petrous internal carotid arteries were injected with red silicone rubber, and the course of the sympathetic fibers was examined after removal of the inferior and superior wall of the carotid canal. The internal carotid artery was removed completely, leaving the sympathetic fibers intact as much as possible. Instead of a plexus-like configuration of the sympathetic fibers around the petrous carotid artery in all specimens, an anterosuperior group and a posteroinferior group of sympathetic fibers were found together, and both closed on the inferior-anterior side of the terminal portion of the horizontal part of the carotid canal. Seventy-three percent of the anterosuperior group of sympathetic fibers consisted of one large bundle, and 27% consisted of two smaller bundles. The majority of the posteroinferior group of sympathetic fibers consisted only of one bundle (93%). In 60% of the specimens, the majority of sympathetic fibers in the carotid canal were found in the anterosuperior group, 20% were found in the posteroinferior group, and in 20%, there was an equal distribution. The formation of the petrous bone and the related structures of the skull base play an important role in the configuration of these groups of sympathetic fibers. This study shows that, in cases of operative intervention in the carotid canal, the anterosuperior group of sympathetic fibers may be encountered. Damage to this bundle may result in sympathicoparesis, as it often contains the most sympathetic fibers. This group of sympathetic fibers can be easily separated from the internal carotid artery.(ABSTRACT TRUNCATED AT 250 WORDS)