[Detection of the pericardial branch of the phrenic nerve by silver impregnation method]

The pericardial branch (R. pericardiacus) of the phrenic nerve (N. phrenicus) was examined in 14 pericardia of 8 male and 6 female adult Japanese cadavers. Specimens were impregnated with silver nitrate, and cleared and mounted in lactic acid. A pericardial branch was detected in the right side of one specimen (No. 273, male). This branch arose from the phrenic nerve at approximately the same level as the root of lung. The branch ran from the cervical plexus together with the proper phrenic nerve. The distribution of this branch to the pericardium could not be determined as the branch was accidentally cut near the above mentioned arising point during the anatomical practice. Even by this impregnation method, the pericardial branch of the phrenic nerve could not be detected in any other specimens.