"Pes anserinus" of the right phrenic nerve innervating the serous membrane of the liver: a case report (anatomical study).

During the preparations of cadavers for educational purposes we followed the course of the right phrenic nerve. On one of them and especially a female cadaver aged 72-year-old we found a branch arising from the thoracic portion of the right phrenic and passing through the two layers of the falciform ligament distributed to the upper surface of the serous layer of the liver in the form of "pes anserinus". As it is known, pain referred from the diaphragmatic peritoneum is classically felt in the shoulder tip but pain from thoracic surfaces supplied by the phrenic nerve is usually located there albeit vaguely. We believe that the above anatomical finding is the explanation of distinct radiating pain from the hepatic region to the right shoulder in some patients. The stimulations is carried through the phrenic nerve to the fourth cervical neurotome from were arise the supraclavicular nerves which are distributed to the shoulder region.