"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.

A variation in the formation of the brachial plexus characterized by the absence of C8 and T1 fibers in the trunk of the median nerve.

During the dissection of a male cadaver, 80 years old, it was observed that the right median nerve was formed by the junction of two nerve trunks, one originating from the upper and the other from the middle trunk of the brachial plexus (C5, C6 and C7 neurotomes), with subsequent absence of formation of the lateral cord of the plexus. The place of junction lay at 52 mm from the exit of the C6 and C7 nerves from the spine. The musculocutaneous nerve arised from the median nerve after a 38 mm course of the latter. Despite the absence of nerve fibers from the C8 and T1 neurotomes in the trunk of the median nerve, the distribution of its branches was normal.