A case report of the anterior pericardial branch of the cervical ansa; a comparative anatomical and ontogenetical consideration.

The anterior pericardial nerve of the cervical ansa was encountered in the left side of a 52 year-old male body during routine student dissection. This nerve was found to issue from the cervical ansa in common with the branches to the sternohyoideus and sternothyreoideus muscles and to the inferior belly of the omohyoideus muscle, descending almost vertically on the front of the internal jugular vein. The anterior pericardial nerve passed downward across the anterior aspect of the fibrous pericardium. The remaining portion of the fibrous pericardium was found to be supplied by the pericardial branches of the main phrenic nerve. The occurrence of variations of nerve branches such as the anterior pericardial nerve seems to reflect noticeable or rather dramatic changes in the morphology of the hypobranchio-pleuro-pericardiaco-pectobrachial region of the human embryos exerted at the early stages of development. The morphological meaning of this nerve was discussed from the comparative anatomical point of view as well as from the ontogenetical point of view.