An abnormal course of the left phrenic nerve: A case report of anatomical variation

Background: The phrenic nerve is an important efferent nerve of the cervical plexus, and its anatomical structural variations have clinical reference value. Methods Adult neck specimens were obtained through the Morphology Experimental Center and dissected under a surgical microscope. Results The phrenic nerve trunk courses along the fascia, situated above the anterior and middle scalene muscles. It then courses anteriorly and inferiorly before bifurcating into two branches - internal and external branch - approximately 1.5 mm later. Inside the thoracic cavity, the internal and lateral branches reunite to form the phrenic nerve. Conclusions This report on the anatomical variations of the phrenic nerve has certain clinical value