An anatomical investigation of the sympathetic and parasympathetic contributions to the cardiac plexus.
The cardiac plexus is “formed by mixed autonomic nerves” that are “described in terms of superficial and deep components, with the superficial located below the aortic arch and anterior to the right pulmonary artery, and the deep located anterior to the tracheal bifurcation (above the division of the pulmonary trunk) and posterior to the aortic arch” (Standring et al., 2008). This investigation aims to review and update the medial cardiac contributions of the cervical and thoracic sympathetic chains to the cardiac plexus and also the contributions from the vagus nerve and its counterpart, the recurrent laryngeal nerve. This study involved the macro and micro-dissection of 100 cadaveric sides of adult and fetal material. The number of ganglia in a cervical sympathetic chain varied from 2 to 5 in this study. This study confirms previous reports on the location of the two components of the cardiac plexus. The origin of the sympathetic contributions to the cardiac plexus in this study were either ganglionic, interganglionic or from both the ganglion and interganglionic chain of the respective ganglia. The superior cervical cardiac nerve had an incidence of 92% while the middle cervical cardiac nerve had an incidence of 65% in the specimens studied. This study also records a vertebral cardiac nerve that arose from the vertebral ganglion in 39% of the cases. The inferior cervical and cervicothoracic cardiac nerves had incidences of 21%, respectively. This investigation records the thoracic caudal limit of the sympathetic contributions to the cardiac plexus as the T₅ ganglion. The findings in this study indicate the importance of understanding the medial sympathetic contributions and their variations to the cardiac plexus as this may assist surgeons during minimal surgical procedures, sympathectomies, pericardiectomies and in the management of diseases like Reynaud’s Phenomenon and angina pectoris (Kalsey et al., 2000; Zhang et al., 2009).