The autonomic nervous system of the human heart with special reference to its origin, course, and peripheral distribution

Abstract

A submacroscopic anatomical investigation of the entire autonomic cardiac nervous system, from origin to peripheral distribution, was performed by examining 36 sides of 18 adult human cadavers under a stereomicroscope. The following new results and points of discussion were obtained: (1) The superior cervical, the middle cervical, the vertebral, and the cervicothoracic (stellate) ganglia, composed of the inferior cervical and 1st thoracic ganglia, were mostly consistent among the specimens. (2) The superior, middle, and inferior cardiac nerves innervated the heart by simply following the descent of the great arteries. In contrast, the thoracic cardiac nerve in the posterior mediastinum followed a complex course because of the long distance to the middle mediastinum. (3) The actual course of the right thoracic cardiac nerve differed from that of the previous descriptions in that it ascended obliquely or ran transversely to the vertebrae, regardless of the intercostal vessels. Regarding the right thoracic cardiac nerve, two descending courses were observed: the descent of the right thoracic cardiac nerve via the azygos vein and right venous porta, and the descent of the recurrent right thoracic cardiac nerve via the aorta. (4) The cranial cardiac nerve and branch tended to distribute into the heart medially, and the caudal cardiac nerve and branch tended to distribute into the heart laterally. (5) The mixing positions (cardiac plexus) of the sympathetic cardiac nerve and the vagal cardiac branch, as well as the definitive morphology of brachial arteries with the recurrent laryngeal nerves, tended to differ on both sides. These new and detailed anatomical descriptions of the human autonomic cardiac nervous system may provide important clues regarding the morphogenesis of autonomic cardiac nerves in addition to contributing to the improvement of cardiac surgery.