The Role of Sympathetic Trunks in the Innervation of the Posterior Mediastinum Blood Vessels in Human Fetuses

Abstract

The purpose of the study was to establish patterns of variation of the branches of the right and left sympathetic trunks in the thoracic aorta azygos and hemiazygos veins during the fetal period of human ontogenesis. Materials and methods. An anatomical study was performed on 47 human fetuses using macromicroscopic preparation of neurovascular branches under the control of binocular magnifier, vascular injection, application contrasting of prepared vessels and nerves, making 3D reconstruction models of the posterior mediastinum structures and morphometry. Results. The anatomical variability of nodes and branches of the thoracic right and left sympathetic trunks involved in the innervation of the thoracic aorta, azygos and hemiazygos veins has been established in the human fetuses of different age groups. The segmental-metameric distribution of the visceral branches of the thoracic sympathetic trunk was revealed, as well as the preservation of the segmental sympathetic innervation of the thoracic aorta, azygos and hemiazygos veins both on the left and on the right. Despite the significant progress in the study of morphological features of innervation of posterior mediastinum organs and structures, the active development of fetal surgery in recent years raises a number of questions related to the sources of sympathetic innervation of the thoracic aorta, azygos and hemiazygos veins. Conclusion. The sources of innervation of the thoracic aorta, azygos and hemiazygos veins in human fetuses are: thoracic nodes and internodal branches of the right and left sympathetic trunks; large visceral nerves; branches of the esophageal, pulmonary and cardiac plexuses; vagosympathetic trunks; collateral trunk. The number of branches to the thoracic aorta from the left sympathetic trunk is 4-16, and from the right sympathetic trunk – 3-14. The largest number of branches that enter the wall of the thoracic aorta, from the left sympathetic trunk skeletotopically determined at the level of III-VI thoracic segments, and from the right sympathetic trunk – at the level of IV-VI thoracic segments. Different skeletotopic levels of the branches of the right and left large visceral nerves are involved in the innervation of the thoracic aorta – from V to X thoracic segments. It is noted that the right and left sympathetic trunks are almost equally involved in the innervation of the azygos and hemiazygos veins. The number of sympathetic branches to the azygos vein ranges from 4 to 7, and the number of sympathetic branches to the hemiazygos vein is usually 2-4