Fetal topography of branches of the cervical and thoracic divisions of the vagus nerves

Abstract

The study of age and individual anatomical variability of vagus nerves and their branches in different age periods of human ontogenesis causes interest among both morphologists and doctors of different specialties.The aim of the study. To find out the topography of the cervical and thoracic divisions of the vagus nerves in human fetuses aged from 4th to 10th gestational months.Materials and methods. The research was conducted on 75 preparations of human fetuses ranging from 81.0 to375.0 mm in parietal-coccygeal length (PCL) using methods of macro-microscopic dissection and morphometry.Results. In human fetuses, the left vagus nerve is placed anteriorly to the left subclavian artery, then on the lateral surface of the Botallo’s arterial duct and the aortic arch. In the neck region, the superior cardiac branch departs from the left vagus nerve and goes to the anterior surface of the left common carotid artery.In the inferior part of the left common carotid artery, the superior cardiac branch gives off two branches: the middle one reaches the aortic arch wall, and the lateral one runs along the anterior surface of the left common carotid artery. The left recurrent laryngeal nerve departs from the left vagus nerve at the level of the inferior border of the aortic arch. The right vagus nerve passes from the right subclavian artery anteriorly and gives rise to the right recurrent laryngeal nerve, which continues inferiorly and posteriorly around the subclavian artery. The superior cardiac branch originates from the right vagus nerve at the level of the inferior border of the thyroid gland. The inferior cardiac branch departs inferiorly and medially from the right laryngeal nerve and is located on the right anterolateral surface of the trachea.Conclusions. During the fetal period of human ontogenesis, age and individual anatomical variations of the branches of the cervical and thoracic vagus nerves is observed, which is manifested by the variability of the structure, asymmetry of the topography of the recurrent laryngeal nerves, bronchial, esophageal and cardiac branches. The left recurrent laryngeal nerve departs from the left vagus nerve at the level of the inferior border of the aortic arch, the right recurrent laryngeal nerve departs from the right vagus nerve at the level of the right subclavian artery. The esophageal nervous plexus is formed by esophageal branches of the vagus nerves, which then forms mainly the posterior vagal trunk. The anterior vagal trunk is a direct continuation of the left vagus nerve branches. The innervation of the aortic arch involves the common cardiac trunk, which is formed by the superior cardiac branch and the superior cardiac nerve and also anastomoses both with vagus nerve and with recurrent laryngeal nerves.