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THORAX-ABDOMINAL VAGUS NERVES in FETUSES Susana N

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THORAX-ABDOMINAL VAGUS NERVES in FETUSES Susana N Vagus nerves in fetuses Rev Arg de Anat Clin; 2015, 7 (3): 145-152 ___________________________________________________________________________________________ Original Communication THORAX-ABDOMINAL VAGUS NERVES IN FETUSES Susana N. Biasutto, Gabriel A. F. Ceccón, Matías de la Rosa, Paulina A. Bortolín Chair and Institute of Normal Anatomy, Faculty of Medical Sciences, National University of Cordoba, Cordoba, Argentina RESUMEN morbidity. Thirty fetuses between 12 to 23 weeks of gestation, mainly male (87%), were dissected from the Los nervios vagos han sido exhaustivamente lower neck to the cardias, identifying vagus nerve estudiados en los adultos pero no en los niños, y trunks and braches. Vagus nerves were described at mayormente en el trayecto intracraneal, más que en la the entrance in the thorax in relation with the carotid periferia. El objetivo de este estudio fue proveer arteries, in their position at the upper third of the información más específica sobre los nervios vagos esophagus associated with the origin of cardiac and toraco-abdominales, describirlos en fetos y asociarlos pulmonary branches, in the lower third of the con la rotación gástrica, de modo que pueda ser esophagus with many variations in their distribution, at aplicada a procedimientos clínicos, reduciendo la the diaphragmatic level in the esophageal hiatus and, morbilidad. Se disecaron treinta fetos entre 12 y 23 finally, in relation with the gastric position. The semanas de gestación, mayormente varones (87%), discussion involved descriptions made by different desde la parte inferior del cuello hasta el cardias, authors including some recent studies providing identificando los troncos y ramas de los nervios vagos. electrophysiological results and considerations on Los nervios fueron descriptos en su ingreso en el tórax clinical aspects, mainly represented by surgical en relación con las arterias carótidas, en su posición procedures and their morbidity associated, both to en el tercio superior del esófago asociados con el vagus nerve injury. origen de las ramas cardíacas y pulmonares, en el tercio inferior del esófago con muchas variaciones en Key words: Vagus nerves, esophageal innervation, su distribución, a nivel diafragmático en el hiato thoracic esophagus, anatomy, surgical anatomy esofágico y, finalmente, en relación con la posición gástrica. La discusión involucró descripciones hechas por diferentes autores incluyendo algunos estudios recientes que proporcionan resultados electrofisio- INTRODUCTION lógicos y consideraciones de aspectos clínicos, principalmente representados por procedimientos quirúrgicos y su morbilidad, ambos asociados con la Vagus nerves have been extensively studied in lesión de los nervios vagos. adults but not in fetuses, and mostly in the intracranial pathway than the peripheral one. Palabras clave: Nervios vago, inervación del esófago, esófago torácico, anatomía, anatomía quirúrgica. (Testut and Latarjet, 1973; Williams and Warwick, 1992; Sadler and Langman, 2007; Takassi et al, 2013). ABSTRACT _________________________________________________ Vagus nerves have been extensively studied in adults but not in fetuses, and mostly in the intracranial * Correspondencia a: Prof. Dr. Susana N. Biasutto. 25 de pathway than the peripheral one. The objective of this Mayo 1076. Bº General Paz. Córdoba. Argentina. study was to provide more specific information on the [email protected] thorax-abdominal vagus nerves, to describe them in fetuses and to associate them with the gastric rotation, Received: 30 October, 2015. Revised: 14 November, 2015. so it could be applied to clinical procedures, reducing Accepted: 16 November, 2015. 145 Todos los derechos reservados. Reg. Nº: 5237680 www.anatclinar.com.ar Vagus nerves in fetuses Rev Arg de Anat Clin; 2015, 7 (3): 145-152 ___________________________________________________________________________________________ Even if we could assume these nerves should not Sadler and Langman, 2007). Based on this significantly vary from fetal to adult life, concept, vagus nerves may vary their location in knowledge of anatomical details may be partic- the lower third of the thorax and the abdominal ularly important at the moment of certain clinical part of the esophagus, following the stomach procedures (mainly surgical ones) in children. changes. Combination of data of adult and fetal specimens The objective of this study was to provide more may provide comprehensive information at the specific information on the thoraco-abdominal time of clinical decisions. vagus nerves, to describe them in fetuses and In the literature, vagus nerves final position at associate them with the gastric rotation, so it diaphragmatic level has been associated to the could be applied to clinical procedures, reducing gastric rotation occurred between the 4th and 7th morbidity. week of gestation (Prives, 1985; Zuidema, 1999; Figure 1.- Dissection of the neck and upper thorax. Vagus nerves at the entrance in the thorax. RVN-Right vagus nerve. LVN-Left vagus nerve. RCCA-Right common carotid artery. LCCA-Left common carotid artery. RJV-Right internal jugular vein. LJV-Left internal jugular vein. AA-Aortic arch. RSA-Right subclavia artery. LSA-Left subclavia artery. 146 Todos los derechos reservados. Reg. Nº: 5237680 www.anatclinar.com.ar Vagus nerves in fetuses Rev Arg de Anat Clin; 2015, 7 (3): 145-152 ___________________________________________________________________________________________ MATERIAL AND METHODS RESULTS Thirty fetuses from the University Hospital of Vagus nerves entered the thorax laterally to the Maternity (provided after approval of the Hospital common carotid arteries and included in the Ethical Committee), between 12 to 23 weeks of same sheath. Internal jugular veins were laterally gestation (mean age: 17.31 weeks), were but significantly separated from each side nerve dissected from the lower neck to the cardias. Age and artery in younger fetuses (Fig. 1). At this was determined by crown-pump length. Most of level nerve thickness compared to the artery was them (87%) were male and only four were bigger than in adults; the diameter of the nerves female. Instead we tried to keep the relations with was approximately half of the diameter of the the neighbouring anatomical structures as far as arteries. They introduced into the mediastinum by possible, cardiac branches always and pulm- passing in front of the subclavia artery and the onary branches sometimes had to be cut to allow arch of Aorta, and giving the inferior laryngeal the nerve dissection around the esophagus under nerve (recurrent). In one case, the right subclavia the level of the hilum of lung. The trachea was artery came from the left pulmonary artery and it partially removed in its lower half and the heart was the only opportunity the right vagus nerve was displaced laterally, usually to the right side. passed behind the aberrant vessel (Fig. 2). The The diaphragm was opened to allow to complete left nerve is flexuous and longer than the right the dissection and to let us the observation of the one in this upper region (Fig.1). stomach position. Trunk and braches of the Pulmonary and cardiac branches had their origin vagus nerves were carefully dissected to identify a little over the hiium level. In this study we only their location and relations among themselves found one right pulmonary branch given by the and to the esophagus and cardias. right nerve, while the left nerve provided the cardiac and left pulmornary branches (Fig. 3). Figure 2.- Relation between the aberrant right subclavia artery and the right vagus nerve. RASA-Right aberrant subclavia artery. RVN-Right vagus nerve. RCA- Right common carotid artery. LVN-Left vagus nerve. 147 Todos los derechos reservados. Reg. Nº: 5237680 www.anatclinar.com.ar Vagus nerves in fetuses Rev Arg de Anat Clin; 2015, 7 (3): 145-152 ___________________________________________________________________________________________ Figure 3.- Cardiac and pulmonar branches of the left vagus nerve. E-Esophagus. T-Trachea. H- Heart, LL-Left lung, LVN- Left vagus nerve. CB-Cardiac brances. LPB-Left pulmonary branch. Cardiac branches found in this study were it was lateral, in 10% it was coming from the usually one, except 2 cases where we found two lateral to the frontal position, in 10% it was lateral branches, both coming from the left vagus nerve. passing to posterior and in 10% of the cases it Left pulmonary branches were 2 in only three was lateral going backward. In 2 specimens there cases and only 1 in the rest. Pulmonar braches were 2 right branches: one (3.33%) with anterior entered the hilum of the lung anteriorly respect to and posterior branches and another (3.33%) with the bronchi. one branch coming from anterior to lateral and According to our observations, the distribution the other passing from posterior to lateral side of and position of vagus nerves under the hilum the esophagus. (Fig. 4) level is variable and complex. They are right in The left vagus nerve was lateral moving to the contact with the esophagus but their position is anterior side of the oesophagus in 46.66% of the not constant. In 26.66% of the cases the right total cases, in 23.33% it was anterior all along the nerve was posterior to the esophagus, in 16.66% infrahilliar section, in 20% it was lateral and in it was anterior, in 13.33% it was passing from 10% it was anterior passing to the posterior side. anterior to posterior next to the hiatus, in 16.66% (Fig. 4) 148 Todos los derechos reservados. Reg. Nº: 5237680 www.anatclinar.com.ar
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