Ultrasound evaluation of vagus nerve cross-sectional area in a community-dwelling elderly Japanese cohort.

OBJECTIVES: Although the vagus nerve (VN) is easily observed by ultrasonography, few studies have evaluated the cross-sectional area (CSA) of the VN in healthy older individuals from East Asia. In this study, we aimed to report reference values for the CSA of the VN in community-dwelling elderly Japanese individuals and to identify any associated medical history and/or lifestyle factors. METHODS: The present study included 336 participants aged ≥ 70 years from a prospective cohort study conducted in Yahaba, Japan from October 2021 to February 2022. The CSA of the VN was measured bilaterally at the level of the thyroid gland by ultrasonography. Simple linear regression analysis and generalized estimating equation were conducted to identify the associations between clinical and background factors and the CSA of the VN. RESULTS: In our cohort, the median CSA of the VN was 1.3 mm2 (interquartile range [IQR] 1.1-1.6) on the right side and 1.2 mm2 (IQR 1.0-1.4) on the left side. Generalized estimating equation showed that history of head injury (ß = 0.19, p < .01), current smoking habit (ß = -0.09, p = .03), and BMI (ß = 0.02, p < .01) were independently associated with the CSA of the VN. CONCLUSION: We have reported reference VN CSA values for community-dwelling elderly Japanese individuals. In addition, we showed that the CSA of the VN was positively associated with a history of head injury and BMI and inversely associated with current smoking habit.

Reducing VNS stimulation parameters: Is it safe?

Introduction Vagal nerve stimulation (VNS) is an adjuvant therapy used in the treatment of patients with refractory epilepsy who are not candidates for resective surgery or who have limited results after surgical procedures. Currently, there is enough evidence to support its use in patients with various types of epilepsy. Therefore, the present study was conducted to explore the possibility of optimizing therapy by reducing the consumption of the system's battery. Methods The prospective and double-blind analysis consisted in the evaluation of 6 patients submitted to VNS implantation for 3 months, followed by adjustment of the stimulation settings and continuity of follow-up for another month. The standard protocol was replaced by another with a frequency value of 20 Hz instead of 30 Hz to increase battery life. The safety of this procedure was evaluated through the assessment of two main variables: seizures and side effects. Results The stimulation at 20 Hz showed 68% reduction in the incidence of seizures (p»0.054) as well as low incidence of side effects. Conclusion The present study suggests that the reduction of the stimulation frequency from 30 to 20 Hz is a safe procedure, and it does not compromise the effectiveness of therapy.

Anatomical variation and distribution of the vagus nerve in the esophageal hiatus: a cross-sectional study of post-mortem cases in Uganda.

PURPOSE: Vagus nerve injuries during gastroesophageal surgery may cause significant symptoms due to loss of vagal anti-inflammatory and neuromodulator function. Many previous studies have shown high anatomical variability of the vagus nerve at the esophageal hiatus, but information on its variability in Uganda specifically and Africa in general is scanty. This study provides a reliable and detailed description of the anatomical variation and distribution of the vagus nerve in the esophageal hiatus region of post-mortem cases in Uganda. METHODS: This was an analytical cross-sectional survey of 67 unclaimed post-mortem cases. Data collection used a pretested data collection form. Data were entered into Epi-Info version 6.0 data base then exported into STATA software 13.0 for analysis. RESULTS: The pattern of the anterior vagal trunk structures at the esophageal hiatus was: single trunk [65.7%]; biplexus [20.9%]; triplexus [8.9%] and double-but-not-connected trunks [4.5%]. The pattern of the posterior trunk structures were: single trunk [85.1%]; biplexus 10.4% and triplexus [4.5%]. There was no statistically significant gender difference in the pattern of vagal fibres. There was no major differences in the pattern from comparable British studies. CONCLUSION: The study confirmed high variability in the distribution of the vagus nerve at the esophageal hiatus, unrelated to gender differences. Surgeons must consider and identify variants of vagal innervation when carrying out surgery at the gastroesophageal junction to avoid accidental vagal injuries. Published surgical techniques for preserving vagal function are valid in Uganda.

The pharyngeal plexus: an anatomical review for better understanding postoperative dysphagia.

The pharyngeal plexus is an essential anatomical structure, but the contributions from the glossopharyngeal and vagus nerves and the superior cervical ganglion that give rise to the pharyngeal plexus are not fully understood. The pharyngeal plexus is likely to be encountered during various anterior cervical surgical procedures of the neck such as anterior cervical discectomy and fusion. Therefore, a detailed understanding of its anatomy is essential for the surgeon who operates in and around this region. Although the pharyngeal plexus is an anatomical structure that is widely mentioned in literature and anatomy books, detailed descriptions of its structural nuances are scarce; therefore, we provide a comprehensive review that encompasses all the available data from this critical structure. We conducted a narrative review of the current literature using databases like PubMed, Embase, Ovid, and Cochrane. Information was gathered regarding the pharyngeal plexus to improve our understanding of its anatomy to elucidate its involvement in postoperative spine surgery complications such as dysphagia. The neural contributions of the cranial nerves IX, X, and superior sympathetic ganglion intertwine to form the pharyngeal plexus that can be injured during ACDF procedures. Factors like surgical retraction time, postoperative hematoma, surgical hardware materials, and profiles and smoking are related to postoperative dysphagia onset. Thorough anatomical knowledge and lateral approaches to ACDF are the best preventing measures.

What Happens in (the) Vagus, Stays in (the) Vagus.

Many cardiothoracic operations put the nerves of the thorax at risk. In fact, nerve injuries are one of the most common reasons cited in malpractice cases brought against cardiothoracic surgeons. While all physicians learn about the nerves of the thorax during anatomy courses in medical school, little is written about avoiding injury to these important nerves in the cardiothoracic surgical literature. We have, therefore, embarked on an effort to collate information on the anatomy, function, and protection of these nerves, with which every cardiothoracic surgeon should be familiar. We will call this effort "The Nerve Protection Project." Acknowledging that the material to be covered is considerable, we will break the project into a series of editorials. The first installment in this series will address the anatomy and function of the vagus nerve and the protection of this nerve and its branches during cardiothoracic surgical operations, as they are in harm's way during many of these procedures.

Anatomical study of jugular foramen in the neck / Estudo anatômico do forame jugular no pescoço

Abstract Introduction The anatomical complexity of the jugular foramen makes surgical procedures in this region delicate and difficult. Due to the advances in surgical techniques, approaches to the jugular foramen became more frequent, requiring improvement of the knowledge of this region anatomy. Objective To study the anatomy of the jugular foramen, internal jugular vein and glossopharyngeal, vagus and accessory nerves, and to identify the anatomical relationships among these structures in the jugular foramen region and lateral-pharyngeal space. Methods A total of 60 sides of 30 non-embalmed cadavers were examined few hours after death. The diameters of the jugular foramen and its anatomical relationships were analyzed. Results The diameters of the jugular foramen and internal jugular vein were greater on the right side in most studied specimens. The inferior petrosal sinus ended in the internal jugular vein up to 40 mm below the jugular foramen; in 5% of cases. The glossopharyngeal nerve exhibited an intimate anatomical relationship with the styloglossus muscle after exiting the skull, and the vagal nerve had a similar relationship with the hypoglossal nerve. The accessory nerve passed around the internal jugular vein via its anterior wall in 71.7% of cadavers. Conclusion Anatomical variations were found in the dimensions of the jugular foramen and the internal jugular vein, which were larger in size on the right side of most studied bodies; variations also occurred in the trajectory and anatomical relationships of the nerves. The petrosal sinus can join the internal jugular vein below the foramen.

Resumo Introdução A complexidade anatômica do forame jugular torna a realização de procedimentos cirúrgicos nessa região delicada e difícil. Devido aos avanços obtidos nas técnicas cirúrgicas, as abordagens do forame jugular têm sido feitas com maior frequência, o que requer uma melhoria correspondente no conhecimento de sua anatomia. Objetivo Estudar a anatomia do forame jugular, da veia jugular interna e dos nervos glossofaríngeo, vago e acessório, assim como as relações anatômicas entre estas estruturas na região do forame jugular e no espaço parafaríngeo. Método Foram examinados 60 lados de 30 cadáveres frescos algumas horas após a morte. Os diâmetros e suas relações anatômicas foram analisados. Resultados Os diâmetros do forame jugular e da veia jugular interna foram maiores no lado direito na maioria dos espécimes estudados. O seio petroso inferior terminava na veia jugular interna até 40 mm abaixo do forame jugular, em 5% dos casos. O nervo glossofaríngeo exibiu uma relação íntima anatômica com o músculo estiloglosso após a sua saída do crânio e o nervo vago exibiu uma relação semelhante com o nervo hipoglosso. O nervo acessório passou em torno da veia jugular interna via sua parede anterior em 71,7% dos cadáveres. Conclusão Foram encontradas variações anatômicas nas dimensões do forame jugular e da veia jugular interna, que apresentaram tamanhos maiores à direita na maioria dos espécimes estudados; variações também ocorreram na trajetória e nas relações anatômicas dos nervos. O seio petroso pode se unir à veia jugular interna abaixo do forame.

Compartmental Subdivisions of the Jugular Foramen: A Review of the Current Models.

BACKGROUND: At present, no consensus has been reached on the compartmental subdivision of the jugular foramen (JF), which can complicate surgical planning in this area and hinder understanding of foraminal tumor growth patterns. The extradural neural axis compartment (EDNAC) might aid in producing a standardized model in the future. In the present review, we have summarized the models of JF compartmentalization and analyzed how sound they are anatomically. METHODS: The present narrative review identified the key studies and supporting reports that had discussed, referenced, or first presented models of JF compartmentalization. RESULTS: Three intraforaminal components serve as the basis for JF compartmentalization: the fibro-osseous bridge, neurovascular contents, and EDNAC. A total of 4 models have been proposed to date. These include the 2-part (bipartite) models by Hovelacque (1934) and Shapiro (1972) and the 3-part (tripartite) subdivisions by Katsuta (1997) and Bernard (2018). CONCLUSIONS: The bipartite model has been criticized as being oversimplified and lacking surgical validity. However, support for this compartmentation has persisted despite the increasing popularity of the tripartite model. The 3-part subdivision of Bernard can be considered the most anatomically faithful model to date owing to the consideration of the dura and EDNAC. It is important that future studies consider the entire anatomy of the JF, which may generate an anatomically accurate and surgically applicable compartmental model.

Defining the Anatomy of the Vagus Nerve and Its Clinical Relevance for the Neurosurgical Treatment of Glossopharyngeal Neuralgia.

The neurosurgical treatment of glossopharyngeal neuralgia includes microvascular decompression or rhizotomy of the nerve. When considering open section of the glossopharyngeal nerve, numerous authors have recommended additional sectioning of the 'upper rootlets' of the vagus nerve because these fibers can occasionally carry the pain fibers causing the patient's symptoms. Sacrifice of vagus nerve rootlets, however, carries the potential risk of dysphagia and dysphonia. In this study, the anatomy and physiology of the vagus nerve rootlets are characterized to provide guidance for surgical decision-making. Twelve patients who underwent posterior fossa craniotomy with intraoperative electrophysiological monitoring of the vagus nerve rootlets were included in this study. In the 7 patients with glossopharyngeal neuralgia, the clinical outcomes and complications were further analyzed. In half of the patients, electrophysiological data demonstrated pure sensory function in the rostral rootlet(s) of the vagus nerve and motor responses in its caudal rootlets. This orientation of the vagus nerve, with some pure sensory function in its most rostral rootlet(s), was defined as Type A. In the other half of patients, all vagus nerve rootlets (including the most rostral) had motor responses. This was defined as Type B. The surgical strategy was guided by whether the patient had a Type A or Type B vagus nerve. For those with Type B, no vagus nerve rootlets were sacrificed. None of the patients with glossopharyngeal neuralgia developed any permanent neurological deficits. We recommend intraoperative electrophysiological testing of the vagus nerve rootlets. If the testing reveals motor innervation in the rostral vagal rootlet (Type B), that rootlet may be decompressed but should not be sectioned to avoid a motor complication. Patients with pure sensory innervation of the rostral rootlet(s) (Type A) can have decompression or section of those rootlets without complication.

Vagal schwannomas of the head and neck: A comprehensive review and a novel approach to preserving vocal cord innervation and function.

BACKGROUND: Schwannomas, benign tumors arising from neurolemmocytes, are the most common type of peripheral nerve tumors. Extracranial schwannomas are most often found in the parapharyngeal space, commonly involving the vagus nerve to cervical sympathetic trunk. Vagal schwannomas present several unique clinical and therapeutic challenges. METHODS: A comprehensive literature review was conducted on 197 articles reporting 235 cases of cervical vagal schwannomas. Presenting symptoms, treatment approach, and postoperative outcomes were recorded and analyzed. RESULTS: Vagal schwannomas commonly present as asymptomatic neck masses. When they become symptomatic, surgical resection is the standard of care. Gross total resection is associated with higher postoperative morbidity compared to subtotal resection. Initial reports using intraoperative nerve monitoring have shown improved nerve preservation. Recurrence rates are low. CONCLUSION: The combination of intermittent nerve mapping with novel continuous vagal nerve monitoring techniques may reduce postoperative morbidity and could represent the future standard of care for vagal schwannoma treatment.

Apparent origin of glossopharyngeal, vagus and accessory nerves: an aspect to consider in human neuroanatomy teaching / El origen aparente de los nervios glosofaríngeo, vago y accesorio: un aspecto para considerar en la enseñanza de neuroanatomía humana

In various neuroanatomy texts and articles related to this area of knowledge, there is a conceptual vacuum associated with the precise sites where the roots of the cranial nerves emerge. The objective of the study was to establish the exact location of the apparent origin of the glossopharyngeal, vagus and accessory cranial nerves in the medulla oblongata of the human being 120 human brainstems, previously fixed in formalin solution at 10 % were assessed, the location where such nerve roots emerge was identified by direct examination and once the piamater was removed at both right and left sides as it has been stated in the literature. It was found that in 100 % of the studied brainstems their nerve roots emerge on average at about 2.63 mm behind the retro-olivary groove, different to what has been stated in the literature. Glossopharyngeal, vagus and accessory human nerves do not emerge directly from the retroolivary groove, as commonly reported; instead, they emerge behind the said groove, specifically in the retro-olivary groove area, where they form a continuous line of nerve roots.

En diversos textos de neuroanatomía y artículos relacionados con esta área del conocimiento, se evidencia un vacío conceptual asociado con los sitios precisos por donde emergen los pares craneales. El objetivo de este estudio fue stablecer la ubicación exacta del origen aparente de los nervios craneales glosofaríngeo, vago y accesorio en el bulbo raquídeo de 120 tallos cerebrales humanos, previamente fijados en solución de formalina al 10 %. Fueron evaluados, el lugar donde surgen tales raíces nerviosas se identificó mediante examen directo y una vez que se retiró la piamadre tanto en el lado derecho como en el izquierdo como se ha dicho en la literatura. Se encontró que en el 100 % de los troncos cerebrales estudiados, sus raíces nerviosas emergen en promedio a unos 2,63 mm detrás del surco retroolivar, diferente a lo que se ha dicho en la literatura. Los nervios humanos glosofaríngeos, vago y accesorio no emergen directamente de la ranura retroolivar, como se informa comúnmente, sino que emergen detrás de dicha ranura, específicamente en el área de surco retroolivar, donde forman una línea continua de raíces nerviosas.

The course of lower cranial nerves within the neck: a cadaveric dissection study.

PURPOSE: To evaluate the course of lower cranial nerves (CNs) within the neck in relation to surrounding structures and anatomic landmarks via a cadaveric dissection study. METHODS: A total of 70 neck dissections (31 bilateral, 8 unilateral) were performed on 39 adult fresh cadavers [mean (SD) age: 38.5 (11.2) years, 29 male, 10 female] to identify the course of lower CNs [spinal accessory nerve (SAN), vagus nerve and hypoglossal nerve] within the neck in relation to surrounding structures [internal jugular vein (IJV), common carotid artery (CCA)] and distance to anatomical landmarks (cricoid cartilage, hyoid bone, digastric muscle). RESULTS: SAN travelled most commonly anterior to IJV (51.4%) at the level of jugular foramen, while travelling lateral to IJV at the post belly of digastric (55.7%) and inferior to digastric muscle (90%) in most neck dissections. Vagus nerve travelled lateral to CCA in majority (94.3%) of dissections, while medial (2.9%), posterolateral (1.4%) and posterior (1.4%) positions were also noted. Average distance of hypoglossal nerve was 27.7 (9.7) mm to carotid bifurcation, 9.3 (3.9) mm to hyoid bone, and 54.7 (18.0) mm to the inferior border of cricoid cartilage. CONCLUSION: In conclusion, our findings indicate that anatomic variations are not rare in the course of lower CNs within the neck in relation to adjacent structures, and awareness of these variations together with knowledge of distance to certain anatomic landmarks may help the surgeon to identify lower CNs during neck surgery and prevent potential nerve injuries.

Surgical anatomy for hemifacial spasm.

Classically in the cerebello-pontine angle the facial (CN VII) and vestibular-cochlear (CN VIII) nerves should run parallel with the anterior inferior cerebellar artery, whereas the lower nerves (CN IX-XI) continue with the posterior-inferior-cerebellar artery (PICA). In fact, this is not always true, particularly when dealing with hemispasm surgery where the relationships between CN VII, CN VIII and PICA are often different and closer. Knowledge of anatomical bases in surgical situation will help neurosurgeons to appreciate anatomical nuances, that are important to increase effectiveness and safety of hemifacial spasm surgery.

Descendens vagohypoglossi: rare variant of the superior root of ansa cervicalis.

Knowledge of variants in the formation and position of the ansa cervicalis is important in head and neck surgery, specifically in reconstructions of the tongue that use the infrahyoid muscles, and in the anastomosis of the ansa cervicalis to the recurrent laryngeal nerve when the laryngeal muscles have been paralysed. We describe a rare variant of the superior root of the ansa cervicalis, which had a contribution from the vagus and hypoglossal nerves. The inferior root was formed by the C2 and C3 ventral rami, but it passed medial to the internal jugular vein before it joined the superior root to form the loop.

High-resolution Imaging of Neural Anatomy and Pathology of the Neck.

The neck has intricately connected neural structures, including cervical and brachial plexi, the sympathetic system, lower cranial nerves, and their branches. Except for brachial plexus, there has been little research regarding the normal imaging appearance or corresponding pathologies of neural structures in the neck. The development in imaging techniques with better spatial resolution and signal-to-noise ratio has made it possible to see many tiny nerves to predict complications related to image-guided procedures and to better assess treatment response, especially in the management of oncology patients. The purposes of this review is to present imaging-based anatomy of major nerves in the neck and explain their relevant clinical significance according to representative pathologies of regarded nerves in the neck.

Microsurgical anatomy of the human carotid body (glomus caroticum): Features of its detailed topography, syntopy and morphology.

The human glomus caroticum (GC) is not readily accessible during ordinary anatomical teaching courses because of insufficient time and difficulties encountered in the preparation. Accordingly, most anatomical descriptions of its location, relationship to neighboring structures, size and shape are supported only by drawings, but not by photographs. The aim of this study is to present the GC with all associated roots and branches. Following microscope-assisted dissection and precise photo-documentation, a detailed analysis of location, syntopy and morphology was performed. We carried out this study on 46 bifurcations of the common carotid artery (CCA) into the external (ECA) and internal (ICA) carotid arteries and identified the GC in 40 (91%) of them. We found significant variations regarding the location of the GC and its syntopy: GC was associated with CCA (42%), ECA (28%) and ICA (30%) lying on the medial or lateral surface (82% or 13%, respectively) or exactly in the middle (5%) of the bifurcation. The short and long diameter of its oval form varied from 1.0 × 2.0 to 5.0 × 5.0mm. Connections with the sympathetic trunk (100%), glossopharyngeal (93%), vagus (79%) and hypoglossal nerve (90%) could be established in 29 cadavers. We conclude that precise knowledge of this enormous variety might be very helpful not only to students in medicine and dentistry during anatomical dissection courses, but also to surgeons working in this field.

Topography and extent of pulmonary vagus nerve supply with respect to transthoracic oesophagectomy.

Pulmonary complications are frequently observed after transthoracic oesophagectomy. These complications may be reduced by sparing the vagus nerve branches to the lung. However, current descriptions of the regional anatomy are insufficient. Therefore, we aimed to provide a highly detailed description of the course of the pulmonary vagus nerve branches. In six fixed adult human cadavers, bilateral microscopic dissection of the vagus nerve branches to the lungs was performed. The level of branching and the number, calibre and distribution of nerve branches were described. Nerve fibres were identified using neurofilament immunohistochemistry, and the nerve calibre was measured using computerized image analysis. Both lungs were supplied by a predominant posterior and a smaller anterior nerve plexus. The right lung was supplied by 13 (10-18) posterior and 3 (2-3) anterior branches containing 77% (62-100%) and 23% (0-38%) of the lung nerve supply, respectively. The left lung was supplied by a median of 12 (8-13) posterior and 3 (2-4) anterior branches containing 74% (60-84%) and 26% (16-40%) of the left lung nerve supply, respectively. During transthoracic oesophagectomy with en bloc lymphadenectomy and transection of the vagus nerves at the level of the azygos vein, 68-100% of the right lung nerve supply and 86-100% of the inferior left lung lobe nerve supply were severed. When vagotomy was performed distally to the last large pulmonary branch, 0-8% and 0-13% of the nerve branches to the right middle/inferior lobes and left inferior lobe, respectively, were lost. In conclusion, this study provides a detailed description of the extensive pulmonary nerve supply provided by the vagus nerves. During oesophagectomy, extensive mediastinal lymphadenectomy denervates the lung to a great extent; however, this can be prevented by performing the vagotomy distal to the caudalmost large pulmonary branch. Further research is required to determine the feasibility of sparing the pulmonary vagus nerve branches without compromising the completeness of lymphadenectomy.

Localization of the cricothyroid muscle under ultrasound guidance for vagal nerve mapping.

During surgical removal of tumors of the skull base or cerebellopontine angle with brainstem compression, the vagus nerve is at a high risk for injury that can result in permanent or transient swallowing and speech dysfunction. Intramuscular recording of cricothyroid muscle can be used for vagal nerve mapping during intraoperative neurophysiologic monitoring so as to prevent the above complications. However, it is a small muscle that lies beneath the strap muscles over the anterior neck and is not easily accessible by a blind approach. Here, we present a case in which cricothyroid muscle was identified for precise electrode placement under ultrasound guidance during preparation for intraoperative monitoring. We concluded that localization of the cricothyroid muscle by ultrasonography proved to be a feasible and easy technique, and the compound muscle action potential recorded by this approach is clearly recognizable during intraoperative vagal nerve mapping.

Distribution and innervation of putative peripheral arterial chemoreceptors in the red-eared slider (Trachemys scripta elegans).

Peripheral arterial chemoreceptors have been isolated to the common carotid artery, aorta, and pulmonary artery of turtles. However, the putative neurotransmitters associated with these chemoreceptors have not yet been described. The goal of the present study was to determine the neurochemical content, innervations, and distribution of putative oxygen-sensing cells in the central vasculature of turtles and to derive homologies with peripheral arterial chemoreceptors of other vertebrates. We used tract tracing together with immunohistochemical markers for cholinergic cells (vesicular acetylcholine transporter [VAChT]), tyrosine hydroxylase (TH; the rate-limiting enzyme in catecholamine synthesis), and serotonin (5HT) to identify putative oxygen-sensing cells and to determine their anatomical relation to branches of the vagus nerve (Xth cranial nerve). We found potential oxygen-sensing cells in all three chemosensory areas innervated by branches of the Xth cranial nerve. Cells containing either 5HT or VAChT were found in all three sites. The morphology and size of these cells resemble glomus cells found in amphibians, mammals, tortoises, and lizards. Furthermore, we found populations of cholinergic cells located at the base of the aorta and pulmonary artery that are likely involved in efferent regulation of vessel resistance. Catecholamine-containing cells were not found in any of the putative chemosensitive areas. The presence of 5HT- and VAChT-immunoreactive cells in segments of the common carotid artery, aorta, and pulmonary artery appears to reflect a transition between cells containing the major neurotransmitters seen in fish (5HT) and mammals (ACh and adenosine).

The pharyngeal plexus-mediated glottic closure response and associated neural connections of the plexus.

IMPORTANCE: There continues to be a paucity of data regarding the pharyngeal plexus (PP) and its interconnectivity with the laryngeal nerves and function. OBJECTIVE: To identify the specific neural pathways involved in the glottic closure reflex (GCR)-like pathway of the PP and other pathways to the thyroarytenoid (TA) muscle in the porcine model. DESIGN, SETTING, AND ANIMAL SUBJECTS: Animal experimental study from September 2013 to June 2014 conducted in a tertiary academic medical center on male Yorkshire pigs. INTERVENTIONS: Contraction of the TA was detected with electromyography (EMG) during electrical stimulation of the PP in 7 porcine necks. Subsequently, the external branch of the superior laryngeal nerve (eSLN), communicating nerve of Galen (NG), and the recurrent laryngeal nerve (RLN) were sequentially transected to help elucidate the path of neural conduction. MAIN OUTCOMES AND MEASURES: Confirmation of TA muscle contraction by EMG. RESULTS: Stimulation of the PP evoked a response from the TA muscle in 6 of 7 subject animals. In 3 of 7 subjects, a long latency response (mean, 14.62 milliseconds) was identified, which was eliminated only after transection of the RLN. In 3 of 7 subjects, a short latency response (mean 3.05 milliseconds) was identified, which disappeared in 1 subject each by eSLN, RLN, and NG transection. CONCLUSIONS AND RELEVANCE: We identified the specific neural pathway involved in the PP's GCR-like pathway. We also noted a variable direct pattern of innervation to the TA.

The recurrent laryngeal cardiac nerve in fetuses / El nervio laríngeo recurrente cardiaco en fetos

The recurrent laryngeal nerve has been reported to supply cardiac branches to the cardiac plexus. A review of anatomical literature on the existing term used to describe these branches revealed that varying interpretations and descriptions exist among various authors. Therefore, this study aimed to investigate the origin and incidence of branches from the recurrent laryngeal nerves to the cardiac plexus and their connections with sympathetic cardiac nerves. The sample comprised 40 cadaveric fetuses (n=80) (gestational ages: 16-30 weeks). The recurrent laryngeal cardiac nerve was described as the cardiac branch that originated directly from the recurrent laryngeal nerve and reached the superficial or deep parts of the cardiac plexus. This study found the recurrent laryngeal cardiac nerve in 76% of the cases contributing direct and indirect branches in 75% and 25% of the cases, respectively. This study recorded only two (2%) of these branches contributing to the superficial cardiac plexus while the rest (74%) of these branches contributed to the deep cardiac plexuses. The remaining 24% had no contributions from the recurrent laryngeal nerve to either the superficial or deep part of the cardiac plexus. The most common point of origin for the recurrent laryngeal cardiac nerve was at the lower distal part in 59% of the specimens. In the remaining 41% of branches, this nerve originated from the point of curvature, upper proximal part and both the point of curvature and lower distal part in 26%, 10% and 5% of the specimens.

El nervio laríngeo recurrente suministra las ramas cardiacas para el plexo cardíaco. Una revisión de la literatura anatómica nos muestra que existen diferentes interpretaciones y descripciones de estas ramas por parte de los distintos autores consultados. En consecuencia este estudio tuvo como objetivo investigar el origen, además de la incidencia de las ramas de los nervios laríngeos recurrentes al plexo cardíaco y sus conexiones con los nervios cardiacos simpáticos. La muestra incluyó 40 fetos (n=80) (edades gestacionales: 16-30 semanas). El nervio laríngeo recurrente cardiaco fue descrito como la rama cardíaca que se originó directamente del nervio laríngeo recurrente, que llega a las partes superficiales o profundas del plexo cardíaco. En este estudio observamos que el nervio laríngeo recurrente cardiaco en el 76% de los casos contribuye a las ramas directas e indirectas, en el 75% y el 25% de los casos, respectivamente. Se observó en este estudio que solamente dos (2%) de estas ramas contribuían en la formación del plexo cardíaco superficial, mientras que el resto (74%) de estas ramas contribuía a los plexos cardíacos profundos. El 24% restante no tenía contribuciones del nervio laríngeo recurrente ya sea para la parte superficial o profunda del plexo cardíaco. El punto de origen más común del nervio laríngeo recurrente cardiaco se observó en la parte distal inferior en un 59% de las muestras. En el 41% restante de las ramas este nervio se originó desde el punto de curvatura, la parte proximal superior y tanto en el punto de curvatura inferior como la parte distal en 26%, 10% y 5% de los especímenes.