Rapid axoplasmic transport of labelled proteins in the vagus and hypoglossal nerves of the rabbit

Summary Axoplasmic transport of labelled proteins was studied in the vagus and hypoglossal nerves of the adolescent rabbit after an intramedullary injection of ³H-leucine.As demonstrated by radioautography, the incorporated activity found in the intramedullary axons had a perikaryal origin and was transported distally at a rate of several mm per hour.The migration of labelled proteins along the axons outside the medulla was followed by measuring the specific radioactivity of the proteins in the hypoglossal and vagus nerves. A rapid transport of labelled proteins in proximo-distal direction was demonstrated at rates of 16–17 mm/h in the vagus nerve and 10–15 mm/h in the hypoglossal nerve. The effect of puromycin and nerve ligature on the rapidly moving component is described.     

Axoplasmic transport of acetylcholinesterase and choline acetyltransferase in the vagus and hypoglossal nerve of the rabbit

Summary Acetylcholinesterase (AChE) and choline acetyltransferase (ChAc) were studied in the vagus and hypoglossal nerve of the rabbit. Under normal conditions the activity of AChE was about twice as high in the vagus as in the hypoglossal nerve. The activity of ChAc, however, was about six times as high in the hypoglossal nerve as in the vagus.When the axons had been crushed by a ligature, the enzymes accumulated proximal to the ligature, presumably a reflection of a proximo-distal transport from the nerve cell soma. The transport velocity, as calculated from the rate of accumulation was highest in the vagus nerve both for AChE and ChAc. Approximately the same rates were observed for both enzymes, i.e., 15 mm/24 h in the vagus nerve and 5 mm/24 h in the hypoglossal nerve. These rates were of the same order as those previously observed for the slow axoplasmic transport of radioactively labelled proteins in unligated nerve.     

Morphometric study of the cervical course of the hypoglossal nerve and its application to hypoglossal facial anastomosis

The hypoglossal nerve is used classically in salvage of facial paralyses in the absence of spontaneous recovery. A variety of ways of transferring and suturing the hypoglossal nerve to the distal segment of the facial nerve have been reported. In order to determine which mode of reconstruction is the best for neurotisation of the facial nerve, the caliber of the hypoglossal nerve was studied in ten subjects at the level of proximal and distal parts of the trunk and the cervical loop. The fascicular surface area of the cervical branch is inadequate for use. The distal extremity of the hypoglossal nerve has an ideal caliber to be sutured to the facial nerve trunk and the proximal part is large enough to allow partial harvesting of the hypoglossal nerve for neurotisation of the facial nerve.     

Intrathoracic blood supply of the left vagus and recurrent laryngeal nerves

Abstract The arteries and veins of the left vagus (VN) and left recurrent laryngeal (RLN) nerves from the thoracic inlet to the subaortic region are described following vascular casting with red colored latex in 6 adult fresh non-embalmed cadavers. In all specimens the anterior bronchoesophageal artery supplied at least one vessel to the VN and RLN in the subaortic region. For the RLN other arterial sources were arteries arising from the aortic arch in 1 specimen, the subclavian artery in 3 specimens, the first intercostal artery in 1 specimen, and the inferior thyroid artery in all specimens. For the VN other arterial sources were arteries arising from the aortic arch in 2 specimens and the inferior thyroid artery in 1 specimen. For both the VN and RLN the veins were located under the pleura and directed towards the internal thoracic vein anteriorly and the thoracic intercostal veins posteriorly. In conclusion, the inferior thyroid artery at the thoracic inlet for the RLN and the anterior bronchoesophageal artery are the more consistent vessels supplying the VN and RLN. Vascular damage occurring during mediastinal lymph node excision to the VN and RLN, especially in the subaortic region, may explain postoperative vocal fold paralysis.     

Intracranial course and relations of the hypoglossal nerve: An anatomic study

This anatomic study describes the course and intracranial relations of the hypoglossal n. in 32 cadavers. The rootlets of the nerve emerged as a fan-shaped distribution (23.44%) or in two bundles (76.56%) and converged towards the hypoglossal canal in the subarachnoid space before piercing the dura mater. In 76.57% of cases the rootlets pierced the dura mater in two separate apertures, less commonly through the same aperture (21.87%), and in rare cases through three individual apertures, as in one of our cases. The distance between the two apertures varied from 0.6 mm to 8.7 mm. Commonly, the two bundles converged together and left the skull through one foramen in the skull. However, in some cases (28.12%), the hypoglossal canal was divided in two by a small bony spicule. In 23.45% of cases the initial course of the posterior inferior cerebellar a. (PICA) passed between the two bundles of the hypoglossal n. before ascending towards the lateral border of the fourth ventricle.     

Development of cranial nerves in the chick embryo with special reference to the alterations of cardiac branches after ablation of the cardiac neural crest

Summary Development of cranial nerve branches in the cardiac region was observed in whole-mount specimens which were stained with a monoclonal antibody, E/C8, after the ablation of the cardiac neural crest. In early embryos, nerve trunks of IX and X were lacking or only poorly developed, while the early development of pharyngeal branch primordia was normal. In day 5 embryos, the nerve trunks of IX–X were present in all the embryos, however; extensive communication was observed between X and XII. On day 6 and later, the spiral pattern of superior cardiac branches was disturbed, as were the blood vessels. Furthermore, the distal branches of XII passed within the superficial layer of cardiac outflow mesenchyme. Vagal branches passed within the deeper layer. There was no apparent change in the development of the sinal branch. Using quail — chick chimeras, it was found that the cardiac neural crest cells formed the Schwann cells of XII, and that they were also associated with the hypobranchial muscle primordium, suggesting that the absence of the cardiac neural crest not only disturbs the development of the cardiac outflow septation, but also affects the normal morphogenesis of the hypobranchial musculature and its innervation. Embryologically, the tongue is located close to the cardiac outflow tract, which is the migration pathway of the cardiac neural crest-derived cells.     

Anatomic variations in the course of the hypoglossal nerve: A case report

To achieve a successful surgical anatomy a detailed knowledge of regional anatomy and anatomical variations is an important fundamental. The extra cranial hypoglossal nerve has a well described course as it traverses the neck, and is frequently identified during neck dissection. This serves a guide to the surgeon of such atypical variations in anatomy to avoid injury to important structures during dissection. We are presenting a case report which demonstrates the extra cranial variation of Hypoglossal nerve.     

The distribution of hypoglossal motoneurons in the dog, rabbit and rat

Summary The distribution of motoneurons innervating the extrinsic tongue muscles was studied in the dog, rabbit and rat using the horseradish peroxidase technique. In these mammals, hypoglossal motoneurons were clustered in roughly ventral (or media) and dorsal (or lateral) groups. Axons of hypoglossal motoneurons in the ventral (or medial) group passed via the medial branch of the hypoglossal nerve, and those in the dorsal (or lateral) group by way of the lateral branch of the hypoglossal nerve. Motoneurons supplying the geniohyoid or genioglossus muscle were distributed, respectively, in the ventral or lateral aspect of the ventral (or medial) cluster of hypoglossal motoneurons. Hyoglossus and styloglossus motoneurons were located in the lateral aspect of the dorsal (or lateral) cluster. The area of distribution of hypoglossus motoneurons overlapped with that of styloglossus motoneurons. It seems likely that motoneurons innervating intrinsic tongue muscles form the remainder of the hypoglossal nucleus. The largest motoneurons in the hypoglossal nucleus were distributed in the cluster of geniohyoid motoneurons. Thus, in the present study a somatotopic arrangement of motoneurons innervating the extrinsic tongue muscles was found, in keeping with previous studies using the retrograde cell degeneration technique.     

Axoplasmic migration of protein a light microscopic autoradiographic study in the avian retino-tectal pathway

Summary The distribution of labeled protein along the pigeon retino-tectal pathway was studied with light microscopic autoradiography after intraocular injection of ³H-l-leucine.Evidence was found that proteins synthesized in the ganglion cell perikarya migrate in the axoplasm. Some data suggested that two separate molecular waves reached regions rich in synaptic endings in the early phase after injection. Their respective speed of migration would be 100–500 mm/day and 20–60 mm/day.The most heavily labeled wave, advancing at a speed of 1–2 mm/day, was detected during the late phase after injection.Supported by grants no 4806, 3.137.69 and 4356 from the Swiss National Fund for Scientific Research, grants no 47 from the Hartmann-Müller foundation, and from the Slack-Gyr-Foundation.     

The microsurgical anatomy of the hypoglossal canal

Background  The hypoglossal canal (HC) is a region of the skull base whose involvement in many pathological entities is often ignored. Adequate knowledge of the anatomy of the HC and its related bony, neural, and vascular structures is essential for surgery of lesions involving this area. Methods  Ten adult human cadaver heads from a US source fixed by formalin (20 sides) and 20 dry human skulls from Indian sources (40 sides) were used in this study. Various aspects of the anatomy of this region including the size, course and variation of the hypoglossal nerve and its relationship to the adjacent and canalicular course were recorded. Results  The left HC was located at 10 o’clock and the right HC at the 2 o’clock position with respect to the foramen magnum. The canal was surrounded superiorly by the jugular tubercle, superolaterally by the jugular foramen, laterally by the sigmoid sinus and inferiorly by the occipital condyle. All dry skulls were drilled in the horizontal plane at an axis of about 45° and directed slightly upwards. Conclusions  Detailed knowledge of the microsurgical anatomy of the region of the HC is crucial when performing surgery for lesions of the condylar region, the lower clivus, and ventral brain stem. This study provides the knowledge required to achieve accurate orientation and effective maneuvers during surgical procedures for treatment of the patient without injuring the vital neural and bony structures.     

A clinico-anatomic study of the auricular branch of the vagus nerve and Arnold’s ear-cough reflex

Summary The results of a clinico-anatomic study of the auricular branch of the vagus nerve (ABVN) and Arnold's ear-cough reflex are presented. The frequency of the ear-cough reflex was found to be 2.3% (12 out of 514 patients). It was bilateral in 3 cases (0.6%). The reflex was elicited by palpation of the postero-inferior wall of the external acoustic meatus (EAM) in 11 patients, and by palpation of the antero-inferior wall in one patient (0.2%). The reflex was frequently noticed to occur after a short latent period. The course of the ABVN inside the jugular foramen (JF), and distribution of the terminal branches of the ABVN in the external acoustic meatus were determined in 8 male cadavers (16 sides). In addition, the length of the mastoid canaliculus (MC) and the relationships of the ABVN with the facial nerve and stylomastoid foramen (SMF) were studied in both cadavers and 25 dry skulls (50 sides). High-resolution computed tomography (HRCT) scanning was also performed in all cadavers prior to microdissections. The ABVN emerged from the superior ganglion of the vagus nerve in all the cadavers. It ran between the internal jugular vein (IJV) and the bony wall of the jugular foramen. The ABVN was encased in a partial bony canal during its course from the jugular foramen to mastoid canaliculus in 18% of all specimens. The average length of the mastoid canaliculus was 5.6 mm (4.2–6.5), and it ran transversely towards the tympanomastoid suture 4.5 mm (4–5.1) above the stylomastoid foramen. The mastoid canaliculus was well demonstrated in all the HRCT scans.

---

Etude anatomo-clinique de la branche auriculaire du nerf vague et du réflexe de toux otogène d'Arnold

Résumé Les résultats d'une étude anatomo-clinique concernant la branche auriculaire du nerf vague (BANV) et le réflexe de toux otogène d'Arnold sont exposés. Un réflexe de toux otogène a été trouvé dans 2,3 % des cas (12 cas sur 514). Il était bilatéral dans 3 cas (0,6 %). Le réflexe a été provoqué par la palpation de la paroi postéro-inférieure du méat acoustique externe dans 11 cas. Il a été provoqué après la palpation de sa paroi antéro-inférieure dans 1 cas (0,2 %). Il faut noter que le réflexe est souvent apparu après une brève période de latence. Le trajet de la BANV à l'intérieur du foramen jugulaire et la distribution des branches terminales de la BANV dans le méat acoustique externe ont été précisés sur 8 sujets mâles (16 côtés). De plus, la longueur du canalicule mastoïdien, les rapports de la BANV avec le nerf facial et le foramen stylo-mastoïdien ont été étudiés à la fois sur des sujets anatomiques et sur 25 crânes secs (50 côtés). Une tomodensitométrie à haute résolution a également été réalisée sur tous les sujets anatomiques avant les microdissections. La BANV émergeait du ganglion supérieur du nerf vague sur tous les sujets. Elle passait entre la veine jugulaire interne et le canal osseux du foramen jugulaire. La BANV était enchâssée dans un canal osseux partiel durant son trajet depuis le foramen jugulaire jusqu'au canalicule mastoïdien dans 18 % des cas. La longueur moyenne du canalicule mastoïdien était de 5,6 mm (4,2 – 6,5), et il se dirigeait transversalement vers la suture tympano-mastoïdienne à 4,5 mm (4 – 5,1) au-dessus du foramen stylomastoïdien. Le canalicule mastoïdien a été bien mis en évidence sur toutes les tomodensitométries.

     

Bilateral vagotomy differentially alters the magnitude of hypoglossal and phrenic long-term facilitation in anesthetized mechanically ventilated rats

Acute intermittent hypoxia elicits long-term increases in respiratory motor output (long-term facilitation, LTF). Most investigators study LTF in mechanically ventilated, bilaterally vagotomized, and anesthetized animals. Vagotomy blocks inhibitory lung-volume feedback that could diminish the magnitude of LTF. However, the effects of vagotomy on LTF may not be so straight forward. In cats, vagotomy increases LTF of upper airway muscles but may decrease LTF of accessory pump muscles. The effects of vagotomy on LTF in rats are unknown. We hypothesized that the magnitude of hypoglossal and phrenic LTF would be differentially regulated by vagal afferent feedback in anesthetized and mechanically ventilated rats. Hypoglossal and phrenic motor outputs were recorded from vagotomized and vagally intact anesthetized mechanically ventilated adult Sprague-Dawley rats before, during, and up to 60-min after intermittent hypoxia. Ventilator frequency (f), pump volume, and peak tracheal pressure were not different between groups. The effects of vagotomy on the magnitude of LTF depended on the motoneuron population in question. The magnitude of hypoglossal LTF increased after vagotomy (vagi intact, -5+/-10%; vagotomy, 66+/-11% above baseline; p<0.05); whereas, the magnitude of phrenic LTF decreased after vagotomy (vagi intact, 135+/-24%; vagotomy, 40+/-13% above baseline; p<0.05). These data support previous work in anesthetized cats, and suggest that the expression of hypoglossal and phrenic respiratory motor plasticity is differentially regulated by vagal afferent feedback.     

大鼠烫伤后迷走神经放电活动的变化

实验中观察到大鼠烫伤后即刻自发性放电活动明显增强,频率增加,呈连续性发放,持续30—90秒,以后放电频率开始减少。烫伤后1～6小时放电频率,10只鼠中7是降低,3只是增高的。由单纤维放电特点分析,烫伤1小时以后,迷走传出神经纤维有一些放电活动增强,频率增加;另一些纤维放电活动减弱,频率减少,甚至完全消失。以上结果表明,烫伤引起大鼠迷走中枢神经活动短暂增加,以后转向抑制,随后有一些神经元活动增加,而有一些神经元活动减弱,甚至完全处于抑制状态。     

The intra-lingual course of the nerves of the tongue

The intra-lingual course of the nerves of tongue has never been studied in the human by the Sihler method. This technique was applied to six human tongues and allowed coloration of the nerves and illustration of the tongue. The course of the hypoglossal, glossopharyngeal, and lingual nerves was defined. Constant anastomoses between the lingual and hypoglossal nerves, between the glossopharyngeal nerve and the hypoglossal and lingual nerves, were demonstrated and may help explain the “neck–tongue” syndrome. This cartography of the nerves of the tongue allowed the definition of the motor and sensory consequences of tongue surgery.     

大鼠迷走神经和膈神经的解剖相关性实验研究

目的 为大鼠迷走神经移位膈神经重建高位颈髓损伤大鼠的膈肌功能提供显微解剖学依据。 方法　10只健康雌性SD大鼠在10倍手术显微镜下解剖双侧膈神经、迷走神经及其分支。用数显卡尺测量迷走神经与膈神经在“膈神经主干起始平面”、“锁骨上平面”、“入膈肌平面”的相对距离,用读数显微镜测量各平面迷走神经和膈神经的直径。 结果　在颈部,迷走神经直径为（0.3284±0.0247）mm,膈神经直径为（0.2267±0.0164）mm,二者的相对距离很接近,无论是在“膈神经主干起始平面”还是“锁骨上平面”,平均都不超过2.5 mm;在“入膈肌平面”平面,迷走神经直径为（0.2912±0.0326）mm,膈神经直径为（0.2794±0.0282）mm,二者的相对距离较颈部远,左侧为（8.71±0.804）mm,右侧为（6.203±0.952） mm。 结论　(1)在颈部,迷走神经与膈神经的直径相差不大,相对距离很接近,二者可直接无张力缝合。(2)在入膈肌平面,迷走神经与膈神经的直径大致相同,相对距离稍远,但将膈神经和迷走神经向上游离一段距离后仍可实现二者的直接无张力缝合。     

Silver impregnation of degenerating dendrites,cells and axons central to axonal transection I. A nauta study on the hypoglossal nerve in kittens

Summary Peripheral transection of the XIIth cranial nerve was performed on the right side in kittens. In Nauta-Laidlaw preparations from the medulla oblongata impregnation was obtained of degenerating hypoglossal dendrites, cells and/or axons on the side of the operation in most of these animals. The morphology of the degenerating parts of the neurones is described. Nerve cell death was shown to be the factor responsible for the impregnation. The influence of animal age at operation and of the period of postoperative survival on the occurrence and appearance of the degeneration was demonstrated. The spatial sequence of the degeneration within the neurone was in proximo-distal direction.These findings are discussed in relation to earlier observations. The probable significance of the findings as a basis for a supplementary technique in experimental neuroanatomy is also discussed.     

Ⅲ—Ⅴ对脑神经生物塑化薄片断层解剖与MRI对照研究

目的：对动眼神经、滑车神经、三叉神经进行塑化切片与MRI对照研究,获得正常影像和断层解剖资料。方法：采用生物塑化技术制作脑神经横断位8例、矢状位和冠状位各1例薄层切片,同时采用FLASH-3D序列完成头颅标本及30例正常人脑干MR扫描,以MPR技术完整显示动眼神经的三叉神经的脑池段全程。结果：塑化薄片断层、标本和活体MR扫描,脑神经行程、解剖形态均有良好的对应关系,滑车神经仅在塑化切片上显示。结论：生物塑化薄层切片能够对脑神经进行准确显示,是脑神经影像学研究的重要对比方法。     

Afferent neurons of the hypoglossal nerve of the rat as demonstrated by horseradish peroxidase tracing

Summary Cell bodies of sensory neurons of the rat's hypoglossal nerve were demonstrated by the somatopetal horseradish peroxidase (HRP) transport technique. Labelled perikarya were found within the second and third cervical spinal ganglia and in the vagal sensory ganglia.After application of HRP to the cut peripheral trunk of the hypoglossal nerve about 200 labelled cell bodies were counted in each animal. The vast majority of the axons from cervical spinal ganglion cells reach the hypoglossal nerve via the descending ramus (N. descendens hypoglossi). However, there may exist an additional pathway, probably via the cervical sympathetic trunk.Application of HRP to the medial and lateral end branches led to a labelling of much fewer spinal ganglion cells while the number of labelled vagal sensory neurons remained unchanged. Thus, it is suggested that the majority of the cervical afferents of the hypoglossal nerve originates within the extrinsic tongue musculature and the geniohyoid muscle, whereas the vagal afferents may perhaps derive exclusively from the intrinsic muscles.Histograms of the mean diameters of labelled cell bodies show a predominance of very small perikarya. This contrasts with the diameter distribution of sensory perikarya labelled after HRP application to nerves supplying other skeletal muscles. It is therefore assumed that the afferent component of the hypoglossal nerve is composed mainly of small-calibre axons.Supported by the Hartmann Müller-Stiftung, ZürichPart of this work was presented at the 74. Versammlung der Anatomischen Gesellschaft in Regensburg, March 1979     

迷走神经电刺激治疗癫痫的现状与展望

Electrical vagus nerve stimulation （VNS） has been approved by FDA and is widely used in recent years for the treatment of epilepsy and possibly other medical conditions such as depression. The current success rate of VNS for epilepsy is about 50%, but there are complications, potential risks and cost concerns. One of the major limitations for this new therapy is that its antiseizure mechanisms are by no means clear. In particular, it is not known whether the therapeutic effect is vagal specific, what types of nerve fibers in the vagus nerve are contributing to the therapeutic effects, or what individual patients would benefit from the use of the expensive and invasive VNS implantation. There are controversies regarding how and where the VNS takes effect on epilepsy in the central nervous system. The poor understanding of VNS has inevitably limited the application and success of the therapy. The current review analyses the pros and cons of VNS for epilepsy in vis-à- vis other available therapies including Chinese medical methods, and explores the possible mechanisms in order to stimulate further improvement of this new technology.