Modeling childhood cancer in Drosophila melanogaster

Childhood cancer is a major cause of death in developed countries, and while treatments and survival rates have improved, long-term side effects remain a challenge. The genetic component of pediatric tumors and their aggressive progression, makes the study of childhood cancer a complex area of research. Here, we introduce the fruit fly Drosophila melanogaster as study model. We emphasize its numerous advantages, including binary gene expression systems that enable precise control over the timing and location of gene expression manipulation, the capacity to combine multiple genes associated with cancer or the testing of human cancer variants within a live, intact animal. As an illustrative example, we focus on the Drosophila cancer paradigm which involves medically relevant genes, the Notch and PI3K/Akt signaling pathways. We describe how this cancer paradigm allows assessing two critical aspects of tumorigenesis during juvenile stages: (1) viability (do animals with particular cancer mutations survive into adulthood?), and (2) tumor burden (what percentage of animals bearing the cancer mutations actually develop cancer and what is the extent of the tumor?). We highlight the potential of Drosophila as a molecular therapeutic tool for drug screening and drug repurposing of medicines already approved to treat other diseases in children, thereby accelerating the potential translation of results into humans. This preclinical animal model sustains huge potential and is cost-effective. It allows screening of thousands of compounds and genes at a relatively low cost and human efforts, opening innovative venues to explore more effective and safer treatments of childhood cancer.

The first report of the buckled thyroid cartilage in a human cadaver

We present the first case of buckled thyroid cartilage identified in a human cadaver. This rare anatomical variant, in patients, often produces dysphonia and is a potential source for diagnostic confusion. In the cadaveric case described, the laryngeal prominence is deviated to the left without deviation of the internal structures of the larynx, such as vocal folds and vocalis muscles. The medical history of the patient is not known. Finally, a review of current literature on the buckled thyroid cartilage is presented. Such a case represents a rare opportunity to visualize this deformity via anatomical dissection.

Embryology of the Abdominal Wall and Associated Malformations—A Review

In humans, the incidence of congenital defects of the intraembryonic celom and its associated structures has increased over recent decades. Surgical treatment of abdominal and diaphragmatic malformations resulting in congenital hernia requires deep knowledge of ventral body closure and the separation of the primary body cavities during embryogenesis. The correct development of both structures requires the coordinated and fine-tuned synergy of different anlagen, including a set of molecules governing those processes. They have mainly been investigated in a range of vertebrate species (e.g., mouse, birds, and fish), but studies of embryogenesis in humans are rather rare because samples are seldom available. Therefore, we have to deal with a large body of conflicting data concerning the formation of the abdominal wall and the etiology of diaphragmatic defects. This review summarizes the current state of knowledge and focuses on the histological and molecular events leading to the establishment of the abdominal and thoracic cavities in several vertebrate species. In chronological order, we start with the onset of gastrulation, continue with the establishment of the three-dimensional body shape, and end with the partition of body cavities. We also discuss well-known human etiologies.

ATHEROMATOSIS OF THE BRAIN-SUPPLYING ARTERIES: CIRCLE OF WILLIS, BASILAR, VERTEBRAL AND THEIR BRANCHES

PURPOSE

Atherosclerotic plaques in the brain-supplying arteries are slowly-developing alterations of vascular structures that can lead to neurological impairment due to stenosis and insufficient oxygenation of eloquent brain areas. The aim of this study is to provide detailed demographic information related to the incidence of atherosclerotic plaques in the cerebral arteries.

MATERIAL AND METHODS

Forty-eight circles of Willis (21 men, 21 women, mean age: 70.26, six samples unknown) were macroscopically analyzed for length, diameter, and presence of atherosclerotic plaques. Statistical analysis was used to identify potential differences in the locations and frequencies of atherosclerotic plaques in relation to age and sex.

RESULTS

The study sample revealed 261 atherosclerotic plaques. The key findings were significant correlations between plaque development and age and between plaque location and age; however, there was no significant sex difference.

CONCLUSION

The upper and lower branches of the middle cerebral artery (MCA) were novel locations predisposing to plaque development. A cut-off value at 60 years revealed a significant difference in plaque development and distribution. There were no significant sex differences in the occurrence of atherosclerotic plaques.

Fat: Quality, or Quantity? What Matters Most for the Progression of Metabolic Associated Fatty Liver Disease (MAFLD)

Objectives: Lately, many countries have restricted or even banned transfat, and palm oil has become a preferred replacement for food manufacturers. Whether palm oil is potentially an unhealthy food mainly due to its high content of saturated Palmitic Acid (PA) is a matter of debate. The aim of this study was to test whether qualitative aspects of diet such as levels of PA and the fat source are risk factors for Metabolic Syndrome (MS) and Metabolic Associated Fatty Liver Disease (MAFLD). Methods: C57BL/6 male mice were fed for 14 weeks with three types of Western diet (WD): 1. LP-WD—low concentration of PA (main fat source—corn and soybean oils); 2. HP-WD—high concentration of PA (main fat source—palm oil); 3. HP-Trans-WD—high concentration of PA (mainly transfat). Results: All types of WD caused weight gain, adipocyte enlargement, hepatomegaly, lipid metabolism alterations, and steatohepatitis. Feeding with HP diets led to more prominent obesity, hypercholesterolemia, stronger hepatic injury, and fibrosis. Only the feeding with HP-Trans-WD resulted in glucose intolerance and elevation of serum transaminases. Brief withdrawal of WDs reversed MS and signs of MAFLD. However, mild hepatic inflammation was still detectable in HP groups. Conclusions: HP and HP-Trans-WD play a crucial role in the genesis of MS and MAFLD.

Comparative anatomo-radiological study of intrahepatic venous vascularization in the Spain

BACKGROUND

Anatomic variations in the hepatic venous system are the least understood aspect of hepatic anatomy. The variations are diverse, and data are lacking with respect to the population of Spain and methods of detection. The objective was to examine morphological patterns of variations in hepatic venous vascularization using cadaveric dissections vs. radiological imaging, and to analyze the findings with respect to Spain and to published studies.

METHODS

Thirty-one livers were anatomically dissected and analyzed for their hepatic venous anatomy and then compared to the venous anatomy of livers examined in 216 CT scans from 119 men and 97 women, ranging between 27 and 89 years of age. Statistical analysis was done using the Chi squared and Fisher homogeneity tests.

RESULTS

The hepatic portal vein showed morphological variations in cadavers vs. CT of 67.3% vs. 67.6% (p-I), 29% vs. 12.2% (p-II), 0% vs. 14.6% (p-III), 0% vs. 14.6% (p-IV), 3.2% vs. 0.5% (p-V) and 6.5% vs. 1.9% (p-VI), respectively in cadavers vs. CT. Hepatic vein pattern variation were found in 64.5% vs. 50.7% (h-I), 32.2% vs. 31.5% (h-II), 0% vs. 2.3% (h-III), 0% vs. 4.7% (h-IV), respectively in dissections vs. CT). In Accessory Hepatic Veins the frequency in pattern variation was 64.5% vs. 18.8% (a-2.1), 29.0% vs. 8.0% (a-2.2), 58.1% vs. 11.3% (a-2.3), 9.7% vs. 0.9% (a-2.4), 67.7% vs. 16.9% (a-2.5), 9.7% vs. 4.2% (a-2.6) and 0% vs. 0.5% (a-2.7), respectively, in cadavers vs. CT. CT showed in 27.2% no accessory hepatic veins. Sex was not a factor influencing patterns of variation.

CONCLUSION

Anatomical variants of the hepatic portal vein, the hepatic vein and accessory hepatic veins are very diverse and show greater variability in the specimens compared to those detected with radiological images, finding a wider spectrum of variations as it allows the clinician to have a more precise definition of the vasculature. A higher precision in the definition of anatomical variations is warranted for surgical planning in liver resection and transplantation.

The bronchial segmentation and its anatomical variations. A clinical-anatomic and bronchoscopy study

The development in interventional respiratory medicine entails the need of bronchial anatomical knowledge, whose variations assume their greatest importance nowadays. The aim of this study was to describe the frequency of these variations and to analyze the bronchial lengths, barely registered before in literature. This observational descriptive study (from June 2018 until April 2019) was conducted in a sample of 17 pairs of lungs, which were dissected and measured at the Cadaver Donation Centre (Universidad Complutense, Madrid), and a second sample of 50 bronchoscopies, performed at the San Carlos Clinic Hospital, which were analyzed during the procedure. Our results show that there are no significant differences in the incidence of variations by sex in any of both samples, and neither in the average length of any bronchus by sex nor lobar pattern. Left main bronchus presents the longest length and left upper lobe bronchus the shortest. The highest percentage of variations is contained in the right lower lobe (25.4%), and the most frequent variation in the subsuperior bronchus (B*) (19.4%). The middle lobe and the left lower lobe present the lowest percentage of variations (11.9%). Only 37.3% of the pairs of lungs/patients did not have any anatomical variation in the general sample. Despite of the small size of the sample, results show a high percentage of variations and a minority of completely normal pairs of lungs, which invites us to reflect about the probable high prevalence of variations in the general population. Further studies with greater samples are needed to confirm our hypothesis.

Vascular clinical anatomy of the submandibular gland

OBJECTIVE

The aim of this study is to describe in depth the precise anatomy of the vascular supply of the submandibular gland, trying to determine the existence of patterns of glandular vascularization. Knowledge of these patterns could facilitate surgical management of the gland and the submandibular gland flap.

MATERIAL AND METHODS

Neck dissections of formaldehyde preserved human cadavers were performed. Submandibular and transmandibular approaches were used during the dissections. All the vascular branches found were registered and classified into 2groups: main or accessory branches. The anatomical data analyzed was: The diameter and length of the main and accessory branches, as well as the most important measurements of the submandibular gland flap pedicle.

RESULTS

33 glands were dissected to study the arterial supply of the submandibular gland (17 right, 16 left; 17 males, 16 females) and 29 were dissected to study the venous supply (15 left, 14 right; 15 males,14 females). A total of 123 arterial branches were found reaching the 33 submandibular glands (47 main and 76 accessories) and 116 venous branches were found draining the 29 submandibular glands (47 main branches and 69 accessory branches). A constant main venous branch that ran parallel to the Wharton duct and drained in the sublingual vein was found in all of cases (Concomitant Wharton Duct Vein or CWDV).

CONCLUSION

The CWDV is a constant venous branch for the drainage of the gland and should be considered as venous pedicle during the dissection of submandibular gland flaps.

Anatomical study of the masseteric and obturator nerves: Application to face transplant and reanimation procedures

The masseteric nerve (MN) and the anterior branch of the obturator nerve (ON) that innervate the transferred gracilis muscle have proved highly efficient for reanimating paralyzed facial muscles when muscle transfer is required. Previous researchers have published the total axonal load for myelinated fibers in both nerves. However, the real motor axonal load has not been established. We performed the study on 20 MN and 13 ON. The segments of the MN and the ON were embedded in paraffin, sectioned at 10 μm, and stained following a standard immunohistochemical procedure using anti-choline acetyltransferase to visualize the motor fibers. The MN has a higher axonal load than the ON. There were statistically significant differences between the axonal load of the proximal segment of the MN and the ON. These findings confirm that end-to-end anastomoses between the MN and the ON should preferably use the proximal segment. However, MN neurotomy should ideally be performed between the proximal and distal segments, preserving innervation to the deep fascicles. Our results show that the MN is ideal as a donor motor nerve for reinnervating transplanted muscle for dynamic reanimation of the paralyzed face. The neurotomy should ideally be performed between the first and second collateral branches of the MN. Clin. Anat. 32:612-617, 2019. © 2019 Wiley Periodicals, Inc.

The morphogenesis of the renal plexus: Renal artery and sympathetic fibers

To examine the origin and development of the renal plexus and its relationship to the renal vessels in embryos and early human fetuses. Serial sections of 34 human embryos (stages 16 to 23 of Carnegie, 4 or 5-8 weeks) and 38 fetuses (9-19 weeks) were analyzed. Throughout the embryonic period, the kidney was not innervated by the renal plexus. Those nerves appeared at the beginning of the early fetal period (9 weeks) as branches given off by the immature autonomic abdominal plexus. The renal nerves started to approach to the kidney during the early fetal period at 9-10 weeks of development. They were distributed in close proximity to the renal arteries and their branches. They were observed first with the settlement of the renal veins. The renal artery is present as a branch of the abdominal aorta at stage 19 (between 6 and 7 weeks) prior to development of the renal plexus. The renal veins were not present during the embryonic period but appeared at the start of the fetal period, along with the renal nerves that emerged from segmented sympathetic para-aortic bodies (SPBs). Clin. Anat. 32:272-276, 2019. © 2018 Wiley Periodicals, Inc.

Proposal of landmarks for clamping neurovascular elements during endoscopic surgery of the supraglottic region

BACKGROUND

Bleeding within the supraglottic region can be a lethal complication after CO(2) laser microsurgery. Our aim was to propose endoluminal anatomical landmarks to locate the superior laryngeal vessels resulting in a safer microsurgery.

METHODS

Endoluminal dissections were made in 22 larynges without laryngeal disease.

RESULTS

The neurovascular structures were in the superior third of a triangle defined by the vocal process, the anterior commissure, and the epiglottic attachment of the aryepiglottic fold. They overlapped in 4 different ways: pattern I (70.4%): superior laryngeal vein (SLV), superior laryngeal artery (SLA), and internal laryngeal nerve (ILN); pattern II (13.6%): SLA, SLV, ILN; pattern III (4.6%): SLV, ILN, and SLA; pattern IV (4.6%): SLA, ILN, and SLV.

CONCLUSION

Microsurgery in the supraglottic region may be safer if surgeons are aware of the superior third of the above-defined triangle, "danger area", where the vascular elements of this region are located.

Recurrent laryngeal nerve landmarks revisited

BACKGROUND

The aim of this work was to evaluate, to prove their reliability, the different surgical landmarks previously proposed as a mean to locate the recurrent laryngeal nerve (RLN).

METHODS

The necks of 143 (68 male and 76 female) human adult embalmed cadavers were examined. RLN origin and length and its relationship to different landmarks were recorded and results compared with those previously reported. Statistical comparisons were performed using the chi-square test (significance, p ≤ .05).

RESULTS

Mostly, RLN is located anterior to the tracheoesophageal sulcus (41.6%), posterior to the inferior thyroid artery (35.8%), lateral to Berry's ligament (88.1%), below the inferior rim of the inferior constrictor muscle (90.4%), and entering the larynx before its terminal division (54.6%).

CONCLUSIONS

The position of the RLN in relation to those structures classically considered as landmarks is highly variable. The most reliable relationships are those with Berry's ligament or the inferior constrictor muscle.

The central projections of the laryngeal nerves in the rat

The larynx serves respiratory, protective, and phonatory functions. The motor and sensory innervation to the larynx controlling these functions is provided by the superior laryngeal nerve (SLN) and the recurrent laryngeal nerve (RLN). Classical studies state that the SLN innervates the cricothyroid muscle and provides sensory innervation to the supraglottic cavity, whereas the RLN supplies motor innervation to the remaining intrinsic laryngeal muscles and sensory innervation to the infraglottic cavity, but recent data suggest a more complex anatomical and functional organisation. The current neuroanatomical tracing study was undertaken to provide a comprehensive description of the central brainstem connections of the axons within the SLN and the RLN, including those neurons that innervate the larynx. The study has been carried out in 41 adult male Sprague-Dawley rats. The central projections of the laryngeal nerves were labelled following application of biotinylated dextran amines onto the SLN, the RLN or both. The most remarkable result of the study is that in the rat the RLN does not contain any afferent axons from the larynx, in contrast to the pattern observed in many other species including man. The RLN supplied only special visceromotor innervation to the intrinsic muscles of the larynx from motoneurons in the nucleus ambiguus (Amb). All the afferent axons innervating the larynx are contained within the SLN, and reach the nucleus of the solitary tract. The SLN also contained secretomotor efferents originating from motoneurons in the dorsal motor nucleus of the vagus, and special visceral efferent fibres from the Amb. In conclusion, the present study shows that in the rat the innervation of the larynx differs in significant ways from that described in other species.

The clinical interest of the ary-thyro-cricoid fascicle

The aim of this work was to study the prevalence and form of the ary-thyro-cricoid (ATC) muscular fascicle, a variable muscular slip connecting the oblique and/or transverse arytenoid muscles with the thyroarytenoid (TA) and/or lateral cricoarytenoid (LCA) muscles resembling a sphincter encircling the glottis. Thirty larynges obtained from necropsies of individuals with no known laryngeal pathology were dissected. The ATC fascicle was observed in 96.7% of the larynges. It appeared bilaterally in 60% of subjects and unilaterally in 36.7%. The posterior attachment of the muscular slip was observed to be in common with either the transverse arytenoid (34%), or the oblique arytenoid (28%) or both muscles (38%). Its fibers terminated by intermingling with either those of the LCA muscle (10.6%), or the TA muscle (38.3%) or both (51.1%). These variable attachments mean that there are nine possible variants of this muscular fascicle. The ATC fascicle was supplied by branches originating bilaterally from the recurrent laryngeal (RLN) and internal laryngeal nerves. The existence of this ATC fascicle could explain the variable position (intermediate, paramedian or lateral) adopted by the vocal folds after lesion of the RLN. The bilateral disposition and innervation of the fascicle could also complicate the interpretation of electromyographic techniques used for testing laryngeal nerve function.

Anatomical variations of the superior thyroid and superior laryngeal arteries

BACKGROUND

There are known to be variations in the origins of the superior thyroid artery (STA), an important surgical landmark, and 1 of its branches, the superior laryngeal artery (SLA).

METHODS

Three hundred thirty human embalmed heminecks were dissected. The results of previous studies were reviewed, and a meta-analysis is presented.

RESULTS

Four different origins for the STA were found. The most frequent was type I, from the carotid bifurcation (49%). Four different origins were also found for the SLA being the most frequent the type I in which the artery arose from STA (78%). The mean external diameters of STA and SLA were 0.26 and 0.20 cm, respectively, with no statistically significant differences by side or sex.

CONCLUSION

Variations in the origin of STA and SLA from the carotid arterial tree and the similarity of their diameters mean that there is a significant possibility of their misidentified during surgery.

Ceratocricoid muscle: an embryological and anatomical study

This study aimed to document the prevalence and morphology of the ceratocricoid muscle in a large sample of fetuses and adults and to explain its possible origin in a sample of embryos. Forty-five embryos, thirty-four fetuses, and ninety human larynges from adults with no known laryngeal pathology were studied. The muscle was observed in 23% of the fetal sample and in 14% of the adult sample. No significant differences were observed in the laterality in any of the groups. The ceratocricoid muscle is attached between the cricoid lamina and the inferior horn of the thyroid cartilage and also into the capsule of the cricothyroid joint. The muscle is innervated by several branches (between one and three) from the anterior division of the recurrent laryngeal nerve as it courses behind the cricothyroid joint. The ceratocricoid muscle develops from tissue within the mesenchymal bridge which connects the external and internal laryngeal sphincters or rings from embryonic stages 15-20. The close relationship of the ceratocricoid muscle to the recurrent laryngeal nerve could mean that it can exert pressure on this nerve. This may be a possible explanation for the causation of certain idiopathic recurrent laryngeal nerve palsies.

[On the number and morphometrical parameters of the nucleus ambiguous neurons after the injury and regeneration of the recurrent laryngeal nerve in the rat]

INTRODUCTION AND OBJECTIVES

In laryngeal nerves injuries it is essential to know the morpho-functional reorganization of the neurons which supply the larynx in order to be successful with the clinical techniques of functional reinnervation and/or orthotopic transplant. Due to the lack of this type of studies in the literature, we investigated the organization of laryngeal motoneurons in the nucleus ambiguous (NA) after the axotomy and regeneration of the recurrent laryngeal nerve (RLN) in adult rats.

MATERIAL AND METHODS

We used biotinylated dextran amines (BDA, 3 kDa), this fact is an innovation in the field, because this is a novel methodological approach to this model. We studied a control group of 14 animals and four experimental groups of between 10 and 16 animals each one. In the experimental groups we studied the regeneration of the axotomized nerve in four different intervals of time after the injury: 21-28 days, 42-60 days, 90-120 days, and 150-180 days. In the control group we traced the RLN without injury while in the experimental groups we traced the axotomized RLN after each regeneration interval.

RESULTS

The number of traced neurons in the control group was 143 +/- 38; in the experimental groups the number was always lower than in the control (21-28 days: 14 +/- 23 neurons; 42-60 days: 46 +/- 49; 90-120 days: 55 +/- 57; 150-180 days: 61 +/- 60). The morphologic parameters studied within the neuronal bodies in the experimental groups were no statistically different when compared with those in the control group.

CONCLUSIONS

Results show that the tracing of the RLN after its axotomy and regeneration, in the adult rat, involves a decrease in the number of traced neurons within the NA but no changes in their size or shape during the analysed periods.

Patterns of the circumflex femoral arteries revisited

Knowledge of variations of the circumflex femoral arteries is important when undertaking clinical procedures within the femoral region and in hip joint replacement. Since the 19th century, many different patterns have been proposed to classify their origins. This work studied a statistically reliable sample, the lower limbs of 221 embalmed human cadavers (equal right-left and approximately equal sex distributions), and reviewed the previous literature to propose a unified and simple classification that will be useful to clinicians. Statistical comparisons were made using the chi(2) test. The medial and lateral circumflex femoral arteries have been classified into three different patterns based on the levels of their origin. Distribution related to sex and side was also studied. Pattern I: Both arteries arose from the deep femoral artery (346 cases, 78.8%). This pattern was more frequent in females, P = 0.01. There was no significant difference between sides. Type Ia, medial circumflex femoral artery origin was proximal to the lateral circumflex femoral artery origin (53.2%); Type Ib, lateral circumflex femoral artery origin was proximal to medial circumflex femoral artery origin (23.4%); Type Ic, both arteries arose from a common trunk (23.4%). Pattern II: One of the arteries arose from the femoral artery and the other from the deep femoral artery (90 cases, 20.5%). Type IIa, the medial circumflex femoral artery arose from the femoral artery (77.8%) and Type IIb, the lateral circumflex femoral artery arose from the femoral artery (22.2%). There were no significant differences between sexes or sides. Pattern III: Both arteries arose from the femoral artery (2 cases, 0.5%). In every disposition there was a significantly higher prevalence of unilateral rather than bilateral occurrence. In one dissection the medial circumflex femoral artery was absent. Awareness of these variations could avoid unexpected injuries.

Femoral nerve entrapment: A new insight

Compression of the femoral nerve in the iliac fossa has been reported as a consequence of several pathologies, but never as a result of muscular compression. Aberrant slips of iliacus, however, have occasionally been reported to cover or split the femoral nerve. This study aimed to assess such variations as potential factors in femoral nerve compression. A large and homogeneous sample of 121 embalmed cadavers (242 specimens) was studied. Statistical comparisons were made using the chi-squared test. Muscular slips from iliacus and psoas, piercing or covering the femoral nerve, were found in 19 specimens (7.9%). No significant differences by sex or side were found. The more frequent variation was piercing of the femoral nerve by a muscular slip (17 specimens, 7.0%). The nerve then entered the thigh as one or more branches. The less frequent variation found was a muscular slip or sheet covering the femoral nerve as it lay on iliacus (2 specimens, 0.8%). Each disposition may be a potential risk for nerve entrapment.

[Central projections of the rat recurrent laryngeal nerve]

Laryngeal nerves contain the fibres that control the laryngeal function. The studies carried out on the rat with the purpose of having a better knowledge of the functional components and the real origin of the fibres conveyed by the recurrent laryngeal nerve (RLN) are few and in disagreement. No one of such papers were developed using biotinylated dextrane amines (BDA), a powerful tool for tracing neural pathways. The aim of our study was to identify in the rat using BDA, the nuclei of real origin of the fibres of the RLN, knowing in this way the functional components of this nerve. The study has been developed in 31 adult male Sprague-Dawley rats, applying the BDA into the lesioned RLN. The results obtained in all the animals show that the rat's RLN does not contain afferent fibres, whereas the efferent fibres were originated within the ipsilateral nucleus ambiguus (NA). So, in the rat, the RLN seems to contain exclusively efferent fibres, probably been the superior laryngeal nerve who conveyed the afferent fibres.

Proyecciones centrales del nervio laríngeo superior de la rata

Laryngeal nerves contain the fibres that control the laryngeal function. On the rat, the studies on the functional components and the real origin of the fibres conveyed by the superior laryngeal nerve (SLN) are few. No one of such works were developed using biotinylated dextrane amines (BDA), a powerful tool for tracing neural pathways. The aim of our study was to identify by using BDA, in the rat, the nuclei of real origin of the fibres of the SLN, knowing in this way the functional components of this nerve. The study has been developed in 11 adult male Sprague-Dawley rats, applying the BDA into the damaged SLN. The results obtained in all the animals shown that the rat SLN carries efferent fibres originated within the ipsilateral nucleus ambiguous (NA) and dorsal nucleus of the vagus (DNV), and that afferent fibres reach the tractus solitari and the nucleus tractus solitari. So, in the rat, the SLN seems to convey efferent fibres from the NA and DNV and, probably, all the laryngeal afferent fibres.

Morfometría de los nervios laríngeos recurrentes de la rata

In mammals the recurrent laryngeal nerves are dissimilar in length between both sides. This asymmetry involves different time of arrival of the stimulus to the laryngeal musculature controlled by each nerve. Thus, several explanations have been addressed to elucidate the closest of the glottis at the same time despite the unlike length of the nerves. However, previous works on the topic lack of several important data. The present study compares, in two groups of 10 and 6 rats, the length and the composition of myelinated fibers in the recurrent laryngeal nerves of both sides, by means of light microscopy and a computerized morphometric analysis. The results show a mean difference of 0,84 cm longer the left than the right recurrent laryngeal nerve. No statistical differences were observed in the number of myelinated fibers between both sides. However, the myelinated fibers of the right side were statistically bigger in diameter than the fibers of the left side. The data are discussed in the context of the mechanisms for the compensation of the dissimilar length of both recurrent laryngeal nerves.

Variability in nerve patterns of the adductor muscle group supplied by the recurrent laryngeal nerve

INTRODUCTION

Accurate knowledge of the nerve supply of each individual muscle is needed to achieve a successful selective reinnervation of the larynx. The aim of the present work was to study the nerve supply of the adductor laryngeal muscles supplied by the recurrent laryngeal nerve.

STUDY DESIGN

Morphologic study of human larynges.

METHODS

The muscular nerve supply was studied in a total sample of 75 human larynges obtained from necropsies (47 males and 28 females, age range from 41-95 years) and examined by careful dissection using a surgical microscope.

RESULTS

The arytenoid muscle received one branch from each recurrent nerve. In 88% of cases, this branch arose in a common trunk with the upper branch of the posterior cricoarytenoid muscle. In 8% of cases, the nerve for the arytenoid muscle also had a branch going to the lateral cricoarytenoid muscle. The arytenoid muscle also received from one to three pairs of branches from the posterior division of the internal laryngeal nerve; these were interconnected ipsi- and contralaterally and were also connected to the two branches coming from the recurrent laryngeal nerve. The lateral cricoarytenoid muscle received from one to six branches from the recurrent nerve, but in 5.8% of cases, it also received a twig from a connecting branch between the recurrent nerve and the external (5.6%) or the internal laryngeal nerves (0.2%). The thyroarytenoid muscle received from one to four branches from the recurrent nerve, but in 5.6% of cases, it also received a twig from a connecting branch between the recurrent nerve with the external (4.6%) or the internal (1%) laryngeal nerves.

CONCLUSION

No abductor or adductor division of the recurrent laryngeal nerve was found in the present study. In 88% of cases, the nerve supply to the arytenoid muscle (adductor) and the posterior cricoarytenoid muscle (abductor) arose from a common trunk, which in 8% of cases, also had a branch to the lateral cricoarytenoid muscle. Furthermore, the high incidence of branches innervating the adductor muscles from connections between the recurrent laryngeal nerve and the internal and external laryngeal nerves led us to reconsider the contribution of these nerves in the supply to this muscle group.

Variability of the nerve supply patterns of the human posterior cricoarytenoid muscle

OBJECTIVES/HYPOTHESIS

To achieve a successful selective reinnervation of the larynx, an accurate knowledge of the nerve supply of each individual muscle is required. The posterior cricoarytenoid muscle, the only abductor or respiratory muscle of the larynx, plays a vital role in cases of recurrent palsy and orthotopic transplantation. Descriptions of the posterior cricoarytenoid muscle nerve supply pattern vary considerably. The goal of the present study was to establish an accurate morphological description of the posterior cricoarytenoid muscle nerve supply in a large sample of human larynges.

STUDY DESIGN

Morphologic study of human larynges.

METHODS

The posterior cricoarytenoid muscle nerve supply was studied in a total sample of 75 human larynges obtained from necropsies (47 male and 28 female samples; age range, 41-95 y) and examined by careful dissection using a surgical microscope.

RESULTS

The posterior cricoarytenoid muscle nerve supply in all cases (100%) came from the anterior division of the recurrent nerve. However, in six cases (4%) a small branch also arose from the ramus anastomoticus. The number of branches coming from the anterior division varied, ranging from one to six. The two-branch pattern was the most frequent (42.7%), followed by the three-branch pattern (34%) and the one-branch pattern (7.3%). The remaining 16% of cases showed patterns of four, five, or six branches. When two or more branches were present, a connection between them was observed in 64% of cases. Five different types of origin of the various branches were observed along the course of the recurrent nerve in relation to the cricothyroid joint: type a, vertical segment below the cricothyroid joint (7.5%); type b) vertical segment behind the cricothyroid joint (40.5%); type c) vertical segment just above the cricothyroid joint (16%); type ) from the genu, in common with the arytenoid branch, above the cricothyroid joint and just below the cricoarytenoid joint (34%); and type e) oblique segment (2%).

CONCLUSION

Despite the variability of the innervation of the posterior cricoarytenoid muscle and its strong connection with the interarytenoid nerve, this should not preclude successful reinnervation.

Is the external laryngeal nerve an exclusively motor nerve? The cricothyroid connection branch

OBJECTIVES

To obtain an accurate morphological description of the nerve that provides communication between the external laryngeal nerve and the recurrent laryngeal nerve in a large sample of human larynges.

STUDY DESIGN

Morphological study of human larynges.

METHODS

Microdissection of 103 human larynges obtained from necropsies was performed. Both the external laryngeal nerve and the recurrent laryngeal nerve were identified and dissected. The existence of a communication between the two nerves was evaluated.

RESULTS

A neural communication between the external laryngeal nerve and the recurrent laryngeal nerve was found in 85% of the larynges studied (bilaterally in 44% and unilaterally in 41%). Two patterns of communication (with single or double branches) were found. The communication between the nerves can appear at different levels, giving off collateral branches to the cricothyroid muscle (23%), the cricothyroid joint capsule (49%), and the subglottic mucosa (50%).

CONCLUSIONS

The nerve supply of the human larynx is more complex than classically considered. Our study does not support the classic neuroanatomical belief that the external laryngeal nerve is purely a motor nerve to the cricothyroid muscle. Our results reveal that it carries sensory and motor fibers on to other muscles (thyroarytenoid) or regions (subglottis mucosa and cricothyroid joint), as has been demonstrated in experimental studies in cats and dogs.

[Glottic immobility: retrospective study of 229 cases]

A retrospective study of the unilateral and bilateral vocal fold immobility cases diagnosed at our hospital between 1985 and 1998 was carried out. Of the 229 cases studied, vocal fold immobility was bilateral in 58 patients (25%), unilateral right in 60 (26%), and unilateral left 111 (49%). The most frequent etiologies in the bilateral cases were thyroid surgery (38%) and prolonged intubation (31%); idiopathic cases (32%) and thyroid surgery (23%) in the unilateral right cases; and idiopathic cases (28%) and extralaryngeal tumors (22%) in the unilateral left cases. Clinical compensation was achieved in more than 85% of cases of unilateral immobility when the etiology was idiopathic or due to surgical damage to the recurrent or vagus nerves, 70% when it was a prolonged intubation, 56% in neurological patients and 38% in extralaryngeal tumors. In patients with bilateral vocal fold immobility, 14% did not require any treatment, 34% had a permanent tracheostomy, and 52% recovered adequate naso-oral ventilation after surgery (tracheostomy only in 12 patients and arytenoidectomy in 18 patients).

An anatomical study of anastomoses between the laryngeal nerves

OBJECTIVE

To systematize the anatomy of the connecting branches between laryngeal nerves.

METHODS

Microdissection of 90 larynges obtained from necropsies (57 men and 33 women; age range, 41-95 y).

RESULTS

Anastomoses between the internal and recurrent nerves appeared in four different patterns: 1) Galen's anastomosis, as the connection between the dorsal branches of both nerves (100%); 2) arytenoid plexus, as the connection between the arytenoid branches of both nerves, in relation with the arytenoid muscle, and divided in a deep part (100%) and a superficial part (86%); 3) cricoid anastomosis, previously only described in cows, located in the front of the cricoid lamina (6/10 cases); and 4) thyroarytenoid anastomosis, as the connection of a descending branch of the internal laryngeal nerve and an ascending branch of the recurrent nerve (14%). Anastomosis between the internal laryngeal and the external laryngeal nerves appeared as a connecting branch throughout the foramen thyroideum (21%). Anastomosis between the external laryngeal and recurrent nerves appeared as a connecting branch throughout the cricothyroid muscle (68%).

CONCLUSION

At least two anastomoses (Galen's anastomosis and arytenoid plexus) appeared in 21% of hemilarynges, and 79% of cases had three or more anastomoses between the laryngeal nerves. The different prevalence of this complex anastomotic pattern suggests functional differences in the sensory and motor innervation of individual subjects.

Foramen thyroideum: a comparative study in embryos, fetuses, and adults

The incidence and characteristics of foramen thyroideum (FT) in embryonic and/or fetal larynges have not been established. In the present study, 90 adult larynges and 53 embryonic-fetal larynges were studied. The incidence of FT during the embryonic-fetal period (57%) was statistically different from the adult period (31%) (P = 0.005). All the FT found in the adult period contained vessels and/or nerves, while in the embryonic and fetal period only 63% presented neurovascular elements (P < 0.001). The origin of FT in the embryonic period and its persistence during adult life is discussed.

Case report: cleidocervical or levator claviculae muscle. A new embryological explanation as to its origin

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