Dissecção do plexo cervical na formação médica: aplicabilidades clínicas e cirúrgicas / Dissection of the cervical plexus in medical training: clinical and surgical applicabilities

A Anatomia da região cervical é de particular importância para os clínicos e cirurgiões de diversas especialidades médicas. Em se tratando da organização nervosa presente na região anterolateral do pescoço, encontra-se o plexo cervical, formado pelos ramos anteriores dos nervos cervicais C1 a C4, cuja função é promover a sensibilidade da pele anterolateral cervical, torácica anterossuperior e do couro cabeludo posterior, na cabeça, além de controlar a musculatura infra-hióidea e diafragmática. Logo, lesões a essa estrutura nervosa e aos seus ramos podem causar graves complicações ao corpo humano. Esse trabalho objetivou utilizar a dissecção da região anterolateral do pescoço como uma ferramenta pedagógica para o estudo das relações anatômicas dos nervos do plexo cervical observados durante essa prática, assim como relatar algumas de suas importâncias clínicas e cirúrgicas. O presente estudo é caracterizado como qualitativo/descritivo. A dissecção foi realizada semanalmente, durante o segundo semestre de 2018 e o primeiro semestre de 2019, com a supervisão do professor responsável e auxílio do técnico de laboratório, no Laboratório de aulas práticas da Universidade Estadual de Londrina (UEL). Considera-se que a dissecção da região anterolateral do pescoço permitiu a visualização de diversos nervos cutâneos e musculares do plexo cervical, assim como de alguns de seus ramos e suas relações anatômicas. Também contribuiu para o conhecimento da topografia em que se encontravam tais estruturas e sua organização em camadas. Esse conhecimento anatômico é essencial para a prática médica, tanto clínica quanto cirúrgica.(AU)

The anatomy of the cervical region is of particular importance for surgeons and physicians of different medical specialties. The cervical plexus can be found in the anterolateral region of the neck, formed by the anterior branches of the cervical nerves C1 to C4, whose function is to promote the sensitivity of the cervical anterolateral skin, anterosuperior thoracic skin, and posterior scalp, on the head, in addition to controlling the infrahyoid and diaphragmatic muscles. Therefore, injuries to this nervous structure and its branches may cause serious complications to the human body. This work aimed at using the dissection of the anterolateral neck region as a pedagogical tool for the study of the anatomical relationships of the cervical plexus nerves observed during this practice, as well as to highlight some of its clinical and surgical importance. This is a qualitative/descriptive study. The dissection was performed weekly, during the second semester of 2018 and the first semester of 2019, with the supervision of the professor in charge and the assistance of the laboratory technician at the Laboratory of Practical Classes at the State University of Londrina (UEL). It is considered that the dissection of the anterolateral neck region allowed the visualization of several cutaneous and muscular nerves present in the cervical plexus. It also contributed to the knowledge of the topography in which these structures were found and their organization in layers. This anatomical knowledge is essential for both clinical and surgical medical practice.(AU)

Classification of the patterns of the emerging branches of the superficial cervical plexus / Clasificación de los patrones de las ramas emergentes del plexo cervical superficial

SUMMARY: The cutaneous branches of the superficial cervical plexus (SCP) emerge at variable points, from beneath the posterior margin of the sternocleidomastoid muscle and from this point radiate like "spokes of a wheel" antero-inferiorly and postero-superiorly. This study aimed to classify the emerging points of the branches of the superficial cervical plexus in relation to their location on the sternocleidomastoid muscle. In order to classify the emerging points of the superficial cervical plexus, the sternocleidomastoid muscle was first measured from mastoid process to clavicle; subsequently each branch of the superficial cervical plexus was measured from the mastoid process to their exit points. The emerging points of the superficial cervical plexus branches were classified according to Kim et al. (2002) seven categories: Type I (32 %); Type II (13 %); Type III (35 %); Type IV (13 %); Type V, VI, VII (2 %). The order in which the superficial cervical plexus branches emerged from the posterior margin of the sternocleidomastoid muscle remained constant, i.e. lesser occipital, great auricular, transverse cervical and supraclavicular nerves. Knowledge of emerging points may assist in the effective anaesthesia to all branches of the superficial cervical plexus during surgical procedures of the neck, viz. carotid endarterectomy and thyroid surgery.

RESUMEN: Las ramas cutáneas del plexo cervical superficial (SCP) emergen en puntos variables, desde el margen pos- terior del músculo esternocleidomastoideo y desde este punto inferior irradian como "radios de rueda" anteroinferior y postero-superior. Este estudio tuvo como objetivo clasificar los puntos emergentes de las ramas del plexo cervical superficial en relación a su ubicación en el músculo esternocleidomastoideo. Para clasificar los puntos emergentes del plexo cervical superficial, primero se midió el músculo esternocleidomastoideo desde el proceso mastoides hasta la clavícula; posteriormente se midió cada rama del plexo cervical superficial desde el proceso mastoideo hasta sus puntos de salida. Los puntos emergentes de las ramas del plexo cervical superficial se clasificaron según Kim et al. (2002) en siete categorías: Tipo I (32 %); Tipo II (13 %); Tipo III (35 %); Tipo IV (13 %); Tipo V, VI, VII (2 %). El orden en el que las ramas del plexo cervical superficial emergían del margen posterior del músculo esternocleidomastoideo se mantuvo constante, es decir, los nervios occipital menor, auricular magno, cervical transverso y supraclavicular. El conocimiento de los puntos emergentes puede ayudar a la anestesia eficaz de todas las ramas del plexo cervical superficial durante los procedimientos quirúrgicos del cuello, a saber, endarterectomía carotídea y cirugía de tiroides.

The Ansa Cervicalis in Fetuses / El Asa Cervical en Fetos

The formation of ansa cervicalis (AC) is somewhat complex with both its course and location along the common carotid artery and internal jugular vein (IJV) varying. The aim of the study was to document the anatomy, formation and variations of AC. Forty fetuses (gestational age: 15 to 28 weeks) were obtained from the Department of Clinical Anatomy, Westville Campus, UKZN. A detailed micro-dissection of the posterior triangle of the neck and AC were completed using standard micro-dissecting instruments. Results of the formation of AC, its relationship to IJV and variations were recorded. The superior root was identified as a long willowy nerve that branched from the hypoglossal nerve, descended on the carotid sheath, anterior to the common carotid artery and IJV in 70 % and posterior to IJV in 30 % of the specimens. The inferior root of AC originated from the ventral rami of C2-C3 in 26%; ventral ramus of C3 in 58% and ventral ramus of C2 in 16%. Variations: a) Formation: (i) Dual formation of AC: The Hypoglossal nerve formed separate loops with the ventral rami of C2 and C3 (3%); (ii) "W" shaped appearance of AC above the superior belly of omohyoid (1%); (iii) A "vago-cervical complex" 3%; b) Origin and course: The superior root of AC received a contribution from the hypoglossal nerve, a short distance later it formed a loop around the IJV to ascend to the ventral ramus of C2 as the inferior root. The precise understanding of the anatomy of AC together with variations may assist anesthetists and surgeons to accurately identify the vascular and neural relations during surgical procedures.

La formación del asa cervical (AC) compleja, tanto en su curso como en ubicación, pueden variar a lo largo de la arteria carótida común y de la vena yugular interna (VYI). El objetivo del estudio fue determinar la anatomía, formación y variaciones del AC en fetos humanos. Cuarenta fetos (edad gestacional: 15 a 28 semanas) fueron obtenidos desde el Departamento de Anatomía Clínica, Westville Campus, UKZN. En cada muestra se realizó una detallada microdisección del triángulo posterior del cuello y del AC utilizando instrumental de microdisección estándar. Fueron registrados los resultados de la formación del AC, su relación con VYI y sus variaciones. La raíz superior fue identificada como un nervio largo y delgado que se ramificaba desde el nervio hipogloso, descendía por la vaina carotídea, anterior a la a. carótida común y la VYI en el 70% de los casos, y posterior a la VYI el 30%. La raíz inferior del AC se originaba desde los ramos ventrales de C2-C3 en el 26% de los casos; desde el ramo ventral de C3 en el 58% y desde el ramo ventral de C2 en 16% de los casos. Se observaron variaciones de formación: (i) dual del AC: el nervio hipogloso formó asas separadas con los ramos ventrales de C2 y C3 (3%), (ii) forma aparente de "W" sobre el vientre superior del m. omohioideo (1%) y (iii) un "complejo vago-cervical" (3%), y variaciones de origen y curso: la raíz superior del AC recibió una contribución del nervio hipogloso, y a corta distancia formó un bucle alrededor de la VYI para ascender al ramo ventral de C2 como una raíz inferior. El conocimiento preciso de la anatomía del AC junto con variaciones pueden ayudar a identificar con precisión las relaciones vasculares y neuronales durante los procedimientos quirúrgicos a anestesistas y cirujanos.

Communication of the anterior branch of the great auricular nerve with the cervical branch of facial nerve and its variant nerve endings deep in the parotid gland / Comunicación del ramo anterior del nervio auricular mayor con el ramo cervical del nervio facial y sus terminaciones nerviosas profundas variantes en la glándula parótida

The communications between the branches of cervical plexus and cervical branch of facial nerve are common and are well known. However, this communication usually occurs between the transverse cervical nerve and cervical branch of facial nerve. During routine dissection classes for the Medical undergraduate students, we came across an anatomical variant of anterior division of great auricular nerve. This variation was found in a 60-year-old male cadaver of South Indian origin and it was unilateral. The great auricular nerve arose from the loop of ventral rami of C2 and C3 spinal nerves and divided into anterior and posterior branches. The anterior branch ran obliquely upwards and forwards on the surface of the sternocleidomastoid muscle along with the external jugular vein towards the apex of parotid gland and divided into many branches. One of these branches gave a communicating branch to cervical branch of facial nerve outside the parotid gland. Nerve endings of the remaining branches were found to penetrate the interlobular septa and a few of them were seen deep in the gland along the ducts and near the vessels. The functional significance of anatomic variations of nerve endings in relation to ducts, thin vessels deep in the parotid gland, observed in the present case are yet to be evaluated...

Las comunicaciones entre los ramos del plexo cervical y ramo cervical del nervio facial son comunes y bien conocidos. Sin embargo, esta comunicación por lo general ocurre entre el nervio cervical transverso y el ramo cervical del nervio facial. Durante las clases de disección de rutina para los estudiantes de pregrado de medicina, nos encontramos con una variante anatómica de la división anterior del nervio auricular mayor, unilateral, en un cadáver de sexo masculino de 60 años, del Sur de la India. El nervio auricular mayor se originó desde el bucle de los ramos ventrales de los nervios espinales C2 y C3, y dividió en ramos anterior y posterior. El ramo anterior se dirigió oblicuamente hacia arriba y adelante sobre la superficie del músculo esternocleidomastoideo junto con la vena yugular externa hacia el ápice de la glándula parótida y se dividió en numerosos ramos terminales. Uno de estos ramos dió un ramo comunicante al ramo cervical del nervio facial fuera de la glándula parótida. Las terminaciones nerviosas de los ramos restantes penetraron en los septos interlobulares. Algunos de éstos se observaron profundos en la glándula a lo largo de los conductos y cerca de los vasos. La importancia funcional de las variaciones anatómicas de las terminaciones nerviosas en relación a los conductos y vasos finos profundos en la glándula parótida aquí observados aún no se han evaluado...

The lesser occipital nerve in fetuses / El nervio occipital menor en fetos

The lesser occipital nerve (LON) is an ascending superficial branch of the cervical plexus that has a variable origin either from the ventral ramus of the second cervical nerve or second and third cervical nerves and is purely sensory. Forty fetuses (right side: 40/80; left: 40/80) with gestational ages between 15 to 28 weeks were microdissected to document the anatomy of the LON. Results: a) Incidence and Morphometry: LON present in 100 percent specimens, with average length on the right and left sides of 23.59 +/- 2.32 mm and 23.45 +/- 2.27 mm, respectively; b) Course: In its ascent towards the occipital region, the LON was located on the splenius capitus muscle in 85 percent of specimens and in 15 percent of the specimens, it ascended vertically on the sternocleidomastoid muscle towards the ear, innervating its superior third; c) Branching pattern: LON displayed (i) single: 70 percent; (ii) duplicate: 26 percent and (iii) triplicate: 4 percent patterns; d) Variation in the course of LON was observed in 6 percent of the specimens. Knowledge of the anatomy and variations of the LON may assist in the understanding of cervicogenic headaches and may be of assistance to anesthetists performing regional anesthesia for surgical procedures in the neck.

El nervio occipital menor (NOM) es una rama ascendente superficial del plexo cervical que tiene un origen variable ya sea del ramo ventral del segundo nervio cervical o de los nervios cervicales segundo y tercero, y es solamente sensitivo. Cuarenta fetos (lado derecho: 40/80; izquierdo: 40/80), con edades gestacionales de 15 a 28 semanas fueron microdisecados para documentar la anatomía del NOM. a) Incidencia y morfometría: el NOM estuvo presente en el 100 por ciento de los especímenes, con una longitud media de los lados derecho e izquierdo de 23,59 +/- 2,32 mm y 23,45 +/- 2,27 mm, respectivamente; b) Curso: en su ascenso hacia la región occipital, el NOM se localiza en el músculo esplenio de la cabeza en el 85 por ciento de las muestras y en el 15 por ciento de las muestras, ascendió verticalmente sobre el músculo esternocleidomastoideo hacia el oído, inervando el tercio superior, c) Patrón de ramificación: el NOM se observa (i) individual: 70 por ciento, (ii) duplicado: 26 por ciento y (iii) triplicado: 4 por ciento de los patrones; d) Variación en el curso de NOM se observó en el 6 por ciento de las muestras. El conocimiento de la anatomía y las variaciones del NOM puede ayudar en la comprensión de los dolores de cabeza cervical y puede ser de ayuda a los anestesiólogos a realizar la anestesia regional para procedimientos quirúrgicos en el cuello.

Histological description of the interaction between muscle fibers and connective tissue of the fascia of the human trapezius muscle / Descripción histológica de la interacción entre las fibras musculares y tejido conectivo de la fascia del músculo trapecio humano

The skeletal muscle fascia corresponds to a condensation of connective tissue. Fascias are highly innervated and sensitive, and can cover non-expandable structures as well as musculature. It is suggested that fascias have a pivotal role in functions such as postural regulation, peripheral motor coordination and proprioception. Also, the presence of inflammation and microcalcification in fascia of patients with localized muscle pain has been described, suggesting a pathogenic role in pain. The aim was to describe the histological structure of the external deep fascia of the trapezius muscle, with emphasis on the content and arrangement of muscle fibers, type I collagen, and adipose tissue. Sample material was obtained from a male cadaver (60-70 years old), by dissection of the posterior cervical region of the superficial fascia of the trapezius muscle and fixed in buffered formalin. Samples were processed by routine histological techniques and embedded in paraffin, obtaining 5 µm-thick sections that were stained according to the van Gieson technique. The trapezius fascia is composed of type I collagen, organized into high-density collagen bundles and oriented in different directions, and by adipocytes disposed in longitudinal groups on the main axis of the fascia. Muscle fibers are organized into bundles that are inserted laterally on the thickness of the fascia. It is possible that lateral transmission of tensional forces between the fibers might be present.

La fascia del músculo esquelético corresponde a una condensación de tejido conectivo. Las fascias están inervadas y son sensibles y pueden cubrir estructuras no distensibles, así como las fibras musculares esqueléticas. Tienen un rol importante en la regulación de la postura, la coordinación motora periférica y la propiocepción. Además, se ha descrito la presencia de inflamación y microcalcificaciones en la fascia de los pacientes con dolor muscular localizado, lo que sugiere un rol patogénico en el dolor. El objetivo del trabajo fue describir la estructura histológica de la fascia externa profunda del músculo trapecio, con énfasis en el contenido y la disposición de las fibras musculares, colágeno tipo I y el tejido adiposo. Material y métodos: El material de la muestra fue obtenido de un cadáver de sexo masculino (60-70 años), por la disección de la región cervical posterior de la fascia superficial del músculo trapecio e inmediatamente fijado en formalina tamponada (pH 7,2) durante 48 horas. La muestra fue procesada por técnicas histológicas e impregnada en parafina (punto de fusión 56-58 C). Secciones de 5 µm de espesor fueron montadas en láminas silanizada para el desarrollo del protocolo de la técnica de van Gieson. Resultados y discusión: Se observa que la fascia del trapecio está compuesta por tejido conectivo denso irregular con abundante colágeno tipo I, organizado en paquetes grandes como verdaderos haces de colágeno de alta densidad orientada en diferentes direcciones; y por adipocitos dispuestos en grupos longitudinales en el eje principal de la fascia. Las fibras musculares estriadas están organizadas en paquetes que se insertan lateralmente en el espesor de la fascia. Es posible que la transmisión lateral de la tensión entre las fibras esté presente.

Anatomia cirúrgica do nervo acessório espinhal: comoevitar lesões em procedimentos cirúrgicos no trígonocervical posterior / Surgical anatomy of the spinal accessory nerve: how to avoid injuries to the posterior cervical triangle during surgical procedures

Introdução: A síndrome resultante da lesão iatrogênica do nervo acessório espinhal (NAE) secaracteriza por dor, paralisia e escápula alada, estando relacionada a morbidade considerável. Opresente estudo investiga o grau de variação na ramificação e no curso do NAE no trígono cervicalposterior (TCP). Método: A região cervical de oito cadáveres foi dissecada bilateralmente paraexpor o NAE. A ramificação e as variações no curso do NAE no TCP foram registradas. Medidasrelacionadas a estruturas anatômicas do Músculo Esternocleidomastóideo (MEC) e do MúsculoTrapézio (MTZ) foram analisadas. Resultados: As 16 dissecções demonstraram padrão de ramificaçãodo NAE como: nenhum ramo em 25%, um ramo em 37,5% e dois ramos em 37,5%dos casos. Considerável variação foi observada na anatomia regional do NAE no TCP. Medidasrevelaram que o NAE tem relação relativamente constante com o nervo auricular magno (NAM)e esta é uma importante referência anatômica para identificação do NAE no TCP. Conclusões:O NAM é uma referência anatômica útil para a identificação do NAE no TCP. Essa abordagemsugere uma possibilidade para diminuição de lesão iatrogênica do NAE, frequentemente relacionadaà manipulação cervical de estruturas anatômicas adjacentes sem exposição direta do nervo.

Background: The resulting syndrome from iatrogenic injury to the spinal accessory nerve (SAN)is characterized by pain, paralysis and winging of the scapula are often the source of considerablemorbidity. This study analyses the degree of ramification and variations of the SAN at the posteriortriangle (PT). Method: The necks of 8 adult cadavers were dissected bilaterally to expose the SAN.The ramifications and variations of the SAN at the PT were recorded. Measurements related toanatomical landmarks of the Sternocleidomastoid Muscle (SM) and the Trapezius Muscle (TM)were analyzed. Results: The sixteen dissections performed showed the ramification pattern ofthe SAN as: no ramus in 25%, one ramus in 37.5% and 2 ramus in 37.5% of cases. Considerablevariation was seen in regional anatomy of the SAN at the PT. Measurements revealed that the SANhas a relatively constant relationship with the great auricular nerve (GAN) and this is a importantlandmark for the identification of the SAN at the PT. Conclusions: The GAN is a useful landmarkfor identification of the SAN at the PT. This approach suggests a possibility to decrease theincidence of iatrogenic injury of the SAN, that is frequently related to dissection of surroundinganatomical structures and reduced direct exposure of the nerve.

Unusual organization of the ansa cervicalis: a case report

The superior root of the ansa cervicalis is formed by C1 fibers carried by the hypoglossal nerve, whereas the inferior root is contributed by C2 and C3 nerves. We report a rare finding in a 40-year-old male cadaver in which the vagus nerve fused with the hypoglossal nerve immediately after its exit from the skull on the left side. The vagus nerve supplied branches to the sternohyoid, sternothyroid and superior belly of the omohyoid muscles and also contributed to the formation of the superior root of the ansa cervicalis. In this arrangement, paralysis of the infrahyoid muscles may result following lesion of the vagus nerve anywhere in the neck. The cervical location of the vagus nerve was anterior to the common carotid artery within the carotid sheath. This case report may be of clinical interest to surgeons who perform laryngeal reinnervation and neurologists who diagnose nerve disorders.

venous plexus around the vertebral artery; does it deserve the term [the atlanto-occipital cavertous sinus]

The brain is supplied with arterial blood via 4 major arteries of two arterial systems. It is well known that the intracranial arteries have a different structure than the extracranial [loosing their elastic, collagenous, and muscular elements, thus becoming thinner]. There is a circumscribed transitional pattern portion in both arterial systems. This transitional pattern portion of the carotid artery [petrous cavernous portion] is the intracavernous portion of the artery. Is there any functional relevance of the complex cavernous venous structure to surround this transitional arterial segment? Does the vertebral artery also have a similar complex venous structure surrounding the transitional pattern portion? If so, is there any functional importance or relation to health and disease of such a complex structure? We studied in depth and detail both the gross and the microsurgical anatomy of the suboccipital region where the vertebral artery transgress the base of the skull before penetrating the dun. This area contains the complex of the vertebral artery [VA], its periarterial autonomic neural plexus, its branches, and the adjacent spinal nerves, all of which are cushioned in a rich venous compartment. This region can be the site of vascular, neoplastic, degenerative, congenital, or traumatic diseases, the surgical management of which demands an in depth understanding of the anatomy. We concentrated upon the third segment [V3] of the VA, which extends from the transverse foramen of the axis to the dural penetration of the VA. We also studied the surrounding venous structures of V3 Our study revealed an astonishing anatomical and structural resemblance between the atlanto-occipital venous compartment and the cavernous sinus. A review of the literature showed their related embryological development as well as their functional and pathological features, in addition to a similar transitional structural pattern of the related V3 and the petrous-cavernous portion of the internal carotid artery [ICA]. Hence we called this anatomical complex the [atlanto-occipital cavernous sinus]. We also discussed its various functional roles and its relationship to the adjacent structures and the clinical and surgical implications of these factors

Variations of the ventral rami of the brachial plexus

We studied the variations in the ventral rami of 152 brachial plexuses in 77 Korean adults. Brachial plexus were composed mostly of the fifth, sixth, seventh and eighth cervical nerves and the first thoracic nerve (77.0%). In 21.7% of the cases examined, the fourth, fifth, sixth, seventh and eighth cervical and the first thoracic nerves contributed to the plexus. A plexus composed of the fourth, fifth, sixth, seventh and eighth cervical and the first and second thoracic nerves, and a plexus composed of the fifth, sixth, seventh eighth cervical nerves were also observed. The plexuses were classified into three groups according to cephalic limitation, and the plexus of group 2 in which the whole fifth cervical nerve enters the plexus, were observed the most frequent. The average diameter of the sixth and the seventh cervical ventral rami of the plexus was greatest and that of the fifth cervical was smallest. The largest nerve entering the plexus was the sixth or the seventh cervical nerve in about 79% of cases. The dorsal scapular nerve originated from the fifth cervical ventral ramus in 110 cases (75.8%). The long thoracic nerve was formed by joining of roots from the fifth, sixth, and seventh cervical nerves in 76.0% of cases. Also, a branch to the phrenic nerve, the suprascapular nerve, a nerve to the pectoralis major muscle and a nerve to the subscapular muscle arising from the ventral rami of the plexus were observed.