Anatomical Variations and Clinical Significance of the Cerebral Arterial Circle in Turkish Cadavers / Variaciones Anatómicas y Significancia Clínica del Círculo Arterial Cerebral en Cadáveres Turcos

SUMMARY: The structure formed by the arteries, which is of great importance in the irrigation of the brain, is called the cerebral arterial circle (Polygon of Willis). Since the cerebral arterial circle provides brain nutrition, vascularabnormalities in this region are highly relevant. Therefore, the aim of our study was to examine the variations of the cerebral arterial circle in cadavers of Turkish individuals. In our study, 32 human cadavers obtained from three different universities were retrospectively examined. Brain tissue obtained from cadavers by craniotomy was kept in 20 % formaldehyde solution for an average of 10 days for fixation. Cerebral arterial circle diagrams were determined in all cadavers by staining and photographs were taken. As a result of the brain examinations, a variation of the cerebral arterial circle was detected in 24/32 brains. Vascular variations have an important place in congenital variations. For this reason, we believe that our brain study will contribute to clinical studies on this topic by investigating variations of the cerebral arterial circle.

La estructura formada por las arterias que tiene una gran importancia en la irrigación del cerebro se denomina círculo arterial cerebral (Polígono de Willis). Dado que el círculo arterial cerebral proporciona la irrigación cerebral, las anomalías vasculares en esta región son muy relevantes. Por lo tanto, el objetivo de nuestro estudio fue examinar las variaciones del círculo arterial cerebral en cadáveres de individuos turcos. En nuestro estudio, se examinaron retrospectivamente 32 cadáveres humanos obtenidos de tres universidades diferentes. El tejido cerebral de los cadáveres fue obtenido por craneotomía y se mantuvo en solución de formaldehído al 20 %, durante 10 días en promedio para su fijación. Se determinaron los diagramas de círculo arterial cerebral en todos los cadáveres mediante coloración y se tomaron fotografías. Como resultado de los exámenes, se detectó una variación del círculo arterial cerebral en 24/32 de los cerebros. Las variaciones vasculares tienen un lugar importante en las variaciones congénitas. Por esta razón, creemos que nuestro estudio contribuirá a estudios clínicos sobre el tema al pesquisar las variaciones del círculo arterial cerebral.

Variations of the cerebral arterial circle: morphological and clinical analysis / Variaciones del círculo arterial cerebral: análisis morfológico y clínico

SUMMARY: The variations knowledge of the cerebral arterial circle (CAC) is relevant due to its influence on the development of ischemic encephalic disorders. Among these variations, when the external diameter of the posterior communicating artery exceeds the posterior cerebral artery caliber, we have a fetal conformation of this circle. The aim of this study was to describe the variations of the CAC in Chilean individuals and to know the type of arterial conformation. Thirty adult brains were used to measure lengths and caliber of the pre-communicating segments of the anterior (A1) and posterior (P1) cerebral arteries, and the anterior (ACoA) and posterior (PCoA) communicating arteries. The arterial conformation type was established, and the length and caliber of these vessels were compared according to the right or left side. It was observed that 76.6 % of the CACs presented aplasia and / or hypoplasia. Of its components, PCoA was hypoplasic in 53.3 %, appearing bilaterally in 40 % of the subjects. The comparison according to the side, indicated that the mean length of A1 and PCoA on the right side was slightly higher. In the case of caliber, the mean of A1, P1 and PCoA was higher on the left side. Regarding P1 and PcoA caliber, 33 % of the CACs presented unilateral fetal conformation. Regardless of the variability presented by the CAC, there is consensus that PCoA exhibits the greatest variability. The understanding of this variability requires an analysis of the embryonic aspects that can explain the fetal conformation of the CAC in the adult.

RESUMEN: El conocimiento de las variaciones del círculo arterial cerebral (CAC) resultan relevantes por su influencia en el desarrollo de trastornos isquémicos encefálicos. De estas variaciones, los cambios del calibre de la arteria comunicante posterior (ACoP) determinan una conformación fetal de este círculo. El objetivo de este estudio fue describir las variaciones del CAC en individuos chilenos y conocer el tipo de conformación arterial. Se utilizaron 30 encéfalos adultos a los que se midieron las longitudes y calibres de los segmentos precomunicante de las arterias cerebrales anteriores (A1) y posteriores (P1), y de las arterias comunicante anterior (ACoA) y ACoP. Se estableció el tipo de conformación arterial y se comparó la longitud y calibre de estos vasos según lateralidad. Se observó que el 76,6 % de los CAC presentaron agenesias y/o hipoplasias. De sus componentes, la ACoP fue hipoplásica en el 53,3 %, presentándose bilateral en el 40 %. La comparación según lateralidad indicó que la longitud media de A1 y ACoP del lado derecho fueron levemente superiores. En el caso de los calibres, la media de A1, P1 y ACoP fue superior en el lado izquierdo. Respecto de los calibres de P1 y ACoP, el 33 % de los CAC presentaron conformación fetal unilateral. Independientemente de la variabilidad que presenta el CAC, existe consenso de que la ACoP exhibe la mayor variabilidad. La comprensión de esta variabilidad requiere un análisis de los aspectos embrionarios que pueden explicar la conformación fetal de esté círculo arterial en el adulto.

Prevalence of anatomical variants of the Willis polygon in cadavers undergoing medico-legal necropsy / Prevalencia de variantes anatómicas del Polígono de Willis en cadáveres sometidos a necropsia medicolegal

The primary function of the circle of Willis is to provide collateral blood flow between the anterior and posterior arterial systems of the brain. Its configuration can vary considering its vascular structures, this being considered an anatomical variant. Our study aims to determine the prevalence of these, discriminated by sex in corpses subjected to medicolegal autopsy at the National Institute of Legal Medicine and Forensic Sciences in 2019, in Cali-Colombia. Retrospective observational descriptive study, of photographic records, inspection records and expert reports, where variables of age, sex, anatomical variants, compromised vascular structures are differentiated. Univariate and bivariate analyzes were performed. The population consisted of 194 cases, with a median age of 33 years (interquartile range between 23-45). 24.4% corresponded to the male sex. A prevalence of 25.3% of cases with non-classic polygon was observed. The most frequent anatomical variant was hypoplasia 14.9%. The vascular structure that presented the most anatomical variants was the posterior communicating artery with 17%.

La función principal del polígono de Willis es proporcionar flujo sanguíneo colateral entre los sistemas arteriales anterior y posterior del cerebro. Su configuración puede variar teniendo en cuenta sus estructuras vasculares, considerándose esto una variante anatómica. En este estudio analizamos la prevalencia de las variaciones, discriminada por sexo en cadáveres sometidos a necropsia medicolegal en el Instituto Nacional de Medicina Legal y Ciencias Forenses en el año 2019, en Cali-Colombia. Estudio descriptivo observacional retrospectivo, de registros fotográficos, actas de inspección e informes periciales, donde se diferencia variables de edad, sexo, variantes anatómicas, estructuras vasculares comprometidas. Se realizaron análisis uni y bivariados. La población estuvo conformada por 194 casos, con una mediana de edad de 33 años (rango intercuartil entre 23-45). El 24.4% correspondieron al sexo masculino. Un 25,3% de casosse encontró un polígono no clásico. La variante anatómica más frecuente fue la hipoplasia 14.9%. La estructura vascular que más variantes anatómicas presentó fue la arteria comunicante posterior con un 17%.

The arterial circle described by Willis, and the contribution of his predecessors / O círculo arterial descrito por Willis e a contribuição de seus predecessores

The description of arteries at the base of the human brain forming an 'arterial circle', named after Thomas Willis, has had a long history after the restoration of human dissection, partly due to the studies of many outstanding anatomists that preceded Willis. He provided, with the collaboration of Richard Lower and Christopher Wren, the first incontestable complete description, as recognized nowadays, accompanied by a superb illustration. Additionally, he presented an explanation for its meaning, indicating for the first time the functional significance of this structure, in health and disease. However, it should be recognized that the initial studies of the arteries of the base of the human brain by Willis' predecessors, as well as those from ancient times, despite their fragmentary descriptions, were certainly pivotal in paving the way for further and more detailed knowledge of this vascular formation.

A descrição das artérias da base do cérebro humano, formando um 'círculo arterial', designado com o nome de Thomas Willis, tem uma longa história após o restauro de dissecções humanas, em parte devido aos estudos de muitos anatomistas de renome que precederam Willis. Ele proveu, com a colaboração de Richard Lower e Christopher Wren, a primeira descrição completa e incontestável, assim como a reconhecida atualmente, acompanhada por uma ilustração soberba. Adicionalmente, apresentou uma explicação quanto ao seu significado, indicando pela primeira vez a importância funcional dessa estrutura, na saúde e na doença. Entretanto, deve ser reconhecido que os estudos iniciais das artérias da base do cérebro humano pelos predecessores de Willis, assim como os de tempos antigos, apesar de suas descrições fragmentárias, certamente foram fulcrais na pavimentação do caminho para o conhecimento mais avançado e detalhado dessa formação vascular.

Evaluación morfológica y variaciones del circulo arterial cerebral: un estudio con material cadavérico en una muestra de población colombianas / Morphological evaluation and variations of the cerebral arterial circle: a study with cadaveric material in a Colombian population sample

RESUMEN: El círculo arterial cerebral (CAC) mencionado también como polígono de Willis es una red de anastomosis vascular situado en la base del cerebro, constituido por ramas de la arteria carótida interna (ACI) y del sistema vertebro-basilar. Este estudio evaluó la morfología de las arterias que conforman el CAC en una muestra de individuos colombianos. Previa canalización de la ACI y de la arteria vertebral (AV), se perfundió con resina poliéster (palatal 85 % y estireno 15 %) los lechos vasculares del CAC de 70 encéfalos extraídos de cadáveres a quienes se les practicó necropsia en el Instituto de Medicina Legal de Bucaramanga, Colombia. La arteria comunicante anterior (ACoA) se observó en 68 encéfalos (97,1 %), con ausencia en 2 de las muestras (2,9 %); en promedio su diámetro fue de 1,91?1,04 mm y su longitud 2,21?0,97 mm respectivamente. Asimismo, se encontró hipoplasia en 6 muestras (8,4 %). La arteria comunicante posterior (ACoP) estuvo ausente en 2 de las muestras (5,7 %); su longitud fue 11,63?2,12 mm, mientras que su calibre fue de 1,21?0,58 mm, siendo ligeramente mayor en el lado derecho, sin diferencias estadísticamente significativas con relación al lado de presentación (p= 0,763). Se encontró hipoplasia de la ACoP en forma bilateral en 19 de las muestras (27,1 %) y unilateral en 15 muestras (21,4 %). En 8 muestras (20 %) de 35 CAC evaluados se observó configuración fetal. La incidencia de hipoplasia de la ACoP y de configuración fetal encontrados en el presente estudio, se ubican en el segmento superior de lo reportado en la literatura. Estas expresiones morfológicas han sido consideradas como coadyuvantes en el desarrollo de accidentes cerebro-vasculares (ACV).

SUMMARY: The cerebral arterial circle (CAC), also referred to as the polygon of Willis is a network of vascular anastomoses located at the base of the brain, consisting of branches of the internal carotid artery (ICA) and the vertebrobasilar system (VBS). This study evaluated the morphology of the arteries forming the CAC in a sample of Colombian individuals. After cannulation of the ICA and the vertebral artery (VA), the vascular beds of the ACC of 70 brains extracted from cadavers at the Institute of Legal Medicine of Bucaramanga, Colombia, were perfused with polyester resin (85 % palatal and 15 % styrene). The anterior communicating artery (ACoA) was observed in 68 brains (97.1 %), with absence in 2 of the samples (2.9 %); on average its diameter was 1.91?1.04mm and its length 2.21?0.97mm respectively. Likewise, hypoplasia was found in 6 samples (8.4 %). The posterior communicating artery (ACoP) was absent in 2 of the samples (5,7 %); its length was 11.63?2.12mm, while its caliber was 1.21?0.58mm, being slightly larger on the right side, with no statistically significant differences in relation to the side of presentation (p= 0.763). Hypoplasia of the ACoP was found bilaterally in 19 of the samples (27.1 %) and unilaterally in 15 samples (21.4 %). Fetal configuration was observed in 8 samples (20 %) of 35 CACs evaluated. The incidence of ACoP hypoplasia and fetal configuration found in the present study are in the upper segment of those reported in the literature. These morphological expressions have been considered as coadjuvants in the development of cerebrovascular accidents (CVA).

Vascularization of the Alouatta belzebul brain base / Vascularização da base do encéfalo de Alouatta belzebul

We studied the arterial circle in the brain of five specimens of the Alouatta belzebul primate. The material had the arterial system perfused (water at 40°C), injected with stained latex (Neoprene 650), fixed in aqueous formaldehyde solution (10%) and dissected for vessel verification. The arterial circle of this primate is composed of two vascular systems: the vertebra-basilar and the carotid ones, which anastomose to close the arterial circuit. In the caudal portion of the arterial circle, there are the vertebral arteries and their branches: the rostral spinal artery and the caudal inferior cerebellar artery. The anastomosis of the vertebral arteries gives rise to the basilar artery. It presented an anatomical variation at the beginning of its path, forming a double basilar artery, called arterial island. In its course, it emitted branches giving rise to the rostral inferior cerebellar artery, the pontine arteries, the rostral cerebellar arteries, the satellite rostral cerebellar arteries and its terminal branch, the caudal cerebral artery, which presented itself in two segments: the pre-communicating one and post-communicating, joining the internal carotid artery and originating the caudal communicating artery. This group of arteries and anastomoses enclose the caudal portion of the arterial circle. From the right and left internal carotid arteries begins the rostral portion of the arterial circle, which consists of the right and left rostral cerebral arteries and the right and left middle cerebral arteries. The rostral cerebral arteries anastomose into a single trunk, giving rise to the interhemispheric artery, and in A. belzebul and Sapajus libidinosus, the rostral communicating artery is absent. The interhemispheric artery goes to the midbrain region and the corpus callosum knee divides into pericalous artery and callosarginal artery, which will supply the pre and post-central regions of the cerebral hemispheres of this species, as well as other non-human and human primates. It is noted that in the first part of the left rostral cerebral artery, there is a direct inosculation between the recurrent branch of the rostral cerebral artery and left middle cerebral artery to supply the entorhinal region. This fact also occurs in Pongo spp. The middle cerebral artery travels along the lateral sulcus where it emits several superficial branches to irrigate the superior and inferior lateral cortical regions of the frontal, parietal and temporal lobes. It is not part of the arterial circle but is the terminal branch of the internal carotid artery. A. belzebul can be considered to depend on two sources of supply to the brain: the vertebra-basilar and carotid systems, contributing to the intervention of veterinarians during clinical and surgical procedures in other primates, as well as the preservation of wild animals.(AU)

Estudamos o círculo arterial no encéfalo de cinco espécimes do primata Alouatta belzebul. O material teve o sistema arterial perfundido (água a 40°C), injetado com látex corado (Neoprene 650), fixado em solução aquosa de formaldeído (10%) e dissecado para verificação dos vasos. O círculo arterial deste primata é composto por dois sistemas vasculares: vértebro-basilar e o sistema carotídeo, que se anastomosam para fechar o circuito arterial. Na porção caudal do círculo arterial encontra-se as artérias vertebrais e seus ramos: artéria espinal rostral e a cerebelar inferior caudal. A anastomose das artérias vertebrais dá origem a artéria basilar. Esta apresentou uma variação anatômica no início do seu trajeto, formando uma dupla artéria basilar, denominada ilha arterial. Em seu trajeto emitiu ramos dando origem a artéria cerebelar inferior rostral, as artérias pontinas, as artérias cerebelares rostrais, as artérias cerebelares rostrais satélites e o seu ramo terminal, a artéria cerebral caudal, que apresentou-se em dois segmentos: o pré-comunicante e pós-comunicante, unindo-se a artéria carótida interna e originando a artéria comunicante caudal. Este grupo de artérias e anastomoses encerram a porção caudal do círculo arterial. Das artérias carótidas internas direita e esquerda, inicia-se a porção rostral do círculo arterial, ao qual é constituído pelas artérias cerebrais rostrais direita e esquerda e as artérias cerebrais médias direita e esquerda. As artérias cerebrais rostrais se anastomosam em um tronco único dando origem a artéria inter-hemisférica e em A. belzebul e Sapajus libidinosus, a artéria comunicante rostral se encontra ausente. A artéria inter-hemisférica segue para região média do encéfalo e no joelho do corpo caloso se divide em artéria pericalosa e artéria calosomarginal, que vão suprir as regiões pré e pós-central dos hemisférios cerebrais desta espécie, assim como outros primatas não humanos e humano. Nota-se que na primeira parte da artéria cerebral rostral esquerda, ocorre uma inosculação direta entre o ramo recorrente da artéria cerebral rostral e artéria cerebral média esquerda para suprir a região entorrinal, esse fato também ocorre em Pongo spp. A artéria cerebral média segue seu trajeto pelo sulco lateral onde emite vários ramos superficiais para irrigar as regiões corticais supero e ínfero lateral do lobo frontal, parietal e temporal, esta não faz parte do círculo arterial mas é o ramo terminal da artéria carótida interna. Pode-se considerar que A. belzebul depende de duas fontes de suprimento para o encéfalo: os sistemas vértebro-basilar e carotídeo, contribuindo na intervenção de médicos veterinários durante os procedimentos clínicos e cirúrgicos em outros primatas, assim como na preservação de animais silvestres.(AU)

Morphological configuration and topography of the brain arterial supply of the one-humped camel ( Camelus dromedarius, Linnaeus 1758) / Configuración morfológica y topografía del suministro arterial del encéfalo del camello de una joroba ( Camelus dromedarius, Linnaeus 1758)

This study investigated the anatomy of the arteries of the brain, including the arterial circle of the brain, its branches and junctions, in five camel (Camelus dromedarius, Linnaeus 1758) following intravascular injection of colored latex via common carotid artery. The course and distribution of the arterial supply to the brain was described and morphological analysis was made. The basilar artery contributed to the blood supply of the brain in the camel in contrast to the situation in other Artiodactyla order.

En presente estudio se analizó la anatomía de las arterias del encéfalo en cinco camellos (Camelus dromedarius, Linnaeus 1758). Después de administrar una inyección intravascular de látex coloreado en la arteria carótida común se estudiaron las arterias incluyendo al círculo arterial del cerebro, sus ramas y uniones. Fueron descritos en detalle el curso y la distribución del suministro arterial al encéfalo y se realizó un análisis morfológico. La arteria basilar contribuyó al suministro de sangre del encéfalo del camello, diferenciando este aspecto en otras especies de Artiodactyla.

Anatomical variants of anterior cerebral arterial circle: a study by multidetector computerized 3D tomographic angiography / Variantes anatómicas de la región anterior del circulo arterial cerebral: estudio por angiotomografía computarizada 3D

One of the most common causes of stroke is rupture of aneurysms whose approach requires knowledge of anatomical variants. The aim of this study was to determine the prevalence of anatomical variants of the anterior cerebral artery (ACA) and the anterior communicating artery (AComA) by 3D computed tomography angiography (3D CTA) in Mexican individuals. A retrospective, observational, cross-sectional descriptive study of 283 patients, independent of sex or age, in which morphometric measurements of cerebral vessels were evaluated using contrasted 3D CTA from a period of two years was performed. We found at least one "atypical" variant in a third of the study population (33.93 %). The most common "atypical" variant was the absence of the AComA (14.1 %). A significant association between the hypoplastic variant of the right A1 segment and hypoplasia of the left A1 and the right A2 was found, while hypoplasia of the left A1 was associated with hypoplasia of the right A2. There is a difference in the prevalence of anatomical variants of the ACA-AComA complex in Mexican population in relation to other populations. The typical variant is the most prevalent form in the study population. However, the presence of atypical variants represents an important number that should be taken into account in clinical and surgical procedures.

Una de las causas más frecuentes de accidente cerebrovascular es la ruptura de aneurismas cuyo abordaje requiere el conocimiento de las variantes anatómicas. El presente estudio tuvo como objetivo determinar la prevalencia de variantes anatómicas de la Arteria Cerebral Anterior (ACA) y la Arteria Comunicante Anterior (AComA) mediante angiotomografías computarizadas 3D (angioTAC 3D) de individuos mexicanos. Se realizó un estudio retrospectivo, observacional, transversal y descriptivo en el que se evaluaron angioTAC contrastados con reconstrucción 3D de 283 pacientes, sin considerar género ni edad, obtenidas durante un periodo de dos años a los que se les realizaron mediciones morfométricas en los vasos de interés. Se encontró al menos una variante "atípica" en un tercio de la población estudiada (33,93 %). La variante "atípica" más común fue la ausencia de AComA (14,1 %). Se encontró asociación significativa entre la variante hipoplásica del segmento A1 derecha y la hipoplasia de A1 izquierda y A2 derecha; mientras que la hipoplasia de A1 izquierda se asoció a la variante hipoplasia de A2 derecha, encontrándose mayor tendencia de aparición de aneurismas en función del menor diámetro del segmento A2 derecho de la ACA. Existe diferencia en la prevalencia de variantes anatómicas del complejo ACA-AComA en población mexicana con respecto a otras poblaciones. La variante típica constituye la forma más prevalente en la población estudiada. Sin embargo, la presencia de variantes atípicas representa una cifra importante que deberá tomarse en cuenta en procedimientos clínicos y quirúrgicos.

Anatomical arrangement and distributionof the cerebral arterial circle in rats

The cerebral arterial circle is a polygonal shape-like arterial anastomosis placed in the brain base, whereit rounds the optic quiasm and the tuber cinereum, and also related to the interpeduncular fossa and theanterior perfurated substance. It is formed by the proximal parts of the anterior, middle and posterior cerebralarteries, and the right and left posterior communicating arteries. In order to describe the cerebral arterial circledisposition we investigated the brains of twenty rats. For each animal, the heart left ventricle was probed andacetone, distilled water at 37 °C and a solution of Neoprene Latex “450” stained with a specific red pigmentwere injected in sequence into it. To fix the brain in a better way, we isolated the head and made an apertureat the dorsal wall of the cranium and the whole specimen was fixed in a 15% formaldehyde solution. We tookoff the brain from the skull with the aid of a cold light source monocular magnifier. To take the photographicdata we used a semi-professional camera. The results showed that the cerebral arterial circle in rats is formedby branches of both internal carotid arteries and of the basilar artery, and is closed rostrally by the rostralcommunicating artery, and caudally by the right and left terminal branches of the basilar artery. We concludedfrom our data that the cerebral arterial circle in rats is compound by branches of both internal carotid arteriesand basilar artery, and that it is rostrally and caudally closed.

Variations in the brain circulation: the circle of Willis

Introduction: Despite being quite common, there is little information concerning the Brazilian population on anatomic variations and anomalies in the brain circulation. This study intends to describe the most common variations found during the autopsies for the AMA Study. Material and methods: Fifty cadavers had their circle of Willis dissected and analyzed. Results: 54% presented at least one variation, and they were more common in the posterior circulation (88.5%) and on the right side of the brain (59.7%); non-classical morphology was more common bilaterally and in the posterior circulation of the circle of Willis (37.1%). The most common finding was the absence of the posterior communicating artery (32%), followed by posterior cerebral arteries originated from the internal carotid artery (18%). There were no variations in the middle cerebral arteries. Accessory anterior cerebral arteries were present in 6%, and A1 segment hypoplasia was present in only 2% of the cases. Conclusion: Brazilian population variations are in accordance with the literature and there seems to be no difference between races in the variation of brain circulation.

[Complex variation in the brain arteries in Tehran]

Variations in the cerebral arterial circle [CAC] correlate with incidence of some cerebrovascular diseases and must be considered during surgical operations [1, 2]. It also seems that different distribution of variations of the CAC is related to the race. This issue may partially explain the different incidences of some of the cerebrovascular diseases in different ethnic or racial groups [3-5]. Although there have been some reports of Variations in the cerebral arterial circle in other part of the world, the evidence for Iranian population is poorly reviewed. A 70 year-old female of Tehran population in central Iran is presented here. In this case Subclaivan and Vertebral arteries have abnormal origin and circumflex of Willis isn't complete because posterior cerebral arteries are absent

Arterias comunicantes del círculo arterial del cerebro: características biométricas y relación con el índice cefálico / Communicating arteries of the cerebral arterial circle: biometric features and their relation with the cephalic index

La clínica neuroquirúrgica tiene la necesidad de un acabado conocimiento anatómico de las arterias comunicantes como integrantes del círculo arterial del cerebro, por su variabilidad morfológica, su relación compleja con las estructuras adyacentes y por la alta frecuencia observada en la conformación de aneurismas. Debido a la importancia de estos vasos, efectuamos un estudio biométrico de los mismas, relacionando datos de calibre y longitud con índice cefálico. En el sexo masculino, el calibre promedio de la ACoP fue de 1,07 mm en el lado derecho y de 1,06 mm en el izquierdo; en el sexo femenino fue de 1,12 mm en el lado derecho y de 1,14 mm en el izquierdo. En el grupo de individuos con índice braquicéfalo, el calibre de la ACoP fue de 1,15 mm y en el grupo dolicomesocéfalo fue de 1,05 mm. Su longitud fue de 18,65 mm en los braquicéfalos y de 16,44 mm en los dolicomesocéfalos.El calibre de la ACoA fue de 1,53 mm en el sexo masculino y de 1,05 mm en el femenino, mientras que su longitud fue de 2,81 mm en el sexo masculino y de 2,33 mm en el femenino. La descripción biométrica y bioantropológica muestra parámetros importantes a considerar en la clínica quirúrgica.

The neurosurgical clinic needs extensive and thorough anatomical knowledge of the communicating arteries as part of the cerebral arterial circle for their morphological variability, their complex relation as adjacent structures, and for the frequency observed in the formation of aneurisms. Considering the importance of these vessels, we conducted a biometric study of these, relating caliber and longitude information to the cephalic index. In the male, the mean caliber of the PCoA < p was of 1.07 mm on the right side and 1.06 mm on the left; in the female it was of 1.12 mm on the right side and of 1.14 mm on the left. In the group of individuals with brachiocephalic index, the caliber of the ACoP was of 1.15 mm and in the dolichomesocephalic groups was 1.05 mm. Its longitude was 18.65 mm in the brachiocephalous and of 16.44 mm in the dolichomesochephalic. The caliber of the ACoA was of 1.53 mm in the male and 1.05 mm in the female, while its longitude was of 2.81 mm in the male and 2.33 mm in the female. The biometric and bioanthropologic description shows important parameters to be considered in clinical surgery.

Cephalometry in 14-18 years old girls and boys of Shiraz-Iran high school / Cefalometría en niñas y niños de 14-18 años de la secundaria de Shiraz, Irán

Cephalometry or skull measurement are used in pediatrics, forensic medicine, plastic surgery, oral surgery and diagnostic comprehension between patient and normal populations. Cephalic index is an important parameter for detecting the race and sex of an individual whose identity is unknown. The most important of cephalometric dimension are height and width of head which determine cephalic index. On the basis of cephalic index four head shapes are determined in international categories, that including dolichocephal, brachycephal, mesocephal and hyperbrachycephal. With noticing the lack of documented research about 14-18 years old girls and boys in this area, this study was planned for determining normal range of head shapes in 867girls and 960 boys in the age of 14-18 in fars-Iran. In regards of cephalic index our results showed that dominent type of head in girls was brachycephalic with 42.5 percent and in boys was hyperbrachycephalic with 34.3 percent, rare type of head shape in girls was dolicocephalic with 4.80 percent and in boys was 7.5 percent. There is significant difference between boys and girls cephalic index.

La cefalometría o medición del cráneo se utiliza en pediatría, medicina forense, cirugía plástica, cirugía oral, diagnóstico del paciente y el entendimiento de las poblaciones normales. El índice cefálico es un parámetro importante para la detección de la raza y el sexo de una persona cuya identidad se desconoce. Las dimensiones cefalométricas más importantes son la altura y peso de la cabeza que determinan el índice cefálico. En base al índice cefálico cuatro formas de la cabeza son clasificadas en categorías internacionales: dolicocefálica, braquicefálica, mesocefálica e hiperbraquicefálica. Debido a la falta de información sobre las niñas y niños de 14-18 años, en este ámbito, se planificó el presente estudio para la determinar el rango normal de la forma de la cabeza, en 867 niñas y 960 niños, de 14 al 8 años de edad en Fars, Irán. Los resultados mostraron que el tipo dominante de cabeza en las niñas fue braquicefálico (42,5 por ciento) y en niños fue hiperbraquicefálico (34,3 por ciento). El tipo de cabeza de forma dolicocefálico en niñas en un 4,80 por ciento y en niños en el 7,5 por ciento. Existen diferencias significativas entre el índice cefálico de niños y niñas.

Absent anterior communicating artery and varied distribution on anterior cerebral artery

During the cerebral dissection of a 67-year-old male cadaver, a unique combination of variations at the circle of Willis and anterior cerebral artery [ACA] distribution were encountered. The A1 segment of both ACA were fused without an anterior communicating artery [ACoA], forming an X shape and giving rise to a common pericallosal artery [CPA], an incomplete distal ACA, and an incomplete distal anterior cerebral artery [IACA]. The IACA had an unusual course, which may be important from the surgical point of view. The CPA continued as the A2 and A3 segments, and bifurcated into 2 pericallosal arteries. Branching patterns of the varied arteries to the interhemispheric region were evaluated, and results were discussed. Additionally, both posterior communicating arteries were hypoplastic. There was no aneurysm formation at the circle of Willis and its branches

Aspectos Biométricos de las Arterias Cerebral Anterior en el Segmento Proximal (Al) y Carótida Interna / Biometrical Aspects of the Anterior Cerebral Artery in its Proximal Segment (Al) and Internal Carotid Artery

La conformación del círculo arterial cerebral tiene relevancia en la clínica neuroquirúrgica por la relación compleja que presentan las arterias que lo originan y su gran variabilidad Debido a a esto, hemos decidido efectuar un análisis biométrico de las arterias cerebral anterior (Al) y de la arteria carótida interna (ACI) por posible asociación o correlación en estas estructuras. El trabajo se realizó en 36 cerebros disponibles en los laboratorios y cuyos datos bioantropológicos estaban registrados. El segmento Al de la arteria cerebral anterior derecha tuvo una longitud y calibre promedio de 12,86+1.58mm y 2,37±0,68mm, respectivamente. En el lado izquierdo la longitud y el calibre promedio de esta arteria fue 12,62+1.96mm y de 2,42±0,75mm, respectivamente. El calibre del lado derecho de la ACI fue 3,84±0,68mm y del lado izquierdo fue 3,96±0,87mm. Se observó variabilidad anatómica de los componentes que constituyen el círculo arterial cerebral cuando se considera lado, sexo e índice cefálico.

The conformation of the arterial circle of the base of the brain has relevancy in the neurochirurgical clinic as the complex relation that there present the arteries that originate it and its great variability. Due to the high frequency the aneurysms observed in the anterior communicating arteries, besides too, in the precommunicating segment (Al) of the anterior cerebral artery, we have decided to carry out a biometrical analysis of these arteries and the ICA for research possible association or correlation in these arteries.The work was realized in 36 available brains in the anatomical laboratories. These specimens had bioanthropological data. The segment Al of the anterior cerebral artery observed a length of 12,86 ± 1.58 mm and presents a diameter of 2.37 ± 0.68 mm in the right side. In the left side the length of this one segment is 12. 62 ± 1.96 mm and presents a diameter of 2.42 ± 0.75 mm. The external diameter of the ACI in the right side was 3.84±0.68 mm and in left side was 3.96 ± 0.87 mm. It is observed variability of the components that constitute the arterial cerebral circle when it is considered to be the side, the sex and cephalic index.

O circuito arterial da base do encéfalo em suínos (Sus scrofa domesticus Linnaeus, 1758), formação e comportamento / The brain arterial circuit in swine (Sus scrofa domesticus Linnaeus, 1758), behavior ad formation

Estudamos em 40 suínos neonatos sem raça definida (SRD), 20 machos e 20 fêmeas, a formação vascular que se dispõe contornando o corpo mamilar, o túber cinéreo, a hipófise e o quiasma óptico na base do encéfalo. Os animais foram provenientes da Fazenda Santa Terezinha município de Uberlândia; 30 deles tiveram seus contingentes arteriais injetados com solução de Neoprene Látex 450, corada com pigmento específico, tendo sido fixados com solução de formal a 15% e dissecados; no restante injetou-se Acetato de Vinil corado seguindo-se corrosão em ácido sulfúrico a 30% os quais eram então lavados em água corrente. Os resultados mostraram que o circuito arterial é uma formação a partir da divisão da artéria carótida do encéfalo em ambos os antímeros, em seus ramos terminais rostral e caudal. Apresenta-se rostralmente em pequeno arco de concavidade medial (antímeros esquerdo e direito); caudalmente apresenta características morfológicas que fazem lembrar figura semelhante a um polígono - metade caudal de um hexágono - (53,3%) e no restante, figura simbólica de um coração (46,7%).0 circuito encontra-se fechado rostralmente pela presença constante da artéria comunicante rostral em todas as preparações e, caudalmente, pela presença dos ramos terminais esquerdo e direito da artéria basilar. Em 10%, além da presença dos ramos terminais esquerdo e direito da artéria basilar, o circuito arterial mostrou no local usual de bifurcação da artéria basilar, duas pequenas anastomoses.

Arrangement and distribution of the arterial circle in brain of wild boar (sus scrofa scrofa) linnaeus (1758): qualitative and quantitative analysis

Thirteen brains of wild boar (Sus scrofa scrofa) were investigated with the purpose to discrebe the formation and the branchings of the brain arterial circle and basilar artery, from injetions of colored latex into the arteries of the base of the brain, and to establish the degree of correlativity between the rostro-caudal, latero-lateral lengths, weight, volume, carotid and basilar arteries diameter and the length of the basilar artery. To the anatomic study male and female heardswere used, from the slaughterhouse Pro Fauna licensed to abate and comercialize wild animal and under the Federal Inspection Service (SIF) control, situated in Iguape city, São Paulo. In all animal latex was injected after what the arteries of the base of the brain were dissected and observed. The obtained results indicated a domination of the internal carotid artery in the vascularization of the brain, and positive correlation between weight and volume in relation to the lenght of the brain in rostro-caudal and latero-lateral senses, in addition weight and volume have a perfect positive correlation, when one grows the other grows in the same rate.

Demostración de las variantes anatómicas del polígono de Willis por angiorresonancia magnética / Magnetic resonance imaging of the circle of Willis and their anatomical variants

Este estudio tiene como objetivo investigar por medio de Angio Resonancia Magnética (ARM), la frecuencia con la que se presentan variantes anatómicas en el polígono de Willis. En un grupo de cien pacientes a los que se les realizó un estudio de ARM, se identificaron básicamente cuatro variantes más de la forma originalmente descrita por Willis. La más común es la persistencia de la arteria comunicante posterior derecha precedida únicamente por la forma habitual del polígono (ausencia de comunicantes). Es importante considerar que en el polígono de Willis existen trayectos vasculares "virtuales", que posteriormente se pueden permeabilizar o llevar a la formación de un trayecto colateral. Ante un evento isquémico u oclusivo, la ARM brinda la opción de poder identificar la dinámica vascular de manera no invasiva y tiene el potencial de poder demostrar variantes anatómicas en el momento del estudio

Consideraçöes sobre o polígono de Willis / Considerations about the circulus arteriosus Willisii

Os autores relatam um estudo anatômico em cinco segmentos cefálicos sobre o circulus arteriosus Willisii e sua contribuiçäo à anastomose vascular cerebral através de uma visäo topográfica e comparativa. Este círculo anastomótico de vasos na base do cérebro comumente está incompleto na populaçäo geral e mais ainda nos indivíduos que sofreram strokes

Agenesias e hipoplasias do polígono de Willis / Agenesias and hypoplasia of the circle of Wills

Variaçöes anatômicas congênitas nas estruturas vasculares que constituem o polígono de Wills säo frequentes. Os autores descrevem o resultado da análise morfológica das artérias encefálicas obtida através de dissecçäo de 112 encéfalos em nosso meio. Constatou-se haver hipoplasias de algum segmento arterial do polígono em 75 por cento dos neonatos, em 57 por cento das crianças e 78 por cento dos adultos