A novel theory for rapid localization of the transverse-sigmoid sinus junction and "keyhole" in the retrosigmoid keyhole approach: micro-anatomical study, technique nuances, and clinical application.

To determine a rapid and accurate method for locating the keypoint and "keyhole" in the suboccipital retrosigmoid keyhole approach. (1) Twelve adult skull specimens were selected to locate the anatomical landmarks on the external surface of the skull.The line between the infraorbital margin and superior margin of the external acoustic meatus was named the baseline. A coordinate system was established using the baseline and its perpendicular line through the top point of diagastric groove.The perpendicular distance (x), and the horizontal distance (y) between the central point of the "keyhole" and the top point of the digastric groove in that coordinate system were measured. The method was applied to fresh cadaveric specimens and 53 clinical cases to evaluate its application value. (1) x and y were 14.20 ± 2.63 mm and 6.54 ± 1.83 mm, respectively (left) and 14.95 ± 2.53 mm and 6.65 ± 1.61 mm, respectively (right). There was no significant difference between the left and right sides of the skull (P > 0.05). (2) The operative area was satisfactorily exposed in the fresh cadaveric specimens, and no venous sinus injury was observed. (3) In clinical practice, drilling did not cause injury to venous sinuses, the mean diameter of the bone windows was 2.0-2.5 cm, the mean craniotomy time was 26.01 ± 3.46 min, and the transverse and sigmoid sinuses of 47 patients were well-exposed. We propose a "one point, two lines, and two distances" for "keyhole" localization theory, that is we use the baseline between the infraorbital margin and superior margin of the external acoustic meatus and the perpendicular line to the baseline through the top point of the digastric groove to establish a coordinate system. And the drilling point was 14.0 mm above and 6.5 mm behind the top point of the digastric groove in the coordinate system.

Venous Anatomy of the Central Nervous System.

Comprehensive understanding of venous anatomy is a key factor in the approach to a multitude of conditions. Moreover, the venous system has become the center of attention as a new frontier for treatment of diseases such as idiopathic intracranial hypertension (IIH), arteriovenous malformation (AVM), pulsatile tinnitus, hydrocephalus, and cerebrospinal fluid (CSF) venous fistulas. Its knowledge is ever more an essential requirement of the modern brain physician. In this article, the authors explore the descriptive and functional anatomy of the venous system of the CNS in 5 subsections: embryology, dural sinuses, cortical veins, deep veins, and spinal veins.

Chordae Willisii of the dural sinuses: an anatomical study using magnetic resonance imaging.

PURPOSE: The chordae Willisii (CWs), trabecular projections into the lumen of the dural sinuses, are not well understood. We aimed to explore them using magnetic resonance imaging (MRI). METHODS: Eighty-five patients underwent volumetric contrast-enhanced MRI, while another 30 underwent a fluid-attenuated inversion recovery (FLAIR) sequence in the coronal section. RESULTS: The CWs were detected as linear filling defects lying in the dural sinuses, adjacent to the surrounding dura mater. They were found in the superior sagittal sinus (SSS) in 68.2% of the patients, most frequently in the middle third, with laminar appearance. In 27.1% of the patients, the CWs divided the SSS lumen into separate channels. The CWs were identified in the transverse sinus, transverse-sigmoid sinus junctional area and sigmoid sinus, and straight sinus in 54.1, 47.1, and 8.2%, respectively. On the FLAIR images, dural septi partially dividing the SSS lumen were identified in all patients. In addition, in 73.3% of the patients, fine linear structures were observed in the lumen with inconstant arrangements. CONCLUSIONS: The CWs may be constant structures distributed over the lumen of the intracranial dural sinuses. Contrast-enhanced MRI may be useful for detecting laminar CWs. The FLAIR sequence may be advantageous for delineating the dural septi projecting into the lumen of the dural sinuses.

[Venous Anatomy of the Superior and Inferior Sagittal Sinuses].

The superior sagittal sinus(SSS)is contained within the dura, which consists of the dura propria and osteal dura at the junction of the falx cerebri, in addition to the attachment of the falx to the cranial vault. The SSS extends anteriorly from the foramen cecum and posteriorly to the torcular Herophili. The superior cerebral veins flow into the SSS, coursing under the lateral venous lacunae via bridging veins. Most of the bridging veins reach the dura and empty directly into the SSS. However, some are attached to the dural or existed in it for some distance before their sinus entrance. The venous structures of the junctional zone between the bridging vein and the SSS existed in the dura are referred to as dural venous channels. The SSS communicates with the lateral venous lacunae connecting the meningeal and diploic veins, as well as the emissary veins. These anatomical variations of the SSS are defined by the embryological processes of fusion and withdrawal of the sagittal plexus and marginal sinus.

[Inferior Petrosal Sinus and Anterior Condylar Confluence and Surrounding Venous Anatomy].

Veins at the craniocervical junction are complex network structures. They empty into two main brain venous drainages, the internal jugular vein and internal vertebral venous plexus, and reroute venous blood according to postural changes. They are also involved in the etiology of dural arteriovenous shunts in this region. Hence, regional venous anatomy is crucial for interventional neuroradiologists to understand the pathophysiology and formulate therapeutic strategies. This article aims to provide a summary on venous anatomy, radiological findings, and related pathological conditions, especially for young and inexperienced interventional neuroradiologists.

Prevalence and Morphometry of Occipital Foramen in Dry Skulls and its Clinical Implications.

The occipital emissary foramen (OEF) located on the occipital bone transmits the occipital emissary vein, which connects the occipital vein to the confluence of cranial venous sinuses. The OEF varies in incidence, number, size, and location. Knowledge of this foramen is essential for carrying out suboccipital and transcondylar surgeries without clinical implications. Hence, the study was planned. The aim of the present study is to elaborate on incidence, location, and morphometry consisting of the number and size of this foramen in light of clinical bearing in the context of the Indian population. The study was carried out in the Department of Anatomy using 80 skulls of unknown age and sex. The occipital bone of the skull was observed for the incidence, number, size, and location of the occipital emissary vein and associated clinical implications were elaborated. The incidence of occipital foramen was 36.25% and detected in 29 skulls. All these occipital foramina were patent. The mean diameter of this foramen was 0.6 mm. The most common location of these foramina was the left side of the foramen magnum, followed by the left side of the external occipital crest. The information about the incidence, number, size, and location of OEF is important to prevent catastrophic bleeding during surgery in the region of the occipital bone. The awareness of differential morphometry and morphology of occipital foramina is of great importance for neurosurgeons during suboccipital craniotomy and skull base surgeries, including far lateral and transcondylar approaches to access posterior cranial fossa for management of pathologies in the cranial cavity.

The Posterior Auricularis Muscle as Superficial Landmark for the Sigmoid Sinus and Transverse-Sigmoid Sinus Junction: An Anatomical Study.

OBJECTIVE: Neuronavigation systems coupled with previously reported external anatomical landmarks assist neurosurgeons during intracranial procedures. We aimed to verify whether the posterior auricularis muscle (PAM) could be used as an external landmark for identifying the sigmoid sinus (SS) and the transverse-sigmoid sinus junction (TSSJ) during posterior cranial fossa surgery. METHODS: The PAM was dissected in 10 adult cadaveric heads and after drilling the underlying bone, the relationships with the underlying SS and TSSJ were noted. The width and length of the PAM, and the distance between the muscle and reference points (asterion, mastoid tip, and midline), were measured. RESULTS: The PAM was identified in 18 sides (9 left, 9 right). The first 20 mm of the muscle length (mean 28.28 mm) consistently overlay the mastoid process anteriorly and the proximal half of the SS slightly posteriorly on all sides. The superior border was a mean of 2.22 mm inferior to the TSSJ and, especially when the muscle length exceeded 20 mm, this border extended closer to the transverse sinus; it was usually found at a mean of 3.11 mm (range 0.0-13.80 mm) inferior to the distal third of the transverse sinus. CONCLUSIONS: Superficial landmarks give surgeons improved surgical access, avoiding overexposure of deep neurovascular structures and reducing brain retraction. On the basis of our cadaveric study, the PAM is a reliable and accurate direct landmark for identifying the SS and TSSJ. The PAM could potentially be used for guiding the retrosigmoid approach.

Mastoid Emissary Foramina in Dry Skulls: Its Morphometry, Topography, and Associated Clinical Implications.

Mastoid emissary foramen transmitting mastoid emissary vein connects the posterior auricular vein with the sigmoid sinus. This foramen and so the mastoid emissary vein varies in prevalence, number, size and location, knowledge of which is essential for carrying out uneventful surgeries, especially retrosigmoid, mastoidectomy, and skull base surgeries. There is a paucity of literature on this foramen in the Indian context, so the study was done. The purpose of the study is to elaborate on the prevalence, number, size, and location of mastoid foramen in dry adult skulls. The study was conducted in the Department of Anatomy using 90 dry skulls of unknown age and sex, and prevalence, number, size, and location in these skulls were noted. The mastoid foramen was detected in 27.8% of skulls, with an incidence of 31.1% and 12.2% on right and left sides of skulls, respectively. The number of foramina ranged between 1 and 4. The mean diameter of this foramen was 0.9 mm, and the most frequent location was mastoid process. The detailed morphology and morphometry of mastoid foramen are of utmost use to neurosurgeons, ENT surgeons, radiologists, and vascular surgeons as it transmits mastoid emissary vein and meningeal branch of the occipital artery, which may be injured during various surgical procedures involving mastoid region and skull base causing catastrophic hemorrhage. In addition to this, mastoid emissary vein may be the source of thrombus, causing thrombus of sigmoid sinus creating helm of neurological complications.

Angulation of the dural venous sinuses of the posterior cranial fossa: Anatomical study with clinical and surgical applications.

Cerebral vein and dural venous sinus thromboses (CVST) account for 0.5%-1% of all strokes. Some structural factors associated with a potentially higher risk for developing CVST have been described. However, angulation of the dural venous sinuses (DVS) has yet to be studied as a structural factor. The current study was performed because this variable could be related to alterations in venous flow, thus predisposing to a greater risk of CVST development. Additionally, such information could help shed light on venous sinus stenosis (VSS) at or near the transverse-sigmoid junction. The angulations formed in the different segments of the grooves of the transverse (TS), sigmoid (SS), and superior sagittal sinuses (SSS) were measured in 52 skulls (104 sides). The overall angulation of the TS groove was measured using two reference points. Other variables were examined, such as the communication pattern at the sinuses' confluence and the sinus grooves' lengths and widths. The patterns of communication between sides were compared statistically. The most typical communication pattern at the sinuses' confluence was a right-dominant TS groove (82.98%). The mean angulations of the entire left TS groove at two different points (A and B) were 46° and 43°. Those of the right TS groove were 44° and 45°. The median angulations of the left and right SSS-transverse sinus junction grooves were 127° and 124°. The mean angulations of the left and right TS-SSJsv grooves were 111° (range 82°-152°) and 103° (range 79°-130°). Differentiating normal and abnormal angulations of the DVSs of the posterior cranial fossa can help to explain why some patients are more susceptible to pathologies affecting the DVSs, such as CVST and VSS. Future application of these findings to patients with such pathologies is now necessary to extrapolate our results.

On the spinal venous sinus of Alligator mississippiensis.

The epidural space of the American alligator (Alligator mississippiensis) is largely filled by a continuous venous sinus. This venous sinus extends throughout the trunk and tail of the alligator, and is continuous with the dural sinuses surrounding the brain. Segmental spinal veins (sl) link the spinal venous sinus (vs) to the somatic and visceral venous drainage. Some of these sl, like the caudal head vein along the occipital plate of the skull, are enlarged, suggesting more functional linkage. No evidence of venous valves or external venous sphincters was found associated with the vs; the relative scarcity of smooth muscle in the venous wall of the sinus suggests limited physiological regulation. The proatlas (pr), which develops between the occipital plate and C1 in crocodylians, is shaped like a neural arch and is fused to the dorsal surface of the vs. The present study suggests that the pr may function to propel venous blood around the brain and spinal cord. The vs effectively encloses the spinal dura, creating a tube-within-a-tube system with the (smaller volume) spinal cerebrospinal fluid (CSF). Changes in venous blood pressure, as are likely during locomotion, would impact dural compliance and CSF pressure waves propagating along the spinal cord.

Different normal anatomical variations of the transverse dural sinus in magnetic resonance venography (MRV): do age and sex matter?

The anatomical variations of the intracranial venous dural sinuses must be put in consideration in diagnosing magnetic resonance venography (MRV) to avoid the diagnostic pitfalls resulting from over-diagnosis of cerebral venous dural sinus occlusion or thrombosis. The available data regarding the age and sex difference of the magnetic resonance venography (MRV) anatomical variations is still limited. A retrospective study is done for 500 patients ranging from 20 to 70 years. Only 363 patients (142 males and 221 females) were included in our final analysis: all have normal MRI brain & posterior fossa. Magnetic resonance venography (MRV) is done to detect the presence or absence of the transverse venous dural sinuses and to detect any age-or sex-related differences. Also 64 dry Egyptian skulls (41 males and 23 females) were employed to detect symmetry of transverse sulcus and to determine age and sex difference. Hypoplastic left transverse sinus was by far the commonest asymmetrical transverse sinus variants representing 22.0% of total: it was noted in 38 male and 38 female. Even if the asymmetrical transverse sinus is more common in females, there is no significant difference between both genders. In the dry skull, symmetrical transverse sulcus was observed in 67.2% of total, while asymmetrical transverse sulcus was recorded in 32.8% of total, which were more observed in female skull 17.2% of total with no significant difference

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Cranial venous sinus dominance: what to expect? Analysis of 100 cerebral angiographies / Dominância dos seios venosos cranianos: o que esperar? Análise de 100 angiografias cerebrais

ABSTRACT We report an analysis of the cranial venous sinuses circulation, emphasizing morphological and angiographic characteristics. Methods Data of 100 cerebral angiographies were retrospectively analyzed (p = 0.05). Results Mean age was 56.3 years, 62% female and 38% male. Measurements and dominance are shown in the Tables. There was no association between age or gender and dominance. Right parasagittal division of the superior sagittal sinus was associated with right dominance of the transverse sinus, sigmoid sinus and internal jugular vein; and left parasagittal division of the superior sagittal sinus was associated with left dominance of the transverse sinus, sigmoid sinus and internal jugular vein. Conclusion A dominance pattern of cranial venous sinuses was found. Age and gender did not influence this pattern. Angiographic findings, such as division of the superior sagittal sinus, were associated with a pattern of cranial venous dominance. We hope this article can add information and assist in preoperative venous analysis for neurosurgeons and neuroradiologists.

RESUMO Relatamos uma análise da circulação dos seios venoso cranianos, enfatizando características morfológicas e angiográficas. Métodos Dados de 100 angiografias cerebrais foram retrospectivamente analisados (p = 0,05). Resultados Média de idade 56,3 anos, 62% feminino e 38% masculino. Medições e dominância expostos em tabelas. Sem associação entre idade ou sexo e dominância. Divisão parassagittal direita do Seio Sagital Superior (SSS) foi associada com dominância direita do Seio Transverso (ST), Seio Sigmóide (SS) e Veia Jugular Interna (VJI), e divisão parassagittal esquerda do SSS foi associada com dominância esquerda do ST, SS e VJI. Conclusão Um padrão de dominância dos seios venosos do crânio foi encontrado. Idade e sexo não influenciaram esse padrão. Achados angiográficos, como divisão do SSS, foram associados com o padrão de dominância venoso cerebral. Esperamos que este artigo acrescente informações e auxilie na análise venosa pré-operatória para neurocirurgiões e neuroradiologistas.

The localization of the asterion according to the anatomical landmarks of posterior cranial fossa in newborns: clinical implications / Localización del asterión de acuerdo con los puntos anatómicos de la fosa craneal posterior en recién nacidos: implicaciones clínicas

The purpose of this study was to determine the localization of the asterion according to the anatomical landmarks of posterior cranial fossa and its relation with sinuses for posterolateral surgical approaches in newborns. On 70 head-halves, a needle about 2 mm with diameter was placed on the centre point of asterion (posterolateral fontanel) by inserting into the whole cranial bony tissue by forming an right angle with the bony surface. Various localizations of asterion and its measurements from the internal and external anatomical landmarks were investigated on term neonatal cadavers. The localization of asterion was found as on the sigmoid-transverse sinus junction (STJ) (5., 6., 7., 8. squares) in 40% of cases on right side and in 34%, on left side. Additionally, it was located below the STJ (9., 10., 11., 12. squares) in 60% of cases, on right side and in 63% of cases on left side. We determined that the most frequent localization of asterion as the 11. square both for the right and left sides 12 (34%) cases for the right side and 11 (31,4%) cases for the left side. The asterion was not located on 1., 2., 3., 4., 5. and 12. squares on right side and 1., 3., 4., 8. and 9. squares on left side. It has been found that the region of asterion has an average distance value of 19.9 mm to internal acoustic meatus (MI), 31.7 mm to posterior clinoid process (PC), 34.4 to dorsum sellae (DS), 19.2 mm to jugular foramen (FJ), 23.0 mm to hypoglossal canal (HC), internally. The distance of asterion as 28.8 mm to zygoma root (ZR) and 22.3 mm to Henle's spine (HS) and 15.8 mm to mastoid tip (MT) and 35.9 mm to external occipital protuberance (PE) were observed. By the guide of point asterion on newborns the area of 1cm2 on this point which was placed on superior 4 squares of our scale diagram is suggested as a safe area of placement of first burr hole to avoid from the risk of bleeding of sigmoid and transverse sinuses on craniotomies of posterior fossa.

El propósito de este estudio fue determinar la localización del asterion de acuerdo con los puntos anatómicos de la fosa craneal posterior y su relación con los senos de abordajes quirúrgicos posterolaterales en los recién nacidos. Fueron utilizadas 70 hemicabezas y se colocó una aguja de alrededor de 2 mm de diámetro en el punto central del asterion (fontanela posterolateral) en todo el tejido óseo craneal produciéndose la formación de un ángulo recto con la superficie ósea. La localización del asterion y las mediciones de los puntos de referencia anatómicos internos y externos fueron investigados en cadáveres de neonatos a término. La localización del asterion se encontró en la unión sinusal transverso sigmoide (STJ) (cuadrados 5., 6., 7., 8.) en el 40% de los casos en el lado derecho y en el 34%, en el lado izquierdo. Además, se encontró por debajo del STJ (cuadrados 9., 10., 11., 12.) en un 60% de los casos en el lado derecho y en el 63% de los casos en el lado izquierdo. Se determinó que la localización más frecuente del asterion fue 11., tanto para los lados derecho e izquierdo, 12 casos (34%) para el lado derecho y 11 casos (31,4%) para el lado izquierdo. El asterion no se encuentra en los cuadrados 1., 2., 3., 4., 5. y 12. del lado derecho y 1., 3., 4., 8. y 9. del lado izquierdo. Se determinó que la región del asterion tiene una distancia promedio de 19,9 mm al meato acústico interno, 31,7 mm al proceso clinoides posterior, 34,4 mm al dorso selar, 19,2 mm al foramen yugular y 23,0 mm al canal hipogloso, internamente. La distancia del asterion a la raíz del hueso cigomático fue 28,8 mm y 22,3 mm a la columna vertebral, siendo de 15,8 mm al proceso mastoides y 35,9 mm a la protuberancia occipital externa. En los recién nacidos, se sugiere un área de 1cm2 y se colocan en 4 casillas superiores de nuestro diagrama a escala, como una zona segura para la realización de la primera trepanación para evitar el riesgo de sangrado de los senos sigmoide y transverso en craneotomías de fosa posterior.

Comparative morphometric study of the sigmoid sinus sulcus and the jugular foramen / Estudo morfométrico comparativo do sulco do seio sigmóideo e do forame jugular

Objective To compare the right and left sides of the same skulls as far as the described landmarks are concerned, and establish the craniometric differences between them. Method We carried out measurements in 50 adult dry human skulls comparing both sides. Results The sigmoid sinus width at the sinodural angle level was larger on the right side in 78% of the cases and at the level of the digastric notch in 72%. The jugular foramen width was also larger on the right side in 84% of the cases. The sigmoid sinus distance at the level of the digastric notch was larger on the right side in 64% of the cases, and the sigmoid sinus distance at the level of the digastric notch to the jugular foramen was larger on the right side in 70% of the cases. Conclusion Significant craniometric differences were found between both sides of the same skulls. .

Objetivo Comparar os lados direito e esquerdo no mesmo crânio nos pontos referenciais descritos e definir as diferenças craniométricas entre ambos. Método Realizamos mensurações em 50 crânios secos de humanos adultos comparando os lados direito e esquerdo. Resultados Como resultado, obtivemos as medidas da largura do seio sigmóideo na altura do ângulo sinodural maiores no lado direito em 78% dos casos e na altura do ponto digástrico em 72%. A largura do forame jugular foi também maior no lado direito em 84% dos casos. A distância do seio sigmóideo na altura do ângulo sinodural até a altura do ponto digástrico foi maior do lado direito em 64% dos casos, e a distância do seio sigmóideo na altura do ponto digástrico até o forame jugular foi maior do lado direito em 70% dos casos. Conclusão Diferenças craniométricas significativas foram encontradas entre os dois lados do crânio. .

Importancia neuroquirúrgica del complejo venoso petroso superior / No disponible

Objetivo Conocer la anatomía microquirúrgica del complejo venoso petroso superior (CVPS).Material y métodos Se realizó estudio descriptivo y prospectivo. Se utilizaron 6 especímenes (12 lados) inyectados. Se estudió la anatomía microquirúrgica del CVPS en los encéfalos, mediante un abordaje retrosigmoideo y transpetroso anterior. Se utilizó instrumental neuroquirúrgico, endoscopio rígido de 0 grados, microscopio quirúrgico OPMI-1 con magnificación 6× a 20×. Se analizó el patrón de drenaje hacia el seno petroso superior, la formación de las venas tributarias, la relación con el nervio trigémino y las variantes del CVPS.Resultados El CVPS se encontró en todos los lados, la vena tributaria que se encontró en el 100% de los lados fue la vena de la fisura cerebelopontina. El patrón de drenaje del CVPS fue dividido en relación a la cresta suprameatal en: lateral, medial y en un punto intermedio. Se encontró el CVPS simple, formado por un tronco con sus tributarias, en 8 lados y duplicado en 4 lados. En el estudio se observó un triángulo formado por el tentorio, el CVPS y parte de la cara petrosa y tentorial del cerebelo con bordes y contenidos bien definidos, el cual se llamó triángulo petroso-tentorial. Conclusión Es necesario entender la anatomía microquirúrgica del CVPS. Así, proponemos el triángulo petroso-tentorial como corredor neuroquirúrgico para el manejo de lesiones del ángulo pontocerebeloso a la región petroclival superior (AU)

Biometria da cabeça e da cavidade craniana de ovinos deslanados sem raça definida (Ovis aries LINNAEUS, 1758) em Petrolina/Pernambuco, Brasil / Biometry of head and cranial cavity of wooless mongrel sheep (Ovis aries LINNAEUS, 1758) in Petrolina/Pernambuco, Brazil

A espécie ovina é largamente utilizada na região Nordeste do Brasil por apresentar alta rusticidade. No entanto, sua anatomia ainda é pouco estudada. Assim, crescem os estudos para gerar subsídios técnico-científicos àqueles profissionais que trabalham com as áreas aplicadas da Medicina Veterinária e afins. O objetivo do presente estudo foi estabelecer correlações entre as dimensões da cabeça e da cavidade craniana, utilizando 80 ovinos, 40 machos e 40 fêmeas, com média de peso entre 27,0 e 33,0 kg. Em fêmeas, foi observada correlação entre a massa corpórea e o comprimento da cabeça; entre a massa corpórea e largura da cabeça; entre o comprimento da cabeça e sua respectiva largura; entre comprimento da cabeça e o comprimento da cavidade craniana e entre a altura da cabeça e o comprimento da cavidade craniana. As demais dimensões, nas fêmeas, não tiveram correlação estatisticamente significativa. Já em animais do sexo masculino, foi possível evidenciar correlação apenas entre a altura da cabeça e altura da cavidade craniana. Desta forma, é possível concluir que, quanto maiores forem as proporções da cabeça, maiores serão as dimensões e volume intracranianos.

The sheep is a commonly used species in Northeast region of Brazil because of its high rusticity. Yet, very little is known about the anatomy of these species. Therefore, the number of studies in this field is increasing to stimulate technical and scientific subsidies to professionals in Veterinary Medicine. The aim of this study was to establish correlations between the head and cranial cavity dimensions, using 80 sheep, 40 males and 40 females, with a medium weight of 27,0 to 33,0 kg. In females, it was observed correlation between corporal weight and length of the head; corporal weight and width of the head; length of the head and its respective width; length of the head and length of the cranial cavity; height of the head and length of the cranial cavity. The other dimensions, in females, had non-significant correlation. In males, the only correlation established was between height of the head and height of the cranial cavity. Thus, it was possible to conclude that the larger the proportions of the cranium are, the larger will be the dimensions and the intracranial volume.

Dimensions of the cranium and of the cranial cavity andintracranial volume in goats (Capra hircus LINNAEUS, 1758)

The aim of this project is to determine the dimensions of the cranium and the cranial cavity and the intracranialvolume in goats, using 64 adults. The dimensions of the cranium and cranial cavity were measured throughmetric tape and paquimeter, considering the intervals of the largest distances. To determine the intracranialvolume, balloons of latex were introduced in the cranial cavity, through the magnum foramen, later on, filledwith water that was transferred for graduate test tube. The average and the standard deviation of length, widthand height of the cranium, in millimeters, were respectively: 218.01 ± 6.96, 120.17 ± 10.01 and 108.14 ± 4.46.The average and the standard deviation of length, width, height, in millimeters, and of the volume of thecranial cavity, in cubic centimeters, were respectively: 109.31 ± 7.25, 61.36 ± 4.51, 63.85 ± 2.88 and119.31 ± 12.21. It was observed that, the width of the cranium possesses positive significant correlationswith the length (r = 0.6865), with the height (r = 0.5644) and with the intracranial volume (r = 0.5436).They were still established, positive significant correlations among the height of the cranial cavity, with thelength (r = 0.5682) and with the intracranial volume (r = 0.5473). Differences were evidenced between malesand females, in relation to the dimensions of the cranium and cranial cavity. There wasn’t difference of theintracranial volume in function of the sex of the goats.

Anatomía topográfica del asterion / Topographyc anatomy of the asterion

Introducción. Las referencias anatómicas que permitenubicar los senos venosos durante los abordajes de fosa posterior, son de utilidad para el neurocirujano. El asterion es usado como referencia para localizar cl seno transverso (ST). Material y método. Se utilizaron 50 hemicráneos de cadáveres adultos. Se estudió la relación del asterion con el ST, la vena emisaria mastoidea (VEM), la cresta suprameatal y el inion. Resultados. Se identificó el asterion en 49 casos. En el 87.8% de las piezas, se situó a la altura del seno transverso. El 72.2% se ubicó sobre el propio seno y el 27.8% sobre su codo. Si se traza una línea desde la cresta suprameatal al inion, el asterion se ubica por debajo de esta línea en el 88% de los casos. El foramen de la VEM se identificó en 46 oportunidades,en el 36% fue doble. Discusión y conclusiones. Según nuestros datos y los de otros autores, el orificio de trépano debe situarse por debajo y algo detrás del asterion para evitar la lesión del seno transverso

Background. In the surgical approaches to the posteriorfossa, the accurate location of the transverse-sigmoidsinus (TS-SS) complex is of great importance. The asterion is a referal landmark to the transverse sinus location. Method. Twenty-Iive skulls of adult cadavers were studied. We seek for the relationships of the asterion with: TS location, mastoid emissary vein, suprameatal crest and inion. Results. The asterion was found in 49 cases. In the great majority of cases (87.8%) the asterion was over the TS (72.2% over the sinus proper, 27.8% over the TS-SS transition). The mastoid emissary vein was present in 46 cases, and in 36% we found two veins. Discussion and conclusions. The burr hole for posterolateral approaches to the posterior fossa must be located below and behind the asterion

Reparos anatomicos superficiales de los senos transverso y sigmoideo. Importancia en la planificacion de un abordaje / Superficial anatomyc repairments of transversal and sigmoid sinus. The importance in planification of the approach

Se realizo un estudio anatomico con el fin de determinar la manera mas confiable de conocer la localizacion de los senos transverso y sigmoideo a traves de reparos anatomicos superficiales. Para desarrollar el trabajo se utilizaron 20 craneos secos. Se dividio el complejo seno transverso - seno sigmoideo en 3 porciones: seno transverso, andgulo de union y seno sigmoideo. Se realizaron mediciones entre los reparos anatomicos elegidos y los 3 sectores del complejo seno transverso - seno sigmoideo. Se observo que:a) la linea arco cigomatico-inion es un buen reparo para localizar el seno transverso; b) la punta de la apofisis mastoides es el reparo oseo mas confiable para localizar el angulo de union c)la linea que va desde la union de la sutura escamosa con la sutura pairetomastoidea a la punta de la apofisis mastoides es confiable para localizar el seno sigmoideo(AU)