Analysis of the Asterion Morphology in Relation to Its Clinical Significance / Análisis de la Morfología del Asterion en Relación con su Importancia Clínica

SUMMARY: The asterion presents a significant anthropological marking and meeting point between three sutures. It is a surface landmark for the transverse-sigmoid venous sinus complex and is also a surgical landmark for access to the posterior cranial fossa, giving it clinical importance. The aim of this research was to analyze the shape of the asterion and to set the measurement methods that will determine distance between the asterion and surrounding features. The study sample, as a part of the Osteological collection of the Department of Anatomy, Faculty of Medicine Novi Sad, consisted of 43 skulls. Morphometric analysis was related to the measurement of the defined parameters and descriptive analysis presented the classification of asterion in relation to the presence of sutural bones, as well as the determination of the position of the asterion according to the transverse-sigmoid venous complex. There was a statistically significant difference between male and female skulls for all the measured parameters. The results show that 34.88 % were type 1 (one or more sutural bones are present) and 65.12 % were type 2 asteria (no sutural bones are present). More frequent occurrence of asteria type 2 was seen on both, male and female skulls. The most frequent position of the asteria on both sides of the skull was in the transverse- sigmoid venous complex (76.92 % on the right side vs. 72.22 % on the left cranial side). Clinical significance of knowing the area of asterion is reflected in order to make the surgical, as well as diagnostic procedures, as successful as possible.

El asterion presenta una importante marca antropológica y punto de encuentro entre tres suturas. Es un punto de referencia de superficie para el complejo del seno venoso sigmoideo transverso y también es un punto de referencia quirúrgico para el acceso a la fosa craneal posterior, lo que le confiere importancia clínica. El objetivo de esta investigación fue analizar la forma del asterión y establecer los métodos de medición que determinarán la distancia entre el asterión y las características circundantes. La muestra del estudio, que forma parte de la colección osteológica del Departamento de Anatomía de la Facultad de Medicina de Novi Sad, estuvo compuesta por 43 cráneos. El análisis morfométrico se relacionó con la medición de los parámetros definidos y el análisis descriptivo presentó la clasificación del asterion en relación a la presencia de huesos suturales, así como la determinación de la posición del asterion según el complejo venoso transverso-sigmoideo. Hubo una diferencia estadísticamente significativa entre los cráneos masculinos y femeninos para todos los parámetros medidos. Los resultados muestran que el 34,88 % eran tipo 1 (hay uno o más huesos suturales presentes) y el 65,12 % eran asteria tipo 2 (no hay huesos suturales presentes). Se observó una aparición más frecuente de asteria tipo 2 en cráneos tanto masculinos como femeninos. La posición más frecuente de la asteria en ambos lados del cráneo fue en el complejo venoso sigmoideo transverso (76,92 % en el lado derecho vs. 72,22 % en el lado craneal izquierdo). La importancia clínica de conocer el área de asterion se refleja en que los procedimientos quirúrgicos y de diagnóstico tengan el mejor resultado posible.

Study on the Incidence of the Occurrence of the Sutural Bones atAsterion in the Dry Adult Human Skulls of the South Indian Population

Background: Asterion is the point of sutural confluence present on the norma lateralis of the skull. Occasionally sutural bones are present at asterion. Asterion is commonly used as a surgical landmark for the lateral approach of the cranial fossa. So, the knowledge on the incidence of the presence of sutural bones at the asterion is important for surgeons. Thus the present study was undertaken to find out the incidence of the occurrence of the sutural bones present at the asterion. Subjects and Methods:70 skulls were collected from the department osteology section.The damaged bones were excluded from the study. A total of 140 asterions were studied. All the skulls were observed and the incidence of type 1 and type 2 asterion was recorded on both sides. The incidence of the multiple sutural bones was also recorded on both the right and left sides. Results: The incidence of type 2 asterion was observed to be higher than the type 1 asterion. The incidence of type 1 and type 2 sutural bones was observed as 27.86% and 72.14% respectively. The incidence of the multiple sutural bones at the asterion was observed as 14.29%. Conclusion: The data on the incidence of occurrence of sutural bones which was presented in the present study may be of great use to the radiologists and neurosurgeons for a better diagnosis and to minimize the complications while performing lateral approaches of the cranial fossa.

Anatomic position of the asterion and implication for neurosurgical procedure / Posición anatómica del asterion y sus implicancias en el procedimiento neuroquirúrgico

SUMMARY: The asterion is the joining of the lambdoid, parietomastoid, and occipitomastoid sutures. It is classified into two types, type I shows small bones or woven bones, while in type II, woven bones are non-existent. In this study, forty cadavers were conducted and observed the asterion on both sides of skulls showing the approximate ratio of type II and type I was 3:2. The asterion was located by measuring the distances from the asterion to skull landmarks, including inion, the root of zygoma, and mastoid tip. The mean distance between asterion and inion was 62.9 ? 6.0 mm. The mean distance between asterion and the root of zygomatic arch was 58.3 ? 6.1 mm, whereas the mean distance between asterion and mastoid tip was 51.1 ? 5.3 mm. The most common location related to the asterion was the dural venous sinuses on 65 % of tested sides, followed by infratentorial dura and supratentorial dura (25 % and 10 %, respectively). However, the authors found no differences between sexes, sides, and types in any underlying structures.

RESUMEN: El asterion es la unión de las suturas lambdoidea, parietomastoidea y occipitomastoidea. Clasificado en dos tipos, el tipo I muestra huesos pequeños o hueso laminar, mientras que en el tipo II, el hueso laminar es inexistente. En este trabajo se estudiaron 40 cadáveres y se observó el asterion en ambos lados de los cráneos correspondientes, mostrando una proporción aproximada de tipo II y tipo I de 3:2. El asterion se localizó midiendo las distancias asociadas a puntos de referencia del cráneo: el inion, la raíz del arco cigomático y el ápice del proceso mastoides. La distancia media entre el asterion y el inion fue de 62,9 ? 6,0 mm. La distancia media entre el asterion y la raíz del arco cigomático fue de 58,3 ? 6,1 mm, mientras que la distancia media entre el asterion y el ápice del proceso mastoides fue de 51,1 ? 5,3 mm. La localización más común relacionada con el asterion fueron los senos venosos durales en el 65 % de los lados evaluados, seguido de la duramadre infratentorial y la dura supratentorial (25 % y 10 %, respectivamente). Sin embargo, los autores no encontraron diferencias entre sexo, lados y tipo en ninguna estructura subyacente.

A 3D-Computed Tomography Angiography Study to Help in Surgical Planning for Retrosigmoid Craniotomies

Aims and Objectives: It is impossible to precisely anticipate the course of the transverse and sigmoid sinuses and theirindividual relationship to superficial landmarks such as the asterion during retrosigmoid approaches. This study was done todetermine the position of the asterion and the relationship between asterion and the transverse-sigmoid sinus junction (TSSJ)in making precise burr hole without damaging sinuses during retrosigmoid craniotomies.Materials and Methods: Computed tomography (CT) angiography was performed in 50 patients to obtain 3D-CT volumerendering images of cranial bone and dural sinuses. After delineating the sinuses, by simple restructuring using software andopacity modulation, bone image is reinforced. Asterion type, distance from the tip of mastoid process to asterion and root ofzygoma (ROZ) to asterion, and location of asterion in relation to TSSJ and distance between asterion and TSSJ were analyzedand measured.Results: The incidence of type 1 (presence of sutural bones) in our study was 24% and type 2 (absence of sutural bones) was76%. There was no statistically significance in the side and gender differences. The distance between the asterion and fromthe ROZ was 54.70 ± 3.68 on the right side and 54.32 ± 3.41 on the left side (P-0.612). The distance between asterion and tipof mastoid was 50.51 ± 2.67 on the right side and 50.12 ± 3.06 on the left side (P-0.716). The asterion was located on the T-Ssinus complex in 36 (72%) cases. The asterion was below the T-S sinus complex in 13 (26%) cases, and above the T-S sinuscomplex in only 1 (2%) cases.Conclusion: 3D-CT volume rendering imaging is capable of accurately visualizing the bony landmark and dural sinuses. Aneasy and simple restructured image provides precision and safety for the patient by ready and easy localization of asterionand TSSJ. This study was done to show that the previous cadaver-based anatomical studies can be done now in a moresophisticated and accurate manner with the latest technological advancements. This offers new options for anatomic researchand morphometric investigations.

A Preliminary Study On Incidence Of Cranial Sutural Bones By 3d Volume Rendering Of Ct Scan In Current Population In Eastern India

Background: Sutural bones are supranumary bones occurring along the sutures and completely surrounded bysutures of the skull. Their number, morphology and location vary in skulls. The knowledge of these bones isimperative in surgery, medicolegal cases involving child abuse or fracture of skulls and for anthropologicidentification of human populations. The studies on sutural bones have traditionally been based on the studiesof dry calvaria which are unreliable for the homogeneity of the population studied. Hence, this pilot study wasundertaken to evaluate the feasibility of 3D volume rendering of CT scan data for study of sutural bones.Method: 3D volume rendering from 64-slice CT scan data from 64 patients was studied for incidence andlocation of occurrence of sutural bones.Results: Overall incidence of sutural bone occurrence was found to be 29.69%. The most common sites forsutural bones, in descending order of occurrence, were found to be parieto-occipital suture, asterion, andlambda.Conclusion: Sutural bone studies in concurrent populations such as this one are rare. The incidence of suturalbones in this study is similar to what another study on concurrent populations has reported. However, locationof occurrence of sutural bones observed in this study was similar to all other sutural bone studies includingthose on dry skulls pointing to probable universality of this statistic. This preliminary study establishes the useof 3D volume rendering of CT scan data to be a valid means to acquire sutural bone data.

Estudio morfométrico del punto asterional y su relación con los senos venosos durales / Morphometric study of the asterional point and its relationship with the dural venous sinuses

INTRODUCCIÓN: la importancia de conocer las diferentes reparaciones anatómicas que involucran la parte ósea de la fosa posterior con estructuras neurovasculares, disminuye la incidencia de complicaciones relacionadas con su acceso dentro del procedimiento neuroquirúrgico. MATERIALES Y MÉTODOS: estudio descriptivo basado en la evaluación de 90 hemicráneas secas, del Museo de Anatomía de la Universidad Mayor de San Andrés. RESULTADOS: la prevalencia de asterión tipo I fue de 28.9%, mientras que la de tipo II fue de 71.1%. La prevalencia del número de venas emisarias fue: una vena 54.4%, dos venas 42.2% y tres venas 3.3%. Los promedios para las características morfométricas son los siguientes: de Asterion a protuberancia occipital externa de 68.8 mm, de Asterion a cresta suprameatal de 50.1 mm, de Asterion a vena emisaria de 54.1 mm, de Asterion a Vértice del proceso mastoideo de 54.1 mm y de asterion a plano horizontal de Francfort 14.6 mm. La ubicación del asterión en el seno transverso fue la siguiente: al mismo nivel del seno, 47.8% de los casos, en el codo en 13.3%, superior al seno 31.1% e inferior a este en el 7.8%. CONCLUSIONES: hay una diferencia en algunos resultados morfométricos del asterión con respecto a otros autores, lo que podría determinar una configuración craneal diferente para nuestra población. Esto debe considerarse para evitar complicaciones durante el período transoperatorio en una cirugía de fosa posterior. Estos resultados reflejan la necesidad de realizar un estudio con una población más grande para obtener resultados reales, estableciendo así parámetros de corte que nos permitirán tener nuestra propia bibliografía sobre cómo proceder en nuestra actividad quirúrgica.

INTRODUCTION: the importance of knowing the different anatomical repairs that involve the bony part of the posterior fossa with neurovascular structures, decreases the incidence of complications related to its access within the neurosurgical procedure. MATERIALS AND METHODS: descriptive study based on the evaluation of 90 dry hemicranial, from the Anatomy Museum of the Universidad Mayor de San Andrés. RESULTS: the prevalence of asterion type I was 28.9%, while that of type II was 71.1%. The prevalence of the number of emissary veins was: One vein 54.4%, Two veins 42.2% and Three veins 3.3%. The averages for morphometric characteristics are as follows: from Asterion to external occipital protuberance 68.8 mm, from Asterion to suprameatal crest 50.1 mm, from Asterion to emissary vein 54.1 mm, from Asterion to Vertex from the mastoid process 54.1 mm and from asterion to horizontal plane of Frankfurt 14.6 mm. The location of asterion in the transverse sinus was the following: at the same level of the sinus 47.8% of the cases, in the elbow in 13.3%, superior to the sinus 31.1% and inferior to this in the 7.8%. CONCLUSIONS: there is a difference in some morphometric results of the asterion with respect to other authors, which could determine a different cranial configuration for our population. This should be considered to avoid complications during the transoperative period in a posterior fossa surgery. These results reflect the need to carry out a study with a larger population, in order to have real results, thus establishing cutting parameters that will allow us to have our own bibliography on how to proceed in our surgical activity.

A Study Of Ossicle At Asterion In Western U.P. Of North Indian Crania.

Background: Studies of non metric cranial variants have been a field of considerable interest to research workers especially because of their racial and regional importance. Methodology: Total of 28 north Indian human crania of western U.P. was studied for the incidence of Ossicle at Asterion a cranial variant. Results: Ossicle at Asterion was found in 4 (14.2%) of total human crania. Conclusion: The presence of Ossicle at Asterion found to be of considerable regional and racial significance.

A Study on the Occurrence of Wormian Bones Among the Male and Female Skulls of Tamil Nadu. India.

Background: Wormian bones, also known as intra sutural bones are extra bone pieces that occur within a suture in the cranium. These are irregular isolated bones which appear in addition to the usual centers of ossification of the cranium and, although unusual, are not rare. The number of sutural bones varies considerably because different individuals and different population have different numbers of sutural bones. They occur mostly along the sutures and meeting point of the cranial sutures. They occur most frequently in the course of the lambdoid suture. They are also occasionally seen within the sagittal and coronal sutures. Materials and Methods: In this present study we analyzed the occurrence of sutural bones among 50 male and female skulls in Tamil Nadu region and we compared the results along with the studies of Indian skulls. Result and Conclusion: Based on the study we concluded that sutural bones are more among male skulls than in females among the skulls of Tamil Nadu and this is exactly the opposite of the results given in Indian population.

Morphometric features of asterion in adult human skulls.

Background: Asterion is the meeting point of temporal, occipital and parietal bones on the posterolateral surface of skull and surgically an important point of reference for approaching the posterior cranial fossa structures. However surgeons have been skeptical about its reliability due to population based differences in its morphology, distance with other external landmarks and also to sigmoid and transverse sinuses. Methods: In this study 50 (27 male & 23 female) adult skulls were investigated to determine the type of asterion, its distance from important bony landmarks and also the nearby venous sinuses were measured. Results: Our study revealed that type II (absence of sutural bones) was commoner than type I (presence of sutural bones) asterion. The asterion was 4.82 ± 0.58 cm from tip of the mastoid process on the right side and 4.70 ± 0.70 cm on the left. It was greater in males than in females, p value being statistically significant (P = 0.00 & P = 0.02 for right & left sides respectively). The distance of asterion from supramastoid crest was 4.22 ± 0.73 cm on the right and 4.23+/-0.58 cm on the left. The distance in males was more than in females. The P value 0.00 was statistically significant on the right side. Regarding the position of the asterion in relation to transverse sinus, it was on the transverse sinus in 62% cases, below it in 32% and above in 6%. Conclusions: The data obtained shows that the asterion is located either at the level or below the level of the transverse sinus in majority of the cases. This information is useful to neurosurgeons to reduce the risk during posterior cranial fossa surgeries. This work will also be useful to anthropologists, forensic science experts for determination of sex of the skull along with other parameters.

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.

Abordaje retrosigmoideo / Retrogigmoid approach

OBJETIVO: describir en forma detallada, paso a paso, la realización de un abordaje retrosigmoideo. DESCRIPCIÓN: posición: existen 3 posiciones descritas para la realización de este abordaje, semisentada, decubito dorsal y en banco de plaza. Incisión: se extiende desde la parte superior del pabellón auricular hasta 2 cm por debajo del vertice mastoideo, y 1 cm medial a la ranura digástrica. Disección de partes blandas: se realiza una disección subperiostica, teniendo especial cuidado con la vena hemisaria mastoidea (posible fuente de embolia aérea). Craniectomía: es necesario identificar previamente algunos puntos anatómicos de referencia para la ubicación de los senos transverso y sigmoides. En la etapa final de la remoción ósea, se procede al fresado de la porción más superior y lateral del abordaje, con la necesaria exposición de la porción inferior del seno transverso y de la porción medial del seno sigmoides. Apertura dural: se realiza una apertura en forma de letra "C" (lado izquierdo), o letra "C invertida" (lado derecho), con base medial, comenzando en la porción superior y medial de duramadre expuesta. Disección microquirúrgica: dependiendo de la ubicación de la patologia a abordar se debe realizar una retracción gentil del hemisferio cerebeloso hacia medial. En la mayoría de los casos es necesario abrir la cisterna cerebelobulbar, con el objeto de evacuar LCR. CONCLUSIÓN: el refinamiento alcanzado actualmente hace que el abordaje retrosigmoideo sea el más utilizado para el tratamiento de las múltiples patologías ubicadas en la región del ángulo pontocerebeloso. El acceso que proporciona esta vía a la mayoría de los nervios craneales que se encuentran en la fosa posterior, y a sus complejos neurovasculares correspondientes, lo convierte en un abordaje de obligatorio aprendizaje para todo neurocirujano

OBJECTIVE: the aim of this paper is to describe, step by step, the retrosigmoid approach to accessing the cerebellopontine angle (CPA). DESCRIPTION: patient position: three potential positions have been described for this approach: semi-sitting, dorsal decubitus and park bench. Incision: The incision extends from the top of the ear to 2 cm below the mastoid apex, and 1 cm medial to the digastric groove. Soft tissue dissection: A subperiosteal dissection is performed, taking special care to avoid the mastoid emissary vein. CRANIOTOMY: At the outset, it is necessary to identify certain anatomical landmarks to localize the transverse and sigmoid sinuses. Dural opening: The dural incision is made in the shape of the letter "C" on the left side or an inverted letter "C" on the right. Microsurgical dissection: Depending on the location of the pathology being treated, it may be necessary to perform gentle cerebellar retraction medially. CONCLUSIONS: the refinements now achieved with the retrosigmoid approach make it the most widely-used approach for the treatment of lesions located within the CPA. The access provided by this approach to the vast majority of the cranial nerves in the posterior fossa, as well as their neurovascular complexes, makes it a mandatory approach for all neurosurgeons to learn

Incidence of sutural bones at asterion in adults Indians skulls / Incidencia de huesos suturales en el asterion de cráneos indios adultos

Asterion is the point of sutural confluence observed in normal lateralis of the skull where parietal, temporal and occipital bone meet. Present study was carried out in the Department of Anatomy, CSM Medical University, Lucknow using fifty five dry human skulls to analyse the incidence of sutural bones at the asterion and its variation. At the asterion, sutural morphology was classified into two types: Type I- Where a sutural bone was present and Type II- Where a sutural bone was absent. Among 27 female skulls, percentage of Type I Asterion was found to be 14.81 and Type II contributed to 85.19 percent 17.86 percent asterion were classified as Type I and 82.14 percent as Type II in male skulls. The examination of 55 skulls (male and female together) brought out 16.36 percent Type I and 83.64 percent Type II asterions. Sutural morphology of asterion is essential in surgical approaches to posterior cranial fossa. Presence of sutural bones at asterion may complicate the surgical orientation. Therefore, the study has been carried out to alert the neurosurgeons. This work may also be useful to anthropologists and forensic science experts in having preliminary idea about male or female skull...

El asterion es el punto de confluencia sutural observado en norma lateral del cráneo, donde se reunen los huesos parietal, occipital y temporal. El presente estudio se llevó a cabo en el Departamento de Anatomía de la CSM Medical University, Lucknow, utilizando 55 cráneos humanos secos para analizar la incidencia de los huesos suturales en el asterion y su variación. En el asterion, la morfología sutural se clasifica en dos tipos: Tipo I, cuando un hueso sutural estaba presente y Tipo II estaba ausente. Entre 27 cráneos femeninos, el porcentaje de asterion Tipo I fue 14,81 por ciento y Tipo II 85,19 por ciento. En los cráneos masculinos, 17,86 por ciento de los asterion fueron clasificados como Tipo I y 82,14 por ciento como tipo II. En el total de la muestra (sin distinción de sexo), el Tipo I fue 16,36 por ciento y 83,64 por ciento Tipo II. La morfología sutural del asterión es esencial para determinar las vías de abordaje hacia la fosa craneal posterior. La presencia de huesos suturales en asterion puede complicar la orientación quirúrgica. Por lo tanto, el estudio se ha llevado a cabo para alertar a los neurocirujanos. Este trabajo también puede ser útil para los antropólogos y expertos en ciencia forense como examen preliminar para diferencias un cráneo masculino o femenino...

Asterion: frontera anatómica en los abordajes supra e infra tentoriales / Asterion: anatomical landmark in posterior fossa approaches

Resultados: la distancia entre el asterion y los puntos seleccionados (inion, CAE, mastoides) se mantiene dentro de rangos acotados. En la distancia Asterion-CAE se aprecia la menor variación en los valores medidos, mientras que en la distancia Asterion - Inion se objetiva la mayor variación entre los ejemplares estudiados. Por lo tanto, las distancias Asterion - CAE y Asterion- mastoides serian las mas seguras y confiables para la determinación de una referencia en la ubicación del asterion, sin que se halle expuesta la superficie ósea y guiándonos solo con puntos palpables.Conclusión: Hemos encontrado una fuerte correlación entre la posición del asterion y del seno transverso, por lo tanto, los orificios de trépano deberían situarse alejados de este punto craneométrico. A la vez, hemos observado que las distancias entre el asterion y los puntos seleccionados (inion, CAE, mastoides) se mantienen dentro de rangos acotados, lo cual permite su utilización en la práctica clínico- quirúrgica para la localización del asterion sin exponer la superficie ósea.

Results: the distance between selected points (inion, EAC, mastoid) and asterion remains within bounded ranges. The EAC-Asterion distance shows the least variation at the measured values while distance between Asterion-Inion manifest the greatest variation at the studied specimens. Therefore, the distances Asterion-EAC and Asterion-mastoid would be the most secures and reliables to locate the Asterion, without bone surface exposure and guided only by tangible points. Conclusion: We found a strong correlation between the position of the asterion and the transverse sinus, therefore, drill holes should be located far away from this point. Also we observed that the distances between asterion and selected points (inion, EAC, mastoid) remains within bounded ranges, allowing their use in clinical-surgical practice for asterion