Cranial dural arteriovenous shunts. Part 1. Anatomy and embryology of the bridging and emissary veins.

We reviewed the anatomy and embryology of the bridging and emissary veins aiming to elucidate aspects related to the cranial dural arteriovenous fistulae. Data from relevant articles on the anatomy and embryology of the bridging and emissary veins were identified using one electronic database, supplemented by data from selected reference texts. Persisting fetal pial-arachnoidal veins correspond to the adult bridging veins. Relevant embryologic descriptions are based on the classic scheme of five divisions of the brain (telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon). Variation in their exact position and the number of bridging veins is the rule and certain locations, particularly that of the anterior cranial fossa and lower posterior cranial fossa are often neglected in prior descriptions. The distal segment of a bridging vein is part of the dural system and can be primarily involved in cranial dural arteriovenous lesions by constituting the actual site of the shunt. The veins in the lamina cribriformis exhibit a bridging-emissary vein pattern similar to the spinal configuration. The emissary veins connect the dural venous system with the extracranial venous system and are often involved in dural arteriovenous lesions. Cranial dural shunts may develop in three distinct areas of the cranial venous system: the dural sinuses and their interfaces with bridging veins and emissary veins. The exact site of the lesion may dictate the arterial feeders and original venous drainage pattern.

Sexual dimorphism determination by piriform aperture morphometric analysis in Brazilian human skulls / Determinación de dimorfismo sexual mediante análisis morfométrico de la apertura piriforme en cráneos humanos brasileños

The sex determination of human skeletons is important in forensic and anthropological research. It can be carried out through qualitative or quantitative analysis of morphological parameters of dimorphism. The shape of the piriform aperture is one of the classic indicators of sexual dimorphism since it describes differences between males and females according to strong population-specific behavior. The purpose of this study was to analyze the presence of sexual dimorphism in the size of the piriform aperture and its relationship with individual skin color. We used 90 human skulls from the Collection of the Federal Universidad de São Paulo (UNIFESP), with registered data on sex, age and skin color (classified as white, black and brown). The dimensions studied were: height, upper width and lower width of piriform aperture. All dimensions were greater in males than females, however, only the piriform aperture height was found to be significant with p <0.01. By analyzing differences and grouping them according skin color, the piriform aperture height was found to be significantly higher (p <0.05) in white, black and brown males. In the group of black individuals skulls, we found significant differences in the upper width (p <0.05). The main differences, related to the piriform aperture height and the low influence of skin color in the presence of sexual dimorphism in the piriform aperture size, are in contrast with what has been reported in the literature and justify the revision of the classic indicators used for diagnosis of sex in specific populations.

El diagnóstico del sexo a partir de osamentas humanas es importante en investigación antropológica y forense, éste puede ser realizado mediante análisis cualitativos o cuantitativos de parámetros morfológicos de dimorfismo. La forma de la apertura piriforme es uno de los indicadores clásicos de dimorfismo sexual, a partir de ella se han descrito diferencias entre hombres y mujeres en sus dimensiones, con un fuerte comportamiento población-específico. El propósito de este estudio fue analizar la presencia de dimorfismo sexual en las dimensiones de la apertura piriforme y su relación con el color de piel de los individuos. Se utilizaron 90 cráneos humanos de la Colección de la Universidade Federal de São Paulo (UNIFESP), con registro de sexo, edad y color de piel (clasificadas en blanco, negro y pardo). Las dimensiones analizadas fueron: altura, ancho superior e inferior de la apertura piriforme. Todas las dimensiones resultaron mayores en hombres que en mujeres, sin embargo, sólo la altura de la apertura piriforme resultó ser significativa con p<0.01. Al analizar las diferencias agrupándolas por color de piel, obtuvimos que la altura de la apertura piriforme resultó ser mayor y significativa (p<0.05) en hombres blancos, negros y pardos. En el grupo de cráneos de individuos negros, además, encontramos diferencias significativas en el ancho superior (p<0.05). Las principales diferencias encontradas, referidas a la altura de la apertura piriforme, y la baja influencia del color de piel en la presencia de dimorfismo sexual en las dimensiones de la apertura piriforme, contrastan con lo reportado en la literatura y justifican la revisión de los indicadores clásicos utilizados para el diagnóstico del sexo en poblaciones específicas.

Clinical anatomy of the human anterior cranial fossa during the prenatal period.

We examined the prenatal development of the human anterior cranial fossa and considered its clinical aspects. Our purpose was an evaluation of anterior cranial fossa geometry, its measurements and connections with the nasal cavity and middle cranial fossa. The study was performed on 29 foetuses from the first and second trimester of pregnancy. New methods of computer image analysis, Scion for Windows 98 and ELFv 4.2, were applied to examine this anatomical region. Different options used were binarisation, equalisation, filters, linear and non-linear transformations and mathematical operations of images. This enabled the dynamics of prenatal development to be accurately evaluated for parts of the base of the human skull. Measurements were taken of angles of the cranial base. The anterior cranial base angle (the apex in the middle of the sella turcica and the arms running through the zygomatic ossification points) decreased gradually between C-R 6 to 23.5 cm from 170 to 120 degrees and afterwards became constant. The contrary-medial cranial base angle (adjacent to the anterior cranial base angle and with a second arm running through the auricular cartilage) increased from 50 to 70 degrees. The anterior cranial fossa was first located on the same level as the middle and posterior fossae. The process of descent of the middle and posterior cranial fossa begins in the 4th gestational month. The geometry of the anterior cranial fossa changes rapidly, especially in the first trimester of pregnancy. The first trimester of pregnancy is crucial for the development of its defects. Preconception prophylaxis of inborn defects of the anterior cranial fossa is therefore extremely important.