Computational macroscopical patterning of the medullary striae of fourth ventricle

The aim of this study was to pattern macroscopically, by use of computational tools, the number and distributionof the medullary striae (MS) of fourth ventricle. After removing 71 fresh human brain stems, each respectiverhomboid fossa was photographed. The MS were carefully identified to be shaped and fulfilled by means ofa digital pen, using the Adobe Photoshop CS3® program. For absolute and relative analyses of number anddistribution, it was considered the maximum and minimum numbers of striae; striae that reached the ipsilaterallateral recess; presence of horizontal or oblique striae, with or without parallelism; and striae located at pontineor bulbar part of the rhomboid fossa. At least two MS per side were macroscopically detectable in 90.6% ofcases; they were bilaterally absent in 5.3% of pieces; and at least one medullary stria was present in both sidesof the rhomboid fossa in 92% of cases. As on the right side (36% of cases) as on the left (26.6%), two MS werefrequently more present. In 60% of cases, striae reached ipsilateral lateral recess on the left, and in 40% of caseson the right. It was detected horizontal, (non-parallel) oblique and parallel striae in 50.7, 86.7 and 26.7%of cases, respectively. Medial medullary striae were observed in the bulbar part of rhomboid fossa in 80% ofpieces, and in 36% of cases in the pontine part. The MS of fourth ventricle show high morphological variabilitydegree in relation to number and distribution.

Los recesos del IV ventrículo / IV ventricle recesses

Objetivo: Analizar la anatomía de los recesos del IV ventrículo y su relación con las vías de abordaje. Método. Se disecaron 3 especímenes de cerebelo en forma sistemática. Se utilizó la técnica de Klinger para las fibras y la cavidad se estudió en 2 moldes de acrilico. Se realizó un análisis bibliográfico. Resultados: Los moldes dieron una idea cabal de los recesos, su ubicación espacial y forma. Hay uno impar, el posterior, ubicado en la línea media y dos pares de recesos simétricos: los posterolaterales, ubicados a los del primero y algo por debajo del mismo, y los laterales, conductos que abrazan la unión bulbo protuberancial y se abren al ángulo bulbo pontocerebeloso por el agujero de Luschka. Para estudiar las relaciones de estas estructuras "in situ" fue útil extirpar primero las amígdalas. El techo de los recesos laterales está constituido por fibras cocleares en su parte medial y el pedúnculo del flóculo en su parte lateral. El núcleo dentado está separado del receso posterolateral por fibras del pedúnculo del flóculo. Conclusión. El IV ventrículo tiene 5 recesos. Los moldes del ventrículo permitieron tener una idea más clara de la disposición tridimensional de ellos. El conocimiento anatómico permitió un abordaje racional y menos traumático para lesiones del IV ventrículo o las estructuras vecinas. Palabras clave: IV ventrículo - flóculo - receso posterolateral.

Objective: To study the anatomy of the anatomy of the IV ventricle recesses and their relationship to the surgical approaches. Methods: Three specimens of brain stem and cerebellum were prepared sistematically and the fiblers were dissected with the Klinger's method. Two acrylic casts were obtained in order to analyze the cavity shape details of the IV ventricle. Results: The recesses of the IV ventricle are better understood by the inspection of the casts. In the midline lies the posterior recess. There are two pairs of symmetrical recesses: the posterolateral and the lateral. The laters, are two ducts that drain into the cerebello ponto medullary angle through the foramina of Luschka. The excision of the amigdala helps to study the anatomical relations "in situ". The roof of the lateral recess is made up by cochlear fibers and the flocculus penduncle laterally. The dentate nucleus us separated from the posterolateral recess by fibers from the flocculus pedicle. Conclusion: the IV ventricle has five recesses. Casts of the ventricle gave a better idea of their tridimensional disposition and relationships. With a proper anatomical knowledge, a rational non traumatic access to the different structures can be achieved. Key words: flocculus, IV ventricle, posterolateral recess.