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Fixed Brain Dissection Initial Steps

Surgical Correlation


Fixed Brain Dissection Initial Steps. A, After the fixed brain is achieved, the arachnoid membrane and its vessels must be taken off using appropriate technique. One of the easiest ways is to hold the major sulcal arteries near the superior convexity border and pull it all the way down following the same direction of the sulci. It will avoid that strong and hard vessels cut the brain surface when pulled off. B, As exposed earlier, the long knife is located in the frontoparietal operculum with the base of the pars triangularis and a point 2 cm superior to the posterior end of the sylvian fissure as landmarks. This cut must be aimed to the superior limit of the corpus callosum, in the midline, to preserve the lateral ventricle roof to be opened later, what can be difficult in some hemispheres. If that is the case, this step should be done with more than one movement, with deeper cuts until it gets in the corpus callosum by the midline. C, The precentral gyrus is separated from the remained frontal and parietal lobes and put in its original position for the study of the relations between the primary motor cortex with the deeper structures as the corpus callosum and foramen of Monro. In the picture, the pos-central gyrus is also placed in anatomic position, defining the “central lobe” and the paracentral lobule in the medial surface. This step can be done before and after the removing of the lateral ventricular roof, as shown in the picture. D, Opening the lateral ventricular roof. With a number 10 blade, the roof of the lateral ventricle is removed, beginning from the frontal horn, in an anterior–posterior way. Care should be taken here, to avoid lesion of the ventricular floor. If the first cut in the hemisphere, made by the long-knife, was successful, the ventricular roof should be thin as 1 to 2 mm, what makes easier the identification of the ventricular cavity to be opened. The ventricular cavity must be entirely exposed, from the frontal horn to the atrium in this step. (Images courtesy of E de Oliveira)