J. Neurosurg. / April 10, 2009 DOI: 10.3171/2008.10.JNS08159 1 D espite great advances in image-guided technolo- gies, studying actual brain structures is still one of utmost importance. A detailed study of neu- roanatomy through dissections in cadavers can provide the best orientation in that regard. 18,22,24,25,27,28 The modern microneurosurgical approaches mainly require gyri and sulci orientation. 3,10,13,20 With the contribution of surgical anatomical studies on the brain surface, several neurosur- gical approaches can be easily performed today. 7,8,11,16,17,23 Despite considerable knowledge of intracranial anatomy, little is known about eloquent brain parts and their bone relationships. Cranial-cerebral relationships, irstly de- scribed in the 19th century by Broca, were reevaluated in this study. Misinterpretation of the gyri and sulci pre- and intraoperatively may increase the complication rates. 16,29,30 Identifying the gyri, especially when they are not neigh- boring the sulci or issures, which are always persistent in the brain, may be very problematic. Therefore, in this study we especially aimed to highlight the methods to identify the gyri with the guidance of the craniometrical points and sutures. Methods Ten formalin-ixed adult skulls were obtained. Skulls with the signs of CNS trauma or disease were excluded. The scalp and cranial muscles were removed. The cranial sutures, lines, and craniometrical points were protected, Window anatomy for neurosurgical approaches Laboratory investigation Simel Kendir, m.d., 1 Halil ibraHim acar, m.d., 1 ayHan comert , m.d., 1 mevci ozdemir, m.d., 2 GoKmen KaHiloGullari, m.d., 2 alaittin elHan, d.v.m., PH.d., 1 and HaSan caGlar uGur, m.d., PH.d. 2 Departments of 1 Anatomy and 2 Neurosurgery, Ankara University, Sihhiye, Ankara, Turkey Object. Knowledge of the cranium projections of the gyral structures is essential to reduce the surgical complica- tions and to perform minimally invasive interventions in daily neurosurgical practice. Thus, in this study the authors aimed to provide detailed information on cranial projections of the eloquent cortical areas. Methods. Ten formalin-ixed adult human skulls were obtained. Using sutures and craniometrical points, the crania were divided into 8 windows: superior frontal, inferior frontal, superior parietal, inferior parietal, sphenoidal, temporal, superior occipital, and inferior occipital. The projections of the precentral gyrus, postcentral gyrus, inferior frontal gyrus, superior temporal gyrus, transverse temporal gyri, Heschl gyrus, genu and splenium of the corpus cal- losum, supramarginal gyrus, angular gyrus, calcarine sulcus, and sylvian issure to cranial vault were evaluated. Results. Three-fourths of the precentral gyrus and postcentral gyrus were in the superior parietal window. The in- ferior frontal gyrus extended to the inferior parietal window in 80%. The 3 important parts of this gyrus were located below the superior temporal line in all hemispheres. The orbital and triangular parts were in the inferior frontal win- dow, and the opercular part was in the inferior parietal window. The superior temporal gyrus was usually located in the inferior parietal and temporal windows, whereas the supramarginal gyrus and angular gyrus were usually located in the superior and inferior parietal windows. The farthest anterior point of the Heschl gyrus was usually located in the inferior parietal window. The mean positions of arachnoid granulations were measured as 3.9 ± 0.39 cm anterior and 7.3 ± 0.51 cm posterior to the bregma. Conclusions. Given that recognition of the gyral patterns underlying the craniotomies is not always easy, aware- ness of the coordinates and projections of certain gyri according to the craniometric points may considerably contrib- ute to surgical interventions. (DOI: 10.3171/2008.10.JNS08159) Key WordS • gyral anatomy • neurosurgical approach • sulcal anatomy • surgical anatomy • window anatomy 1 This article contains some figures that are displayed in color online but in black and white in the print edition.