A fracture of the anterior fossa which was followed by the development of meningitis 275 84. Basal meningitis secondary to temporo-sphenoidal abscess 277 85 A and B. To illustrate the exposure of the lateral sinus (after Hunter Tod) 285 86. A case of Hernia cerebri and the abscess after removal 292 87. Diagrammatic illustration of the three forms of ‘gutter’ fracture 297 88. Diagrammatic representation of the effects produced on bone and brain by a perforating bullet-wound 299 89 A and B. Sheen’s bullet probe, forceps, and telephone bullet-detector 302, 303 90. To illustrate the operations on the Gasserian ganglion 317 91. To illustrate the operations for exposure of the Gasserian ganglion 321 92. Ivory exostoses of the skull 326 93. The development of the frontal bone 327 94. An exostosis of the orbit 330 95. An extrinsic sarcoma of the skull 331 96. An intrinsic sarcoma of the skull 333 THE SURGERY OF THE SKULL AND BRAIN CHAPTER I CRANIO-CEREBRAL TOPOGRAPHY The surgeon who is called upon to carry out operations on the skull and brain must possess an accurate knowledge of the anatomy of the parts involved. Added to this, he must have at his command some simple method of depicting on the surface of the skull the more important structures. The more complicated systems of cranio-cerebral topography are of little practical value to the surgeon. Simplicity is essential, and the following outline will be found to furnish an adequate practical guide. Firstly, the skull can be divided into two lateral halves by the surface-marking of the superior longitudinal venous sinus. =The superior longitudinal sinus.= This sinus originates at the crista galli and, passing backwards along the attached margin of the falx cerebri, terminates at the internal occipital protuberance. It may be represented by a line drawn from the base of the nose (the nasion), over the vertex of the skull, to the external occipital protuberance (the inion)--this line corresponding in its course to the occasionally persistent metopic suture between the two halves of the frontal bone, to the sagittal suture between the parietal bones, and to the middle line of the upper or tabular portion of the occipital bone. Secondly, each lateral half of the skull can be subdivided into supra- and infratentorial regions by a line which marks the external attachment of the tentorium cerebelli; in other words, by the line of the lateral sinus.