=The influence of basic foramina.= It has often been stated that a basic fracture is arrested on meeting one of the larger foramina of the skull. With this view I am not in agreement, for not only are the larger foramina frequently involved, such as the foramen lacerum posterium and medium, but the largest foramen of all, the foramen magnum, is often implicated. It will be granted that certain foramina are but rarely involved, but this is due to the fact that they are aside of the chosen and definite paths of basic fracture. Thus, the foramen ovale and the foramen spinosum are only exceptionally involved because they lie immediately anterior to the petro-sphenoidal suture, whilst the anterior condyloid foramen--transmitting the hypoglossal nerve--is rarely implicated because it lies internal to the usual posterior fossa fracture. On the other hand, the foramen lacerum medium is involved in nearly every fracture that passes from one middle fossa to the other. =The probable line of basic fracture in any given case.= When the various weaker lines and areas are taken into consideration, and when the direction and site of the applied force are known, one is generally enabled to foretell with considerable accuracy the probable transbasic course of the fracture. After investigating over 300 cases, I was enabled to frame the following rules with respect to the probable line of transbasic fracture. _Direction, &c., of _Probable resultant basic fracture._ the applied force._ 1. Force applied to The fracture passes backwards from the the median frontal perpendicular plate of the frontal bone to the region. cribriform plate of the ethmoid, thence between the optic foramina to the body of the sphenoid, the thin sinus roof being usually comminuted. From there the fracture diverges to the opposite side, and tearing off the posterior clinoid process, passes along the petro-occipital suture to the jugular foramen, being then continued on the other side of that foramen along the masto-occipital suture, and so again to the vault. [Illustration: FIG. 32. DIAGRAM OF LINES PURSUED BY BASIC FRACTURES. Force applied to the median frontal region.]