Licence: In copyright
Credit: Handbook of surgical anatomy / by G.A. Wright and C.H. Preston. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
101/238 (page 89)
![bone overHes the parietals at the inner parts of the coronal sutures, whilst the reverse is the case at the outer parts. Hence blows upon the middle of the head over the frontal or parietal bones would tend to force outwards the lower parietal margins. But these in turn are overlapped by the great wings of the sphenoid and squamous plates of the temporal bones, and are thus kept in. The local thickenings and ridges are so arranged as to give additional support. Such are the internal longitudinal ridge from the occiput to the nose, the mastoid processes and petrous parts of the temporal bones and the ridge between the mastoid processes, along the line of the lateral sinuses. Externally, the skull is strengthened by the supra-orbital ridges, the temporal ridges, the zygomatic arches and the malar bones. It is in part due to the radiation of the violence that the internal table of the skull is often more widely fractured than the external, or may be the only one broken. Fractures of the base of the skull following Fractured base violence applied to the vault of the cranium usually occur in a situation corres]3onding to the part of the Force applied vertex injured. Thus blows upon the frontal region ^° vault may result in fracture of the anterior fossa, blows upon the parietal in fracture of the middle fo'Ssa, and blows upon the occipital in fracture of the posterior fossa—that is, the fracture of the vertex tends to travel downwards to the base in a straight line, but its course is modified by the lines of strength above mentioned.](https://iiif.wellcomecollection.org/image/b21906774_0101.jp2/full/800%2C/0/default.jpg)
