From the time of Hippocrates to the early 19th century, knowledge advanced but that was an uneven process. Anatomy was basically defined by Galen and remained cast in stone until the early 16th century. Neuroanatomy was described by Galen but had little practical value, as brain surgery was not possible. The anatomy of the cranium was known and was largely correct. Care was taken to avoid the frontal air sinuses and the venous sinuses and the temporal region. The role of the brain in consciousness was not understood. It was considered the seat of the soul but there was a lack of understanding that damage to it could induce clinical symptoms such as stupor or paralysis. These were variously attributed to injuries to the meninges or the bone. This error was finally corrected in the 18th century when the brain was identified as responsible for much of the clinical disturbance following cranial trauma. All awareness that post traumatic neurological deficit was contralateral was ignored until the late 18th century, although several authors noted it. Likewise, the presence of CSF had to wait until the 18th century until it was recognized. Fissures were treated with trepanation, because of a perceived risk of infection developing between the bone and the dura. Depressed fracture fragments were elevated, replaced, or removed according to the details of the injury. Finally, for centuries surgeons blocked patients ears to reduce the sound of drilling, despite the fact that such a blocking would amplify the noise.

Over the last 50 years the significance of Galen\'s contributions to the arts of medicine and surgery have been increasingly recognized. Despite his errors, his contributions to medical and surgical practice have been profound. In the present context, his teachings on cranial surgical instruments and technique would continue to be influential throughout one and a half millenia. His technical advice was sound. His error about the anatomy of blood vessels supplying CNS were not of much consequence since the CNS would remain surgically inaccessible until the end of the 19th century. He reclassified fractures as extending to the diploe or through the internal table. Moreover, they could be simple, comminuted, depressed, or elevated. He did not mention indications or clinical changes, on the other hand he had many sensible remarks to make on the instrumentation required for cranial surgery. As will be seen in what follows, he was much quoted in justification of the decisions of his successors. The major errors of significance related to his description of the anatomy of the cranium and its sutures. His concern about the cranial attachment, vascular components and excretory functions of the sutures added to Hippocrates\' concerns about their inherent weakness resulted in the teaching that trepanation should avoid these structures. This was to have a limiting effect on the placement of trepanation openings which was of no benefit to the patients. Moreover, his enthusiasm for bloodletting would also serve to potentiate Hippocrates teaching on this matter, to the advantage of nobody.

Celsus gave an adequate description of the bones and sutures of the calvarium. His classification of injuries was simple including fissures and depressions. He is the first to relate specific symptoms to specific tissue injury. In addition, he was aware that fractures could be present in the absence of typical findings. He was also the first to note the meningeal vessels could rupture producing severe localized pain. His treatment was more conservative than that of Hippocrates. Plasters were to be used and if there was no deterioration trepanation was avoided. He described the use of the crown trepan (modiolus) and the instrument with a smaller tip which expands rapidly to prevent penetration. He also described the technique of rotating the trepan between the palms. His description of operations for depressed fractures were unusually clear and relevant even by modern standards. His wound care is strikingly different from that of Hippocrates as he advocates various dressings soaked in vinegar and as time passes plasters should be softened with rose oil. Regrettably, Celsus influence would not be felt until the time of the Renaissance, because his texts were lost. However, his \"De Medicina\" was rediscovered and became the first medical text to be published using the new moveable type printing press, in the year 1478. Thus, his influence was minimal in the Arabic world and the early Renaissance. Thereafter it was profound.