Headache, fatigue, and vertigo are collectively the commonest symptoms encountered in clinical medicine, yet in many cases their true aetiopathogenesis is unknown or unclear. It is postulated that an important reason why little significant progress is being made towards discovering the true aetiology of these symptoms is because physicians, almost universally, are failing to examine a large part of the head for common, readily observable intraosseous pathology which could conceivably cause these symptoms. The region not examined comprises the mandible, maxillae, and their appendages, and the intraosseous pathology not examined for includes impacted teeth, devitalized teeth, and residual infection, amongst others. The non-examination for pathology which could cause these symptoms has thus created a major blind spot in clinical medicine. It is conservatively estimated that more than 50 million people on the American and European continents may thereby be denied a proper clinical examination for the aetiology of these symptoms. Readily testable data, indicating the extent to which the medical profession as a whole has overlooked this pathology, is provided.