During the initial examination of a patient, the orthodontist may encounter various findings that will, for the most part, be normal or variants of normal. Most pathological conditions encountered will be derived from structures normally found in the anatomic locations examined. Knowledge of the anatomy and common pathological entities based on location can prove helpful when abnormalities are encountered. This article describes anatomic locations and their contents in and around the oral cavity and discusses pathological processes commonly encountered in these locations. Syndromes involved with various abnormalities also are briefly mentioned. The intent of this article is to give the clinician a working knowledge of commonly occurring pathological entities.