The mouth is a valuable indicator of systemic disease, as well as local pathology. It has a complex embryological origin, being the site of the junction of ectoderm and endoderm, and receiving contributions from pharyngeal arch mesoderm. The tongue muscles are derived from suboccipital somites that have migrated forward around the pharynx, bringing their nerve supply with them. This origin is also reflected in the variety of diseases. These include skin and gut mucosal abnormalities, together with other lesions that encompass a number of medical and surgical disciplines.

The breath must be examined for halitosis (offensive or abnormal – fetor oris). This is most commonly due to poor local hygiene, but may be an indicator of respiratory, upper alimentary or systemic disease, and local disease within the oral cavity. Alimentary odors may be related to gastroenteritis, obstruction of the pylorus, and small and large gut, and over-indulgence of food and alcohol, the latter aroma depends on the timing and quantity imbibed.

Ask the patient to put out their tongue to assess hydration and say ah, to observe the oropharynx (figure 22a,b). A more detailed examination may require a torch and spatula (figure 23a,b), as considered in other sections.

The general examination described is undertaken in all patients, it is followed by examination of one or more systems, depending on the presenting problem, as considered in subsequent sections. On completion of the examination of each region and system, cover the patient and make sure they are comfortable.