INTRODUCTION Swallowing requires the coordinated activity of muscles in three regions of the head and neck: the oral cavity, the pharynx and larynx, and the oesophagus. This complex sequence of motor behaviour is part reflex and partly under voluntary control. It has been extensively investigated using a variety of techniques including videofluoroscopy, endoscopy, radiography, ultrasound, electromyography (EMG) recording and functional MRI, together with observations on individuals with dysphagia. Swallowing as a motor behaviour is so complex that some details have remained difficult to resolve. The literature is often contradictory, particularly the earlier studies based on inferential analysis of radiographic data. Careful analysis of swallowing using newer techniques shows that there is a surprising amount of variation between individuals. This chapter will survey the current state of knowledge concerning the normal anatomy and physiology of swallowing and what might be considered as the limits of normality, essential to the understanding of dysphagia. Neural control and the coordination of breathing and swallowing will also be addressed.