The present study aimed at identifying underlying parameters that govern the shape of the tongue. A functional topography of the tongue surface was developed based on three-dimensional ultrasound scans of sustained speech sounds in ten normal subjects. A principal component analysis extracted three components that explained 89.2% of the variance at 33 measurement points on the tongue surface. The results from the principal component analysis supported a physiologically plausible three-component model of tongue movement. This model breaks tongue movement down into a protrusion and retraction component that is represented by the measurement points on the posterior tongue, a tongue tip control component that is represented by the measurement points on the tongue blade, and a dorsal height and position control component that is represented by the measurement points on the tongue dorsum. A case series of three patients with partial glossectomies illustrates how this measurement system can be applied to surgically altered tongues to allow a detailed analysis of post-surgical function.