This research examined cineradiographic films (CRF) of articulatory movements in a person with congenital aglossia (PWCA) during speech production of four phrases. Pearson correlations and a multiple regression model investigated co-variation of independent variables, positions of mandible and hyoid; and pseudo-tongue-dependent variables, positions of mylohyoid and tongue base. Results suggest that backing/fronting of the mandible assisted the mylohyoid/tongue base in making mid-antero-posterior constrictions. Co-linearity findings suggest the best predictor of tongue base movement was mandible for back sounds. Hyoid movement was highly correlated with mandibular movement horizontally, but hyoid acted independently vertically and possibly with greater phonemic specialty in the PWCA. Findings suggest hyoid was a strong determinant of vertically dependent variable movement in all phrases. The extent of hyoid activity was a unique finding and one that may begin to explain relative intelligibility in this PWCA. Observed changes in vocal tract length may have influenced F2 transitional/vowel midpoint values.