High-resolution manometry (HRM) is used to analyze upper esophageal sphincter (UES) physiology. Conventional HRM can yield imprecise measurements of UES resting pressure given its unidirectional sensors and averaging of circumferential pressure. In contrast, three-dimensional (3D) measurements can yield precise UES resting pressure data over the entire length of the UES. This study conducted a detailed analysis of UES resting pressure as evaluated by 3D-HRM.Seventeen young, healthy adult participants (7 females and 10 males) were recruited. The 3D-HRM system used includes a pressure sensor catheter (outer diameter, 4 mm) and eight-channel transducers arranged circumferentially to acquire pressure data at 45° intervals. The catheter was inserted transnasally into the esophagus and automatically retracted at a speed of 1 mm/s. Participants performed the following tasks: maintain resting breathing, perform breath holding, and perform the Valsalva maneuver. Data were obtained and compared per millimeter over the longitudinal UES length.Clear 3D waveforms were identified, with greater mean UES pressures in anterior-posterior directions than in lateral directions ( < .05). The anterior distribution was located superior to the posterior portion. Significant differences were observed in mean UES pressures and UES resting integrals between resting breathing and the Valsalva maneuver ( < 0.05). No differences in functional UES length were observed.The normal UES resting pressure was not directionally uniform in the luminal structure. 3D-HRM imaging of UES resting pressure can help deepen our understanding of UES physiology.4.