The blood-spinal cord barrier (BSCB) prevents drug delivery to spinal cord parenchyma. Focused ultrasound can temporarily increase BSCB permeability in small animal models. The human vertebral column distorts ultrasound foci, preventing clinical translation of this technique. Beamforming must be used to correct focal distortion and may be performed using ray acoustics and patient-specific preoperative CT scans. We evaluate the simulation accuracy of ray acoustics, applied to trans-vertebral ultrasound propagation, through comparison with experiment. Trans-vertebral ultrasound propagation was measured for a spherically focused transducer geometrically focused to the centre of individual thoracic vertebral foramen. Simulation pressures were compared to experiment pressures. Simulation error in voxel pressure was evaluated using root-mean-square error, and was similar to error in a water-only case. Average simulation error across all measurements and simulations in maximum pressure location and weighted >50% focal volume location were 2.3 mm and 1.5 mm, respectively. Simulation error is small relative to the dimensions of the transducer focus (4.9 mm full width half maximum), the spinal cord (8–10 mm diameter), and vertebral canal diameter (15–20 mm diameter), suggesting that ray acoustics may be sufficiently accurate for ultrasound beamforming to the vertebral foramen.