W hiplash injuries occur due to differential accelerations in the hum an body. Neck injuries are predom inant, but a considerable body of clinical evidence suggesting a close relationship between whiplash and tem porom andibular joint (TM J) disorders has also accumulated. These soft-tissue injuries are generally treated conservatively and may take several years to resolve. The symptoms are well established but their cause is unclear as the validity of retrospective clinical studies is compromised by their subjective nature. Two main injury hypotheses have been proposed, but these lack experim ental evidence. This thesis presents the development and sled-testing of a physical model of the head, neck and mandible designed to simulate in vivo behaviour in a low velocity rear-end collision. Extensive instrumentation and a new angular displacement transducer for the head have given detailed kinematic information regarding mouth-opening and accelerations at the TMJ. Soft-tissue tensile tests using in vitro specimens have given an indication of the structural properties of the TMJ. The results indicate clearly that the mandible and TMJ are not harm ed during a low-velocity rear-end collision. Excessive levels of m outh-opening do not occur during whiplash resulting from Δv's of up to 9.2km /h. Active bracing of the jaw muscles prevents m outh-opening. A 2-D kinematic model of the head/jaw complex has been developed. The input to this model is given by the measured rotational kinematics of the model head. Simulations have shown a good correlation with experim ental d ata and a param etric analysis showed rem arkable stability of the model. The latter indicates th at norm al geometric variations are unlikely to influence loading at the TM J significantly. The model was used to estim ate the m agnitude of loading at the TMJ during retroflexion. Com parison with a simple free body diagram of the m andible shows th at reactive forces across the TMJ in functional chewing are much higher. These results are in direct conflict with the predom inant Inertial Injury Theory. In contrast, the results of this thesis are in agreement with the post-accident neuro-m uscular changes proposed by the Late TMJ Injury Theory.