The etiology of temporomandibular joint (TMJ) disorders, including osteoarthritis, is largely unexplained. TMJ disc integrity is crucial, since its failure appears to precede degeneration of the joint. During mandibular function, the TMJ disc undergoes displacements and deformations, generating strains and stresses. Dynamic stereometry, a combination of imaging and jaw tracking, yields a non invasive, three-dimensional and dynamic representation of the relationship between the articular surfaces of the human TMJ. Aim of this study was to refine this method in order to depict also movement and deformation of the TMJ disc during jaw opening/closing. Data collected in four asymptomatic subjects (2 M and 2 F, aged between 24 and 32) indicated large disc displacements and deformations that can load TMJ soft tissues during opening and closing jaw movements. Such displacements and deformations can trigger disc damage during dysfunctional loading and/or compromised state of TMJ tissues. These displacements and deformations can also be utilized for numerical joint modeling.