MUSCULO-ARTICULAR MODELING OF THE TRICEPS BRACHII

With the aim of proposing modelling equations for the length, force an d shortening velocity of the triceps brachii, an X-ray and biomechanic al study was carried out on the elbow joint. Two series of three upper right limbs removed from cadavers were used. Il. allowed us to situat e the articular rotational axis of the elbow and to modelise the lever arm of the muscle group of the elbow extensors. Eight superimposed X- ray films with opaque markers at different articular angles show that the rotational axis of the elbow is different from the epitrochlea-epi condyle axis, commonly localised by palpation and used as such in func tional and biomechanical explorations. This rotational axis of the elb ow, situated in the trochlea, is fixed at the centre of the articular range and moves noticeably to both extremities of this range. Biomecha nical study, based on measurement of internal and external torques est ablished using an overload, allowed us to modelize the lever arm of th e triceps brachii between 0 and 2.44 radians, according to length of t he: ulna. The applications concerning length, force and shortening vel ocity of the triceps brachii are described. This method of modelling i s applicable to other joints and muscle groups.