The aim of this paper is focused on the use of a mathematic model, similar to the glenohumeral joint system, to develop a dimensional analysis of this, in order to get mechanical parameters and, based in the results, we implement a shoulder prosthesis prototype. The mechanical model is based on a simplification of the musculoskeletal shoulder. The system consist in an arm with forces: the arm weight, six scapulo-humeral muscles and the reaction at the glenohumeral joint, wich was considered as a spherical joint. We use the mathematic model proposed by Terrier A. The prototype will emulate the basic movements of the shoulder (flexion-extension and abdution-adution). The construction will be made with the selected materials based on the results obtained through a virtual effort analysis. The components of the preliminary prototype have been test with forces on the virtual analysis. The prosthesis design of the glenohumeral joint match with the motion parameters proposed and it have 3 degrees of freedom.