The waists are studied customarily in separated form together with the corresponding member. The muscles associated with them are jointed in base with an exclusively topographic criterion, resulting the following groups: muscles of the back, of the neck, of the thorax and of the pelvic member. The muscles associated to the thoracic waist are tried as common muscles of the member, without taking into account its insert neither its inervation. The homotipia criteria among both waists are established in this work, and standards to homologate the muscles that join the thoracic members and pelvics with the axial form are proposed. The classification in extrinsic or intrinsic in base to embriologic origin, its distal insert and its inervation is appealed for this purpose