Spiral galaxies exhibit a disc-shaped structure with relatively small thickness compared to their radial extent. Typically, these systems maintain a stable configuration, particularly in their innermost regions, where stars and gas follow nearly circular orbits around the galactic center under the influence of the gravitational field generated by the overall matter distribution of the galaxy. However, it is well-established that both in our own galaxy and in external galaxies, the motions of stars and other emitters are not solely confined to circular paths. Instead, they can exhibit additional components, such as radial or vertical motion. These non-circular motions arise due to various factors, including distortions in the mass distribution at large scales (e.g., the presence of spiral arms that represent local over-densities), deformations of the disc shape, or interactions with satellite galaxies. Such non-circular motions are prevalent and leave distinctive imprints on the velocity maps of galaxies.