Three regimes may be distinguished: that within \angupr 1 pc from the center containing fast-moving compact HII regions, observed principally in the NeII line at 12.8 μm, the region within \angupr 300 pc with its very high density of molecular clouds, and the region between roughly 1 and 3 kpc containing extended features the motions of which deivate widely from circular motions. The compact HII clumps must be short-lived. No entirely satisfactory explanation of their origin has yet been found. The non-circular motions and the tilted distribution of the large HI features have alternatively been ascribed to eruptive activity from the nucleus and to large-scale streamings in a non-axisymmetric potential field. Recent studies of orbits in three-axial ellipsoids have shown the existence of ''anomalous'' orbits in tilted planes which may explain at least part of the observed features. It is doubtful whether the motions of the molecular clouds within 300 pc can be interpreted in a similar manner. Strong asymmetries and the existence of ring-like expanding feature point rather to explusion from the nucleus.