Understanding how mechanical forces drive cell and tissue flows and deformations is crucial to shed light on processes involved in morphogenesis. Forces are generated within cells by molecular motors acting on cytoskeletal networks. We investigate here how actomyosin-based forces give rise to motion at the scale of the organism during zebrafish epiboly, an event in the early development of the zebrafish where a superficial tissue, the enveloping layer, expands and spreads over the yolk of the embryo. We show that a similar physical description allows describing how cell flows and deformations combine to give rise to Walker cell motion in confinement. Finally, we discuss the process of contraction of a tissue in three dimensions during dorsal closure in the Drosophila embryo.