Super M-brane actions in adS₄ x S⁷ and adS₇ x S⁴

The world-volume action of the M2 brane and the M5-brane in an adS_4 x S^7 and a adS_7 x S^4 background is derived to all orders in anticommuting superspace coordinates. Contrary to recent constructions of super p-brane actions relying on supercoset methods, we only use 11 dimensional supergravity torsion and curvature constraints. Complete agreement between the two methods is found. The simplification of the actions by choosing a suitable kappa-gauge is discussed.