We present two approaches for reconstructing a patient’s atrial myocardium from morphological image data. Both approaches are based on a segmentation of the left and right atrial blood masses which mark the inner border of the atrial myocardium. The outer border of the atrial myocardium is reconstructed differently by the two approaches. The surface manipulation approach is based on a triangle manipulation procedure while the label-voxel-field approach adds or deletes label-voxels of the segmented blood mass labelset. Both approaches yield models of a patient’s atrial myocardium that qualify for further applications. The obtained atrial models have been implemented many times in the construction of a patient’s volume conductor model needed for solving the electrocardiographic inverse problem. The label-voxel-field approach has to be favored because of its superior performance and ability of implementation in a segmentation pipeline.