The thin skirt is obtained by separating the diaphragm from its costal attachments by means of cutting along the internal surface of the last ribs. After that, all membranous tissue not covering lean red muscle is trimmed off. As an alternative, membrane which directly covers the fleshy portion of the muscle may be removed.

The internal surface of the last eight ribs, their corresponding cartilages and the caudal end of the sternum make up the skeletal references.