intercostal muscle http://upload.wikimedia.org/wikipedia/commons/f/f2/Gray411.png EFO:0001368 GAID:159 musculus intercostalis NCIT:C32824 uberon respiratory muscle UBERON:0001111 MA:0002324 SCTID:181746004 EHDAA2:0000841 UMLS:C0021724 FMA:13354 intercostales EMAPA:18521 MA:0003165 The respiratory muscles that arise from the lower border of one rib and insert into the upper border of the adjoining rib. rib muscle MESH:D007366 BTO:0005281 Inspiration by active expansion of the thorax evolved later, in the ancestor of reptiles, birds, and mammals. This was powered originally by the intercostal muscles (as in lizards or crocodilians) and later (in mammals only) by a muscular diaphragm.[well established][VHOG] Wikipedia:Intercostal_muscle EHDAA:5988 VHOG:0000903 muscle organ