human_reference_atlas Homo sapiens intercostal muscle internal intercostal muscle http://upload.wikimedia.org/wikipedia/commons/f/f2/Gray411.png Wikipedia:Intercostal_muscle EMAPA:18523 intercostales internus The internal intercostals are responsible for the depression of the ribs decreasing the transverse dimensions of the thoracic cavity. the innermost intercostal muscle, the deep layers of the internal intercostal muscles which are separated from them by the neurovascular bundle. Both the external and internal muscles are innervated by the intercostal nerves, and are provided by the intercostal arteries and intercostal veins. Their fibers run in opposite directions internal intercostal muscle EHDAA2:0000875 UMLS:C1744536 VHOG:0000905 FMA:9757 uberon intercostal muscle internal layer An intercostal muscle that aids in forced expiration (quiet expiration is a passive process). UBERON:0002403 Behind the thorax, the lateral group (of muscles in reptiles and mammals) remains essentially as for amphibians. (It breaks into three sheet-like layers: external oblique muscle, the internal oblique, and the transversus). More anteriorly, however, the ribs, now enlarged, penetrate and alter this group of muscles. The transversus is excluded from the thorax and the external and internal obliques become, respectively, the external and internal intercostal muscles, which contribute to the new function of ventilation of the lungs.[well established][VHOG] internal intercostal muscle AS MA:0002326 SCTID:244890001 NCIT:C32848 thoracic wall muscle