What is Intercostal muscle?
[[File:Internal intercostal muscles animation.gif|thumb|right|200px|{{Center|Internal intercostal muscles (shown in red)}}]] The '''intercostal muscles''' (''intercostales interni'') are a group of [[Skelton|skeletal]] [[muscle]]s between the [[rib]]s.<ref>{{cite web |url=http://www.healthline.com/human-body-maps/intercostal-muscles |title=BodyMaps; Intercostal muscles |author= |date= |website= |publisher=Healthline Networks, Inc |accessdate=12 March 2015 |archive-date=15 March 2015 |archive-url=https://web.archive.org/web/20150315234114/http://www.healthline.com/human-body-maps/intercostal-muscles |url-status=dead }}</ref> These muscles help expand and shrink the size of the [[thorax|chest cavity]] to help [[breathing]]. When breathing in, the muscles of the [[diaphragm]] contract. This pulls the diaphragm downwards, and increases the volume of the [[thorax]]. At the same time, the external intercostal muscles contract. This pulls the ribcage upwards and outwards. This also increases the volume of the thorax. There are three main layers; #''External intercostal muscles'' help [[inhalation]]. They pull up the ribs and bend them more open. This expands the [[chest|thoracic cavity]]. #''Internal intercostal muscles'' help in ''forced'' breathing out (quiet expiration is a passive process). They depress the ribs and bend them inward. This decreases the width of the thoracic cavity. #''Innermost intercostal muscle'' reduces thorax volume, so are also expiratory muscles. == References == {{commons}} {{reflist}} {{-}} {{biology-stub}} [[Category:Human body features]] [[Category:Muscles]]