Unlike the other two
intercostal muscles
Intercostal muscles are many different groups of muscles that run between the ribs, and help form and move the chest wall. The intercostal muscles are mainly involved in the mechanical aspect of breathing by helping expand and shrink the size of ...
, the
external intercostal muscle does not retain its muscular character all the way to the
sternum
The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. ...
, and so the tissue in this location is called the external intercostal membrane.
The fibers of the external intercostal muscles run downward and forward between adjacent ribs. Each muscle begins posteriorly at the tubercles of the ribs and extends anteriorly to the costochondral junction, the junction between the costal cartilage and the sternal end of the rib. The muscle between the costal cartilages is replaced by a membranous layer called the external intercostal membrane.
Links and References:
Grant's: 1.15, 1.20
Netter: 176
Rohen/Yokochi: 193, 194
See also
Aponeuroses
External links
* - "Thoracic Wall: The External Intercostal Muscle"
Musculoskeletal system
{{musculoskeletal-stub