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External intercostal muscles also known as intercostalis externus aid in quiet and forced inhalation. They originate on ribs 1–11 and have their insertion on ribs 2–12. The external intercostals are responsible for the elevation of the ribs and bending them more open, thus expanding the transverse dimensions of the thoracic cavity. The ...
The internal intercostal muscles (intercostales interni) are a group of skeletal muscles located between the ribs.They are eleven in number on either side. They commence anteriorly at the sternum, in the intercostal spaces between the cartilages of the true ribs, and at the anterior extremities of the cartilages of the false ribs, and extend backward as far as the angles of the ribs, hence ...
A cutout of the thoracic wall showing the three layers of intercostal muscle - from the left wall. The muscles extend from the tubercles of the ribs behind, to the cartilages of the ribs in front, where they end in thin membranes, the external intercostal membranes, which are continued forward to the sternum.
Origin: Infero-posterior border of each rib (above) Insertion: Supero-posterior border of the rib (below) Artery: Intercostal arteries: Nerve: Intercostal nerves: Actions: Through adduction of upper ribs to the lower ribs the muscles narrow intercostal slits and diminish thorax volume, therefore the muscles represent expiratory muscles ...
Insertion The attachment point of the muscle, on a bone or otherwise, that moves during the action. Artery The artery which supplies the muscle with blood. The term "artery" is included to avoid confusing columns. Nerve The nerve(s) which tell the muscle to act (innervates the muscle). The term "nerve" is included for clarity. Action
The external intercostal muscles are most important in respiration. These have fibres that are angled obliquely downward and forward from rib to rib. [ 2 ] The contraction of these fibres raises each rib toward the rib above, with the overall effect of raising the rib cage , assisting in inhalation.
The transversus thoracis muscle (/ t r æ n z ˈ v ɜːr s ə s θ ə ˈ r eɪ s ɪ s /), also known as triangularis sterni, lies internal to the thoracic cage, anteriorly.It is usually a thin plane of muscular and tendinous fibers, however on athletic individuals it can be a thick 'slab of meat', situated upon the inner surface of the front wall of the chest.
The intercostal space (ICS) is the anatomic space between two ribs (Lat. costa). Since there are 12 ribs on each side, there are 11 intercostal spaces, each numbered for the rib superior to it. Since there are 12 ribs on each side, there are 11 intercostal spaces, each numbered for the rib superior to it.