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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.
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 ...
Origin The bone or other structure the muscle is attached to that remains immobile during the action. The term "bone" is omitted from bone names. 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 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.
Unlike the other two intercostal muscles, the external intercostal muscle does not retain its muscular character all the way to the sternum, 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.
Origin: Nuchal ligament (or ligamentum nuchae) and the spinous processes of the vertebrae C7 through T3: Insertion: The upper borders of the 2nd through 5th ribs: Artery: Intercostal arteries: Nerve: 2nd through 5th intercostal nerves: Actions: Elevates ribs 2-5 [1] Identifiers; Latin: musculus serratus posterior superior: TA98: A04.3.01.011 ...
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 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 ...