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External intercostal muscles
Last reviewed: 23.04.2024
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The outer intercostal muscles (mm., Intercostales externi) in number 11 on each side begin at the lower edge of the overlying rib, outside of its furrow, and, going down and forwards, attach to the upper edge of the underlying rib. The muscles occupy the intercostal spaces from the ribs of the ribs to the costal cartilages in the front, where their extension to the edge of the sternum is the outer intercostal membrane (membrane - membrana intercostalis externa). On the back of the chest, the bundles of these muscles are oriented obliquely downward and laterally, on the lateral and front sides - down, forward and medially. These muscles form a thicker layer than the internal intercostal muscles.
Function of external intercostal muscles: lift ribs; their posterior parts strengthen the costal-vertebral joints.
Innervation of the external intercostal muscles: intercostal nerves (ThI-ThXI).
Blood supply of external intercostal muscles: posterior intercostal arteries, anterior intercostal branches of the internal thoracic artery, muscular-diaphragmatic artery.
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