External intercostal muscle
Updates to Article Attributes
The external (or outermost) intercostal muscles are an important muscle of respiration. ThereThey number eleven on each side and are located in theintercostal spacesspace, which expand the transverse dimension thoracic of the thoracic cavity during inspiration.
Gross anatomy
The external intercostal muscles are the outermost muscle of the 3 three intercostal muscles and arise from the lower border of the rib above the space. The fibres run in a downardsdownwards, forwards and medial direction (like putting your hands in your pockets) and insertion intoterminationinsertion they end in thin anterior intercostal membranes that continuethat continues towards the sternum. Anteriorly the lower muscles become continuous with the external oblique muscles in the anterolateral abdominal wall. As their name indicates, they are external to theinternal intercostal muscles.
Blood supply
- arterial supply: internal thoracic artery and segmental intercostal arteries
- venous drainage: internal thoracic vein and intercostal veins
Nerve supply
Muscular branches from the intercostal nerves of the respective intercostal space (T1-T11), which run with the intercostal vesslesvessels under the costal groove in between the internal and innermost intercostal muscles.
Action
External intercostal muscle contraction causes expansion of the thoracic cavity in the transverse dimension and causes an influx of air into the lungs during inspiration. They are stronger than the internal intercostal muscles.
-<p>The <strong>external </strong>(or<strong> outermost</strong>)<strong> intercostal muscles</strong> are an important muscle of respiration. There number eleven on each side located in the<a href="/articles/intercostal-spaces"> intercostal spaces</a> which expand the transverse dimension thoracic cavity during inspiration.</p><h4>Gross anatomy</h4><p>The external intercostal muscles are the outermost muscle of the 3 <a href="/articles/intercostal-muscles">intercostal muscles</a> and arise from the lower border of the <a href="/articles/rib">rib</a> above the space. The fibres run in a downards, forwards and medial direction (<em>like putting your hands in your pockets</em>) and insertion into the outer lip of the superior border of the rib below. At their termination they end in thin anterior intercostal membranes that continue towards the <a href="/articles/sternum">sternum</a>. Anteriorly the lower muscles become continuous with the <a href="/articles/external-oblique-muscles">external oblique muscles</a> in the anterolateral abdominal wall. As their name indicates, they are external to the<a href="/articles/internal-intercostal-muscles"> internal intercostal muscles</a>.</p><h4>Nerve supply</h4><p>Muscular branches from the <a href="/articles/intercostal-nerves">intercostal nerves</a> of the respective intercostal space (T1-T11), which run with the intercostal vessles under the costal groove in between the <a href="/articles/internal-intercostal-muscles">internal</a> and<a href="/articles/innermost-intercostal-muscles"> innermost intercostal muscles</a>.</p><h4>Action</h4><p>External intercostal muscle contraction causes expansion of the thoracic cavity in the transverse dimension and causes an influx of air into the <a href="/articles/lung">lungs</a> during inspiration. They are stronger than the internal intercostal muscles.</p>- +<p>The <strong>external </strong>(or<strong> outermost</strong>)<strong> intercostal muscles</strong> are an important muscle of respiration. They number eleven on each side and are located in the <a href="/articles/intercostal-spaces">intercostal space,</a> which expand the transverse dimension of the thoracic cavity during inspiration.</p><h4>Gross anatomy</h4><p>The external intercostal muscles are the outermost muscle of the three <a href="/articles/intercostal-muscles">intercostal muscles</a> and arise from the lower border of the <a href="/articles/rib">rib</a> above the space. The fibres run in a downwards, forwards and medial direction and insert into the outer lip of the superior border of the rib below. At their insertion they end in thin anterior intercostal membranes that continues towards the <a href="/articles/sternum">sternum</a>. Anteriorly the lower muscles become continuous with the <a href="/articles/external-oblique-muscles">external oblique muscles</a> in the anterolateral abdominal wall. As their name indicates, they are external to the <a href="/articles/internal-intercostal-muscles">internal intercostal muscles</a>.</p><h4>Blood supply</h4><ul>
- +<li>arterial supply: <a href="/articles/internal-thoracic-artery">internal thoracic artery</a> and segmental <a href="/articles/intercostal-arteries">intercostal arteries</a>
- +</li>
- +<li>venous drainage: internal thoracic vein and intercostal veins</li>
- +</ul><h4>Nerve supply</h4><p>Muscular branches from the <a href="/articles/intercostal-nerves">intercostal nerves</a> of the respective intercostal space (T1-T11), which run with the intercostal vessels under the costal groove in between the <a href="/articles/internal-intercostal-muscles">internal</a> and<a href="/articles/innermost-intercostal-muscles"> innermost intercostal muscles</a>.</p><h4>Action</h4><p>External intercostal muscle contraction causes expansion of the thoracic cavity in the transverse dimension and causes an influx of air into the <a href="/articles/lung">lungs</a> during inspiration. They are stronger than the internal intercostal muscles.</p>
References changed:
- 2. Handbook of Cardiac Anatomy, Physiology, and Devices. Humana Press. ISBN:1603273719. <a href="http://books.google.com/books?vid=ISBN1603273719">Read it at Google Books</a> - <a href="http://www.amazon.com/gp/product/1603273719">Find it at Amazon</a><span class="auto"></span>
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