Musculophrenic artery

Arteria musculoohrenica

The lateral terminal branch of the internal thoracic artery, running along the costal margin behind the lower costal cartilages.

At a glance

English
Musculophrenic artery
Latin (TA2)
Arteria musculoohrenica
System
Artery
Region
Trunk
Side
Paired, left and right

About the musculophrenic artery

At about the sixth intercostal space the internal thoracic artery, which has run down inside the front chest wall beside the sternum, ends by splitting into two. Its medial branch, the superior epigastric artery, carries on into the rectus sheath. The lateral branch is the musculophrenic artery, so named because it serves both the muscles of the lower chest wall and the diaphragm.

It runs downwards and outwards behind the cartilages of the seventh, eighth and ninth ribs, following the curve of the costal margin. In its course it lies on the inner face of the chest wall, close to the attachment of the diaphragm, and it pierces the diaphragm at about the level of the eighth or ninth costal cartilage. It ends near the last intercostal space, where its branches thin out in the diaphragm and the upper abdominal wall.

Its branches carry on the pattern begun by the internal thoracic artery. In each of the seventh, eighth and ninth intercostal spaces it gives a pair of small anterior intercostal arteries; one runs close under the rib above the space and the other along the top of the rib beneath it, and both join the posterior intercostal artery of the same space and its collateral branch. Other branches go to the costal part of the diaphragm and the abdominal wall muscles near the costal margin.

Its links with the inferior phrenic, posterior intercostal and deep circumflex iliac arteries give the lower chest wall and diaphragm several overlapping sources of blood. The vessel can be injured when a chest drain or needle is passed through the lower front chest wall too close to the costal margin, and it is kept in mind when the internal thoracic artery is harvested for coronary bypass grafting.

Course and supply

Arises from
The lateral of the two terminal branches of the internal thoracic artery, arising at about the sixth intercostal space.
Ends in
Ends near the last intercostal space after giving the anterior intercostal arteries of the seventh to ninth spaces and branches to the diaphragm.
Supplies
Supplies the lower intercostal spaces, the costal part of the diaphragm and the upper abdominal wall muscles.

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