Anterior Intercostal Arteries

arteriae intercostales anteriores

The anterior intercostal arteries are paired small vessels in the front part of the upper nine intercostal spaces. They come from the internal thoracic artery and its musculophrenic branch and join the posterior intercostal arteries to form a continuous arterial loop in each space. The lower two spaces have no anterior intercostal arteries and are supplied by the posterior intercostal vessels alone.

Anatomical Data

Course & Branches

Origin	Internal thoracic artery for the first six spaces; musculophrenic artery for the seventh to ninth spaces
Course	Two small arteries run laterally in each of the upper nine intercostal spaces, one near the upper and one near the lower border, between the internal and innermost intercostal muscles, to anastomose with the posterior intercostal arteries and their collateral branches
Branches	Muscular branches to the intercostal and pectoral muscles Branches to the skin and breast Branches to the ribs and periosteum

Clinical Relevance

Clinical Notes

The anterior intercostal arteries provide an important collateral route in coarctation of the aorta, where enlarged intercostal vessels erode the undersurfaces of the ribs to produce rib notching on chest radiographs. They may bleed after chest wall trauma, parasternal procedures or chest drain insertion placed too anteriorly. They also contribute to the blood supply of the sternum, which is reduced after internal thoracic artery harvest.

Pathology

Common Injuries & Conditions

Intercostal Artery Bleeding

Laceration from rib fracture, chest drain insertion or parasternal procedures causing chest wall haematoma or haemothorax, usually managed conservatively or by embolisation.

Rib Notching in Coarctation

Enlarged intercostal collateral vessels in aortic coarctation erode the inferior rib margins, a classic radiographic sign of long-standing coarctation.

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