Arteries - Trunk Walls
Key Points of Thoracic Arterial Supply:
- There are 12 ribs and 11 intercostal spaces, which lie between the ribs ("costal" means rib).
- Intercostal space numbering begins with the space between ribs 1 and 2.
- The space inferior to rib 12 is called the "subcostal" space, since it is below ("sub") the rib.
- The thoracic walls are primarily supplied by intercostal arteries, which travel within the intercostal spaces between the ribs.
Review branches of the aorta
Review thoracic cage
Anterior intercostal arteries:
- Anterior intercostal arteries 1-6 arise directly from the internal thoracic artery (a branch of the subclavian artery).
- Anterior intercostal arteries 7-9 which arise from the musculophrenic artery (a branch of the internal thoracic artery).
- Neither 10 nor 11 contain anterior intercostal arteries.
- Anterior intercostal arteries are paired.
- The larger of the pair travels within the costal groove along the inferior border of the upper rib.
- The smaller branch (aka collateral branch), travels along the superior border of the lower rib.
- Posterior intercostal arteries 1 and 2 are derived from the superior (aka, supreme) intercostal artery (a branch of the costocervical trunk of the subclavian artery).
- Posterior intercostal arteries 3-11 arise from the descending thoracic aorta.
- The subcostal artery, which arises posteriorly, supplies the space under the 12th rib, and will be addressed with abdominal wall arterial supply.
- The posterior intercostal arteries send off collateral branches that anastomose with those of the anterior intercostal arteries.
- The posterior intercostal arteries give rise to dorsal branches that supply the posterior thorax, including spinal cord, vertebral column, back muscles and skin.
- The anterior and posterior intercostal arteries anastomose with each other.
- Within the intercostal spaces, the vessels travel between the internal and innermost intercostal muscles.
Abdominal Arterial Supply:
The posterior abdominal wall is primarily supplied by:
- Lumbar arteries
- Median sacral artery (and other arteries)
- Superior and inferior epigastric arteries
- Extend vertically along the abdominal wall
- Subcostal artery
- Arises from the abdominal aorta below the 12th rib, and,
- Ascending branch of the deep circumflex artery
- Arises in the hip
Clinical Correlations:
The internal thoracic artery (aka, mammary artery) is a preferred artery in coronary artery bypass grafts because it is relatively resistant to atherosclerosis, and thus is more durable.