Dorsal Branches of the Posterior Intercostal Arteries

Description

Running along each thoracic interspace, the posterior intercostal arteries course laterally from the thoracic aorta and give off dorsal branches that turn posteriorly toward the vertebral column and overlying back. Each dorsal branch passes near the head and neck of the rib and the transverse process, then divides into medial and lateral branches that spread superiorly and inferiorly within the deep back. Segmental repetition is clear from rib to rib, with the vessels lying deep to the scapulae and posterior ribs and superficial to the vertebrae, creating a ladder-like pattern flanking the spinous processes. Red arterial channels contrast against the posterior thoracic skeleton. Dorsal branches matter because they are the principal segmental arterial supply to the posterior thoracic wall, including the paraspinal musculature and overlying skin via posterior cutaneous branches that accompany the dorsal rami. Bleeding from these vessels is a real concern in posterior thoracotomy, rib fracture near the costovertebral junction, and posterior chest wall dissection, where the artery can be injured close to the rib head before it subdivides. Their relationship to the vertebrae and ribs also makes them relevant when correlating segmental vascular anatomy with paravertebral blocks and surgical approaches to the thoracic spine. Small vessels, big consequences. Educators can drop this view straight into gross anatomy labs on the thorax, neurovascular supply of the back, or integrated teaching on segmental anatomy and dermatomes, even when nerves are not emphasized. It also suits surgical atlases, trauma education modules, and radiology primers that explain why posterior intercostal arteries and their dorsal branches can be encountered near the costovertebral region during CT-guided procedures. Anatomical accuracy verified by SciePro's Medical Advisory Board.