Clinically relevant anatomical variations in posterior intercostal neurovascular bundle

This study focused on variations of the structures in the posterior intercostal neurovascular bundle.

The posterior intercostal spaces (1st-11th) of 12 cadavers were dissected from the vertebral body to the anterior to the mid-axillary line. Variations in the arrangement, course, relations, and patterns, and rare features of the structures, were observed.

In the neurovascular bundle, four types of arrangement of the structures from superior to inferior were observed. The presence of a foetal connecting branch between the left 9th and 10th posterior intercostal veins and the left 7th and 8th intercostal nerves was noted. The posterior intercostal artery passed lateral to the white ramus communicans of the corresponding intercostal nerve. The 1st thoracic ventral ramus and 2nd intercostal nerve were connected to the stellate and 2nd thoracic ganglia by different white rami communicantes. In the 1st intercostal space, type A and D intrathoracic nerves of Kuntz were observed. Collateral intercostal nerves had different points of origin, reaching the superior border of the inferior rib, and had communications and terminations. A left 7th collateral intercostal nerve originated from the connecting branch between the 7th and 8th intercostal nerves. A left 9th lateral cutaneous nerve originated from the collateral intercostal nerve.

Intercostal nerve block and thoracic clinical procedures require an understanding of the variations in the neurovascular bundle. Awareness of the different types of intrathoracic nerves of Kuntz and white rami communicantes and foetal connecting branches between adjacent intercostal nerves and posterior intercostal vessels in adults is valuable in surgical approaches.