The sixth thoracic ventral spinal rami exit the vertebral column through the intervertebral foramina between the pedicles of T6 and T7.  They emerge above the transverse processes of T7 and pass into the intercostal spaces between the pleura and internal intercostal membrane (fascia), where each ramus receives at least one grey (proximal) and white (distal) rami communicantes from adjacent sympathetic ganglia.

The rami then pass below the intercostal vessels in the neurovascular plane between the sixth internal and innermost intercostal muscles.  Before reaching the costal angle they give rise to collateral and lateral branches.  The collateral branches follow the inferior borders of the intercostal spaces and near the sternum they pass anterior to the internal thoracic vessels, pierce the internal intercostal muscles, external intercostal membrane and pectoralis major muscles to terminate as the sixth anterior cutaneous nerves of the thorax.  The lateral cutaneous branches pierce the intercostal muscles obliquely and then divide into anterior and posterior branches, which pierce serratus anterior to supply the overlying skin.

Supply
The sixth thoracic ventral rami supply the sixth intercostal muscles and adjacent skin over the front and sides of the chest and the upper digitations of the external oblique muscle.