This study examined 22 Korean adult cadavers donated to Kangwon National University School of Medicine (17 males, 34 sides; 5 females, 10 sides; mean age 79 ± 8.3 years) to analyze the morphological characteristics and variations of the rami communic...
This study examined 22 Korean adult cadavers donated to Kangwon National University School of Medicine (17 males, 34 sides; 5 females, 10 sides; mean age 79 ± 8.3 years) to analyze the morphological characteristics and variations of the rami communicantes originating from the first and second thoracic sympathetic ganglia, as well as the intrathoracic nerve. Based on these findings, the study aimed to identify the potential neural connections between the upper thoracic sympathetic ganglia and the brachial plexus.
A total of 150 rami communicantes were identified from the first thoracic sympathetic ganglion, and 77 from the second thoracic ganglion. Sixteen intrathoracic nerves were also observed. In 50% of the samples, the first thoracic sympathetic ganglion was fused with the inferior cervical ganglion to form the stellate ganglion. The rami communicantes were classified into three components—transverse, ascending, and descending rami—according to the direction in which they connected to the ventral ramus of the spinal nerve. Among these, both superficial and deep branches were identified in the transverse and ascending rami. The superficial branches were readily observed after removing the parietal pleura, whereas the deep branches were obscured by the sympathetic ganglion or coursed behind the rib head, requiring lateral retraction of the ganglion or removal of the rib head for visualization.
For the first thoracic sympathetic ganglion, the combination of all three components (transverse, ascending, and descending rami) was most frequently observed (63.1%). In contrast, for the second thoracic sympathetic ganglion, the presence of only transverse rami was most common (61.4%). The intrathoracic nerve was primarily found between the first and second thoracic nerves (30%) and was also observed between the second and third thoracic nerves (7%). Based on the combinations of the three components of the rami communicantes and the intrathoracic nerve from the first and second thoracic sympathetic ganglia, four types (Type I–IV) were classified.
The results of this study suggest the presence of various potential neural pathways connecting the upper thoracic sympathetic ganglia and the brachial plexus. In particular, the identification of deep branches through rib-head removal or sympathetic ganglion mobilization provides important anatomical evidence that may explain variant neural patterns previously mentioned only partially in earlier literature. These anatomical findings are expected to contribute to understanding the anatomical basis for symptom recurrence or residual symptoms following thoracic sympathectomy performed for the treatment of palmar hyperhidrosis.