Introduction. Classic anatomical literature frequently describes C7 contribution to ulnar nerve (UN) formation as a casual event. However, surgical practice and dissections frequently reveal a recurrent presence of a lateral cord component of the UN. This study aimed to seek through literature to establish the frequency and degree of this contribution.
Methodology. We ran a literature review searching on Pubmed, MEDLINE, Embase and Web of Science databases for ulnar nerve anatomy and described discursively the results.
Results and discussion. We found 9 articles that described quantitatively and qualitatively the contribution of C7 on the formation of the UN. The prevalence described ranged from 2 to 100%, depending on the methodology used and population characteristics. When present, studies described a contribution from 9,9% to 30,4%, sending even more fibres than T1 root on average.
Conclusion. The C7 root can be considered a frequent and important component of the ulnar nerve, explaining UN territory repercussions on C7 radiculopathies. This knowledge is important on surgical approaches, maybe avoiding iatrogenic lesions and negative outcomes.