Frequency and Quantity of the C7 Contribution to the Ulnar Nerve

Abstract

Many anatomists and clinicians who investigate the peripheral nerve concern about the composition of the spinal roots of each terminal nerve of the brachial plexus. From this viewpoint, the spinal root composition of the ulnar nerve is still unclear. Several anatomy textbooks describe that the ulnar nerve is composed of the ventral rami of the C8, T1 and often C7. There is no literature regarding the frequency and contribution quantity of C7 to the ulnar nerve. The purpose of present study was to determine frequency and contribution quantity of the C7 to the ulnar nerve. Fifty cadavers of brachial plexus were obtained from cadavers of Korean adults. The brachial plexus containing the ulnar nerve were extracted from the axilla and the extracted samples were immersed in Guanidine-HCl (0.2 M)for 2 weeks to soften the connective tissue around the nerve bundles. C7 was contributed to the ulnar nerve in all sides (100%). The numbers of the myelinated axons of C7 participating to the ulnar nerve was 1,452±429 (mean ±S.D.). Thus the C7 can be considered as always participating component of the ulnar nerve, not often participation,although numbers of the myelinated axons of C7 was lesser than those of the C8, but similar to those of the T1. The results of the study provide a reference for accurate diagnosis and treatment regarding ulnar nerve injury due to various accidents.