Destination of the C4 component of the prefixed brachial plexus

This study was carried out to elucidate the destination of the C4 ventral ramus that forms the prefixed brachial plexus. A total of 43 sides of Korean adults (male, 22; female, 18; unknown: 3 and right, 23; left, 20) were investigated. The various C4 destinations and their frequencies were as follows: suprascapular nerve, 97.7% (42/43); musculocutaneous nerve, 79.1% (34/43); the axillary nerve, 48.8% (21/43); and the nerve to subclavius, 16.2% (7/43). The mean quantity of nerve fibers destined to the suprascapular, musculocutaneous, and axillary nerves and the nerve to subclavius was 441.8 ± 316.5 (Mean ± S.D.), 298.2 ± 209.8, 245.8 ± 239.0, and 66.4 ± 17.2, respectively. The mean nerve fibers number of C4 contributing to the brachial plexus was 983.6 ± 618.0 (range: 100-1729). The main component that contributes to the terminal nerves (suprascapular, musculocutaneous, axillary nerves, and nerve to subclavius) is C5. These results may be useful to surgeons and clinicians dealing with terminal nerves of the brachial plexus, especially the suprascapular, musculocutaneous, and axillary nerves.