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.
The coracobrachialis muscle (Cb M) receives nerve branches from the musculocutaneous nerve (Mc N). Many textbooks describe that the Cb M is innervated by the C5, C6, and C7 spinal nerves. The present study was performed to identify the spinal nerve composition of the nerve branches innervating the Cb M and to evaluate the number of myelinated axons of the nerve branches. Two types of spinal nerve compositions were observed: type I, composed of both C6 and C7 nerves, comprised 88.9% (40/45) of the sides; and type II, composed of only C7 nerves, comprised 11.1% (5/45) of the sides. Of the type I branches, 245.4 +/- 26.3 (mean +/- SD, range 201-267) of the myelinated nerve fibers were derived from C6 and 520.0 +/- 41.8 (range 469-567) of the fibers were derived from C7. Of the type II branches, 836.4 +/- 125.5 (range 709-991) of the nerve fibers were derived from C7. Imbroglio Modometer version 2.0 was used to count the number of fibers innervating the Cb M. The main component of these nerve branches was the C7 spinal nerve. The C5 spinal nerve, did not contribute to innervating the Cb M in the present study. The number of branches varied from one to four, with C7 being concentrated in the first and second branches. Therefore, these two branches may be suitable for the neurotization procedure as a donor nerve at the upper trunk (C5 and C6) lesion of the brachial plexus.
These findings may be helpful to diagnose damage to axillary nerve structures that occur in such injuries as humerus fractures.
Several anatomy textbooks describe that the ulnar nerve is composed of the ventral rami of the C8, T1 and often C7 [1][2][3][4]. Those of the C7 components may supply the flexor carpi ulnaris muscle in the anterior compartment of the forearm. However, there are few literatures regarding contributing frequency and quantities of the C7 to the ulnar nerve. Fuss (1989) [5] reported the lateral cord contribution to the ulnar nerve was in 56% of the 158 brachial plexus. Pyun et al. (2010) [6] reported that the connection between lateral cord and ulnar nerve was observed at 13.1% (5/38) in their anatomic study and the flexor carpi ulnaris muscle was abnormal electromyographic findings at the 46.2% (36/78) in the C7 radiculopathy. Therefore differencies between anatomic study and electromyographic diagnosis exist. This study was aimed to determine frequency and the number of the myelinated axons of the C7 in the ulnar nerve. Materials and MethodsFifty cadavers of brachial plexus were obtained from cadavers of Korean adults (Male: 58, Female: 42, average age: 69.7 years). 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 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.
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