Spinal nerve root compositions of musculocutaneous nerve: an anatomical study

This study was aimed to investigate the variations in the spinal nerve root compositions of musculocutaneous nerve and to confirm which spinal nerve root is the main ingredient in participating amount. A total of 20 fresh cadavers were dissected. Brachial plexus and its branches were extracted. Musculocutaneous nerve stump was traced back to the roots to identify its fascicular origin. The number of fascicles originating from a particular nerve root and their axial location with in the nerve were noted. The most frequent type of spinal nerve compositions of musculocutaneous nerve was C5, C6, and C7 with incidence of 60%. Musculocutaneous nerve had bundles from C5 root in all specimens, 90% of the specimens had contribution from C6 and only 70% of them had bundles from C7 root. There were a total of 46 (37.7%) bundles in C5 fascicles, 48 (39.3%) bundles in C6 fascicles, and 28 (22.9%) bundles in C7 fascicles. In electrophysiological studies it should be remembered that C7 or C6 lesions may not impair musculocutaneous nerve functions. The success of musculocutaneous nerve neurotization may be improved if care is taken to ensure whether or not C7 root is contributing to the musculocutaneous nerve.