Determining C5, C6 and C7 myotomes through comparative analyses of clinical, MRI and EMG findings in cervical radiculopathy

Abstract

Highlights We determined C5/C6/C7 myotomes from patients with MRI-confirmed single-root radiculopathy. The brachioradialis was mainly innervated by C5. C6 muscles were the pronator teres and extensor carpi radialis brevis.

Reliability and Diagnostic Accuracy of Standard Dermatomes and Myotomes for Determining the Pathologic Level in Surgically Verified Patients With Cervical Radiculopathy

“…Most authors agree that lesions of C8 cause most marked weakness in the intrinsic muscles of the hand. 17 Based on our results, relative to muscle weakness, the pathologic nerve could be localized correctly in 67.3% (74 of 110). However, the motor weakness of C5/6 radiculopathy (C6 nerve lesion) showed much more variance, with typical motor weakness demonstrated in 47.6% (20 of 42) of the patients.…”

“…The diversity of muscle units in which the C6 nerve root is involved may confuse C6 radiculopathy with C5 and C7 nerve root symptoms. 17 Our study has certain limitations inherent to retrospective studies. First, the examiner was not blinded to other information.…”

“…[19][20][21] Additionally, when evaluating motor function, certain joint motions cannot separate the actions of individual muscles. 8,17 Muscle function tests for the biceps and brachioradialis are such examples. It has been proposed that the biceps and brachioradialis can be separately evaluated by changing the forearm position for pronation/supination.…”

“…Lesions of root C7 have resulted in weakness mainly in the triceps according to some authors, but others have included weakness in the biceps and deltoid also. Most authors agree that lesions of C8 cause most marked weakness in the intrinsic muscles of the hand [ 17 ].…”

“…These variations may lead to deviation from the expected dermatome distribution as well as differences in the motor innervation of muscles of the upper limb [ 19 - 21 ]. Additionally, when evaluating motor function, certain joint motions cannot separate the actions of individual muscles [ 8 , 17 ]. Muscle function tests for the biceps and brachioradialis are such examples.…”