Which nerves arise from the ventral rami of the roots before formation of the brachial plexus?
• Dorsal scapular nerve , from C5 to rhomboid and levator scapula muscles; responsible for elevation and stabilization of the scapula.
• Long thoracic nerve , from C5, C6, and C7 to serratus anterior; responsible for abduction of the scapula.
Testing these nerves is useful in differentiating between root and plexus lesions. If there is a deficit in one of these nerves (clinically or electrically), the lesion is proximal to the plexus.
