Nerves in the upper extremities are connected to the spinal cord via five nerve roots: C5, C6, C7, C8 and T1 (C stands for cervical and T for thoracic); the roots mingle together into a complex network called brachial plexus from which all the nerves in the upper extremity arise. Nerve roots, components of brachial plexus and the nerves in the upper extremity all have 2 major functions: 1. Form part of the “information highways” letting our brain know what is in the hand (Example, making it instantly possible to sense if you hold a ball vs rock vs pear vs apple). 2. Carry bioelectric signals to the different muscles of the upper extremity to perform all kinds of activities (Example, to bring the coffee cup to the mouth, throw a stone, punch someone or caress the kid). Nerve conduction and EMG studies are crucial in determining where the problem is (nerve root/plexus/nerve/muscle) and how bad it is. For more information: Cervical radiculopathy, Brachial and Lumbar plexopathies