Review Question - QID 8016

Compression of the C4 nerve root can cause sensory deficits in the lower neck and upper shoulder region. The C4 contributes innervation to the diaphragm. C5 nerve root lesions cause pain in the upper shoulder and arm region but not below the elbow. Sensory loss is typically in an oval patch over the lateral upper arm. The most commonly affected muscles are the deltoid and infraspinatus and supraspinatus muscles. A C6 nerve root lesion causes pain in the lateral forearm with the classic numbness in the thumb and index finger. Motor deficits include the brachialis, biceps, and brachioradialis (the wrist extensors). A C7 nerve root lesion generates pain in the posterior arm and scapula region with radiation to the dorsal forearm. The sensory examination often reveals involvement of the second and third fingers. A C8 radiculopathy creates pain in the medial forearm and into the axilla occasionally. Sensory loss is usually in the medial forearm and fifth digit. C8 motor weakness occurs with the long flexors of the thumb and index finger. There is often intrinsic finger weakness as well if there is also T1 nerve root involvement. A C6 nerve root lesion affects the bicep reflex, a C7 nerve root lesion affects the triceps, and a C8 lesion can affect the finger flexor reflex.