Which muscles are affected by a lower motor neuron injury at the C6 level?

In a lower motor neuron injury at the C6 level, the affected muscles include the biceps and radial extensor. This is due to the location of the C6 spinal nerve root and its role in innervating specific muscles.

The biceps brachii is primarily responsible for elbow flexion and is innervated by the musculocutaneous nerve, which receives its fibers from C5 and C6. The radial extensor, which assists in wrist extension, is innervated by the radial nerve, which also receives contributions from C5 and C6 spinal roots. Therefore, an injury at this level would directly influence the functioning of these muscles, leading to weakness or paralysis due to the disruption of motor signals.

In contrast, the other muscle groups listed in the other options are not primarily affected by an injury occurring at the C6 level. For example, the triceps, wrist flexors, deltoid, finger extensors, and flexors are innervated by different nerve roots or higher levels of the spinal cord, decreasing their likelihood of being impacted by a lower motor neuron injury specifically at C6.