What capability is indicative of a C4 spinal cord injury?

A C4 spinal cord injury affects the nerve pathways in the spinal cord at the fourth cervical vertebra, which can significantly impact the body's motor and sensory functions. Individuals with a C4 injury typically retain some movement in the neck and shoulders, as the key muscles that control these areas, such as the trapezius and sternocleidomastoid, are still innervated at this level.

The ability to control neck movements is important for functions like turning the head or lifting it, which can assist in communication and maintaining awareness of the surroundings. The shoulder movement becomes possible due to the remaining functionality of the associated musculature that is above the injury level.

While individuals at this level may have limited functionality, the presence of movement in both the neck and shoulders is a critical indicator of a C4 spinal cord injury. Full arm mobility is not typically achievable at this level, as arm movement usually requires intact spinal cord function at lower cervical levels. Similarly, movement confined to the chin or limited head movement does not reflect the broader capabilities present in someone with a C4 injury, as they do retain some neck and shoulder mobility.