C5

C5 refers to the fifth cervical nerve in the neck region of the spinal cord. It plays a crucial role in controlling certain shoulder and upper arm muscles, helping movements like lifting the arm sideways. Additionally, it provides sensation to parts of the neck, shoulder, and the outer part of the upper arm. If this nerve is injured or compressed, it can cause weakness or numbness in these areas, affecting shoulder movement and sensation. Overall, C5 is essential for shoulder function and upper limb sensation.