How many cervical spinal nerves are there, and what do they control?

• A. Eight cervical spinal nerves; diaphragm C1-4, chest and wall muscles, arms and shoulders
• B. Ten cervical spinal nerves; legs
• C. Six cervical spinal nerves; facial muscles
• D. Nine cervical spinal nerves; swallowing

Answer: (A)

The cervical region has eight spinal nerves, labeled C1 through C8, which emerge from the neck and primarily control functions in the upper body. These nerves innervate neck and shoulder muscles and extend to the arms and hands, with breathing influenced by the diaphragm through the phrenic nerve, which mainly involves fibers from C3 to C5 (C4 is often emphasized). Therefore, the statement that there are eight cervical nerves and that they control the diaphragm along with chest wall muscles and the upper limbs best reflects the actual distribution and role of cervical nerves. The other options give incorrect counts or assign control to areas not primarily governed by the cervical nerves, such as the legs or swallowing.