Which plexus is composed of spinal nerves C1 to C4?

• A. Cervical plexus
• B. Brachial plexus
• C. Lumbar plexus
• D. Sacral plexus

Answer: (A)

The correct choice is the cervical plexus, which is formed from the anterior rami of the spinal nerves C1 to C4. This plexus primarily innervates muscles and skin in the neck, as well as providing sensory and motor functions. The cervical plexus plays a critical role in controlling neck movement and sensation, and it is essential for the function of the diaphragm through its contribution to the phrenic nerve, which arises from C3 to C5.

Other plexuses consist of different sets of spinal nerves; for instance, the brachial plexus originates from C5 to T1 and is responsible for innervating the upper limb. The lumbar plexus is made up of spinal nerves L1 to L4, serving mainly the lower abdomen, pelvis, and part of the lower limb. Lastly, the sacral plexus arises from L4 to S4 and innervates the lower limbs and pelvic region. Thus, the cervical plexus is specifically distinguished by its association with the C1 to C4 spinal nerves.