Which of the following plexuses is formed by the ventral rami of spinal nerves C1 to C4 and supplies the muscles and skin of the neck and part of the head?

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

Answer: (C)

Verified step by step guidance

1. Understand the concept of a nerve plexus: A nerve plexus is a network of intersecting nerves formed by the ventral rami of spinal nerves. These plexuses serve specific regions of the body by providing motor and sensory innervation.
2. Identify the spinal nerve roots involved: The problem specifies spinal nerves C1 to C4. These are cervical spinal nerves located in the neck region.
3. Learn the function of the cervical plexus: The cervical plexus is formed by the ventral rami of spinal nerves C1 to C4. It supplies motor and sensory innervation to the muscles and skin of the neck, as well as parts of the head, including the ear and shoulder region.
4. Compare the other plexuses mentioned: The sacral plexus (L4-S4) supplies the lower limbs, the lumbar plexus (L1-L4) supplies the lower back and thighs, and the brachial plexus (C5-T1) supplies the upper limbs. None of these are formed by C1 to C4 or supply the neck and head.
5. Conclude that the cervical plexus is the correct answer based on its spinal nerve roots (C1-C4) and its function of supplying the neck and part of the head.