Which of the following spinal nerve plexuses is responsible for innervating the diaphragm?

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

Answer: (D)

Verified step by step guidance

1. Understand the concept of a spinal nerve plexus: A plexus is a network of intersecting nerves that serve specific regions of the body. Spinal nerve plexuses are formed by the anterior rami of spinal nerves and are responsible for innervating various muscles and skin areas.
2. Identify the function of the diaphragm: The diaphragm is a dome-shaped muscle that plays a critical role in respiration by contracting and relaxing to facilitate breathing.
3. Learn which nerve innervates the diaphragm: The phrenic nerve is the primary nerve responsible for innervating the diaphragm. It controls its motor function and provides sensory information.
4. Determine the origin of the phrenic nerve: The phrenic nerve arises from the cervical plexus, specifically from spinal nerves C3, C4, and C5. A common mnemonic to remember this is 'C3, C4, C5 keep the diaphragm alive.'
5. Match the cervical plexus to the question: Since the phrenic nerve originates from the cervical plexus and is responsible for innervating the diaphragm, the correct answer to the question is the cervical plexus.