Which nerve provides motor innervation to the diaphragm?

Which nerve provides motor innervation to the diaphragm?

• A. Intercostal nerves
• B. Vagus nerve
• C. Phrenic
• D. Accessory nerve

Answer: (C)

Motor control of the diaphragm comes from the phrenic nerve, which carries fibers from the spinal roots C3 to C5. This nerve travels into the thorax and provides the actual motor innervation to the diaphragmatic muscle, driving contraction during inspiration. If the phrenic nerve is damaged, the diaphragm on that side can become paralyzed, leading to impaired ventilation. Intercostal nerves supply the intercostal muscles and contribute to chest wall movement, but they do not innervate the diaphragm. The vagus nerve provides parasympathetic innervation to thoracic and abdominal organs and some sensory input to mediastinal surfaces, not motor to the diaphragm. The accessory nerve innervates the trapezius and sternocleidomastoid muscles, not the diaphragm.

Motor control of the diaphragm comes from the phrenic nerve, which carries fibers from the spinal roots C3 to C5. This nerve travels into the thorax and provides the actual motor innervation to the diaphragmatic muscle, driving contraction during inspiration. If the phrenic nerve is damaged, the diaphragm on that side can become paralyzed, leading to impaired ventilation.

Intercostal nerves supply the intercostal muscles and contribute to chest wall movement, but they do not innervate the diaphragm. The vagus nerve provides parasympathetic innervation to thoracic and abdominal organs and some sensory input to mediastinal surfaces, not motor to the diaphragm. The accessory nerve innervates the trapezius and sternocleidomastoid muscles, not the diaphragm.