Motor fibres of the vagus nerve supply which parts?

• A. Larynx and thoracic & abdominal viscera
• B. Diaphragm and intercostal muscles
• C. Skin and fascia of neck
• D. Limbs and trunk muscles

Answer: (A)

Vagus nerve motor fibers mainly handle two tasks: moving the muscles of the larynx to control voice and airway protection, and providing parasympathetic (involuntary) control to thoracic and upper abdominal organs. In the head and neck, the intrinsic muscles of the larynx are innervated by branches of the vagus—most intrinsic muscles by the recurrent laryngeal nerve, with the cricothyroid muscle supplied by the external branch of the superior laryngeal nerve. In the chest and abdomen, the vagus carries parasympathetic fibers that slow the heart, regulate bronchial glands and smooth muscle, and promote digestion by increasing secretions and peristalsis from the esophagus to much of the large intestine.

Often-mistaken alternatives don’t fit because the diaphragm and intercostal muscles are primarily moved by the phrenic and intercostal nerves, not the vagus; the skin and fascia of the neck receive sensory and autonomic supply from cervical nerves; and limb and trunk muscles are controlled mainly by spinal nerves.