Question

which of the following statements about the vagus nerve (cranial nerve x) is true?
the vagus nerve is purely a sensory nerve.
the vagus nerve innervates structures in the head and neck but not in the thorax and abdomen.
the vagus nerve is responsible for controlling the heart rate and gastrointestinal motility.
the vagus nerve exits the skull through the optic foramen.
damage to the vagus nerve does not affect swallowing or speech.

Explanation:

• The vagus nerve (cranial nerve X) is a mixed nerve (both sensory and motor), so the statement "The vagus nerve is purely a sensory nerve" is false.
• It innervates structures in the head - neck, thorax, and abdomen, so "The vagus nerve innervates structures in the head and neck but not in the thorax and abdomen" is false.
• The vagus nerve (parasympathetic part) slows the heart rate (by releasing acetylcholine on the SA node) and stimulates gastrointestinal motility.
• The vagus nerve exits the skull through the jugular foramen, not the optic foramen. So "The vagus nerve exits the skull through the optic foramen" is false.
• Damage to the vagus nerve can affect swallowing (as it supplies muscles involved in swallowing) and speech (as it is involved in the innervation of some laryngeal muscles), so "Damage to the vagus nerve does not affect swallowing or speech" is false.

Answer:

The vagus nerve is responsible for controlling the heart rate and gastrointestinal motility.