Question

All CN are peripheral nerves except which one?

a) CN X (Vagus)
b) CN III (Oculomotor)
c) CN VII (Facial)
d) CN XII (Hypoglossal)

Answer 1

The Vagus nerve (CN X) is the only cranial nerve that extends beyond the head and neck regions, making it the exception as a peripheral nerve. The Facial nerve (CN VII) contains preganglionic parasympathetic fibers.

Step-by-step explanation:

Of the cranial nerves (CN), all are considered peripheral nerves, but the exception is the Vagus nerve (CN X), which extends beyond the head and neck to the thorax and abdomen. This makes it unique compared to the primarily head and neck-restricted domains of the other cranial nerves such as the Oculomotor nerve (CN III), Facial nerve (CN VII), and Hypoglossal nerve (CN XII).

Regarding preganglionic parasympathetic fibers, the Facial nerve (CN VII) contains these fibers. The Vagus nerve (CN X) is also notable for its preganglionic parasympathetic fibers that innervate thoracic and abdominal visceral organs.

For the gustatory system, which is responsible for taste, the glossopharyngeal nerve (CN IX) and vagus nerve (CN X), as well as the Facial nerve (CN VII), are involved. The gag reflex is specifically coordinated by the Vagus nerve (CN X).