How many cranial nerves are there?
10 or 12
The main idea is that cranial nerves connect the muscles and sense organs of the head and thoracic region directly to the brain. The number of cranial nerves varies. Keep in mind the fact that in higher vertebrates (reptiles, birds, mammals) there are 12 pairs of cranial nerves: olfactory (I), optic (II), oculomotor (III), trochlear (IV), trigeminal (V), abducent (VI), facial (VII), vestibulocochlear (VIII), glossopharyngeal (IX), vagus (X), accessory (XI), and hypoglossal (XII). On the other hand, the lower vertebrates (fishes, amphibians) have only 10 pairs.