Cranial nerves are twelve pairs of nerves that emerge from foramina in the skull. These nerves originate from the brainstem and generally distribute within the head and neck regions. Only the vagus nerve (cranial nerve X) extends its distribution beyond the head and neck, reaching the thoracic and abdominal organs.
Cranial nerves are designated by Roman numerals or by their specific names:

I. Olfactory nerve (N. olfactorius)
II. Optic nerve (N. opticus)
III. Oculomotor nerve (N. oculomotorius)
IV. Trochlear nerve (N. trochlearis)
V. Trigeminal nerve (N. trigeminus)
VI. Abducent nerve (N. abducens)
VII. Facial nerve (N. facialis)
VIII. Vestibulocochlear nerve (N. vestibulocochlearis)
IX. Glossopharyngeal nerve (N. glossopharyngeus)
X. Vagus nerve (N. vagus)
XI. Accessory nerve (N. accessorius)
XII. Hypoglossal nerve (N. hypoglossus)

Cranial nerves are classified according to the types of fibers they contain:
I, II, VIII: Carry only sensory fibers.
IV, VI, XI, XII: Carry only motor fibers.
III: Carries motor and parasympathetic fibers.
V: Carries both motor and sensory fibers.
VII, IX, X: Mixed cranial nerves; they carry motor, sensory, and parasympathetic fibers.