Human Anatomy - Kotsan I. Y. 2009

Peripheral nervous system
Cranial nerves

The nerves emerging from the Brain are called Cranial Nerves (nn. craniales). Humans have 12 pairs of cranial nerves. Each pair has its own specific name and ordinal number. The ordinal number is designated by Roman numerals and reflects the sequence in which the nerves exit:

I — olfactory nerves (nn. olfactorii);

II — Optic nerve (n. opticus);

III — Oculomotor nerve (n. oculomotorius);

IV — Trochlear nerve (n. trochlearis);

V — Trigeminal nerve (n. trigeminus);

VI — Abducens 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);

ХІІ — Hypoglossal nerve (n. hypoglossus).

Almost all cranial nerves originate from the Brainstem (except for the olfactory nerves) and emerge from the brain substance on the ventral surface of the brain (except for the trochlear nerve). Based on the Functional Characteristics of their nerve fibers, cranial nerves are classified into sensory, motor, and mixed.

Sensory nerves: olfactory (pair I), optic (pair II), vestibulocochlear (pair VIII).

Motor nerves: trochlear (pair IV), abducens (pair VI), accessory (pair XI), hypoglossal (pair XII).

Mixed nerves: oculomotor (pair III), trigeminal (pair V), facial (pair VII), glossopharyngeal (pair IX), vagus (pair X).