CRANIAL NERVES
{Since you must know the nerves by name and number, some students find the following saying helpful in learning the names of the nerves. The first letter of each word in the saying corresponds to the first letter of each cranial nerve. “On Old Olympus’ Towering Top, A Finn And German Viewed A Hop.”}
I. OLFACTORY NERVE
Arises from cerebrum.
Function: Special Sensory only. Sense of smell.
II. OPTIC NERVE
Arises from diencephalon.
Function: Special Sensory only. Vision.
III. OCULOMOTOR NERVE
Arises from brain stem.
Function: Predominantly motor nerve. Motor to intrinsic and extrinsic eye muscles. Sensory for muscle sense (proprioception) of same area.
IV. TROCHLEAR NERVE
Arises from brain stem.
Function: Predominantly motor nerve. Motor to extrinsic eye muscles. Sensory for muscle sense of same area.
V. TRIGEMINAL NERVE
Arises from brain stem.
Ophthalmic branch, Maxillary branch, Mandibular branch Function: Mixed nerve. Mandibular branch carries special visceral motor fibers to branchiomeric mandibular muscles of first visceral arch/mastication muscles and Tensor tympani muscle; proprioceptive to same area. Ophthalmic and maxillary (infraorbital) branches are sensory to face, scalp, tear glands, mucous membranes of the nasal cavity and mouth.
VI. ABDUCENS NERVE
Arises from brain stem.
Function: Predominantly motor nerve. Motor to extrinsic eye muscles. Sensory for muscle sense of same area.
VII. FACIAL NERVE
Arises from brain stem.
Function: Mixed nerve. Motor to branchiomeric muscles of second visceral arch/ muscles of mammal facial expression. Motor for salivation and lacrimation. Sensory for taste and muscle sense.
VIII. ACOUSTIC = VESTIBULOCOCHLEAR NERVE
Arises from brain stem.
Function: Sensory only. Vestibular branch is sensory for equilibrium; cochlear branch is sensory for hearing.
IX. GLOSSOPHARYNGEAL NERVE
Arises from brain stem.
Function: Mixed nerve. Motor to branchiomeric muscles of third visceral arch/pharyngeal muscles for swallowing in tetrapods. Motor for salivation. Sensory for taste and muscle sense.
X. VAGUS NERVE
Arises from brain stem.
Function: Mixed nerve. Motor to branchiomeric muscles of visceral arches 4-7/pharynx and larynx. Motor to viscera of thorax and abdomen (Parasympathetic Nervous System). Sensory for muscle sense to same areas, pharynx, gills, coelomic viscera and taste.
XI. ACCESSORY NERVE
In amniotes only. Comprised of 2 nerves; cranial one arises from brain stem, spinal nerve arises from cervical spinal cord.
Function: Mixed nerve. Motor to muscles of pharynx and larynx (branchiomeric muscles). Cranial branch has some fibers distributed to coelomic viscera along with the vagus nerve. The spinal root is motor to head movement muscles (Sternocleidomastoid, Trapezius). Sensory for muscle sense to the same area and sensory for coelomic viscera.
XII. HYPOGLOSSAL NERVE
In amniotes only. Arises from brain stem.
Function: Predominantly motor nerve. Motor to tongue muscles. Sensory for muscle sense of tongue.