Objectives-3, BIO 2310, Cranial Nerves

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.

Exits skull through olfactory foramina in cribriform plate of ethmoid.

Function: Sensory only. Sense of smell.

 

II. OPTIC NERVE

Arises from diencephalon.

Exits skull through optic foramen of sphenoid.

Function: Sensory only. Vision.

 

III. OCULOMOTOR NERVE

Arises from brain stem.

Exits skull through superior orbital fissure of sphenoid.

Function: Mixed nerve. Motor to intrinsic and extrinsic eye muscles. Sensory for muscle sense (proprioception) of same area.

 

IV. TROCHLEAR NERVE

Arises from brain stem.

Exits skull through superior orbital fissure of sphenoid.

Function: Mixed nerve. Motor to extrinsic eye muscles. Sensory for muscle sense of same area.

 

V. TRIGEMINAL NERVE

Arises from brain stem.

Ophthalmic branch exits skull through superior orbital fissure.

Maxillary branch exits skull through foramen rotundum of sphenoid.

Mandibular branch exits skull through foramen ovale of sphenoid.

Function: Mixed nerve. Motor to mastication muscles. Sensory to face, scalp, tear glands, mucous membranes of the nasal cavity and mouth.

 

VI. ABDUCENS NERVE

Arises from brain stem.

Exits skull through superior orbital fissure.

Function: Mixed nerve. Motor to extrinsic eye muscles. Sensory for muscle sense of same area.

 

VII. FACIAL NERVE

Arises from brain stem.

Exits skull through stylomastoid foramen of temporal bone.

Function: Mixed nerve. Motor to muscles of facial expression, salivation, and lacrimation. Sensory for taste and muscle sense.

 

VIII. ACOUSTIC = VESTIBULOCOCHLEAR NERVE

Arises from brain stem.

Exits skull through internal auditory meatus of temporal bone.

Function: Sensory only. Vestibular branch is sensory for equilibrium; cochlear branch is sensory for hearing.

 

IX. GLOSSOPHARYNGEAL NERVE

Arises from brain stem.

Exits skull through jugular foramen of temporal bone.

Function: Mixed nerve. Motor to swallowing and salivation. Sensory for taste from posterior part of tongue and muscle sense.

 

X. VAGUS NERVE

Arises from brain stem.

Exits skull through jugular foramen.

Function: Mixed nerve. Motor to pharynx, larynx, viscera of thorax and abdomen (Parasympathetic Nervous System). Sensory for muscle sense to same areas and taste.

 

XI. ACCESSORY NERVE

Comprised of 2 nerves; cranial one arises from brain stem, spinal nerve arises from cervical spinal cord.

Exits skull through jugular foramen.

Function: Mixed nerve. Motor to muscles of pharynx and larynx, and to head movement muscles (Sternocleidomastoid, Trapezius). Sensory for muscle sense to the same area.

 

XII. HYPOGLOSSAL NERVE

Arises from brain stem.

Exits skull through hypoglossal canal of occipital bone.

Function: Mixed nerve. Motor to tongue. Sensory for muscle sense of tongue.