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There are 12 pairs of cranial nerves. These nerves arise from the brain and brain stem,carrying motor and or sensory information.

Cranial nerve I: Olfactory nerve 

The olfactory nerve is composed of axons from the olfactory

receptors in the nasal sensory epithelium. It carries olfactoryinformation (sense of smell) to the olfactory bulb of the brain. This

is a pure sensory nerve fiber.

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Cranial nerve II: Optic nerve

The optic nerve is composed of axons of the ganglion cells in the

eye. It carries visual information to the brain. This is a pure sensorynerve fiber. This nerve travels posteromedially from the eye, exiting

the orbit at the optic canal in the lesser wing of the sphenoid bone.The optic nerves join each other in the middle cranial fossa to form

the optic chiasm.

Cranial nerve III: Oculomotor nerve 

The oculomotor nerve is composed of motor axons coming from the

oculomotor nucleus and the edinger-westphal nucleus in the rostralmidbrain located at the superior colliculus level. This is a pure

motor nerve. It provides somatic motor innervation to four of theextrinsic eye muscles: the superior rectus, inferior rectus, medial

rectus, and the inferior oblique muscles. It also innervates themuscles of the upper eyelid and the intrinsic eye muscles (the

 pupillary eye muscle.) Together, CN III, CN IV and CN VI control the six muscles of the eye.

Cranial nerve IV: Trochlear nerve

The trochlear nerve provides somatic motor innervation to the superior oblique eye muscle. Thiscranial nerve originates at the trochlear nucleus located in the tegmentum of the midbrain at the

inferior colliculus level and exits the posterior side of the brainstem. It is also a pure motor nervefiber.

Cranial nerve V: Trigeminal nerve

The trigeminal is the largest cranial nerve . It provides sensoryinformation from the face, forehead, nasal cavity, tongue, gums and

teeth (touch, and temperature) and provides somatic motor innervation to the muscles of mastication or ³chewing´.

This cranial nerve has 3 branches: the ophthalmic, maxillary andmandibular branches.

It is composed of both sensory and motor axons. The sensory fibers are located in the trigeminal

ganglion and the motor fibers project from nuclei in the pons.

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Cranial nerve VI: Abducens nerve

The abducens nerve carries somatic motor innervation to one of the extrinsic eye muscles, thelateral rectus muscle. It is another pure motor nerve fiber and originates from the abducens

nucleus located in the caudal pons at the facial colliculus level.

Cranial nerve VII: Facial nerve

The facial nerve carries somatic motor innervation to the manymuscles for facial expression. It carries sensory information form the

face (deep pressure sensation) and taste information from theanterior two thirds of the tongue. It arises at the pons in the

 brainstem and it emerges through openings in the temporal bone andstylomastoid foramen and has many branches. It is composed of both

sensory and motor axons.

Cranial nerve VIII: Vestibulocochlear

nerve

The vestibulocochlear nerve innervates the hair cell receptors of the

inner ear. It carries vestibular information to the brain from the

semicircular canals, utricle, and saccule providing the sense of  balance. It also carries information from the cochlea providing thesense of hearing. This cranial nerve branches into the Vestibular 

 branch (balance) and the cochlear branch (hearing). The cochlear fibers originate from the spiral ganglion. It is pure sensory nerve fiber.

Cranial nerve IX: Glossopharyngeal nerve 

The glossopharyngeal nerve innervates the pharynx (upper part of 

the throat), the soft palate and the posterior one-third of the tongue.It carries sensory information (touch, temperature, and pressure)

from the pharynx and soft palate. It carries taste sensation from thetaste buds on the posterior one third of the tongue. It provides

somatic motor innervation to the throat muscles involved inswallowing. It provides visceral motor innervation to the salivary

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glands. This cranial nerve also supplies the carotid sinus and reflex control to the heart . It iscomposed of both sensory and motor axons and originates from the nucleus ambiguous in the

reticular formation of the medulla.

Cranial nerve X: Vagus nerve

The vagus nerve consists of many rootlets that come off of the

 brainstem just behind the glossopharyngeal nerve. The branchialmotor component originates from the nucleus ambiguous in the

reticular formation of the medulla. The visceral componentoriginates from the dorsal motor nucleus of the vagus located in the

floor of the fourth ventricle in the rostral medulla and in the centralgrey matt er of the caudal medulla. It is the longest cranial nerve

innervating many structures in the throat, including the muscles of 

the vocal cords, thorax and abdominal cavity. It provides sensory information (touch,temperature and pressure) from the external auditory meatus (ear canal) and a portion of theexternal ear. It carries taste sensation from taste buds in the pharynx. It also provides sensory

information from the esophagus, respiratory tract, and abdominal viscera (stomach, intestines,liver, etc.). It provides visceral motor innervation to the heart, stomach, intestines, and

gallbladder. It is part of the ANS, the parasympathetic branch. It is composed of both sensoryand motor axons. Other parasympathetic ganglia include CN III , CN VII and CN IX .

Cranial nerve XI: Spinal Accessory nerveThe spinal accessory nerve has two branches. The cranial branch

 provides somatic motor innervation to some of the muscles in thethroat involved in swallowing. This cranial branch is accessory to

CN X, originating in the caudal nucleus ambiguous, with the fibersof the cranial root traveling the same extracranial path as the

 branchial motor component of the vagus nerve. The spinal branch provides somatic motor innervation to the trapezius muscles,

 providing muscle movement for the upper shoulders head and neck.It is pure motor nerve fiber.

Cranial nerve XII: Hypoglossal nerve 

The hypoglossal nerve provides somatic motor innervation to the muscles of the tongue. This pure motor nerve originates from the hypoglossal nucleus located in the tegmentum of the

medulla.

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Here are a few pneumonic devices to help you remember the cranial nerves and which ones

carry sensory, motor or both!

Cranial NerveMnemonic 1

(nerves)

Mnemonic 2

(alternate)

Mnemonic

3*(Sensory

vs. Motor)I. Olfactory On Oh Some*

II. Ocular Old Oh Say

III. Oculomotor Olympus' Oh Marry*

IV. Trochlear Towering To Money

V. Trigeminal Tops Touch But*

VI. Abducens A  And My

VII. Facial Fin Feel Brother 

VIII. Vestibulocochlear/Acoustic And A  Says

IX. Glossopharyngeal German Good Big

X. Vagus Viewed Vein Business

XI. Accessory (Spinal Accessory) Some Ah Makes

XII. Hypoglossal Hops Heaven Money

*S: sensory *M: motor *B: both

Additional Study Questions

1.  Which cranial nerve is the largest?2.  Which cranial nerve is the longest?

3.  How many cranial nerves carry both sensory and motor impulses? Name them.4.  How many cranial nerves carry only sensory impulse?

5.  What two cranial nerves carry sensory information about BP to the brain?6.  Which cranial nerve innervates the muscles of the vocal cords?

7.  How many cranial nerves are responsible for eye movements?

8.  What are the three divisions of the Trigeminal nerve CN V?

9.  The facial nerve provides motor to the ______ and sensation to the ______ .

10. Rise of the soft palate when phonating 'AAHH' is controlled by what cranial nerve?

11. Protrusion of the tongue and wagging tongue side to side is controlled by what cranial

nerve?

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Answers to Cranial Nerve Study Questions 

1. CN V

2. CN X

3. Four, CN V, CN VII, CN IX and CN X

4. Three, CN I, CN II and CN VIII

5. CN IX and CN X

6. CN X

7. Three, CN III, CN IV and CN VI

8. V1 Opthalmic V2 Maxillary V3 Mandibular 

9. Face, Tongue

10. Glossopharyngeal CN IX

11. Hypoglossal CN XII