The Cranial Nerves

Question 1

Twelve pairs of nerves that are associated with the brain.

Answer 1

Cranial Nerves

Question 2

Cranial Nerve I

Answer 2

Olfactory Nerves

Question 3

Origin and Course of the Olfactory Nerve

Answer 3

Arise in olfactory epithelium of nasal cavity. Passes through cribriform plate of the ethmoid bone and synapses in the olfactory bulb. The olfactory tract terminates in the primary olfactory cortex.

Question 4

Function of the Olfactory Nerve

Answer 4

Purely sensory; carries afferent impulses for sense of smell.

Question 5

Cranial Nerve II

Answer 5

Optic Nerve

Question 6

Origin and Course of the Optic Nerve

Answer 6

Arise in the retina of the eye. Passes through the optic canal of the orbit. Converges to form the optic chiasma. Synapses at the thalamus. The optic radiation fibers run to the primary visual cortex.

Question 7

Function of the Optic Nerve

Answer 7

Purely sensory; carries afferent impulses for vision.

Question 8

Cranial Nerve III

Answer 8

Oculomotor Nerve

Question 9

Origin and Course of the Oculomotor Nerve.

Answer 9

Extends from the ventral midbrain and passes through the superior orbital fissure to the eye.

Question 10

Function of the Oculomotor Nerve.

Answer 10

Chiefly motor neurons. Somatic motor fibers to inferior oblique; and the superior, inferior, and medial rectus muscles. Parasympathetic motor fibers to the sphincter pupillae and ciliary muscles. Sensory afferents from the skeletal muscles.

Question 11

Cranial Nerve IV

Answer 11

Trochlear Nerve

Question 12

Origin and Course of the Trochlear Nerve

Answer 12

Emerges from dorsal midbrain and enter the orbit through the superior orbital fissure.

Question 13

Function of the Trochlear Nerve

Answer 13

Primarily motor nerves. Somatic motor fibers to superior oblique muscle, which passes through pulley-shaped trochlea.

Question 14

Cranial Nerve V

Answer 14

Trigeminal Nerve

Question 15

First Division of the Trigeminal Nerve

Answer 15

Ophthalmic Nerve (V1)

Question 16

Origin and Course of the Ophthalmic Nerve

Answer 16

Run from face through superior orbital fissure to pons.

Question 17

Function of the Ophthalmic Nerve

Answer 17

Sensory, conveys impulses from anterior scalp, upper eyelid, nose, nasal cavity mucosa, cornea, and lacrimal gland.

Question 18

Second Division of the Trigeminal Nerve.

Answer 18

Maxillary Nerve (V2)

Question 19

Origin and Course of the Maxillary Nerve

Answer 19

Runs from face through the foramen rotundum to the pons.

Question 20

Function of the Maxillary Nerve

Answer 20

Sensory, conveys impulses from nasal cavity mucosa, palate, upper teeth, skin of cheek, upper lip, lower eyelid.

Question 21

Third Division of the Trigeminal Nerve

Answer 21

Mandibular Nerve (V3)

Question 22

Origin and Course of the Mandibular Nerve

Answer 22

Passes through skull via foramen ovale.

Question 23

Function of the Mandibular Nerve

Answer 23

Sensory: Conveys impulses from anterior tongue, temporal region of the scalp, skin of the chin. Motor: muscles of mastication

Question 24

Cranial Nerve VI

Answer 24

Abducens Nerve

Question 25

Origin and Course of the Abducens Nerve

Answer 25

Leave inferior pons and enter the orbit via the superior orbital fissure.

Question 26

Function of the Abducens Nerve

Answer 26

Motor fibers to the lateral rectus muscle. Sensory fibers from the same muscle.

Question 27

Cranial Nerve VII

Answer 27

Facial Nerve

Question 28

Origin and Course of the Facial Nerve

Answer 28

Runs from pons, enters temporal bone via the internal acoustic meatus, emerges through stylomastoid foramen, continues to lateral aspect of the face.

Question 29

Function of the Facial Nerve

Answer 29

Mixed nerves. Chief motor nerves of the face. Sensory fibers of the same muscles. Parasympathetic motor impulses to lacrimal glands, nasal and palatine glands, and submandibular and salivary glands. Sensory impulses from taste buds of anterior two-thirds of the tongue.

Question 30

Cranial Nerve VIII

Answer 30

Vestibulocochlear Nerve

Question 31

Origin and Course of the Vestibulocochlear Nerve

Answer 31

Arise from hearing and equilibrium apparatus in the inner ear, passes through internal acoustic meatus to pons-medulla border.

Question 32

Function of the Vestibulocochlear Nerve

Answer 32

Mostly sensory, vestibular division transmits impulses for sense of equilibrium, cochlear division transmits impulses for sense of hearing. Motor component adjusts the sensitivity of sensory receptors.

Question 33

Cranial Nerve IX

Answer 33

Glossopharyngeal Nerve

Question 34

Origin and Course of the Glossopharyngeal Nerve

Answer 34

Emerges from the medulla and leaves skull via jugular foramen.

Question 35

Function of the Glossopharyngeal Nerve

Answer 35

Mixed nerve. Sensory motor fibers to and from stylopharyngeus, which elevates the pharynx during swallowing. Parasympathetic motor fibers to parotid glands. Sensory fibers conduct taste and general sensory impulses from pharynx and posterior tongue, chemoreceptor in carotid body which monitor O2 and CO2 levels and regulate respiratory function, baroreceptors of carotid sinus which monitor blood pressure.

Question 36

Cranial Nerve X

Answer 36

Vagus Nerve

Question 37

Origin and Course of the Vagus Nerve

Answer 37

Extends beyond the head and neck region. Emerges from the medulla, passes through skull via jugular foramen, descends into thorax and abdomen.

Question 38

Function of the Vagus Nerve

Answer 38

Mix nerve. Mostly motor fibers. Parasympathetic motor fibers supply heart, lungs, and abdominal viscera. Sensory impulses from thoracic and abdominal viscera, aortic arch baroreceptors, carotid and aortic bodies, taste buds on the epiglottis, skin on external ear. Proprioceptor fibers from muscles of larynx and pharynx.

Question 39

Cranial Nerve XI

Answer 39

Accessory Nerve

Question 40

Origin and Course of the Accessory Nerve

Answer 40

Rootlets emerge from spinal cord. Pass along spinal cord and enter skull via foramen magnum, exit skull through jugular foramen.

Question 41

Function of the Accessory Nerve

Answer 41

Mixed nerves. Motor fibers to trapezius and SCM muscles. Proprioceptor impulses from same muscles.

Question 42

Cranial Nerve XII

Answer 42

Hypoglossal Nerve

Question 43

Origin and Course of the Hypoglossal Nerve

Answer 43

Arise by series of roots from medulla and exit skull via hypoglossal canal to tongue.

Question 44

Function of the Hypoglossal Nerve

Answer 44

Mixed nerve, primarily motor. Somatic motor fibers to intrinsic and extrinsic muscles of tongue. Proprioceptors from same muscles.