DENT 1020 Cranial Nerves

Question 1

I — Olfactory - afferent (sensory)

Answer 1

a. transmits smell
b. enters the skull through the cribriform plate of the ethmoid bone
c. olfactory bulbs - connect to the brain

Question 2

II — Optic - afferent (sensory)

Answer 2

a. transmits sight
b. enters skull through the optic canal of the sphenoid bone
c. optic chiasma - where many optic nerves cross to the opposite side
d. optic tracts - connected to the brain

Question 3

III — Oculomotor - efferent (motor)

Answer 3

a. moves the eyeball along with the trochlear and abducens
b. has some parasympathetic fibers that innervate the ciliary muscles as well
c. lies in the lateral wall of the cavernous sinus and exits the skull through the superior orbital fissure of the sphenoid bone

Question 4

IV — Trochlear - efferent (motor)

Answer 4

a. helps move the eyeball

b. runs through the cavernous sinus as well and exits out the superior orbital fissure

Question 5

V — Trigeminal - both efferent/afferent (motor/sensory)

Answer 5

a. efferent components: muscles of mastication, some cranial muscles
b. afferent components: teeth, tongue, oral cavity, most of the skin of the face

Question 6

VI — Abducens - efferent (motor)

Answer 6

a. moves the eyeball

b. exits the skull through the superior orbital fissure along with other nerves that move the eyeball

Question 7

VII — Facial - both efferent/afferent (motor/sensory)

Answer 7

a. efferent component: muscles of facial expression
i. parasympathetic n. travel alongside this nerve
& innervate various structures: Lacrimal,
sublingual and submandibular glands
b. afferent component: taste sensation, patch of skin behind the ear, and tongue (body)

Question 8

VIII — Vestibulocochlear - afferent (sensory)

Answer 8

a. transmits sound and aids in balance

b. enters the cranial cavity through the internal acoustic meatus of the temporal bone

Question 9

IX — Glossopharyngeal - both efferent/afferent (motor/sensory)

Answer 9

a. innervates the pharyngeal muscles
b. has parasympathetic (preganglionic n.) that innervates the PAROTID SALIVARY GLAND
i. preganglionic n. relays info to otic ganglion
ii. lesser petrosal n. travels alongside the
mandibular division of the trigeminal n., exiting
through the foramen ovale and then synapses
with the otic ganglion
c. afferent for the sensation of taste and general sensation from the base of the tongue as well as sensation of the pharynx and carotid artery
d. it enters the skull through the jugular foramen

Question 10

X — Vagus - both efferent/afferent (motor/sensory)

Answer 10

a. efferent (large): innervates the muscles of the soft palate, pharynx, and larynx
b. has parasympathetic innervation to many of the organs of the thorax and abdomen - thymus, heart, stomach
c. afferent (smaller): skin around the ear and taste sensation from the epiglottis
d. passes through the skull through the jugular foramen

Question 11

XI — Accessory - efferent (motor)

Answer 11

a. efferent: innervates the trapezius and sternocleidomastoid muscle, muscles of the soft palate and pharynx
b. has 2 roots - 1 is a cranial root and arises from the brain; the other from the spinal cord
c. exits the skull through the jugular foramen

Question 12

XII — Hypoglossal - efferent (motor)

Answer 12

a. muscles to the tongue (intrinsic and extrinsic)

b. exits the skull through the hypoglossal canal of occipital bone