L20: Cranial Nerves - A

Question 1

A ___ is an organ made of nerve fibers (+ connective tissues) that connects the CNS to the periphery (muscles, glands, skin). It belongs to the PNS.

Answer 1

nerve

Question 2

There are 31 pairs of mixed ___ nerves that originate from sensory and motor nuclei located in spinal cord to serve the body
A. Cranial nerves
B. Spinal nerves

Answer 2

B. Spinal nerves

Question 3

____: Pair of nerves made of fibers that give rise from either sensory or motor (or both) nuclei located in the brainstem (pons, medulla, or midbrain) and serve head and neck

Answer 3

Cranial nerves

Question 4

Which cranial nerve is an exception, since it supplies abdomen and thorax?

Answer 4

Vagus nerve

Question 5

Why are cranial nerves referred to as 10+2 pairs of nerves?

Answer 5

10 originate in brainstem
2 originate in sensory structures

Question 6

Which cranial nerves are
- pure sensory nerves?
- pure motor nerves?
- mixed?

Answer 6

pure sensory: I, II, and VIII
pure motor: III, IV, VI, XI, XII
mixed: V, VII, IX, X

Question 7

True or False: Somatic motor nuclei host population of neurons (LMN) that send out efferent motor fibers to muscles

Answer 7

True

Question 8

The motor nuclei receives impulses from the cerebral cortex (motor areas) through the ____ fibers. Where do these fibers originate?

Answer 8

corticonuclear
- fibers originate from pyramidal cells (UMN) located in motor cortex and descend to brain stem

Question 9

True or False: Upper motor neurons synapse with LMN’s in cranial nerve motor nuclei

Answer 9

True

Question 10

True or False: The majority of the corticonuclear fibers cross midline before reaching nuclei

Answer 10

True

Question 11

True or False: The way the cranial nerves are ordered, from III to XII correlates with position of their nuclei in the brainstem – from rostral (midbrain) to caudal (medulla)

Answer 11

True

Question 12

Which two cranial nerves emerged from the cerebrum itself?

Answer 12

CN I and II

Question 13

Which CN is composed of fibers that originate from neuroreceptors located in olfactory mucosa in nasal cavity and end in olfactory bulb?

Note: The pathway carries out smell sensations and continue with olfactory tract, direct to olfactory area o the cerebral cortex

Answer 13

Olfactory Nerve - CN 1

Question 14

Which fiber of CN VIII is best described as “peripheral receptors located in semicircular canals of the vestibule in the inner ear. Fibers originate from vestibular ganglion and convey information about linear and angular acceleration of the head”?

A. Cochlear Fibers
B. Vestibular Fibers

Answer 14

Vestibuar fibers

Question 15

Which fibers of CN VIII originate from spiral ganglion in cochlea of inner ear. The peripheral branch of the fiber contacts organ of Corti, which hosts the receptors for sound, while the central branch conveys acoustic sensory information to the brainstem?

A. Cochlear Fibers
B. Vestibular Fibers

Answer 15

A. Cochlear Fibers

Question 16

The motor nucleus of which CN is located in the midbrain? Further, axons of these LMN’s exit nucleus of the CN to enter the ipsilateral CN?

Answer 16

Oculomotor nerve

Question 17

Which 5 extraocular muscles does the oculomotor nerve innervate?

Answer 17

1. Superior Rectus
2. Inferior Rectus
3. Medial Rectus
4. Inferior Oblique
5. Levator Palpebrae Superioris

Question 18

In the oculomotor nerve, pre-ganglionic fibers originate from the ____ nucleus and synapse with neurons located in the ____ ganglion

Answer 18

Edinger-Westphal; ciliary

Question 19

The post-ganglionic fibers of CN III innervate ___ ___ of iris and ciliary muscles to constrict pupil and change lens shape, for accommodation

Answer 19

constrictor papillae

Question 20

Which cranial nerve is found in the midbrain and has axons of LMN the decussate and exit brainstem on dorsal suface?

Answer 20

CN IV

Question 21

What does CN IV innervate?

Answer 21

Contralateral superior oblique m.

Question 22

Which CN is found in caudal pons and axons of the LMN exit brainstem at pontomedullary junction?

Answer 22

Abducens n.

Question 23

Which CN innervates lateral rectus m?
A. Oculomoter
B. Trochlear
C. Abducens
D. Trigeminal

Answer 23

Abducens

Question 24

True or False: Abducens also contains interneurons that project to c/l oculomotoer nucleus, so that anytime we look to left/right, we can control contraction of lateral rectus of one eye + medial rectus of other eye at same time

Answer 24

True

Question 25

Which CN is found in hypoglossal nucleus of medulla an axons of lower motor neurons enter hypoglossal nerve?

Answer 25

CN XII

Question 26

Which CN innervates intrinsic and extrinsic muscles of the tongue?

Answer 26

Hypoglossal

Question 27

Which CN is located at ventral horn of SC at cervical levels.

Note: This CN innervates sternocleidomastoid and trap muscle

Answer 27

Accessory n.

Question 28

Which four CN are mixed?

Answer 28

Trigeminal
Facial
Vagus
Glossopharyngeal

Question 29

____: A cranial nerve that is the principal somatosensory nerve for the head, with afferents arriving via ophthalmic, maxillary, and mandibular division

Answer 29

Trigeminal nerve

Question 30

Which CN innervates muscles of mastication?

Answer 30

Trigeminal

Question 31

Which CN has sensory fibers that recruit taste from anterior 2/3 of tongue, as well as from floor of mouth and palate?

Answer 31

Facial Nerve

Question 32

True or False: The facial nerve is found in the caudal pons and axons of these LMN’s exit facial motor nucleus to enter motor root of facial nerve

Answer 32

True

Question 33

Which CN innervates muscles of facial expression?

Answer 33

Facial nerve

Question 34

The parasympathetic fibers of CN VII are located in the superior ___ nucleus in the pons.

Answer 34

salivary

Question 35

Which CN innervates the lacrimal gland, submandibular, and sublingual salivary glands?

Answer 35

Facial Nerve

Question 36

Which CN recruits taste from posterior 1/3 of tongue and innervates stylopharyngeus m?

Answer 36

CN IX

Question 37

Parasympathetic neurons of ____ hav inferior salivary nucleus that provide innervation to parotid gland
A. X
B. III
C. IV
D. IX

Answer 37

D. IX

Question 38

Which CN provides visceral sensory info from larynx, esophagus, trachea, and abdominal/thoracic viscera, as well as stretch-R of aortic arch + chemoreceptors of aortic bodies?

Answer 38

CN X

Question 39

Where is CN X found? Where do axons of these LMN enter?

Answer 39

Nucleus ambiguus
- Enter ipsilateral vagus nerve

Question 40

What does the vagus nerve innervate?

Answer 40

Soft palate + m of pharynx, larynx, and vocal cords