Cranial Nerves - Medulla

Question 1

What is Cranial Nerve XII?

Answer 1

Hypoglossal Nerve

Question 2

Is CN XII Hypoglossal sensory or motor?

Answer 2

motor

Question 3

What does CN XII Hypoglossal supply?

Answer 3

both intrinsic and extrinsic muscles of the tongue

Question 4

Where are the cell bodies of the LMN of CN XII Hypoglossal located?

Answer 4

Hypoglossal Nucleus

Question 5

Where is the Hypoglossal Nucleus located?

Answer 5

near the midline of the medulla (ventral to the central canal or 4th ventricle)

Question 6

Where do the CN XII Hypoglossal LMN axons pass and in relation to what two structures?

Answer 6

The axons pass inferolateral next to the medial lemniscus and pyramid

Question 7

Where do the CN XII Hypoglossal LMN axons exit the medulla?

Answer 7

as rootlets in the ventrolateral (preolivary) sulcus

Question 8

What are UMN of CN XIII Hypoglossal known as?

Answer 8

Corticobulbar fibers (cortical control)

Question 9

Where do CN XIII Hypoglossal UMN Corticobulbar fibers arise from?

Answer 9

tongue region of the precentral gyrus (Primary motor cortex)

Question 10

Where do CN XIII Hypoglossal UMN Corticobulbar fibers descend

Answer 10

with the corticospinal tract to the medulla

Question 11

What do most of the CN XIII Hypoglossal UMN Corticobulbar fibers do at the medulla and where do they synapse?

Answer 11

most of the fibers cross the midline and synapse in the contralateral hypoglossal nucleus.

Question 12

Where does the hypoglossal nucleus receive indirect sensory information from and what type of info?

Answer 12

Solitary Nucleus (Taste)
and
Sensory Trigeminal Nuclei (bolus of food in oral cavity)

Question 13

How does the hypoglossal nucleus receive indirect sensory information from the Solitary Nucleus and Sensory Trigeminal Nuclei?

Answer 13

by way of multisynaptic connections in the reticular formation

Question 14

What is this reflex pathway of controlling the tongue involved in?

Answer 14

swallowing, suckling, and chewing

Question 15

Clinically, what does a LMN lesion of the CN XIII Hypoglossal or nucleus result in?

Answer 15

paralysis and muscle wasting of both intrinsic and extrinsic muscles on the ipsilateral side.

Question 16

How does the tongue respond in a LMN lesion of CN XIII Hypoglossal?

Answer 16

upon protrusion of the tongue, it deviates toward the side of the lesion due to the unopposed action of the intact contralateral genioglossus muscle.

Question 17

What will patients have difficulty with in a LMN lesion of the CN XIII Hypoglossal?

Answer 17

eating and speaking (dysarthria)

Question 18

Clinically, what does a UMN lesion of the CN XIII Hypoglossal that occurs at a level prior to the crossing result in?

Answer 18

results in weakness of only the extrinsic muscles (primarily genioglossus) on the side contralteral to the site of the lesion.

Question 19

Which way will the tongue deviate upon voluntary protrusion in a UMN lesion of the CN XIII Hypoglossal that occurs at a level prior to the crossing?

Answer 19

it deviates away from the side of the lesion due to the crossing fibers and unopposed action of the intact contralateral genioglossus muscle

Question 20

A stroke of the paramedian branch of the anterior spinal artery may result in combinations of damage to the

Answer 20

• hypoglossal nerve fibers,
• the adjacent pyramid
• medial lemniscus
• ventral trigeminothalamic tract

Question 21

Would would be the result of a stroke of the paramedian branch of the anterior spinal artery - hypoglossal nerve fibers?

Answer 21

LMN symptoms involving the tongue

-paralysis and muscle wasting of both intrinsic and extrinsic muscles on the ipsilateral side

Question 22

Would would be the result of a stroke of the paramedian branch of the anterior spinal artery - hypoglossal nerve fibers -the adjacent pyramid?

Answer 22

UMN symptoms involving the pyramid

Contralateral axial and appendicular musculature - Initial flaccid paralysis followed by: Abnormal cutaneous reflexes (Babinski sign), Abnormal reflexes: clonus, clasp knife), Spasticity – velocity dependent hypertonia, Abnormal timing of muscle activation (slower onset, prolonged contraction), Paresis or plegia (weakness)

(corticospinal fibers prior to decussating and forming the lateral corticospinal tract)

Question 23

Would would be the result of a stroke of the paramedian branch of the anterior spinal artery - hypoglossal nerve fibers -medial lemniscus?

Answer 23

Loss of Contralateral Body Sense:

• Sterogenesis
• -Conscious Proprioception
• -Two Point Discriminative Touch
• Vibratory

Question 24

Would would be the result of a stroke of the paramedian branch of the anterior spinal artery -ventral trigeminothalamic tract?

Answer 24

Somatosensation of the Face by CN V Trigeminal Nerve

Contrallateral loss of Nociception and Thermal Sensation

Contralteral Touch (discriminative and light non-discriminative) and Conscious Proprioception should be preserved due to bilateral represetation via dorsal trigeminothalamic tract?

Question 25

What is alternating hemiplegia?

Answer 25

Combination of lower and upper motor neuron signs that are demonstrated on opposite sides of the neuraaxis as seen with a stroke with the paramedian branch of anterior spinal artery.

Question 26

Where are the regions that alternating hemiplegia occur?

Answer 26

Where a motor cranial nerve exits along the midline adjacent to the descending corticospinal fibers.

Question 27

What are the two other likely regions this might occur?

Answer 27

III - Oculomotor VI - Abducens although these two are for tongue? VII - Facial Nerve XI - Glossopharyngeal

Question 28

CNXI - Accessory Nerve contains a few LMN in ___

Answer 28

nucleus ambiguus

Question 29

CNXI - Accessory Nerve LMN in nucleus ambiguus innervate a few of the ____

Answer 29

laryngeal muscles (cranial component)

Question 30

CNXI - Accessory Nerve cell bodies innervating the sternocleidomastoid and trapezius muscles (spinal components) are located in

Answer 30

cervical levels of the spinal cord dorsal to the ventral horn

Question 31

Where do CNXI - Accessory Nerve axons of the spinal component go?

Answer 31

they leave the spinal cord and ascend into the cranial cavity to re-exit the skull as the accessory nerve

Question 32

Where do CNXI - Accessory Nerve axons of the cranial comonent go?

Answer 32

a small number of fibers exit the medulla long with the vagus nerve.

Question 33

CNXI - Accessory Nerve UMN (corticobulbar fibers) descend with the ___

Answer 33

corticospinal fibers

Question 34

After CNXI - Accessory Nerve descend with the corticospinal fibers they ___

Answer 34

decussate at the pyramidal decussation

Question 35

Where do CNXI - Accessory Nerve terminate?

Answer 35

in the cervical region (C2-4)

Question 36

Clinically, how do you test for involvement of the spinal part of CNXI - Accessory Nerve?

Answer 36

the patient is asked to turn the head (sternocleidomastoid) or shrug the shoulders (trapezius).

Question 37

T/F: The cranial component of CNXI - Accessory Nerve is indistinguishable from CNX - Vagus Nerve?

Answer 37

True

Question 38

CNX - Vagus Nerve UMN (corticobulbar) innervate ___

Answer 38

nucleus ambiguus

Question 39

CNX - Vagus Nerve UMN (corticobulbar) innervate nucleus ambiguus ipsilaterally, contralaterally, or bilaterally?

Answer 39

bilaterally i.e., both sides.

Question 40

T/F: because CNX - Vagus Nerve UMN innervates nucleus ambiguus bilaterally, a unilateral lesion of the upper motor neuron can be easily distinguished.

Answer 40

FALSE: a unilateral lesion of the upper motor neuron would not be easily distinguished

Question 41

CNX - Vagus Nerve LMN located in nucleus ambiguus innervate what? (3)

Answer 41

``` Skeletal Muscles of the 1. Soft Palate 2. Larynx 3. Pharynx including vocalis muscle (true vocal folds). ```

Question 42

Where is Nucleus ambiguus located?

Answer 42

reticular formation

Question 43

T/F: Nucleus Ambiguus is not easily identified.

Answer 43

True

Question 44

Nucleus Ambiguus contains lower motor neurons for what Cranial Nerves? (3)

Answer 44

CN IX - Glossopharyngeal CN X - Vagus Cranial Part of CN XI - Accessory Nerve

Question 45

Where are preganglionic parasympathetic cell bodies for CNX - Vagus Nerve located primarily?

Answer 45

in the dorsal motor nucleus of X

Question 46

The preganglionic parasympathetic axons for CNX - Vagus Nerve go from the cell bodies on dorsal motor nucleus of X and ____

Answer 46

exit the medulla as rootlets of X

Question 47

Where do the axons of the preganglionic parasympathetic axons for CNX - Vagus Nerve synapse?

Answer 47

on postganglionic neurons in visceral walls of glands, cardiac muscle, and smooth muscle of the throax and abdomen.

Question 48

CNX - Vagus Nerve sensory fibers travel along the

Answer 48

solitary tract

Question 49

CNX - Vagus Nerve sensory fibers travel along the solitary tract and end in the

Answer 49

solitary nucleus

Question 50

CNX - Vagus Nerve sensory fibers component carry

Answer 50

pain and pressure from pharynx, larynx, thorax, and abdomen

Question 51

Where do some of the CNX - Vagus Nerve sensory fibers enter and why?

Answer 51

Spinal Trigeminal Nucleus because pain of the face.

Question 52

What are the three important reflexes carried by the CNX - Vagus Nerve?

Answer 52

1. Carotid Sinus Reflex 2. Carotid Body Reflex 3. Cough, gag, and vomiting reflexes

Question 53

Carotid Sinus Reflex - Where does the afferent limb originate?

Answer 53

from baroreceptors along the carotid artery near the bifurcation into internal and carotid arteries

Question 54

Carotid Sinus Reflex - Which cranial nerve carries afferent information?

Answer 54

fibers of CN IX - Glossopharyngeal

Question 55

Carotid Sinus Reflex - CN IX - Glossopharyngeal carries afferent information to

Answer 55

solitary nucleus

Question 56

Carotid Sinus Reflex - CN IX - Glossopharyngeal carries afferent information to solitary nuclues, then relayed to the

Answer 56

dorsal motor nucleus of X

Question 57

Carotid Sinus Reflex - Which cranial nerve carries efferent information?

Answer 57

CNX - Vagus

Question 58

Carotid Sinus Reflex - The efferent limb, CNX - Vagus, of the reflex arc innervates what and does what?

Answer 58

the heart to slow heart rate

Question 59

Carotid Body Reflex - uses what cranial nerve for one of its sensory afferent components?

Answer 59

CNX - Vagus

Question 60

Carotid Body Reflex - What sensory afferent information does CNX - Vagus carry?

Answer 60

the chemoreceptor sensation from lung bronchioles

Question 61

Carotid Body Reflex - What sensory afferent information does CNX - Vagus carry chemoreceptor sensation from lung bronchioles, which synapse in the

Answer 61

"medullary respiratory center" (an area in the reticular formation)

Question 62

Carotid Body Reflex - What does it help control?

Answer 62

breathing rhythm

Question 63

Carotid Body Reflex - The efferent limb carries what information where?

Answer 63

descending information to spinal cord levels controlling inspiration (intercostals and diaphragm)

Question 64

Cough, gag, and vomiting reflexes - involves sensory fibers from what two cranial nerves from where?

Answer 64

CNIX - Glossopharyngeal (oral/nasal cavity) | CNX - Vagus (gut)

Question 65

Cough, gag, and vomiting reflexes - where is the sensory information relayed?

Answer 65

to appropriate lower motor neurons in nucleus ambiguus and spinal cord, and preganglionic parasympathetics in dorsal motor nucleus of X

Question 66

Do lesions of CNX - Vagus Nerve result in sensory or motor deficits?

Answer 66

both sensory and motor deficits

Question 67

Unilateral lesions of lower motor neurons of CNX - Vagus result in ___ (3)

Answer 67

1. Difficulty swallowing 2. Hoarseness (dysphonia) 3. inability to raise the soft palate on ipsilateral side

Question 68

Lesions of the preganglionic parasympathetic fibers of CNX - Vagus Nerve cause

Answer 68

disruption of some gut reflexes (but are less important for diagnosis of lesion location than are deficits assocaited with somatomotor LMN component).

Question 69

Hyperactivity (excess firing) of preganglionic parasympathetic fibers of CNX - Vagus Nerve can cause

Answer 69

excess gastric acid secretion = ulcers

Question 70

Large bilateral lesions of the medullary reticular formation can

Answer 70

disrupt normal breathing rhythms and reflex control of vascular resistance to blood flow and result in coma. Patient with this type of damage may need life support systems and have a poor prognosis.

Question 71

CNIX - Glossopharyngeal Nerve cortical control UMN in cortex descends as part of

Answer 71

corticobulbar synapses

Question 72

CNIX - Glossopharyngeal Nerve cortical control UMN in cortex descends as part of corticobulbar system to synapse on

Answer 72

lower motor neurons in nucleus ambiguus

Question 73

CNIX - Glossopharyngeal Nerve UMN synapses on nucleus ambiguus ipsilaterally, contralaterally, or bilaterally?

Answer 73

bilaterally

Question 74

Where are CNIX - Glossopharyngeal Nerve LMN's located in nucleus ambiguus?

Answer 74

rostral end

Question 75

What cranial nerves have LMN's in Nucleus Ambiguus?

Answer 75

CN IX - Glossopharyngeal CN X - Vagus Cranial Part of CN XI - Accessory Nerve

Question 76

CNIX - Glossopharyngeal Nerve LMN from nucleus ambiguus innervate

Answer 76

stylopharyngeus muscle

Question 77

CNIX - Glossopharyngeal Nerve preganglionic parasympathetic neuron cell bodies located in

Answer 77

reticular formation

Question 78

CNIX - Glossopharyngeal Nerve preganglionic parasympathetic neuron cell bodies located in reticular formation; axons exit the

Answer 78

medulla

Question 79

CNIX - Glossopharyngeal Nerve preganglionic parasympathetic neuron cell bodies located in reticular formation; axons exit the medulla to synapse on

Answer 79

postganglionic neurons in otic ganglion

Question 80

CNIX - Glossopharyngeal preganglionic parasympathetic nerves from the otic ganglion then innervate

Answer 80

the parotid gland (remember from anatomy that this component follows the auriculotemporal branch of V3

Question 81

CNIX - Glossopharyngeal sensory neurons central processes synapse in the (2)

Answer 81

1. caudal part of the solitary nucleus | 2. sensory trigeminal nuclei; primarily spinal nucleus of V

Question 82

CNIX - Glossopharyngeal sensory neurons central processes synapse in the caudal part of solitary nucleus and carry

Answer 82

the afferent limb of the carotid sinus reflexs

Question 83

CNIX - Glossopharyngeal sensory neurons central processes synapse in the sensory trigeminal nuclei; primarily spinal nucleus of V carries

Answer 83

somatic sensations (touch, pressure, pain) from pharynx and posterior 1/3 of tongue (gag reflex)

Question 84

CNIX - Glossopharyngeal sensory neurons central processes synapse in the sensory trigeminal nuclei; primarily spinal nucleus of V carries what information to anterior part of solitary nucleus?

Answer 84

taste sensation from posterior 1/3 of tongue (mainly bitter sensation)

Question 85

CNIX - Glossopharyngeal carries the afferent or efferent limb for several reflexes?

Answer 85

afferent (sensory)

Question 86

CNIX - Glossopharyngeal is the efferent limb for several reflexes whose efferent limb is carried by (3)

Answer 86

CNX - Vagus CNXII - Hypoglossal Spinal Cord LMN's

Question 87

What reflexes does CNIX - Glossopharyngeal carry afferent (sensory) information for? (4)

Answer 87

Carotid Sinus Reflex Gag Reflex Vomiting Reflex Swallowing Reflex

Question 88

The motor component of CNIX - Glossopharyngeal participates in what reflexes? (2)

Answer 88

Swallowing Reflex | Salivation-Taste Reflex

Question 89

Unilateral lesions of CNIX - Glossopharyngeal can produce

Answer 89

difficulty with speech and swallowing

Question 90

T/F: defitis from unilateral lesions from CNIX - Glossopharyngeal are less severe than with CNX - Vagus Nerve.

Answer 90

True

Question 91

Similar to CNX - Vagus, CNIX - Glossopharyngeal lesions can result in

Answer 91

some visceral reflexes

Question 92

What is the most diagnostic deficits which distinguish between CNIX - Glossopharyngeal and CNX - Vagus lesions?

Answer 92

Loss of gag reflex to touching the pharynx compared to deviation of uvula

Question 93

Loss of gag reflex to touching the pharynx would indicate a lesion with

Answer 93

CNIX - Glossopharyngeal (afferent limb)

Question 94

Loss of deviation of uvula would indicate a lesion with

Answer 94

CNX - Vagus (efferent limb)