Nsp Week 3: Cranial Nerves (Blair)

Front 1

Where is the hypoglossal nucleus located?

As the nucleus extends rostrally, what does it create on the surface of the 4th ventricle?

Back 1

Caudal medulla
(adjacent to midline)

*Hypoglossal trigone

Front 2

Which nerve is primarily responsible for controlling movements of the tongue?

All of the muscles of the tongue are innervated by this nerve except one. What is the exception?

Back 2

Hypoglossal nerve

*Palatoglossus is only muscle in tongue not innervated by CN XII. Instead, it is innervated by CN X.

Front 3

Which neurons does the Hypoglossal nucleus contain?

Back 3

alpha-motor neurons that innervate:
1. intrinsic tongue muscles
2. Genioglossus M
3. Styloglossus M
4. Hyoglossus M

Front 4

Does the genioglossus muscle receive bilateral or contralateral input?

Back 4

Contralateral

Front 5

The hypoglossal nucleus receives input from which 3 major sources?

Back 5

1. Face region of cerebral motor cortex
2. Sensory fibers from the Solitary nuclei
3. Sensory fibers from the Trigeminal nuclei

Front 6

Damage to the hypoglossal nerve or nucleus will have what consequence?

Back 6

Weakness (or paralysis) of the IPSILATERAL tongue
(When the tongue is protruded, it will deviate towards side of nerve damage)

Front 7

Damage to the corticobulbar pathway will have what sort of consequence on tongue movement?

Back 7

Upon protrusion, the tongue will deviate to the CONTRALATERAL side of the lesion site
(corticobulbar innervation to the nucleus is contralateral)

Front 8

Which neurons form the spinal accessory nucleus and where is this located?

Back 8

Motor neurons in C1-C5 spinal segments for the spinal accessory nucleus in the lateral ventral gray matter.

Front 9

The spinal accessory nerve innervates which 2 muscles?

What are the actions of these muscles?

Back 9

1. Trapezius--> helps elevate shoulder
2. Sternocleidomastoid --> turns head to opposite direction

Front 10

The spinal accessory nucleus receives input from which source?

Back 10

Corticospinal tract

Front 11

What fibers are sometimes called the cranial root of the spinal accessory nerve?

Back 11

Neurons from the caudal nucleus ambiguus that course with the accessory nerve as it leaves the jugular foramen

Front 12

Damage to the spinal accessory nerve or nucleus will produce what kind of deficit?

Back 12

Weakness or paralysis in the trapezius and/or sternocleidomastoid muscles

Front 13

Which nerve exits the brainstem near the postolivary sulcus and courses to the periphery through the jugular foramen?

Back 13

Vagus N.

Front 14

Where are parasympathetic preganglionic cell bodies located?

Most parasympathetic neurons to the heart originate in which nucleus?

Back 14

1. Dorsal motor nucleus (bump on floor of 4th ventricle, forms vagal trigone) <-- OTHER ORGANS
2. Nucleus ambiguus <-- HEART

Front 15

The nucleus ambiguus contains cell bodies for what kind of fibers?

Back 15

Special visceral efferent fibers that innervate PHARYNGEAL muscles that control swallowing and speaking

Front 16

The visceral efferent fibers that innervate pharyngeal muscles that control swallowing and speaking originate from what nucleus?

Back 16

Nucleus ambiguus
(these are fibers of Vagus N)

Front 17

Describe the somatic afferent component of the vagus nerve

Back 17

Transmits pain, temperature, and touch information from the:
1. Larynx
2. Pharynx
3. External ear and external auditory meatus
4. Tympanic membrane
5. Meninges in the posterior cranial foss

Front 18

What is the function of the visceral afferent fibers of the Vagus N?

Back 18

Transmit taste from epiglottis and esophagus

Front 19

Where are Vagus N somatic afferent cell bodies located?
Where are the visceral afferent cell bodies located?

Back 19

Somatic afferent --> Superior (jugular) ganglion
Visceral afferent --> Inferior (nodose) ganglion

Front 20

Where do the central processes of the somatic and visceral afferent fibers of the Vagus N terminate?

Back 20

Solitary nucleus

Front 21

What are the deficits in sensory and visceral function w/ unilateral vagal damage?

Back 21

Usually none
(the other vagus nerve can compensate)

Front 22

The major deficit in the Vagus N is due to interruption of fibers originating from where?

Back 22

Nucleus ambiguus

Front 23

What is the consequences of damage to fibers originating in the nucleus ambiguus?

Back 23

(these are visceral efferent fibers that innervate muscles used for swallowing and speaking)

* Uvula will deviate towards CONTRALATERAL SIDE of the lesion
(lower motor neuron)

Front 24

What is the consequence of an upper motor lesion that damages the descending corticobulbar fibers that innervate the uvula?

Back 24

Uvula will deviate towards IPSILATERAL side of the lesion

Front 25

Which nerve exits from the ventrolateral medulla between the olive and inferior cerebellar peduncle near the junction of the pons, and exits the skull through the jugular foramen?

Back 25

Glossopharyngeal (CN IX)

Front 26

The somatic afferent fibers of the Glossopharyngeal nerve have what funciton?

Back 26

Transmit pain, temperature, and touch information from the:
1. *Posterior 1/3 of the tongue
2. *Pharynx
3. Middle ear
4. Skin on the back of the ear

Front 27

Fibers from which nerve from the pharynx mediate the sensory limb of the gag reflex?

Where do these fibers terminate?

Back 27

Glosspharyngeal (CN IX)

*Terminate in the nucleus of the solitary tract

Front 28

Fibers from which nerve form the baroreceptors in the carotid sinus and chemoreceptors from the carotid body?

Back 28

Glossopharyngeal (CN IX)

Front 29

What is the function of the special visceral afferent fibers of the Glossopharyngeal nerve?

Back 29

Mediate taste sensation from the posterior 1/3 of the tongue

Front 30

List the various types of fibers that comprise the Glossopharyngeal N

Back 30

1. Somatic afferent
2. Visceral & special visceral afferent
3. Visceral efferent

Front 31

List the 2 visceral efferent functions of the Glossopharyngeal N
These fibers originate from different nuclei. Which nuclei?

Back 31

1. Parasympathetic innervation of parotid gland (Inferior salvitory nucleus)
2. Innervation of the Stylopharyngeus muscle, which elevates the pharynx (nucleus ambiguus)

Front 32

Describe the innervation to the parotid gland

Back 32

1. Parasympathetic preganglionic neurons originate in inferior salvitory nucleus
2. Axons course in CN IX to the otic ganglion
3. Fibers reach parotid gland

*Inferior salvitory nucleus (rostral medulla) --> otic ganglion --> parotid gland

Front 33

What is the function of the Stylopharyngeus, and which nerve innervates it?

Back 33

Elevates the pharynx when speaking or swallowing

*Innervated by Glossopharyngeal (CN IX)

Front 34

Loss of the gag reflex on the side of a lesion would be caused by damage to which nerve?

Back 34

Glossopharyngeal (CN IX)

Front 35

Intense pain occurring spontaneously after swallowing, coughing, or talking may be due to what condition?

Back 35

Glossopharyngeal neuralgia
(damage to CN IX)

Front 36

Describe the sensory and motor limbs of the gag reflex (which nerves are involved and nuclei they originate in or terminate in)

Back 36

SENSORY LIMB:
Glossopharyngeal N fibers --> Pharyngeal M --> terminate in nucleus of solitary tract

MOTOR LIMB:
Nucleus ambiguus --> SVE fibers--> Pharyx and Palate
Hypoglossal nuclues --> GSE fibers --> Tongue

Front 37

Describe the functions of the 2 special visceral afferent fibers originating from the Vestibulocochlear N (CN VIII)

Back 37

Cochlear Afferents:
Transmit auditory information (sound) from the cochlea

Vestibular afferents:
Trasmit balance and equilibrium information from the utricle, saccule, and semicircular canals of the inner ear

Front 38

Where are the cell bodies of the cochlear afferent fibers located?

Back 38

Spiral ganglion of the cochlea

Front 39

Where are the cell bodies of the vestibular afferent fibers located, and where do the fibers terminate?

Back 39

CELL BODIES --> vestibular ganglion

TERMINATE--> In the 4 vestibular nuclei in the upper medulla and lower pons

Front 40

What are the two major branches of the facial nerve?

Back 40

1. Motor root
2. Nervus intermedius

Front 41

Where are the cell bodies of the special visceral efferent fibers of the Facial nerve located?

Back 41

Facial nucleus

Front 42

What are the innervations of the motor root of the Facial nerve (CN VII)?

Back 42

1. *Muscles of facial expression
2. *Stapedius
3. Stylohyoid
4. Platysma
5. Posterior belly of digastric

Front 43

The Stapedius M is innervated by which CN?

Back 43

Facial (CN VII)

Front 44

List 2 visceral efferent branches of the nervus intermedius of the Facial N

Back 44

1. Greater petrosal N
2. Chorda tympani N

Front 45

Where does the Greater Petrosal N branch from, where does it synapse, and what do the postsynaptic fibers innervate?

Back 45

Branches from nervus intermedius (CN VII)
Synapses in pterygopalatine ganglion
Fibers innervate lacrimal gland and mucous glands of the nasopharynx

Front 46

Where does the Chorda tympani N branch from, where does it synapse, and what do the postsynaptic fibers innervate?

Back 46

Branches from nervus intermedius (CN VII)
Synapse in submandibular ganglion
Fibers innervate sublingual and submandibular salivary glands

Front 47

Which glands does the Facial N innervate?

Back 47

1. Lacrimal gland (via Greater petrosal N)
2. Nasopharyngeal mucous glands (via Greater petrosal N)
3. Sublingual glands (via chorda tympani N)
4. Submandibular glands (via chorda tympani N)

Front 48

All sensory fibers of CN VII course in what branch?

Back 48

Nervous intermedius

Front 49

The cell bodies of visceral afferent fibers of CN VII are located where?

Back 49

Geniculate ganglion

Front 50

The Greater petrosal N has visceral efferent and afferent fibers. Describe the functions of these fibers

Back 50

Visceral efferent fibers innervate:
1. Lacrimal gland
2. Nasopharyngeal mucous glands
Visceral afferent fibers provide input from:
1. Taste from the palate

Front 51

The chorda tympani nerve has visceral efferent and afferent fibers. Describe the functions of these fibers

Back 51

Visceral efferent fibers innervate:
1. Sublingual salivary glands
2. Submandibular salivary glands

Visceral afferent fibers provide input from:
*Taste from anterior 2/3 of the tongue

Front 52

Which nerves are involved in transmitting taste information from the tongue?

Back 52

1. Chorda tympani N (CN VII)--> anterior 2/3 of tongue
2. Glossopharyngeal N --> posterior 1/3 of tongue

Front 53

What is the somatic afferent function of the Facial N?

Back 53

Sensation from external auditory meatus

Front 54

Damage to which nerve results in Bell's palsy? List some characteristic deficits of this condition

Back 54

Damage to the facial nucleus, fibers, or nerve

1. Ipsilateral facial weakness/ paralysis
2. Loss of taste from anterior 2/3 of tongue
3. Difficulties with salivation
4. Abnormal sounds

Front 55

Describe the pathophysiology of "central seven" or "supranuclear facial palsy."

Back 55

Damage to UMN produce contralateral paralysis of the lower face, but the upper face is spared.

*Remember, the lower portion of the face receives information originating from the cerebral cortex, while the upper portion of the face receives information from the cingulate cortex (emotional motor system)

Front 56

What are the functions of the Trigeminal N (CN V)?

Back 56

Mediates most sensations from the face and controls the muscles of mastication

Front 57

What are the 3 limbs of the Trigeminal N (CN V)?

Back 57

V1- Opthalmic
V2- Maxillary
V3- Mandibular

Front 58

General somatic afferent information from the anterior 2/3 of the tongue is transmitted by which nerve?

Back 58

Mandibular (V3)

Front 59

Describe the different functions of the main sensory nucleus and the spinal trigeminal nucleus?

Back 59

Main sensory nucleus mostly involved in discriminative touch
Spinal trigeminal nucleus mostly involved in pain and temperature

Front 60

Large diameter fibers that signal discriminative touch from the face terminate in which nucleus?

Back 60

Main sensory nucleus

Front 61

Small diameter fibers, after entering the pons, terminate in which nucleus?

Back 61

Spinal trigeminal nucleus

Front 62

Where is the main sensory nucleus located?
Where do axons from this nucleus travel?

Back 62

Middle pons
*Axons travel through ventral/dorsal trigeminothalamic tracts to the ventroposterior medial nucleus of the thalamus (VPM)

*Remember the VPL received sensory information from the spinothalamic and dorsal column-medial lemniscus sensory pathways

Front 63

Where is the spinal trigeminal nucleus located?
Where do the axons from this nucleus travel?

Back 63

It is a long strip that extends from the main sensory nucleus caudally through the medulla and into the first few cervical segments, where it merges with the dorsal horn

*Axons travel to the VPM in the ventral trigeminothalamic tract

Front 64

The ventral trigeminothalamic tract consists of axons from which 2 nuclei?

Back 64

1. Main sensory nucleus (discriminative touch)
2. Spinal trigeminal nucleus (pain, temp)

Front 65

Proprioceptive input from muscle spindles in the muscles of mastication travel through which nerve?

Back 65

V3 (Mandibular div. of CN V)

Front 66

Cell bodies of sensory fibers involved in proprioception of the muscles of mastication are located where?

Back 66

Mesenchephalic trigeminal nucleus

Front 67

Damage to the trigeminal nerve or motor nucleus will produce what kind of deficits?

Back 67

1. Inability to chew normally-- jaw will deviate TOWARD the side of the lesion upon opening the mouth
2. No sensation from the face

Front 68

Trigeminal neuralgia most commonly involves which branch?

Back 68

V2

Front 69

List 3 cranial nerves which innervate portions of the ear

Back 69

CN VII, IX, and X

Front 70

What is the function of the Abducens N (CN VI)?

Back 70

Innervates the lateral rectus muscle, which abducts (moves laterally) the eye

Front 71

Where is the abducens nucleus located?

Back 71

Dorsal pons

Front 72

Which two nuclei participates in the horizontal conjugate gaze movements?

Back 72

Abducens nucleus
Oculomotor nucleus

Front 73

What is the result of LMN damage to the Abducens N (CN V)?

Back 73

Weakness/ paralysis of the lateral rectus muscle, preventing lateral gaze of the ipsilateral eyeball
*Eye deviates medially

*This condition is called STRABISMUS

Front 74

What is the function of the Trochlear n?

Back 74

Innervates the superior oblique muscle, which inwardly rotates and produces downward/lateral movements of the eye

Front 75

What are the actions of the Superior Oblique muscle and which nerve innervates it?

Back 75

"SO-LID"

Rotates the eye:
1. Lateral
2. Inward
3. Downward

Front 76

List the 4 reasons the Trochlear N is unique to all the cranial nerves

Back 76

1. All axons cross to the contralateral side
2. Exists the brainstem DORSALLY
3. Longest intracranial course
4. Fewest number of axons

Front 77

Describe the different deficits caused by damage to the internal and external courses of the trochlear nerve

Back 77

Damage to INTERNAL course --> weakness paralysis of CONTRALATERAL superior oblique muscle

Damage to EXTERNAL course--> weakness of the IPSILATERAL superior oblique muscle

*Causes the eyeball to extort (rotate outward), causing diplopia and problems with downward gaze

Front 78

An eyeball that is rotated outward may signify a problem with which CN?

Back 78

Trochlear (CN IV)

Front 79

An eyeball that is rotated medially may signifay a problem with which CN?

Back 79

Abducence (CN VI)

Front 80

Which nucleus is located in the dorsomedial midbrain, ventral to the cerebral aqueduct of Sylvius, at the level of the superior colliculus?

Back 80

Oculomotor (CN III)

Front 81

Which nucleus is part of the oculomotor nucleus, and is located medially at the rostral end of it?

What type of cell bodies are located here?

Back 81

Edinger-Westphal nucleus

*Cell bodies of Preganglionic parasympathetic neurons to the eye

Front 82

Describe the innervation of the ciliary muscle and pshincter pupillae of the iris

Back 82

Edinger-Westphal nucleus --> synpase in ciliary ganglion --> ciliary muscle (accomodation) + sphincter pupillae (pupillary diameter)

Front 83

List the 5 signs associated with "oculomotor opthalmoplegia."

Back 83

1. Strabismus --> diplopia
2. Ptosis
3. Pupillary dilation
4. Eye is abducted (down-lateral)
6. Paralysis of accomodation

Front 84

The Oculomotor N innervates all extraocular muscles except 2. Which 2 does it not innervate?

Back 84

1. Lateral rectus (Abducens, CN VI)
2. Superior oblique (Trochlear, CN IV)