Chapter 12 part 2 (CNs, etc)

Question 1

1) What is the brainstem?
2) What are its 3 parts?
3) What is it the base of?
4) What does it carry?
5) What does it contain?

Answer 1

1) A stalk like structure
2) Midbrain, pons and medulla
3) Cerebral hemispheres
4) Almost all of the information between the brain and the remainder of the body.
5) Its own nuclei

Question 2

What 6 things do the brainstem nuclei control?

Answer 2

1) Cranial nerves
2) Level of consciousness
3) Cerebellar circuits
4) Muscle tone
5) Posture
6) Most vital functions

Question 3

On the dorsal surface of the midbrain are 2 pairs of bumps, the _____________ and _______________

Answer 3

superior and inferior colliculi

Question 4

What do the superior colliculi do?

Answer 4

Visual attention/orientation/discrimination/perception

Question 5

What is on the ventral surface of the medulla?

Answer 5

The pyramids (corticospinal tracts); can be seen descending from the pontomedullary junction to the pyramidal decussation

Question 6

The 4th ventricle joins the cerebral aqueduct which runs through the midbrain and drains into the subarachnoid space. The 4th ventricle ends where?

Answer 6

At the entry of the spinal cord

Question 7

1) CNI (olfactory) connects to what?
2) Where does CN1 run through? Along what?
3) What detects olfactory stimuli? Be specific

Answer 7

1) To the forebrain
2) Through the olfactory tracts; along the ventral surface of the fontal lobes in the olfactory sulci
3) Special chemoreceptors on bipolar sensory neurons in the olfactory neuroepithelium in the upper nasal cavity.

Question 8

1) The axons of the bipolar sensory neurons in the olfactory neuroepithelium in the upper nasal cavity travel where?
2) Where does the information travel after it leaves those axons?

Answer 8

1) Travel the olfactory nerves to the olfactory bulbs.
2) Travels the olfactory tracts in the olfactory sulcus and processing area (NOT through the thalamus)

Question 9

Define anosmia

Answer 9

Loss of smell

Question 10

When testing olfaction, one must test each nostril separately. Why?

Answer 10

Patients with unilateral deficit rarely notice [that there is a deficit] because the other nostril compensates

Question 11

List some potential causes of anosmia

Answer 11

1) Some neurodegenerative diseases (such as Parkinson’s and Alzheimer’s)
2) Head trauma
3) Viruses (incl COVID 19)
4) Lesions
5) Intracranial tumors
6) Metastases
7) Sarcoidosis
8) Obstruction

Question 12

Trace the path of CNII (optic nerves)

Answer 12

1) Come out of the back of the eye
2) Meet at the optic chiasm
3) Go through the optic tracts
4) Wrap around the midbrain to the LGN of the thalamus

Question 13

1) Where does optic information from the thalamus come from?
2) Where does it go?

Answer 13

1) Nucleus in the thalamus that receives information from the retina
2) It sends its axons to the visual cortex through the optic radiations

Question 14

What cranial nerve exits at the spinal cord?

Answer 14

CN XI (11)

Question 15

What do CN III,IV, VI (oculomotor, trochlear and abducens) do?

Answer 15

Control the extraocular muscles

Question 16

1) What does the CNIV (4) (trochlear nerve) do?
2) What is the trochlea?

Answer 16

1) Rotates the top of the eye medially and downward
2) Trochlea is a pulley-like structure

Question 17

What does CNVI (6) (abducens) do?

Answer 17

Abducts the eye laterally in the horizontal direction

Question 18

What does CN III (oculomotor nerve) do?

Answer 18

All other eye movements not done by the trochlear and abducens nerves, including pupillary control

Question 19

1) What does CN V (trigeminal) mainly do? What does this include?
2) What does it also supply?

Answer 19

1) Supplies sensory to the face
-Nose, mouth, sinuses
-Anterior 2/3 of tongue
2) Motor to the mandible and the anterior portion of the external ear

Question 20

What are the 3 branches of CNV? Where do they exit the skull?

Answer 20

V1-Ophthalmic
V2-Maxillary
V3-Mandibular
The branches each exit the skull in different places

Question 21

1) Define Trigeminal Neuralgia (tic doulouruex) and what nerve branches are involved
2) When does it usually start and what causes episodes of it?

Answer 21

1) Recurrent episodes of brief pain, that last seconds to minutes in the distribution of V2/V3.
2) Usually begin after age 35, and are set off by chewing, shaving or touching a specific trigger point on the face.

Question 22

1) What is a potential cause of tic douloureux (since cause is typically unknown)?
2) What two other disorders have this cause?

Answer 22

1) Demyelination of the nerve
2) MS and optic neuritis

Question 23

What can cause CV sensory loss?

Answer 23

Trauma, tumors, herpes zoster, aneurysms of the internal carotid, schwannomas or meningiomas.

Question 24

Do V2/V3 fibers cross over? What is the implication of that?

Answer 24

These fibers do not cross over, so lesions cause ipsilateral deficits

Question 25

1) What does the facial nerve (CNVII) do?
2) What does a small branch of it do?
3) What is its path once it exits the brainstem?

Answer 25

1) Controls muscles of facial expression
2) Carries fibers for parasympathetic, visceral and somatosensory functions (tears, salivation, taste)
3) It runs through the auditory canal of the temporal bone, then takes a turn and runs in the facial canal, medial to the middle ear.

Question 26

1) What are the facial nerve’s (CNVII) sensory neurons for?
2) What is its path once it exits the skull?

Answer 26

1) Sensation of the external ear
2) Passes through the parotid gland and splits into 5 major branches that control the facial expressions.

Question 27

1) What is Bell’s Palsy?
2) What does it cause?
3) Besides its symptoms, what do neuro exam and imaging studies look like with this condition?

Answer 27

1) Most common facial nerve disorder; all divisions of the facial nerve are impaired
2) Unilateral facial weakness
3) The remainder of the neuro exam and any imaging studies are typically normal.

Question 28

1) What is Bell’s palsy recovery like?
2) What is its cause?
3) What are its other symptoms?

Answer 28

1) Gradual recovery, but ~ 80% of patients fully recover in 3 weeks.
2) Unknown cause - thought to be viral or inflammatory in nature.
3) Ear pain from the somatosensory component, dry eye from decreased lacrimation.
-Can also be associated with loss of taste

Question 29

What is the most common facial nerve (CNVII) disorder?

Answer 29

Bell’s palsy

Question 30

1) What can happen after Bell’s palsy recovery?
2) Give an example.

Answer 30

1) Sometimes when facial nerves recover, they reach the wrong target.
2) For example, rogue parasympathetic fibers may create “crocodile tears, In which these patients lacrimate instead of salivate when they see food.

Question 31

Recurrent episodes of Bell’s Palsy warrant what?

Answer 31

An extensive work up to rule out tumors, infiltrating diseases, Lyme’s disease sarcoid, and HIV.

Question 32

1) What does Vestibulocochlear Nerve VIII do?
2) Where does it go?

Answer 32

1) Hearing and vestibular sensation
2) Enters internal auditory and then travels with the facial nerve in the auditory canal to the cochlea and the vestibular organs (semicircular canals, utricle and saccule.)

Question 33

What are the two types of hearing loss? Define each.

Answer 33

1) Conductive HL: abnormalities of the external auditory canal or middle ear
2) Sensorineural HL: disorders of the cochlea or CN VIII common

Question 34

What are some common causes of conductive HL ?

Answer 34

Cerumen in auditory canal, otitis, perforation of TM, and sclerosis of the middle ear ossicles

Question 35

What are some common causes of sensorineural HL?

Answer 35

1) Exposure to loud sounds
2) Meningitis
3) Ototoxic drugs (like gentamicin)
4) Head trauma
5) Viral infection
6) Aging
7) Meniere’s disease
8) Acoustic neuroma

Question 36

1) What most common tumor of the inner ear?
2) What is it? What CN is involved?
3) What is the average age of onset?
4) Does it cause unilateral or bilateral hearing loss?

Answer 36

1) Acoustic Neuroma
2) A slow growing tumor that occurs where CN VIII (8) enters the internal auditory meatus
3) 50 years old
4) Almost always unilateral.

Question 37

A) What are the symptoms of acoustic neuroma?
B) What can it affect? What does this cause?

Answer 37

A1) Unilateral hearing loss
2) Tinnitus (ringing in the ear)
3) Unsteadiness (why?)
B) The trigeminal nerve that is nearby; causes facial pain and sensory loss

Question 38

What 5 things does the glossopharyngeal nerve (CNIX) convey?

Answer 38

1) Parasympathetic (motor) to parotid gland
2) Sensation from ear (external auditory meatus,)
3) Pharynx and posterior 1/3 of tongue
4) Taste from posterior 1/3 of tongue
5) Chemo/baroreceptors of carotid body

Question 39

Which nerve supplies anterior 2/3 of tongue?

Answer 39

CNV Trigeminal

Question 40

1) What are the main functions of the vagus nerve (CNX)?
2) Name two of its branches and what they do

Answer 40

1) Swallowing and gag reflex
2) Recurrent and superior laryngeal nerves; control all laryngeal muscles and the cricothyroid

Question 41

Besides its main functions, what else does the vagus nerve convey? (3 things)

Answer 41

1) Parasympathetics (motor) to heart, lung and GI tract to the splenic flexure
2) Sensation from the pharynx and small region near the external auditory meatus
3) Visceral sensory from chemo/baroreceptors in the aortic arch and GI tract

Question 42

1) Where does the spinal accessory nerve (CN XI) arise from?
2) What is its function?
3) What would a lesion of it cause?

Answer 42

1) The cervical spinal cord
2) Motor innervation to sternocleidomastoid and trapezius muscles
3) Weakness of ipsilateral shoulder shrug and weakness of head turning AWAY from the lesion

Question 43

1) What does the hypoglossal nerve (CNXII) provide?
2) What happens when there’s a lesion in it?

Answer 43

1) Motor to tongue
2) Weakness of tongue points towards the side of lesion when protruding

Question 44

1) Disorders of CNs __________ are uncommon
2) Most disorders of these nerves are associated with what?
3) They can also be affected by the common offenders, which are what?

Answer 44

1) CNs IX-XII (9-12)
2) Central lesions
3) DM, demyelination, trauma, inflammatory, tumors.

Question 45

1) What is Glossopharyngeal Neuralgia?
2) What does it cause?

Answer 45

1) Similar to Trigeminal Neuralgia except in CN IX (9) distribution.
2) Episodes of severe throat and ear pain

Question 46

1) What an occur during surgeries of the neck?
2) What does this cause?

Answer 46

1) Injury to the recurrent laryngeal nerve
2) Unilateral vocal cord paralysis and hoarseness

Question 47

What causes aspiration pneumonia? What is this a common cause of?

Answer 47

Cause by impaired swallowing, is a common cause of death in the elderly

Question 48

1) What nerve is responsible for palate elevation?
2) What happens if there’s a lesion in it?

Answer 48

1) CNX (vagus)
2) The soft palate and uvula will deviate towards the normal side, while the soft palate on the abnormal side hangs low (stage curtain sign).