Brainstem I and II

Question 1

What divides the rhomboid fossa into two symmetrical halves?

Answer 1

Median sulcus

Question 2

What divides each side of the midline of the rhomboid fossa?

Answer 2

Sulcus limitans

Question 3

What is the main eyelid elevator and what innervates it?

Answer 3

Levator palpebrae superioris, innervated by CN 3

Question 4

What problems would you have with a hypothetical facial nerve lesion? (4 big groups)

Answer 4

1. Loss of facial expression muscles
2. Digastric stylohyoid and stapedius muscles (hyperacusis)
3. Taste on anterior 2/3 of tongue
4. loss of parasympathetic to salivary glands (except parotid) and lacrimal and nasal glands

Question 5

What carries taste from posterior 1/3 of tongue?

Answer 5

CN 9

Question 6

Name 4 big functions of glossopharyngeal nerve?

Answer 6

1. Taste from posterior 1/3 of tongue
2. Sensory inputs from external ear, tympanic membrane and wall of upper pharynx
3. Visceral afferents from aortic arch and carotid sinus
4. Parasympathetic input to parotid gland and motor innervation of stylopharyngeus

Question 7

Where are the neurons for parasympathetic outflow through CN 3?

Answer 7

In the Edinger-Westphal nucleus.

Question 8

How does visual information reach the Edinger-Westphal nucleus?

Answer 8

• Visual input goes to superior colliculus, to pretectal nuclei.
• Pretectal nucleus project to EW nucleus
• Pretectal axons cross to contralateral side in posterior commissure (this ensures the direct and consensual response)

Question 9

Where do the parasympth neurons in the Edinger-Westphal nucleus synapse?

Answer 9

In the ciliary ganglion, where the postganglionic neurons synapse to the sphincter pupillae

Question 10

What two muscles contribute to eyelid retraction?

Answer 10

Levator palpebrae superioris (innervated by CN 3)

Superior tarsal muscle (sympathetic fiber innervation)

Question 11

What happens to the eye when the superior oblique muscle is contracted?

Answer 11

Depression and intorsion of the eye

Question 12

Lesion of what CN is likely to cause diplopia? What will the patient do to compensate?

Answer 12

Lesion of CN 4, due to the inability of the eye to intort or depress. The affected eye drifts upward. The patient tilts head forward to comp for the upward drift, and also tilts to the unaffected side to compensate for the inability to intort.

Question 13

What muscle does the left CN 4 innervate?

Answer 13

The RIGHT (contralateral) superior oblique

Question 14

What is the mesencephalic nucleus of CN 5?

Answer 14

Has unipolar cell bodies with peripheral sensory fibers, so it is comparable to a sensory ganglion. Receives proprioception from the jaw to control mastication

Question 15

What deficit results with a CN 6 lesion?

Answer 15

Inability to abduct the affected eye

Question 16

Where do auditory afferents from CN 8 terminate?

Answer 16

In the dorsal and ventral cochlear nuclei

Question 17

Where do the parasympathetic fibers destined for the parotid gland from the CN 9 originate from?

Answer 17

From inferior salivatory nucleus

Question 18

CN 9 carries both afferents and efferents. What 2 locations do the afferents go, and what 2 locations do the efferents go?

Answer 18

NTS and trigeminal project (which only carries limited portion of outer ear) are the afferents.
The efferents (parotid gland and the stylopharyngeus) originate from the inferior salivatory and the nucleus ambiguus, respectively.

Question 19

What 2 zones are in the reticular formation?

Answer 19

Medial zone: mix of larg and small neurons, source of most long ascending and descending within reticular formation.
Lateral zone: cranial nerve reflexes and visceral functions.
Also at the midline are the raphe nuclei

Question 20

What supplies the caudal medulla?

Answer 20

Anterior and posterior spinal arteries, vertebral artery

Question 21

What supplies the rostral medulla?

Answer 21

Vertebral arteries, PICA.

Question 22

What supplies the pons?

Answer 22

Basilar artery, AICA, and superior cerebellar artery

Question 23

What supplies the midbrain?

Answer 23

Primarily the posterior cerebral artery

Question 24

What are the symptoms in Wallenberg syndrome?

Answer 24

1. Contralateral loss of pain and temp in body
2. Ipsilateral loss of pain and temp in face
3. Vertigo and nystagmus
4. Ipsilateral cerebellar signs
5. Difficulty in swallowing and gag reflex diminished
6. Horner’s syndrome common

Question 25

What are the 3 key features of Horner’s syndrome?

Answer 25

Ptosis, miosis, anhydrosis

Question 26

What are the signs and symptoms of medial medullary syndrome (Dejerine)

Answer 26

1. Damage to corticospinal tract
2. Damage to medial lemniscal pathway
3. Damage to hypoglossal

Question 27

Occlusion of what artery causes lateral pontine syndrome and what are the signs?

Answer 27

AICA

1. Vestibular problems
2. Ipsilateral deafness
3. Ipsilateral paralysis of face
4. Ipsilateral loss of lacrimation and reduced salivation
5. Ipsilateral loss of taste from anterior 2/3s
6. Ipsilateral loss of pain and temp on face
7. Contralateral loss of pain and temp on body
8. Horner’s syndrome

Question 28

What is Bell’s Palsy?

Answer 28

Damage to cranial nerve VII (7) likely due to viral infection such as herpes

Question 29

What are the symptoms of Bell’s Palsy?

Answer 29

1. Facial paralysis (central facial palsy)
2. Inability to close the eyes
3. Decrease in lacrimation and salivation
4. Loss of taste from anterior 2/3s of tongue

Question 30

What is different about the facial muscle innervation of 7 for the upper and lower face?

Answer 30

Upper face receives bilateral innervation, lower face receives only contralateral innervation

Question 31

What symptoms are present in oculomotor palsy?

Answer 31

1. Down and out position of the eye
2. Ptosis
3. Mydriasis (dilation due to loss of parasympathetic input to sphincter pupillae) (e.g. blown pupil)

Question 32

Aneurysm in what artery commonly causes oculomotor palsy?

Answer 32

PComm