Monday, 4-25-Brainstem Morphology (Stephens)

Question 1

Identify the following components of the METENCEPHALON:

Roof: __
Ventricular cavity: __
Basilar portion: __

Answer 1

Roof: Cerebellum
Ventricular cavity: 4th ventricle
Basilar portion: Pons

Question 2

IDentify the following components of the MYELENCEPHALON:

Roof: __
Ventricular cavity: __
Basilar portion: __

Answer 2

Roof=posterior columns
Ventricular cavity=central canal
Basilar portion=pyramids

Question 3

__ conveys pain and temp information from the opposite 1/2 of the body. It is either lateral or posterolateral to the medial lemniscus

Answer 3

SL

Question 4

__ conveys proprioceptive, vibratory, and 2-pt tactile discriminative information from the opposite 1/2 of the body. At the level of the upper pons and midbrain, it also contains fibers that convey taste info from the ipsilateral 1/2 of the tongue and pharynx

Answer 4

ML

Question 5

__ conveys pain, temp, and crude tactile sensation from opposite 1/2 of face. It is located between the ML and SL

Answer 5

TL

Question 6

__ conveys bilateral auditory information but predominantly information from the opposite ear

Answer 6

LL

Question 7

__ conveys vestibular influences to the CN III, IV, VI and also contains fibers for the oculomotor system. It is consistently located next to the midline and anterior to the central gray. In the medulla, it is located at the dorsal tip of the ML

Answer 7

MLF

Question 8

Lesions of the MLF result in:

Answer 8

Internuclear ophtalmoplegia (syndrome of the MLF). Pts have abnormal response to horizontal gaze in the direction opposite the lesion

Question 9

Unilateral lesions of the MLF result in an __

Answer 9

Impairment or loss of adduction (medial rectus) of the ipsilateral eye, and a nystagmus of the abducting eye

Question 10

__ conveys descending descending motor info from the motor cortex. In the midbrain, it comprises the middle 3/5’s of the crus cerebri. In the pons, it splits into numerous fascicles by the pontine nuclei and pontocerebellar fibers. In the medulla, it forms the pyramids, and the fibers will partially decussate in the medulla

Answer 10

CST

Question 11

A unilateral lesion of the CST is classically described as a __

Answer 11

Contralateral spastic hemiplegia

Question 12

The brainstem CN motor nuclei are innervated by the __ fibers.

Answer 12

Corticobulbar tract

Question 13

Most corticobulbar fibers decussate in the ___ between the levels of the trigeminal and abducens nerves

Answer 13

Lower pons

Question 14

Unilateral lesions of the corticobulbar fibers results in ___

Answer 14

Denervation of the brainstem motor nuclei below the level of the lesion

Question 15

Unilateral lesions of the corticobulbar fibers above the level of the decussation result in ___

Answer 15

Contralateral paralysis or paresis of the mimetic muscles of the lower 1/2 of the face (supranuclear facial palsy) as well as other cranial palsies due to denervation of the abducens nucleus, hypoglossal nucleus, and nucleus ambiguus.

Question 16

Lesions of the CBT below the decussation result in ___

Answer 16

Ipsilateral CN palsies

Question 17

A unilateral lesion of the corticobulbar fibers to the facial nucleus results in __

Answer 17

Paralysis of the contralateral lower quadrant of the face, i.e., droopy smile and drooling on 1 side

Question 18

Identify the following components of the MESENCEPHALON:

Roof: __
Ventricular cavity: __
Basilar portion: __

Answer 18

Roof=tectum
Ventricular cavity=cerebral aqueduct
Basilar portion=crura cerebri

Question 19

List the CN’s at the brainstem level of the diencephalon;:

Answer 19

II

Question 20

List the CNs at the brainstem level of the midbrain:

Answer 20

III, IV

Question 21

List the CNs at the level of the Pons:

Answer 21

V

Question 22

List the CNs at the level of the pontomedullary sulcus:

Answer 22

VI, VII, VIII

Question 23

List the CNs at the level of the medulla oblongata

Answer 23

IX, X, XII, XI

Question 24

Lesion of the __ results in deviation of the uvula away from the affected nucleus

Answer 24

Nucleus ambiguus

Question 25

Lesion of the __ leads to a protruded tongue that deviates toward the side of the affected nucleus

Answer 25

Hypoglossal nucleus

Question 26

A lesion of this structure results in bilateral loss of pain/temp sensation (syringomyelia):

Answer 26

AWC

Question 27

A lesion of this structure results in unilaterla hemianalgesia and themal hemianesthesia of the face:

Answer 27

Desc nucleus and tract (V)

Question 28

Which MRI section of the brainstem will you best see a view of the fastigial, globose, emboliform, and dentate nuclei?

Answer 28

Upper medulla/lower pons

Question 29

Which level of the brainstem are you most likely to see the trigeminal nerve on MRI?

Answer 29

Pons

Question 30

When looking at an MRI, what is a feature that tells you that you are looking at the midbrain?

Answer 30

Cerebral aqueduct is visible

Mickey mouse appearance of the midbrain

Question 31

What structures can be seen on MRI of a brainstem section at the midbrain/thalamus level at the posterior commissure?

Answer 31

Pulvinar (look for LGB and MGB)
Pineal body
Post commissure
Cerebral aqueduct
Red nucleus

Question 32

The majority (~80%) of strokes occur here:

Answer 32

Basal ganglia (caudate, putamen, globus pallidus) and internal capsule