Brainstem

Question 1

Features of ventral midbrain

Answer 1

cerebral peduncles

Question 2

features of dorsal midbrain

Answer 2

superior and inferior colliculi, SCP, cerebral aqueduct

Question 3

features of ventral pons

Answer 3

pontine protuberance, middle cerebellar peduncles (laterally)

Question 4

features of dorsal pons

Answer 4

MCP, cerebellum, 4th ventricle

Question 5

features of ventral medulla

Answer 5

inf. olive (rostral), pyramids –> CS tract decussation (caudal)

Question 6

features of dorsal medulla

Answer 6

4th ventrical (rostral), nucleus cuneatus and gracilis (caudal)

Question 7

Rule of 4 of the brainstem

Answer 7

M = medial; Motor nuclei (3, 4, 6, 12), Medial longitudinal fasciculus, Medial lemniscus, Motor pathway

S = sides; Spinocerebellar, Spinothalamic, Sympathetic, Sensory nucleus of 5

Question 8

“Rule of 4” of cranial nerves

Answer 8

4 at (III and IV) and rostral to (I and II) midbrain

4 at pons (V, VI, VII, VIII)

4 at medulla (IX, X, XI, XII)

Question 9

Which cranial nerve originates on the dorsal side of the brainstem?

Answer 9

CN IV

Question 10

Auditory pathway

Answer 10

cochlea –> spiral ganglion –> auditory nerve (CN VIII) –> rostral medulla –> cochlear nuclei on dorsal/lateral aspects of ICP –> trapezoid body in mid pons (some decussation) –> superior olivary complex –> ascend in lateral lemniscus –> inferior colliculus (some decussation) –> medial geniculate of thalamus –> primary auditory cortex at sup temporal gyrus

Question 11

Pain and temp from face

Answer 11

trigeminal nerve –> trigeminal ganglion (1st order nucl.) –> SpV (2nd order nucl.) –> contralateral VPM of thalamus (3rd order nucleus) –> sensory cortex

Question 12

Pain and temp from body

Answer 12

peripheral nerve –> DRG (1st order nucl.) –> nucleus proprius (2nd order nucl.) –> decussation –> spinothalamic tract –> contralateral VPL –> sensory cortex

Question 13

touch and vibration from body

Answer 13

DCML: peripheral nerve –> DRG (1st order nucl.) –> fasciculus gracilis/cuneatus –> nucleus gracilis/cuneatus (2nd order nucl.) –> decussation –> contralateral VPL of thalamus (3rd order nucl.) –> sensory cortex

Question 14

touch and vibration from face

Answer 14

trigeminothalamic pathway: trigeminal nerve –> trigeminal ganglion (1st order nucl.) –> main sensory nucleus of V (2nd order nucl.) –> decussation –> contralateral VPM of thalamus (3rd order nucl.) –> sensory cortex

Question 15

Role of MLF in vestibuloocular reflex

Answer 15

connects vestibular nuclei with motorneurons of extraocular muscles

Question 16

Preganglionic parasympathetic fibers

Answer 16

originate in dorsal motor nucleus of CN X (Vagus); innervate heart, thoracic and abdominal viscera

Question 17

Nucleus ambiguous

Answer 17

CN X motor neurons –> swallowing, talking, gagging, uvula

Question 18

Solitary nucleus

Answer 18

taste from CN VII, IX, X

Question 19

gag reflex

Answer 19

Afferent: IX (glossopharyngeal)

Efferent: X (vagus, nucleus ambiguous)

Question 20

jaw jerk reflex

Answer 20

Afferent: stretch receptors in masseter –> mesencephalic nucl. of V

Efferent: main motor nucleus of V –> bilateral contraction of masseter

Question 21

Motor control of CN V

Answer 21

muscles of mastication

Question 22

corneal blink reflex

Answer 22

Afferent: cornea touch –> spinal nucleus of V

Efferent: motor nucleus of VII –> blink

Question 23

pupillary light reflex

Answer 23

light in one eye –> pupil constriction in both eyes

Afferent: CN II

Efferent: CN III (edinger-westphal –> ciliary ganglion)

Question 24

describe the corticobulbar pathway

Answer 24

motor cortex –> internal capsule –> midbrain (3 and 4 terminate) –> pons (5, 6, 7, 8 terminate) –> medulla (9, 10, 11, 12 terminate)

Question 25

Corticobulbar tract: bilateral UMN

Answer 25

3, 4, 5, 6, upper of 7, nucleus ambiguous (10)

Question 26

Corticobulbar tract: contralateral UMN

Answer 26

12, lower of 7

Question 27

Corticobulbar tract: LMN

Answer 27

all, except 4: ipsilateral to their targets