Lecture 4: Brainstem

Question 1

true or false. brainstem functions are cranial nerve nuclei, conduit, and integrative functions AND are NOT exclusive to each other.

Answer 1

true

Question 2

3 divisions of the brainstem - contains? function?

1. basilar:
2. Tegmentum:
3. Tectum:

Answer 2

1. descending tracts and pontine nuclei ; mainly motor functions
2. ascending tracts and most nuclei, including cranial nerve nuclei ; sensory relay and head functions/special sensation
3. only in midbrain, deep nuclei ; relay pathways for vision and audition, reflexive pathways

Question 3

border of the brainstem

Answer 3

around cerebral aqueduct and anterior to the 4th ventricle

Question 4

which cranial nerves connect to the
- midbrain
- pons
- medulla

which one attaches to the spinal cord?

Answer 4

• III, IV
• V, VI, VII, VIII
• XII, IX, X

CN XI

Question 5

slide 8 picture

Question 6

the sulcus limitans has a _____ component in the lateral portion and a ______ component in the medial portion.

what are the functions of the two components?

Answer 6

dorsal - sensory
ventral - motor

Question 7

the cranial nerve nuclei in the tegmentum of the brainstem ordered from medial to lateral is:

Answer 7

somatic motor
branchial motor*
visceral motor
visceral sensory
somatic sensory
special sensation*

Question 8

how is branchial motor different from somatic motor?

Answer 8

branchial motor is special visceral motor –> controls muscles associated with head and neck (CN VII, IX, X)

somatic motor is voluntary skeletal muscles

Question 9

how is special sensation different from visceral sensation?

Answer 9

special sensation is conscious sensory info transmitted by CN

visceral sensation is unconscious sensory info from internal organs to brain/spinal cord

Question 10

which cranial nerve nuclei spans from midbrain to spinal cord?
comes from _______ nucleus which is actually a ______

Answer 10

CN V
- all face and anterior 1/2 scalp somatic sensory

mesencephalic (sensory) ; ganglion

Question 11

which cranial nerves have 4 functional components and carry branchial motor fibers?

Answer 11

CN VII, IX, X

Question 12

solitary tract is comprised of CN ____,____,_____ and plays a role in _____

Answer 12

VII, IX, X
visceral sensory

Question 13

ambiguous nucleus is comprised of CN _____,____ and plays a role in _____

Answer 13

IX, X
somatic motor - throat and neck, speech and swallowing

Question 14

slide 13 picture

Question 15

what two CN run through rostral midbrain?
what are their specific nucleus?

Answer 15

CN V - mesencephalic nucleus, true ganglion

CN III - edinger-westphal nucleus: parasympathetic and somatic motor nucleus

Question 16

what two CN run through caudal midbrain?
what are their specific nucleus?

Answer 16

CN IV - trochlear nerve nucleus: only one crossing over and exit post. brainstem

CN V - mesencephalic nucleus

Question 17

slide 14 picture

Question 18

what CN connects rostral pons to their functional components?

Answer 18

CN V: motor and principal sensory nuclei

Question 19

picture slide 15

Question 20

cortico-______/_______/______ fibers and ____ nuclei are diffusely dispersed in basilar pons

Answer 20

pontine/bulbar/spinal
pontine

Question 21

which cranial nerves are housed in the caudal pons? what are their nuclei?

Answer 21

CN V - spinal trigeminal nucleus
CN VI - abducens nucleus
CN VII - facial nucleus
CN VIII - vestibular and cochlear nuclei
CN VII/IX: superior/inferior salivatory nuclei

Question 22

what cranial nerves are housed in the middle pons?

Answer 22

CN V - motor and principal sensory nucleus
CN VIII - vestibular nuclei

Question 23

what cranial nerves are housed in the rostral medulla? what is the nucleus?

Answer 23

CN V: spinal trigeminal nucleus
CN VIII: vestibulocochlear nuclei
CN IX/X: ambiguous nucleus, Sm
CN X: dorsal motor nucleus, Vm
CN XII nucleus
solitary nucleus: CN VII/IX/X parasympathetic, Vs

Question 24

what cranial nerves are housed in the caudal medulla? what is the nucleus?

Answer 24

CN V: spinal trigeminal nucleus
–> nuclei for CN VII/IX/X Ss components
CN XII nucleus

Question 25

slide 21 picture

Question 26

the dorsal horn of the spinal cord is for _______ the ventral horn of the spinal cord is for ________

Answer 26

sensory motor

Question 27

what cranial nerves are housed in the spinal cord? what is the nucleus?

Answer 27

CN V: spinal trigeminal nucleus, continuous to dorsal horn laminae II/III/IV to C2 level CN XI: spinal accessory nerve, C1-C5

Question 28

what are the two ascending tracts from the spinal cord? what do they sense?

Answer 28

DCML - proprioception, vibration, fine touch. deeper sensations anterolateral spinothalamic tract: pain/crude touch/temperature. superficial sensations

Question 29

what is the flow of the neurons in the DCML? - 1st order neuron in - axons synapse with 2nd order neuron in - axons decussate and synapse with 3rd order neuron in

Answer 29

- DRG - middle/caudal medulla - VPL (ventral posterolateral nucleus)

Question 30

Somatic sensory flow of DCML: sensation detected in DRG of ____ order neurons. _____________ transmits fine touch, proprioception, and vibration from T6 and below. ___^^__ synapses with _________ (2nd order neuron). ___________ transmits sensory info from T6 and above. ___^^___ synapses with _________ (2nd order neuron). axons of 2nd order neurons decussate to form _________. That projects to _______ where 3rd order neurons locate for synapses.

Answer 30

1st Fasciculus gracilis (FG) FG nucleus gracilis Fasciculus cuneatus FC nucleus cuneatus medial lemniscus (ML) VPL

Question 31

in the DCML, ________ is maintained but ______ is rotated

Answer 31

somatotopy orientation

Question 32

slide 25 picture

Question 33

the somatotopy turns _____ degrees along the DCML

Answer 33

180

Question 34

the somatotopy rotation neck to foot is _____ at the following locations: - FG in spinal cord and caudal medulla - ML in caudal medulla - ML in caudal pons - ML in caudal midbrain

Answer 34

- lateral to medial - posterior to anterior - medial to lateral - anterior to posterior

Question 35

what are the two descending tracts of the brainstem from the neocortex? - where do they end? - do they decussate? - function? - what is unique?

Answer 35

1. corticobulbar/corticonuclear tracts - end in brainstem - with or without decussation - CN Sm functions (face, neck, head) - bilateral projection 2. corticospinal tract 75-90% motor decussate at caudal medulla --> lateral tract: distal limb, contralateral --> anterior tract: axial muscles, ipsilateral 10-25% not decussate --> ipsilateral weakness after stroke so they can function better - all end in spinal cord - motor functions

Question 36

what are the two descending pathways of the brainstem from the midbrain? - decussation in? - function?

Answer 36

1. rubrospinal tract - midbrain - similar pathway for lateral corticospinal tract (hand movements) 2. tectospinal tract - midbrain - descends to medial ventral horn for postural control --> generally, visual and auditory reflexes

Question 37

where does the dorsal column tract synapse to form the medial lemniscus? how is the somatotopy maintained before medial lemniscus is formed?

Answer 37

- caudal medulla --> before synapse, DCML --> after synapse, ML - from lower limb to anterior part of the neck

Question 38

what is the ascending limb of the medial longitudinal fasciculus responsible for? - what reflex?

Answer 38

voluntary control of vertical eye movement, gaze and visual stability - vestibuloocular reflex (VOR)

Question 39

what is the descending limb of the medial longitudinal fasciculus responsible for? - what reflex? - what are its two tracts?

Answer 39

voluntary control of proprioception and balance, posture - vestibulocolic and vestibulospinal reflexes (VCR/VSR) - lateral vestibulospinal tract: ipsilateral proximal extremity muscles AND medial vestibulospinal tract: bilateral trunk, mainly neck & upper body

Question 40

what are the three pathways of the sympathetic motor system? - mainly from: - ends in:

Answer 40

1. medial forebrain bundle - limbic system, olfactory tract - spinal cord T1-L2 2. dorsal longitudinal fasciculus - hypothalamus - spinal cord T1-L2 3. mammillotegmental tract - hypothalamus - brainstem

Question 41

visceral sensory follows the sympathetic motor tract to mainly detect ________ stimuli (____)

Answer 41

nociceptive stimuli (pain)

Question 42

where does the sensory and motor decussation happen along the brainstem?

Answer 42

caudal medulla

Question 43

what is the parasympathetic motor pathway for the: - head: - thorax/abdomen - abdomen/pelvis (state which nucleus & CN)

Answer 43

- Edinger Westphal nucleus: Vm for CN III Salivatory nuclei: superior for CN VII, inferior for CN IX - dorsal nucleus for vagus nerve: Vm for CN X until end of midgut - pelvic splanchnic nerve: S2-S4, hindgut and pelvis

Question 44

visceral sensory follows parasympathetic motor pathway to detect ____ and ______ stimuli

Answer 44

chemical and mechanic

Question 45

signals travel into the cerebellum through _______ tracts that descend and synapse with ________. post synaptic fibers decussate in ______ through the _________ to the _______ part of the cerebellum

Answer 45

corticopontine pontine nuclei pons middle cerebellar peduncle contralateral

Question 46

signals travel out of cerebellum through the _________ and decussate in the __________. they project to the thalamus then to the ______ cortex --> therefore, cerebellum modulates ______ motor functions

Answer 46

superior cerebellar peduncle caudal midbrain motor ipsilateral

Question 47

the reticular formation is diffusely dispersed in the _____

Answer 47

tegmentum

Question 48

the reticular formation is the most complicated because ____

Answer 48

its neurons have synapses in the whole CNS so it modulates all 3 parts of the CNS - psychomotor, cognition, affect (emotion)

Question 49

reticular descending system has _____ and ______ sensory functions

Answer 49

motor and sensory

Question 50

which component of the reticulospinal tract descends to the medial ventral horn and involved in postural control?

Answer 50

pontine reticulospinal tract

Question 51

which component of the reticulospinal tract descends to the anterolateral ventral horn and involved in fine motor control

Answer 51

medullary reticulospinal tract

Question 52

what motor pathway of the reticular descending system descends to the dorsal horn to inhibit nociception?

Answer 52

periaqueductal gray-raphe nuclei pathway

Question 53

how can cerebellum control ipsilateral body without lateralization as the cerebrum?

Question 54

what is the function of the ascending reticular activating system (ARAS)?

Answer 54

arousal and consciousness

Question 55

what major vital centers are stationed in the brainstem?

Answer 55

body temp: intra-hypothalamic nucleus RR HR BP

Question 56

is size important for functional importance of the integration of reticular formation with cranial nerves?

Answer 56

no