Lecture 4: Brainstem Flashcards
true or false. brainstem functions are cranial nerve nuclei, conduit, and integrative functions AND are NOT exclusive to each other.
true
3 divisions of the brainstem - contains? function?
- basilar:
- Tegmentum:
- Tectum:
- descending tracts and pontine nuclei ; mainly motor functions
- ascending tracts and most nuclei, including cranial nerve nuclei ; sensory relay and head functions/special sensation
- only in midbrain, deep nuclei ; relay pathways for vision and audition, reflexive pathways
border of the brainstem
around cerebral aqueduct and anterior to the 4th ventricle
which cranial nerves connect to the
- midbrain
- pons
- medulla
which one attaches to the spinal cord?
- III, IV
- V, VI, VII, VIII
- XII, IX, X
CN XI
slide 8 picture
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?
dorsal - sensory
ventral - motor
the cranial nerve nuclei in the tegmentum of the brainstem ordered from medial to lateral is:
somatic motor
branchial motor*
visceral motor
visceral sensory
somatic sensory
special sensation*
how is branchial motor different from somatic motor?
branchial motor is special visceral motor –> controls muscles associated with head and neck (CN VII, IX, X)
somatic motor is voluntary skeletal muscles
how is special sensation different from visceral sensation?
special sensation is conscious sensory info transmitted by CN
visceral sensation is unconscious sensory info from internal organs to brain/spinal cord
which cranial nerve nuclei spans from midbrain to spinal cord?
comes from _______ nucleus which is actually a ______
CN V
- all face and anterior 1/2 scalp somatic sensory
mesencephalic (sensory) ; ganglion
which cranial nerves have 4 functional components and carry branchial motor fibers?
CN VII, IX, X
solitary tract is comprised of CN ____,____,_____ and plays a role in _____
VII, IX, X
visceral sensory
ambiguous nucleus is comprised of CN _____,____ and plays a role in _____
IX, X
somatic motor - throat and neck, speech and swallowing
slide 13 picture
what two CN run through rostral midbrain?
what are their specific nucleus?
CN V - mesencephalic nucleus, true ganglion
CN III - edinger-westphal nucleus: parasympathetic and somatic motor nucleus
what two CN run through caudal midbrain?
what are their specific nucleus?
CN IV - trochlear nerve nucleus: only one crossing over and exit post. brainstem
CN V - mesencephalic nucleus
slide 14 picture
what CN connects rostral pons to their functional components?
CN V: motor and principal sensory nuclei
picture slide 15
cortico-______/_______/______ fibers and ____ nuclei are diffusely dispersed in basilar pons
pontine/bulbar/spinal
pontine
which cranial nerves are housed in the caudal pons? what are their nuclei?
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
what cranial nerves are housed in the middle pons?
CN V - motor and principal sensory nucleus
CN VIII - vestibular nuclei
what cranial nerves are housed in the rostral medulla? what is the nucleus?
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
what cranial nerves are housed in the caudal medulla? what is the nucleus?
CN V: spinal trigeminal nucleus
–> nuclei for CN VII/IX/X Ss components
CN XII nucleus
slide 21 picture
the dorsal horn of the spinal cord is for _______
the ventral horn of the spinal cord is for ________
sensory
motor
what cranial nerves are housed in the spinal cord? what is the nucleus?
CN V: spinal trigeminal nucleus, continuous to dorsal horn laminae II/III/IV to C2 level
CN XI: spinal accessory nerve, C1-C5
what are the two ascending tracts from the spinal cord?
what do they sense?
DCML - proprioception, vibration, fine touch. deeper sensations
anterolateral spinothalamic tract: pain/crude touch/temperature. superficial sensations
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
- DRG
- middle/caudal medulla
- VPL (ventral posterolateral nucleus)
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.
1st
Fasciculus gracilis (FG)
FG
nucleus gracilis
Fasciculus cuneatus
FC
nucleus cuneatus
medial lemniscus (ML)
VPL
in the DCML, ________ is maintained but ______ is rotated
somatotopy
orientation
slide 25 picture
the somatotopy turns _____ degrees along the DCML
180
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
- lateral to medial
- posterior to anterior
- medial to lateral
- anterior to posterior
what are the two descending tracts of the brainstem from the neocortex?
- where do they end?
- do they decussate?
- function?
- what is unique?
- corticobulbar/corticonuclear tracts
- end in brainstem
- with or without decussation
- CN Sm functions (face, neck, head)
- bilateral projection - 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
what are the two descending pathways of the brainstem from the midbrain?
- decussation in?
- function?
- rubrospinal tract
- midbrain
- similar pathway for lateral corticospinal tract (hand movements) - tectospinal tract
- midbrain
- descends to medial ventral horn for postural control –> generally, visual and auditory reflexes
where does the dorsal column tract synapse to form the medial lemniscus?
how is the somatotopy maintained before medial lemniscus is formed?
- caudal medulla
–> before synapse, DCML
–> after synapse, ML - from lower limb to anterior part of the neck
what is the ascending limb of the medial longitudinal fasciculus responsible for?
- what reflex?
voluntary control of vertical eye movement, gaze and visual stability
- vestibuloocular reflex (VOR)
what is the descending limb of the medial longitudinal fasciculus responsible for?
- what reflex?
- what are its two tracts?
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
what are the three pathways of the sympathetic motor system?
- mainly from:
- ends in:
- medial forebrain bundle
- limbic system, olfactory tract
- spinal cord T1-L2 - dorsal longitudinal fasciculus
- hypothalamus
- spinal cord T1-L2 - mammillotegmental tract
- hypothalamus
- brainstem
visceral sensory follows the sympathetic motor tract to mainly detect ________ stimuli (____)
nociceptive stimuli (pain)
where does the sensory and motor decussation happen along the brainstem?
caudal medulla
what is the parasympathetic motor pathway for the:
- head:
- thorax/abdomen
- abdomen/pelvis
(state which nucleus & CN)
- 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
visceral sensory follows parasympathetic motor pathway to detect ____ and ______ stimuli
chemical and mechanic
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
corticopontine
pontine nuclei
pons
middle cerebellar peduncle
contralateral
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
superior cerebellar peduncle
caudal midbrain
motor
ipsilateral
the reticular formation is diffusely dispersed in the _____
tegmentum
the reticular formation is the most complicated because ____
its neurons have synapses in the whole CNS so it modulates all 3 parts of the CNS
- psychomotor, cognition, affect (emotion)
reticular descending system has _____ and ______ sensory functions
motor and sensory
which component of the reticulospinal tract descends to the medial ventral horn and involved in postural control?
pontine reticulospinal tract
which component of the reticulospinal tract descends to the anterolateral ventral horn and involved in fine motor control
medullary reticulospinal tract
what motor pathway of the reticular descending system descends to the dorsal horn to inhibit nociception?
periaqueductal gray-raphe nuclei pathway
how can cerebellum control ipsilateral body without lateralization as the cerebrum?
what is the function of the ascending reticular activating system (ARAS)?
arousal and consciousness
what major vital centers are stationed in the brainstem?
body temp: intra-hypothalamic nucleus
RR
HR
BP
is size important for functional importance of the integration of reticular formation with cranial nerves?
no
