Brainstem I Flashcards

1
Q

Brainstem functions

A
  • conduit for info to/from spinal and supraspinal levels
  • origin of descending pathways (motor, pain)
  • processes/integrates info
  • centers for respiration, HR, BP, consciousness
  • cranial n.=spinal n. (equivalent functions), and convey taste, hearing, equilibrium
  • preganglionic parasympathetic neurons (thoracic and abd viscera, pupillary sphincter, salivation/ lacrimation)
  • synthesis of NTs (CNS)
  • critical functions = small region
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2
Q

Characteristics of SPINAL CORD LESIONS involving LONG TRACTS

A
  1. effects observed at level of lesion and below
  2. pain and temp loss side opposite of lesion
  3. weakness, position sense and vibration sense lost ipsilaterally
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3
Q

Characteristics of BRAINSTEM LESIONS

A
  1. lesions of 3 long tracts in brainstem –> contralateral deficits
  2. cranial nerve signs will reveal the level of the lesion in brainstem
  3. cranial nerve signs observed on the side of lesion
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4
Q

3 parts of the brainstem

A

medulla
pons
midbrain

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5
Q

____ a. –> supplies medulla

A

vertebral a. –> supplies medulla

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6
Q

____ a. –> supplies pons

A

basilar a. –> supplies pons

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7
Q

the basilar a. ends at the level of the ____, giving rise to the ____ a. –> which supplies the ____

A

the basilar a. ends at the level of the MIDBRAIN, giving rise to the POSTERIOR CEREBRAL a. –> which supplies the MIDBRAIN

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8
Q

The ventral surface of the brainstem contains

A

pyramids (corticospinal path decussation)
olives
cranial nerve rootlets of IX, X, XI. XII

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9
Q

midline bulge of medulla

A

pyramid

where corticospinal tract crosses

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10
Q

between pyramids and olive, CN __ exits

A

between pyramids and olive, CN XII exits

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11
Q

___ forms roof of fourth ventricle

___ forms floor of fourth ventricle

A

CEREBELLUM forms roof of fourth ventricle

MEDULLA/PONS forms floor of fourth ventricle

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12
Q

The dorsal surface of the brainstem contains

A

inferior/superior colliculus

inferior/middle/superior cerebellar peduncle

F. cuneatus/F. gracilis (dorsal column paths)

cuneate tubercle/gracile tubercle (surface elevations formed by second order neurons for dorsal column path which reside underneath)

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13
Q

reticular formation

A

central core of medulla,
pons and midbrain

controls…
respiration
BP
HR

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14
Q

medial lemniscus is formed by fibers leaving the

A

nucleus gracilis and nucleus cuneatus

becomes more horizontal and unites with spinothalamic path as you ascend through brainstem

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15
Q

medial medullary lesion

A
TRACTS LOST:
Reticular Formation
-respiration, BP, HR
Medial Lemniscus
-dorsal column pathway
-position, vibration loss (contralateral) 
Corticospinal Tract
-fine, distal movement (hemiparesis contralaterally)
CN SIGNS
CN XII: Hypoglossal
-ipsilateral tongue paralysis
-fasiculations 
-protrusion causes tongue deviation TWD lesion
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16
Q

LMN send axons out to

A

striated m.

analogous to LMN in spinal cord, also receive input

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17
Q

motor cranial n. nuclei receive cortical input via ______

w/ the exception of…

A

motor cranial n. nuclei receive cortical input via CORTICOBULBAR PATHWAY

w/ the exception of CN NUCLEI INNERVATING EYE

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18
Q

corticobulbar pathway

A

UMN synapse on facian nucleus either bilaterally (upper face) or contralaterally (lower face) on motor nuclei of the brain stem

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19
Q

alar plate gives rise to

A

sensory neurons

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20
Q

basal plate gives rise to

A

motor neurons

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21
Q

motor nuclei are (medial/lateral) to sensory nuclei in the brainstem, and are separated by _______

A

motor nuclei are medial to sensory nuclei in the brainstem, and are separated by sulcus limitans

22
Q

2 sets of nuclei that innervate striated muscle, which are most medial?

A

somatic motor nuclei (most medial)

somatosensory nuclei (most lateral)

23
Q

which nuclei are adjacent to the sulcus limitans?

A

visceromotor (VM) viscerosensory (VS)

24
Q

lateral strokes involve which nuclei?

A

pharyngeal motor (branchial motor)

25
Q

medial strokes involve which nuclei?

A

somatic motor nuclei

26
Q

columns of CN nuclei (midline to lateral)

A

somatic motor (hypoglossal)

branchial motor AKA pharyngeal (ambiguous - CN IX, X, XI)

visceral motor (dorsal X)

visceral sensory (solitarius)

somatosensory (spinal V)

social senses (vestibular, cochlear)

27
Q

caudal medulla: motor decussation

A

on ventral aspect, the descending lateral corticospinal tract fibers and corticobulbar tract fibers from cortical UMNs decussate through the pyramids to the side they will be innervating

28
Q

caudal medulla: sensory crossing

A

on the dorsal aspect, the ascending dorsal column fibers run in fasiculus gracilis and fasiculus cuneatus

synapse to their respective nuclei gracilis/cuneatus

second order neurons project fibers which decussate through the medial lemniscus on their way to the thalamus.

(CROSS SECTION LOOKS LIKE ARTIST PALETTE)

29
Q

if there are fibers in medial lemniscus –> they are (ipsilateral/contralateral) to site of origin

A

if there are fibers in medial lemniscus –> they are CONTRALATERAL to site of origin

lesion will cause contralateral damage

30
Q

lesion to nucleus gracilis or nucleus cuneatus –> (ipsilateral/contralateral) damage

A

lesion to nucleus gracilis or nucleus cuneatus –> (IPSILATERAL) damage

31
Q

distinct feature of nucleus solitarius

A

found lateral to dorsal motor nucleus of CN X

has tract running through it

32
Q

hypoglossal nucleus

A

innervates intrinsic/extrinsic m. of tongue

33
Q

lesion of hypoglossal nucleus

A
  1. paralysis of tongue on side of lesion
  2. fasciculations - LMN sign
  3. upon protrusion, tongue deviates to side of lesion
34
Q

nucleus ambiguus

A

innervates larynx, pharynx, soft palate (CN IX, X)

35
Q

lesion of nucleus ambiguus

A

hoarsness
difficulty swallowing

sx: arch of soft palate is drooped, uvula deviated AWAY from side of lesion

36
Q

preganglionic parasympathetics for thoracic and abd viscera are carried in

A

visceral motor column (dorsal motor nucleus of X)

T1-L2

37
Q

preganglionic parasympathetics to pelvic viscera

A

S2-S4 of spinal cord

38
Q

sympathetic outputs arise from thorcacolumbar spinal cord segments and synapse where?

A

in paravertebral and prevertebral ganglia

39
Q

parasympathetic outputs arise from craniosacral regions and synapse where?

A

in ganglia in/near effector organs

40
Q

nucleus solitarius receives taste and sensation from viscera via

A

CN VII, IX, X

41
Q

spinal nucleus of V

A

receives pain and temp info from face and oral cavity
(also receives input from VII, IX, X - area around ear)

lesions –> ipsilateral deficit pain/temp from face

(loss of nearby SST –> contralateral deficit pain/temp of body)

42
Q

lateral medullary lesion

A

STT:
pain/temp loss in body (contralateral)

Ambiguus (IX, X):
hoarseness, uvular deviation (contralateral)

Solitarius (VII, IX, X):
taste/sensation from viscera

Spinal V (V. ~VII, IX, X):
pain/temp loss in face (ipsilateral) 

VIII/ICP:
ataxia/vertigo (ipsilateral)

Horner’s syndrome: damage to descending sympathetics from hypothalamus to ipsilateral face

43
Q

ventral lesion in spinal cord will probably affect which tracts?

A

lesion of corticospinal/corticobulbar tracts

44
Q

damage to inferior cerebellar peduncle may result in ____ on the side of the lesion

A

damage to inferior cerebellar peduncle may result in ATAXIA on the side of the lesion

45
Q

Lateral medullary lesions can result in _______ syndrome

A

Horner’s syndrome

damage to fibers that originate in the hypothalamus and descend to the spinal cord to control sympathetic NS to ipsilateral face

46
Q

inferior cerebellar peduncle

A

located dorsolaterally in the rostral medulla.

receives fibers from spinal cord and inferior olivary peduncle.

the major communication cable between the medulla and the cerebellum.

47
Q

middle cerebellar peduncle

A

info from cerebellum –> brainstem –> cortex

48
Q

____________ sit on top of inferior cerebellar peduncle

A

cochlear nuclei sit on top of inferior cerebellar peduncle

49
Q

pontine nuclei sends axons to

A

middle cerebellar peduncle

50
Q

CN VI and CN III are controlled by

A

PPRF which receives info from cortex

51
Q

paralysis of LOWER face tells you right away that you have a lesion

A

in contralateral corticobulbar pathway

52
Q

paralysis of WHOLE side of face indicates which type of lesion

A

lesion of facial nucleus or nerve (LMN)