Lecture 8 Flashcards
decussation
crossing midline
rostral
relating to, or being near the head of the body. interchangeable with superior if a human is standing upright
caudal
relating to, or being near the tail or posterior part of the body
CN 1 and 2
do not emerge from brainstem
CN 3-12
emerge from brainstem
CN 3 and 4
emerge from midbrain
CN 5,6,7 and 8
emerge from pons
CN 9,10,11 and 12
emerge from medulla
three horizontal regions of brainstem
midbrain, pons, medulla
external midbrain structures
CN 3 and 4
cerebral peduncles - descending motor tracts
superior colliculus - sub cortical visual reflexes
inferior colliculus - sub cortical auditory reflexes
internal midbrain structures
cerebral aqueduct
periaqueductal gray area (PAG)
nuclei for CN 3 and CN 4
red nucleus
substantia nigra
descending motor tracts in the cerebral peduncles
pons structures
CN 5-8
motor tracts that descend in the anterior pons
4th ventricle
medulla structures
CN 9-12
pyramids - descending motor tracts
pyramidal decussation - descending motor tracts cross midline
tectum
posterior column
tegmentum
middle column
basis
anterior column
tectum location
posterior column of brainstem that is visualized primarily in midbrain
“everything posterior to cerebral aqueduct”
tectum structures
superior colliculus - visual reflexes
inferior colliculus - auditory reflexes
reticular formation
ascending somatosensory tracts
nuclei of CN 3-12
descending motor tracts - originate from brainstem nuclei
midbrain tegmentum
CN 3 and 4
pons tegmentum
CN 5-8
medulla tegmentum
CN 8-12
basis location
the most anterior column of brainstem
basis structures
descending motor tracts that originate from the cortex
corticospinal tract
corticobulbar tract
corticopontine tract
reticular formation location
cluster of nuclei located in tegmentum throughout length of brainstem
rostral reticular formation
upper pons and midbrain
caudal reticular formation
lower pons and medulla
caudel reticular formation function
regulates and modulates most areas of the CNS
modulate respiratory and cardiovascular nuclei of brainstem
modulate motor functions
modulate nociception (pain) pathways
rostral reticular formation function
modulate consciousness (level of consciousness)
alertness
attention
awareness
states of impaired consciousness
brain death
coma
vegetative state
minimal conscious state
stupor, lethargy, delirium
status epilepticus
akinetic mutism, abulia
sleep - normal and abnormal
states that mimic impaired consciousness
locked in syndrome
dissociative disorders
coma
remain unconscious
no meaningful response to stimuli
after 2-4 weeks coma will either “progress or digress” into different category
areas affected = severely depressed function of cortex and sub-cortical regions
reflexes expected to be intact = spinal cord reflex, brainstem reflexes
vegetative state
remain unconscious
no meaningful response to stimuli
will display some sub-cortical function
areas effected = severely depressed function of cortex, partially depressed function of sub-cortical region
reflexes expected to be intact = spinal cord reflexes, brainstem reflexes, some arousal reflexes
brain death
extreme irreversible form of coma
areas effected = absent function of cortex, sub-cortical, arousal system and brainstem
reflexes expected to be intact = spinal cord reflexes
vertebral artery
small branches supply most of the medulla
PICA (posterior inferior cerebellar artery)
supplies lateral medulla as it makes it way to the cerebellum
basilar artery - pontine arteries
small branches supply most of the pons
AICA (anterior inferior cerebellar artery)
branches from basilar artery and supplies small portion of the pons (lateral region of lower pons) as it makes it way to the cerebellum
posterior cerebral artery
small branches supply midbrain
Weber’s syndrome
blood vessel = right or left PCA
unilateral stroke of the anterior midbrain
region/structure damaged = basis of the midbrain - damages descending motor tracts, CN 3 is damaged as it exits the front of the midbrain
clinical findings = contralateral hemiplegia/paresis, ipsilateral CN III palsy
Pure motor hemiparesis (PMH)
blood vessel = right or left pontine arteries of basilar artery along the right or left anterior pons
unilateral stroke of the anterior pons
region/structure damaged = bases of the pons - damages descending motor tracts
clinical findings = contralateral hemiplegia/paresis
Locked-in syndrome
blood vessel = basilar artery
bilateral stroke of the anterior pons
region/structure damaged = basis of upper pons - damages right and left descending motor tracts
clinical findings = quadriplegia with intact sensation and cognition
Wallenberg Syndrome (lateral medullary syndrome)
most common brainstem stroke
blood vessel = vertebral artery, PICA or small branches of PICA
unilateral stroke of the lateral medulla
region/structure damaged = lateral medulla and may also involve inferior cerebellum
clinical findings = loss of pain/temp to: face - ipsilateral, body - contralateral
