Neuro Flashcards
What are the components of the CNS? What CN exit at the level of the CNS but really are part of the PNS?
Brain and SC. CN 1 and 2.
What is the organization of the CNS?
Spinal cord level, brainstem and subcortical level, cortical level.
Describe the SC level of the CNS organization?
Lowest functional leve; controls reflexes
Describe the brainstem and cortical level of CNS organization?
Second functional level; controls BP, RR, HR, equilibrium, primitive emotions
Describe the cortical level of CNS organization?
Highest level; cognition, storage and retrieval of information, thinking, memory
How many CN are there? How many spinal nerves are there?
12 pairs. 31 pairs.
Describe the 4 main regions of the brain
Cerebrum, brainstem, cerebellum, diencephalon
What are the components of the cerebrum?
Frontal, parietal, temporal, occipital, limbic
What is the frontal region of the cerebrum responsible for?
high level cognitive fx, personality, behaviour, emotions
What is the parietal region of the cerebrum responsible for?
sensation, touch, receptive speech and language
what is the temporal region of the cerebrum responsible for?
auditory, interpreting information, wernickes area
what is the occipital region of the cerebrum responsible for?
visual perception, smooth eye movement
what is the limbic region of the cerebrum responsible for?
self-preservation, recall, modification of mood/emotional responses in relation to perceived event
what are the components of the brainstem? what does it control?
midbrain, pons, medulla oblongata
control HR, RR, BP, and activity from cerebellum with rest of brain
what is important to remember about the medulla oblongata?
point at which the crossing of motor fibres occurs (R controls L, vice versa)
what is another name for the cerebellum? what are the main functions?
little brain
coordination, balance, fine movement
what are the three special systems in the brain?
reticular formation, reticular activating system, and limbic
what does the reticular formation control?
sensation, consciousness, movement, reflexive behaviours
what is the RAS controlling?
sleep/wakefulness, cognition/attention, consciousness
what does the limbic system control?
fear, hunger, sleep, short term memory
what is the tentorium? what occurs if volume expansion happens?
fold in dura mater that covers cerebellum and occipital lobes of cerebrum
brain can get pushed down thorough tentorium (herniation) and will put pressure on CN 3
what 4 things protect the CNS?
cranial and spinal bones
meninges
CSF
BBB
what are the three meningeal layers?
pia, arachnoid, dura
describe the pia mater
lies next to CNS. produces CSF.
describe the arachnoid mater
above pia mater. contains CNS vasculature
describe the dura mater
thickest layer. lies next to bone. forms tentorium
where are the 4 sites for hemorrhage
epidural space, subdural space, subarachnoid space and intracerebral
where is the epidural space located? what type of a bleed occurs here?
between the skull and dura mater. arterial bleed.
where is the subdural space located? what type of a bleed occurs here?
between the dura mater and arachnoid mater. venous bleed.
where is the subarachnoid space located? what circulates in this space?
in between arachnoid and pia mater. CSF circulates here.
what is the function of CSF? how much is made daily? how much is circulating in the ventricular system at any given time? where is CSF reabsorbed?
shock absorber, protective layer for brain/SC. 500 ml. 125-150 ml. by arachnoid mater.
what CN do we often test in critical care? what are their functions?
CN 3 - oculomotor. pupil response, eye movement
CN 5 - trigeminal; corneal reflex
CN 9 - glossopharyngeal, gag reflex
CN 10 - vagus, gag reflex
What CN are we likely to see damage to in cases of inc ICP? Is this nerve contralateral or ipsilateral? What does that mean?
CN 3, oculomotor, pupillary response. Ipsilateral - the damage to whichever side of the brain will show deficit to pupil on same side as injury.
What is the first clue to neuro deterioration?
change in LOC
what influences cerebral blood flow?
MAP, CPP, CVR
how do we calculate CBF?
CPP/CVR
CBV + CPP
how do we calculate CPP?
CPP = map - icp
what is normal CBV?
750 ml
What mechanisms regulate CBF?
autoregulation (vasoconstriction/vasodilation) chemical and metabolic regulation
what is normal CPP?
60-80(100 in text)
what influences CVR?
autoregulation and ICP, cerebral metb demand
what controls CPP?
CVR.
what is autoregulation? describe how this process works
homeostatic mechanism that ensures maintenance of CBF is constant despite marked changes in arterial pressure. if MAP decreases, dilation of CBV will occur to allow CBF to remain relatively constant despite change to CPP
what does decreased CPP indicate? increased CPP?
vasoconstrcition, vasodilation
when is autoregulation functional?
with normal MAP parameters, normal ICP parameters, and normal CPP parameters
what patient’s is autoregulation dysfunctional in? what happens when autoregulation fails?
pt with TBI. CBF will fluctuate in changes with MAP (systemic BP)
what are two ways in which autoregulation occurs?
biophysical and chemical
describe the biophysical way in which autoregulation occurs?
stretch receptors in BV regulate CBF. if there is dec MAP and dec stimulation of receptors, CBV will relax and increase BF and vice versa
what are chemical ways in which autoregulation occurs?
effect of co2, o2, and hydrogen on diameter of CBV
CO2 and H are potent vasodilators - in event of these increasing CBV will dilate and inc BF, PaO2 levels below 50 will stim CBV dilation
what are three things that affect cerebral metb rate/metabolic demand?
stress (emotional, critical illness), temp, activity (suctioning, turning, seizures, shivering)
what things affect CBF in the o2 s and d framework?
CPP and CVR. ICP affects both CPP and CVR. cerebral metb rate affects CVR.
what components make up ICP? what is normal ICP?
brain tissue (80%), blood volume (10%), CSF volume (10%). 0-15 mmHg
what is the monroe-kelli theory about ICP?
any increases to one of the ICP values must have the decrease in one or both of the others to compensate