Apex Unit 7 Flashcards Neuro
Name 4 types of glial cells and describe the function of each.
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List the name and function of the 4 lobes of the cerebral cortex.
Frontal – contains the motor cortex
Parietal – contains somatic sensory cortex
Occipital – contains vision cortex
Temporal – contains auditory cortex and speech centers
Wernicke’s area = understanding speech
Broca’s area = motor control of speech
Name the 12 cranial nerves.
Mnemonic: On Occasion Our Trusty Truck Acts Funny Very Good Vehicle Any How

What cranial nerves provide motor control of the eyes? How does each nerve contribute to the eye’s movement?

What bedside tests are used to assess the cranial nerves?
CN 1- 6

What bedside tests are used to assess the cranial nerves? CN 7-12

Which cranial nerve resides in the central nervous system? What is the implication of this?
With the exception of the optic n. (CN II), all of the cranial nerves are part of the peripheral nervous system. This means that the optic n is the only cranial nerve that is surrounded by the dura.
Because the optic nerve is part of the CNS, it is bathed by CSF. If you inject local anesthetic into the optic nerve during regional anesthesia of the eye, you will have a big problem.
What is tic douloureux? What cranial nerve contributes to this problem?
Tic douloureux (trigeminal neuralgia CN V) causes excruciating neuropathic pain in the face.
What is Bell’s palsy?
What cranial nerve contributes to this problem?
Bell’s palsy results from injury to the facial n. (CN VII).
This causes ipsilateral facial paralysis
What is the function of CSF, and where is it located?
The cerebrospinal fluid cushions the brain, provides buoyancy, and delivers optimal conditions for neurologic function. It is located in the:
Ventricles (left lateral, right lateral, third, and fourth)
Cisterns around the brain
Subarachnoid space in brain and spinal cord
What regions of the brain are NOT protected by the blood-brain-barrier?
The blood brain barrier separates the CSF from the plasma. It has tight junctions that restrict pass of large molecules and ions.
The BBB is not present at the chemoreceptor trigger zone, posterior pituitary gland, pineal gland, choroid plexus, and parts of the hypothalamus.
What is the normal volume and specific gravity of CSF?
CSF volume = 150 mL
Specific gravity = 1.002 - 1.009
Describe the production, circulation, and absorption of CSF.
CSF production: Ependymal cells of the choroid plexus at a rate of 30 mL/hr
Circulation: Remember - Love My 3 Silly 4 Lorn Magpies (match to image)
Reabsorption: Venous circulation via the arachnoid villi in the superior sagittal sinus.

What is the formula for cerebral blood flow? What are the normal values for global, cortical, and subcortical flow?

What are the 5 determinants of cerebral blood flow?
- Cerebral metabolic rate for oxygen (CMRO2)
- Cerebral perfusion pressure
- Venous pressure
- PaCO2
- PaO2

What is the normal value for CMRO2? What factors cause it to increase? To decrease?
CMRO2 describes how much O2 the brain consumes per minute. The reference value is 3.0 – 3.8 mL/O2/100g brain tissue/min.
Decreased by hypothermia (7% per 1 degree decrease), halogenated anesthetics, propofol, etomidate, and barbiturates.
Increased by hyperthermia, seizures, ketamine, and nitrous oxide.
What is the formula for cerebral perfusion pressure? What is normal?
CPP = MAP - ICP (or CVP) whichever is higher
The cerebral vasculature autoregulates its resistance (vessel diameter) to provide a constant cerebral perfusion pressure of 50 – 150 mmHg.
This ensures a relatively stable blood flow and confers protection against swings in blood pressure.
Autoregulation is influenced by products of local metabolism, myogenic mechanisms, and autonomic innervation.
Notice that 50 – 150 is cerebral perfusion pressure and NOT mean arterial pressure. This is an important point. To ensure a CPP of 50 mmHg, MAP must be 60 – 65 mmHg if ICP is in the normal range of 10 – 15 mmHg. If ICP is elevated, cerebral perfusion requires a higher mean arterial pressure.

What are the consequences of a CPP that exceeds the limits of autoregulation (too high and too low)?

List 4 conditions that reduce CPP as a function of increased venous pressure.
A high venous pressure decreases cerebral venous drainage and increases cerebral volume. This creates a backpressure to the brain that reduces the arterial/venous pressure gradient (MAP – CVP).
Conditions that impair venous drainage include:
Jugular compression secondary to improper head positioning
Increased intrathoracic pressure secondary to coughing or PEEP
Vena cava thrombosis
Vena cava syndrome
What is the relationship between PaCO2 and CBF? What physiologic mechanism is responsible for this?
There is a linear relationship between PaCO2 and CBF.
The pH of the CSF around the arterioles controls cerebral vascular resistance.
At a PaCO2 of 40 mmHg, CBF is 50 mL/100 g brain tissue/min.
At what PaCO2 does maximal cerebral vasodilation occur? How about maximal cerebral vasoconstriction?
For every 1 mmHg increase (or decrease) in PaCO2, CBF will increase (or decrease) by 1 – 2 mL/100g brain tissue/min.
Maximal vasodilation occurs at a PaCO2 of 80 – 100 mmHg.
Maximal vasoconstriction occurs at a PaCO2 of 25 mmHg.
What is the relationship between CMRO2 and CBF?
As a general rule:
Things that increase the amount of O2 the brain uses (CMRO2) tend to cause cerebral vasodilation (increased CBF). Examples include hyperthermia or ketamine.
Things that decrease the amount of O2 the brain uses (CMRO2) tend to cause cerebral vasoconstriction (decreased CBF). Examples include hypothermia, propofol, and thiopental.
Halogenated anesthetics are an exception - the decouple the relationship between CMRO2 and CBF. Said another way, they reduce CMRO2, but they cause cerebral vasodilation. This explains why a patient with intracranial hypertension is better served with TIVA.
How do acidosis and alkalosis affect CBF?
Respiratory acidosis increases CBF.
Respiratory alkalosis decreases CBF.
Metabolic acidosis or alkalosis do not directly affect cerebral blood flow. This is because H+ does not pass through the blood brain barrier. A compensatory change in minute ventilation can, however, affect CBF.
How does PaO2 affect CBF?
A PaO2 below 50 – 60 mmHg causes cerebral vasodilation and increases CBF.
When PaO2 is above 60 mmHg, it does not affect cerebral blood flow.

























