Central Nervous System Issues Flashcards
What is the correct order (from outwards in) of the spinal meninges?
DAP! Dura mater, arachnoid, pia mater
Afferent nerves are ________ and enter the spinal cord from the _______ side.
sensory; dorsal (posterior)
Efferent nerves are ______ and exit the spinal cord from the ______ side.
motor; ventral (anterior)
The spinal nerve root is connected to the _________ ______ ________ by communicating channels called the _____ and ______ rami communicans.
paravertebral sympathetic ganglia; white and gray
Which ramus is primarily preganglionic?
White
Which ramus is primarily postganglionic?
Gray
______ rami carry myelinated sympathetic ____-ganglionic neurons and _____ rami carry unmyelinated sympathetic ____-ganglionic neurons (C-fibers).
White; preganglionic; Gray; postganglionic
______ nerves to skeletal muscle arise from the anterior horn of the spinal cord.
Motor
What are the two divisions of the peripheral nervous system and their primary function?
somatic (motor nerves to skeletal muscle and sensory nerves for pain, touch, pressure, temperature) and the autonomic division (sympathetic and parasympathetic)
Where is the epidural space located in relation to the ligamentum flavum? (anterior, posterior, superior, inferior, or lateral)
anterior
The medial rectus ________ the eye.
Adducts
The lateral rectus ________ the eye.
Abducts
What nerve innervates the medial rectus muscle and causes the eye to adduct?
oculomotor nerve (III)
What nerve innervates the lateral rectus muscle and causes the eye to abduct?
abducens nerve (VI)
Where is the site of CSF formation?
choroid plexuses of lateral, third, and fourth ventricles
Where is the site of reabsorption for CSF?
arachnoid villi
Name the cerebrospinal circulation pathway.
choroid plexus–>lateral ventricles–>foramina of Munro–> third ventricle–> aqueduct of sylvius–> fourth ventricle—> then to the foramina of Lushka OR THE foramen of Magendie–> subarachnoid space of spinal cord–> brain—> arachnoid villi
What is the purpose of the circle of Willis?
permits collateral blood flow in the event that a major vessel (right or left carotid artery or basilar artery) becomes occluded
What major vessels supply the circle of Willis?
right and left internal carotid basilar artery (which is supplied by the right and left verterbral arteries)
What does stump pressure measure?
the pressure transmitted through the circle of willis back to the carotid artery for which endarterectomy is proposed; a good stump pressure indicates that the brain will be perfused adequately during the procedure
What is a normal or acceptable stump pressure?
> 60 mmHg is normal….. but they are frequently falsely low or falsely high
What effect does N2O ALONE have on CBF and CMRO2?
increases due to sympathomimetic activity
What effect does volatile anesthetics have on CMRO2 and CBF?
decrease CMRO2 and increase CBF
With the exception of _______, IV anesthetics ______ CMRO2 and _______ CBF.
except ketamine, all decrease both CMRO2 and CBF
Ketamine causes a ______ in CBF and ______ in CMRO2.
increase in both due to stimulation of SNS
The major source of blood flow (75%) to the spinal cord is the _______ ________ ________ which traverses the length of the spinal cord.
anterior spinal artery; there is only 1 of them
The ______ ______ ______ supplies 25% blood flow to the posterior cord.
posterior spinal artery; there are 2 of them
The ____ ___ _______ enters the vertebral canal from the left side in the majority of patients (it is not bilateral) in the lower thoracic region or upper lumber region.
artery of Adamkiewicz (artery radicularis magna)
What is the significance of the artery of Adamkiewicz?
May be the MAJOR source of blood to the lower 2/3rds of the spinal cord…. interruption of flow through this vessel can lead to paraplegia
With cross clamping of the descending thoracic aorta, you would be MOST concerned about interrupting flow through what vessel supplying the spinal cord? Why?
artery of Adamkiewicz; paraplegia
What is the difference in decorticate and decerebrate posturing?
Decorticate is FLEXION (to the CORE) caused by damage above the cerebellum and brainstem (supratentorial)
DecErebrate is EXTENSION (extend to HEAD) caused by damage to brainstem or cerebral lesions that compress the thalamus and brainstem
Inverse steal is also known as ______ steal or the _______.
reverse steal; robin hood effect
What is normal ICP?
<10
What is Cushing’s Triad?
1) reflex increase in MAP
2) reflex bradycardia
3) irregular respirations
* * in response to increase in ICP
What is cerebral steal or luxury perfusion?
involves vasodilators or hypoventilation; BAD; CO2 increase–> ischemic brain portion receives less blood flow because the non-ischemic portions that have more tone dilate and receive even more blood flow; the RICH get RICHER
What is the robin hood effect or reverse steal?
involves hyperventilation; GOOD; the ischemic brain region is hyperventilated–> CO2 decreases–> non-ischemic brain regions constrict since they have the ability to change their tone–> the ischemic portions receive more blood flow
Where do the frontal lobes of the brain rest?
on the anterior cranial fossa
Where do the temporal lobes rest?
on the middle cranial fossa
Where do the brainstem and cerebellum rest?
on the posterior cranial fossa
Where is the correct placement of a single orifice catheter for withdrawing air entrained into the circulation during a craniotomy when patient is in the sitting position?
3cm above the SVC-atrial junction
What is the best catheter to remove air entrained into the circulation during a craniotomy, and where is the correct placement?
BEST is multi orifice catheter; 2cm below SVC-atrial junction
The anterior fontanelle closes approximately around _____ months.
18 months
The posterior fontanelle closes approximately around ______ months.
2 months
The anterolateral fontanelle closes approximately around ____ months.
2 months
The posterolateral fontanelle closes approximately around _____ months.
2 years; 24 months
Which fontanelle is the last to close?
posterolateral; 2 years
Which fontanelles close first?
the posterior and anterolateral
Which fontanelles close around 18 months?
anterior
What nerves originate in the intermediolateral horn of the spinal cord?
sympathetic preganglionic neurons
What nerve fibers pass through the gray rami communicans?
sympathetic post-ganglionic neurons
What spinal cord tract modulates pain?
dorsolateral
What area of the brain is responsible for keeping the individual awake?
reticular activating system
Which of the evoked potentials is LEAST sensitive to anesthetics?
brainstem auditory evoked potentials
Where do C fibers synapse in the dorsal horn?
Rexed’s lamina II and III
Pain afferent nerve fibers enter the dorsal cord and ascend or descend 1-3 segments in what tract before entering and synapsing in the dorsal horn?
Tract of Lissauer
Pain transmitted from the periphery by A-delta fibers terminate primarily in Rexed’s lamina: _________
I and V
Which neurotransmitter is released from A-delta and C fibers?
A-delta= glutamate
C fibers= substance P
Early depression of ventilation (within 2 hours) after intrathecal or spinal injection of the opioid results from what?
systemic absorption of opioid
Late depression of ventilation after intrathecal or epidural placement of opioid requires what?
hydrophilic opioid and significant rostral (headward) spread
Which drug is most responsible for delayed depression of ventilation (6-12 hours) occuring after neuraxial injection?
morphine
What would you expect to see if nalbuphine was giving to a patient emerging from a high dose sufentanil anesthesia?
reversal of respiratory depression and maintenance of analgesia
After cerebral spinal fluid passes through the foramina of Munro, it enters the _______.
3rd ventricle
If the right lateral spinothalamic tract is severed at C4, what sensations are lost where?
pain and temp sensation on LEFT side of body
What substance decreases the release of substance P in the spinal cord?
enkephalins
Where does epidural morphine work?
in the substantia gelatinosa
What brain region controls events in the substantia gelatinosa?
periventricular/periaquaductal gray
What area of the brain mediates spinal analgesia after administration of an IV opioid?
periventricular/periaquaductal gray of brainstem
What are the major vessels supplying the circle of Willis?
basilar and internal carotids
What is the minimum stump pressure that demonstrates that the brain will be adequately perfused during a CEA?
60mmHg
What gland is found in the sella turcica?
pituitary
The brainstem and cerebellum are found in the _______ _______ _______.
posterior cranial fossa
In this type of posturing, the patient requires a ventilator and has the arms extended?
decerebrate rigidity
A patient with a sudden rise in ICP will exhibit what?
HTN and bradycardia; Cushings triad
Which cranial nerve controls the musculature of the tongue?
Hypoglossal
Which cranial nerve controls the lateral rectus muscle?
Abducens
What is another name for cerebral steal?
luxury perfusion
What could cause the Robin Hood effect?
hyperventilation; decrease in CO2
Muscles for chewing are controlled by which cranial nerve?
V; trigeminal
Which cranial nerve controls motor activity for the larynx and pharynx?
vagus
Where are the arachnoid villi and granulations?
part of the arachnoid membrane
What is the site of reabsorption of CSF?
arachnoid villi (smaller) and arachnoid granulations (larger)
