Unit 9: spinal/arterial circulation Flashcards
which groove does the anterior spinal artery fit into?
anterior median fissure
where do the posterior spinal arteries get their blood supply? (3)
- vertebral arteries (from above cord)
- cerebellar arteries (2/3) (from above cord)
* AICA
* PICA - intercostal arteries (from lower cord)
what do radicular arteries do? where are they located?
radicular arteries connect intercostal arteries to either the anterior spinal artery or the posterior spinal arteries
radicular arteries are “EITHER/OR”, but they do NOT connect from BOTH the anterior AND posterior on the same level
how many intercostal arteries are there?
24 total
(12 sets)
radicular artery aliases (2)
segmental arteries
medullary arteries
relate the following terms: coronal arteries, SC, colateral circulation
the SC does NOT have as good of colateral circulation as there is in the brain; the coronal arteries are not continuous around the cord.
what percentage of the SC gets blood supplied by the anterior spinal artery? posterior spinal arteries?
75% from anterior s.a.
25% from posterior s.a’s (combined; 12.5% each)
how many posterior spinal veins run along the spinal cord? anterior spinal veins?
3 posterior spinal veins (one midline, two lateral)
1 midline anterior spinal vein
what is the spinal branch? where is the spinal branch located?
the spinal branch “branches” off the dorsal branch into the spinal cord circulation
the spinal branch lies on top of the spinal root ganglion
occurs on every level of SC
with aortic cross clamping, what complications would you expect?
- SC injury (ischemia > neuronal death)
- ischemia to the lower extremities
- ischemic organ damage (ex. kidney injury)
about how many radicular arteries feed the anterior spinal artery in the neck? thorax? lumbar region?
2-3 in the neck
2-3 in the thorax
1-3 in the lumbar region
what is the Great Radicular Artery (GRA)?
- this is the “feed artery” that supplies blood to the lower 2/3 of the spinal cord
- this structure is AKA Artery of Adamkiewicz
- the GRA typically enters on the left side of spinal cord d/t the aorta also being on the left side
localize the great radicular artery
most approximate location: T10
range: T9-T12 (in the vast majority of people)
extreme range: T5-L5
what are the implications of cross clamping above or below the GRA?
cross clamping below GRA:
* not an issue; no obstruction to flow
cross clamping above GRA:
* possible lower extremity paralysis
* GRA feeds into anterior spinal artery which is the most important artery in the anterior spinal cord
* Ant. SA is closest to gray matter in spinal cord, where many motor neurons are located > possible ischemia > possible paralysis
the lower the GRA is in the SC, the safer it is to do an aneurysm repair
if imaging can be done prior to AAA repair, MRI can be done to localize
cerebral perfusion pressure (CPP) = ?
MAP - ICP
“normal 50-150 mmHg” per schmidt
by how much does aortic cross clamping increase a patient’s CSF pressure?
an increase in 10 mmHg
this is why putting in a lumbar drain might be beneficial
while patient is cross clamped, what are (3) interventions to consider to prevent ischemic injury?
- inflammation reduction
- slowing metabolic rate
* slower energy reserve consumption - preventing reperfusion injury (by gradually restoring blood flow rather than all at once; or, by measuring oxygen levels to not overload)
what is reperfusion injury?
in terms of cross clamping, reperfusion injury occurs when a massive blood flow is restored to an ischemic tissue too rapidly and the oxygen and free radicals can actually overwhelm the regulatory anti-oxidants and destroys the tissue
describe the spinocerebellar tracts
- anterior spinocerebellar tract
* located on anterior/lateral SC
* ascends sensory info about the level of synaptic activity in the ventral horn to the cerebellum
* this info gets routed through the anterior spinocerebellar tract > superior cerebellar peduncle > cerebellum - posterior spinocerebellar tract
* located on posterior/lateral SC
* ascends sensory info about the tendons (golgi tendons) & muscle spindle activity to the cerebellum
* this info gets routed through the posterior spinocerebellar tract > inferior cerebellar peduncle > cerebellum
describe parietal pain
- connective tissue pain
- direct conduction into SC from peritoneum, pleura, or pericardium (3P)
- highly localized
- sharper pain/faster pain (delta fibers)
describe visceral pain
- organ pain
- transmitted through ANS
- difficult to localize; pain may be referred outside the origin
- dull/achy pain/slower pain (c-fibers)
what is referred pain?
pain that is sensed outside the origin of pain
ex) pain from kidney stones may be felt as back pain
ex) stomach pain > umbilicus
why is appendix pain considered dual pain?
parietal pain:
* pain localized to RLQ
* can induce lateral inhibition w/ pressure (once pressure is released, pain will return)
visceral pain:
* pain felt in the umbilicus
* cannot induce lateral inhibition by pressing on umbilicus
why does the heart refer pain to the LEFT arm as opposed to the RIGHT arm?
visceral pain from the heart is referred to the left arm not because the heart is to the left of the thorax, but because the right heart is less prone to ischemia
describe the structures of the limbic system and where they’re located
- amygdala
* on bilateral sides of the diencephalon -
HYPOthalamus
* in the diencephalon - cingulate gyrus
* buried deep in the middle of the brain, part of the cerebral cortex
motor neurons use these neural fibers:
A-alpha
also
* muscle spindles
* muscle tendons
* pressure sensors
DCML pathway uses these types of neural fibers
A-alpha to A-gamma
lateral inhibition uses these neural fibers:
A-beta
fast pain uses these neural fibers
A-delta
also stabbing/sharp pain
slow pain uses these neural fibers:
C-fibers
achy pain
dull pain
thermal pain
still can move quickly, but just longer than A or B fibers
this type of pain engages the limbic system
if you smash your hand with a hammer, what is the neural fiber pathway
- pressure noticed first (A-alpha)
- sharp pain second (A-delta)
- dull achy pain (C-fibers)
