Exam 3 - Lecture 5 Flashcards
Cerebral circulation does a great job of autoregulating just like
spinal circulation
3 fairly large arteries that run longitudinally down spine
1 anterior spinal artery and 2 posterior spinal arteries.
Source of blood for posterior spinal arteries near the top of cord comes from
Vertebral arteries and cerebral arteries
Specific cerebellar arteries that supply posterior spinal arteries
Posteroinferior cerebellar artery and and anteroinferior cerebellar artery
Feed vessel that connects intercostal artery to anterior and posterior spinal arteries
anterior and posterior Radicular arteries
Radicular arteries are also called
medullary and segmental arteries
can even combine both, or all 3 into one named artery. Segmental medullary radicular artery!
As we get lower in cord, the posterior arteries are supplied by
intercostal -> radicular arteries
Branching of feed vessels is ________ and ________
inconsistent; varies person to person.
Sometimes just from one side, sometimes just to front or back, higher or lower, etc. VERY INCONSISTENT
Typically, each side of cord has _________ radicular artery.
Just 1. Either goes to posterior or anterior, not both. Very seldomly breaks into two to supply both posterior and anterior.
Smaller arteries on outer surface of cord
coronal arteries
Spinal cord does not have ______ like the brain.
Collateral circulation (like circle of Willis)
Do coronal arteries wrap around entire cord?
No.
Difference with venous/artery placement
there is a posterior spinal vein in the posterior medial fissure
Intercostal arteries branch off of the
aorta
Route from thoracic aorta to cord (varies from level to level, but this is generalized possiblity) and how many arteries are typically per level?
Intercostal artery -> dorsal branch -> spinal branch -> radicular artery
just 1.
Where does spinal branch artery sit?
Branches off intercostal artery and sits on top of spinal root ganglia
What keeps the ribcage healthy and perfused?
Intercostal artery
Decently large arteries that come off abdominal aorta
Renal arteries
Big juicy artery that comes off abdominal aorta
Mesenteric artery
If we need to repair an aortic aneurysm, need to _________ the aorta and will cause _________ and may lead to things like ________
Clamp; downstream ischemia; acute renal failure (anything that is supplied below the clamp)
Anterior spinal artery covers ____ of the cord tissue blood supply.
75%
Posterior spinal arteries cover _____ of the cord tissue blood supply.
25% or 12.5% per posterior artery
It is correct to assume that ________ supplies more of the blood in the spinal cord.
Anterior spinal artery
How many anterior feed vessels in the neck of the spinal cord?
Typically, 2 per level of cord
How many anterior feed vessels in the thorax of the spinal cord?
Typically 2-3 per level of cord
How many anterior feed vessels in the lumbar area of the spinal cord?
Typically 1-2 per level of cord
Super important anterior feed artery that provides blood supply to the lower 2/3rds of the spinal cord
“Great” radicular artery of Adamkiewicz
The Great radicular artery comes in from the ______ side of the patient. Why?
Left. Because of the aorta.
The single level where the great radicular artery is located if you could only pick one? Range of vast majority of people? Overall total range?
T10
T9-T12
T5 - L5
Great radicular artery of Adamkiewicz is abbreviated as
GRA
If aneurysm is at the lower section of the aorta and you cross clamp below GRA
Then you should be good, as majority of blood supply goes through GRA, and it is not cut off.
If aneurysm is at the lower section of the aorta and you cross clamp above GRA
Then it is a cause of concern for patient waking up paralyzed since spinal cord isn’t getting normal blood supply.
What would be beneficial before operating on an Aortic Aneurysm if you have time?
Do imaging to see where GRA is, but often times an aortic aneurysm is an emergency.
Usually, the _______ is the most concerning with ischemic spinal cord injuries.
Motor function. Typically, sensory function isn’t as effected.
Generally, the _____ your GRA is, the safer it is for an aortic aneurysm repair.
The higher up. If its super low, more risk since youre more likely to clamp above it.
Perfusion pressure for cerebrum is (equation)
MAP - ICP
A high ICP will be an impediment to blood flow.
ICP is more or less of a concern for cord perfusion?
Less. its more flexible so its less effected by ICP.
When cross-clamping aorta, you should also be concerned about
CSF pressure.
How much does aorta cross clamping increase CSF pressure?
usually by about 10mm Hg, which would double the ICP to 20.
How to avoid CSF pressure rise during aorta clamp?
Put in a drain for CSF
Why are sensory deficits not a concern when waking up from an aorta aneurysm repair?
Because the posterior part of the cord isnt supplied with blood from the aorta.. only the anterior part of the cord is.
Things you could do to help with ischemia before aneurysm repair
Reduce inflammation and slow down metabolic rate of the cord so they chew through energy reserves better.
Whats another risk with aorta repair once the clamp is no longer needed? Why? How can you prevent this?
Reperfusion injury. The blood vessels are wide open, and the sudden rush of massive blood flow when the clamp is released can cause injury as it gets overwhelmed. Reduce oxygen levels or release clamp in a graded approach.
What causes rust on steel car?
Oxygen
what keeps oxygen induced damages in check?
Antioxidants
what does immune system use to destroy stuff?
oxygen!
Corticospinal tract path
Motor cortex -> to internal capsule -> Thalamus -> Brain stem -> Crossover at decussation of pyramids -> lateral corticospinal tract -> interact with motor neurons to relay signal at level of cord needed.
Where anterior corticospinal tract cross over?
At the level of the spinal cord where it needs to talk to motor neuron.
Spinocerebellar tracts
Feedback tract that sends information to the cerebellum for complicated motor movements with lots of muscles involved.
Where are the sensory pathways for spinocerebellar tracts?
At the most lateral side of spinal cord, each side. Anterior/ventral and posterior/dorsal.
Ventral Spinocerebellar tract
Sends information to cerebellum regarding level of synaptic activity in the anterior horn.
Sensors off the side of anterior horn
Measure activity of neurons for complicated motor movements in ventral horn and sends information via ventral spinocerebellar tract
Where does ventral spinocerebellar tract go through in cerebellum?
The superior cerebellar peduncle, looks like the top side of the cerebellum.
The ventral cerebellar tract in the brainstem/cord/cerebellum is a
Bundle of axons
Dorsal spinocerebellar tract sends
Info to cerebellum regarding tendons and muscle spindle stretch sensors. Detect changes of tension in skeletal muscles, letting it know that the muscle contractions happened.
The golgi tendon also tells cerebellum regarding tension.
Where is the dorsal spinocerebellar tract sent via in the cerebellum?
Inferior cerebellar peduncle, and it fans out in the lower part of cerebellum.
Chemical that can elicit pain (on top of the 7 previously mentioned)
Ischemia/muscle spasm.
It’s a buildup of metabolic waste product such as lactic acid.
Temperatures mentioned that cause pain
<5 degrees celcius and >45 degrees celsius.
Pain threshold
Ease or difficult to elicit a painful feeling. Likely due to genetics and environmental (whether they have chronic pain or not)
Pain threshold may relate to?
Membrane potentials. A more positive membrane potential may make it easier to elicit pain.
Pain threshold has a high ______
degree of variability
Chronic pain will reduce your
Pain threshold
Visceral pain
Internal organ pain - usually referred, via autonomic nerve bundles.
How is visceral pain transmitted? What does it make difficult?
Through the autonomic nervous system. Makes it difficult to localize, thats why its referred pain.
Referred pain
Pain felt in part of body that is fairly remote from the tissue causing the pain
Parietal pain
Refers to tissue pain, usually more superficial structure.
Is parietal pain easy to localize?
yes
Is visceral pain easy to localize?
Yes
How is parietal pain transmitted?
Direct conduction into spinal cord from peritoneum, pleura, or pericardium. Highly localized.
With both types of pain (visceral and parietal),
Many of our organs dont have __________ like our skin does.
tactile pain, theyre not suited for touch
also called touch sensor
Tactile sensory is transmitted via _______ and highly found on the ________
DCML; skin.
Tactile pain or “touch sensors” are
highly localized.
Can parietal pain come from an organ?
Yes, on the superficial part. Visceral is on the inside of the organ.
What specific organ doesnt really have pain sensors on the inside?
Lungs, soft tissue in lungs does not have pain sensors thats why we can smoke for 30 years.
Liver - the inside doesnt have pain sensors, thats why you can drink alcohol for 30 years. The outside (capsule) does have pain sensors
Parietal pain tends to be a ________ pain. Which fibers?
Fast/sharp. A-delta.
Visceral pain tends to be _________ pain. Which fibers?
Dull/achy, likely C fibers.
Kidney pain is usually referred out to
the back
Some organs are capable of producing __________ pain.
Dual. This means both visceral and parietal pain
Is appendix pain dual?
Yes.
Where is the parietal pain for the appendix?
Looks like the tissue surrounding it below. Sent up to L-1 part of cord.
Where is the visceral pain for the appendix?
routed up the sympathetic chain along spinal cord and enters the t-10 cord level (umbilicus)
Visceral pain is usually fed up _________ and jumps __________
autonomic ganglia and jumps 2-3 levels, then enters cord via pain transmission pathways.
With visceral pain being referred, can the body use lateral inhibition? why?
No, theres no tactile sensory associated with it.
Can you relieve appendix pain with pressure on lower right quadrant?
Yes, since this is where the parietal pain is. But it will be painful when you release.
Heart pain radiates out to
Left shoulder, because the left side of the heart is more prone to ischemia unlike the right side.
If pressure in heart was high on right side, pain would go?
Both shoulders
Heartburn is felt
above umbilical region and into chest, may mistake for heart attack.
Limbic system is the:
emotional center of the brain
Where does the limbic system sit?
On top of brain stem
Why does slow pain affect emotion?
Because it terminates near the limbic system
Some of the slow pain signals dont make it out of the brain stem and terminate at ______ and _______
Reticular formation; limbic system
Coronal section of brain, where is amygdala?
lateral each side of diencephalon (thalamus and hypothalamus)
First thing you should think of when you think of limbic system
Amygdala
3 parts of limbic system in order of most important to least important
- Amygdala
- Hypothalamus
- Cingulate Gyrus (right outside corpus callosum on mid-sagittal cross-section view)
Cingulate gyrus
Just outside corpus callosum and this is buried in middle of brain, part of cerebral cortex, processes some of the slow pain information.
On coronal cross section view, the cingulate gyrus is
Superior to diencephalon and looks like its above ventricles
Chronic pain can cause _________ in the deeper emotional areas of brain
depression/anxiety
Lightly myelinated fibers and C fibers will be in _________ parts of nervous system
Primitive. Autonomic.
Myelinated fibers are more _______ and _______.
developed and quicker.
Motor neurons are likely _____ fibers.
A-alpha
Skeletal muscles in motor function use _______ fibers.
A-alpha
Muscle spindles use _____ fibers in motor function, and in sensory function they use _______ fibers.
A-delta; A-beta to A-gamma
Muscle tendons (golgi tendon) use _________ fibers.
A-alpha
Generally speaking, DCML uses
Large myelinated neurons to transmit information.
Lateral inhibition uses _________ fibers.
A-beta
Crude senses that use c-fibers (5 of them)
Nausea, achy pain, crude touch and pressure, tickle, cold/warmth
Deep pressure and touch fibers?
A-delta and gamma
Pricking or stabbing pain
Mostly A-delta
A-beta is primarily used in
DCML pathway and lateral inhibition
If you hit your hand with a hammer on top of desk, first thing to sense will be (3 phases)
Pressure of hammer hitting skin
Very shortly after will be sharp pain
After that, dull achy pain.
Pressure, sharp, dull.
Does cerebral cortex have pain sensors?
Nope. Lots of pain sensors in dura mater but not once you’re inside the brain.
When you touch something very hot, why can it feel cold? and phantom limb pain?
Makes the nervous system very confused.
A good portion of phantom limb pain can be fixed by
epidural or nerve block
