Exam 2 Neuro: Spinal Cord Anatomy Flashcards
What are the 3 spinal meningeal layers & their order inner to outer?
Pia Mater (inner), then Arachnoid layer(middle), & Dura (outer layer)
Collection of nerve roots come from where?
Cauda Equina
What is the end of the spinal cord is called?
Conus Medullaris
What fastens/anchors the base of the spinal cord? At what skeletal landmark?
Filum Terminale & sacral hiatus
What are the two parts of the Filum terminale?
- Filum Terminale internum (Inside the Dural sac)
- Filum Terminale externum
Where does the Dural sac terminate?
S-2
Where does the spinal cord end in an adult?
L-1 to L-2
The Pia mater layer sits right on top of what?
Nervous system tissue (neurons & supporting cells).
Between which 2 layers does CSF flow & what is that space called?
Between Pia & Arachnoid. Called the subarachnoid space.
Where does the Dura layer taper off & why?
At the spinal ganglia. CSF give cushion & nutrition to the neurons
What 2 things are directly located above the dural space?
Fatty tissue & veins
Why are epidurals performed below S-2?
Cauda equina has more space & Dural sac is larger
What wraps around the cauda equina?
The Dural sac
Where are the 2 spinal cord enlargements & why?
- At cervical C3 thru C6 & between T11 thru L1.
- Lots of synapse & cell bodies making decisions for upper & lower extremities
Why does the spinal cord narrow in the thorax?
Not as many sensors. More for signal transport.
Where does the spinal cord end in a newborn?
L-2 to L-3
What is another name for the Dural sac?
Lumbar cistern
What is an incomplete fusion & adjustments should one make?
- Ligmentum flava does not have complete midline fusion.
- Come slightly off midline with epidural.
What is another name for the Pyramidal tracts?
Corticospinal tracts
What is the medulla crossover point for corticospinal tract #1 called & where is it?
Pyramidal Decussation & in the Medulla
What is the primary way for efferent corticospinal tract #1?
Cortex -> Internal capsule -> Pyramids of Medulla -> Pyramidal decussation -> descending the lateral corticospinal tracts -> then lateral tract talks to anterior horns thru, Lamina 8, to motor neuron -> signal exits anterior rootlets
What percentage of pathway does not cross over & travels down which tract?
1-2% & travels down the uncrossed lateral corticospinal tract
Where is the crossover point for the 2nd corticospinal tract?
In the spinal cord at the same level it initiates activity
What is the purpose for Spinocerebellar tracts?
Feedback about movement, coordination
Dorsal spinocerebellar tracts are ______ feedback & ventral spinocerebellar tracts are _____feedback.
Muscle spindle & Golgi tendon
Ventral spinocerebellar tracts terminate at the ___ cerebellar peduncle & dorsal tracts terminate at the ___cerebellar peduncle.
Superior & inferior
Fast pain ascends through the ____ pathway & slow pain ascends through the ____pathway.
Lateral & anterior
What neurotransmitter is used by fast pain?
Glutamate
What neurotransmitters are used by slow pain?
Substance P, CGRP, & Glutamate
What is an example of slow pain?
Stomachache, hot & cold
What signal travels through Lamina 1?
Fast pain
What is another name for slow pain tract?
Paleospinothalamic tract
What is another name for fast pain tract?
Neospinothalamic tract
Where do pain signals cross over?
Anterior White Commissure at the same level it enters
Where does a lot of slow pain signals terminate?
In the Reticular formation in the PONS
How much of slow pain makes it to the thalamus?
~ 15%
The Reticular Formation plays a role in our?
Level of awareness & emotions
If a person has a hard time sleeping, feels emotionally crappy and has a lot of pain, what is most likely being overstimulated?
The Reticular Formation
The part of slow signal that makes it through the thalamus get relayed to the?
Parietal lobe
Where does fast pain cross over?
Lamina 10
What does fast pain pass through on its way to the thalamus?
The Ventrobasal complex
What are the Extrapyramidal tracts called?
Vestibulospinal, Olivospinal, Reticulospinal, Rubrospinal
What is the function of the Vestibulospinal tract?
Eye fixation, muscle orientation during acceleration
What is the function of the Olivospinal tract?
Coordinate activation or inactivation of movement
What is the function of the Reticulospinal tract?
Maintenance of muscle tone
What is the function of the Rubrospinal tract?
Modulation of voluntary movement
In someone with a stroke showing abnormal jerking movement would have a problem with this tract?
Reticulospinal
Where does the process of the DIC start & then descends?
In the brainstem
Where can the DIC system be activated?
The periventricular nuclei or the Periaqueductal gray
What are the 1st order neurons in the DIC?
Enkephalins neurons
What are the 2nd order neurons in the DIC?
Serotonergic neurons
What is the connection point between 1st & 2nd order neurons?
Raphe magnus nucleus
Where would 3rd order neurons be located?
In the spinal cord
What kind of neuron is the 3rd order?
Enkephalin neuron
3rd order neurons receive information from the 2nd order via what?
Serotonin
What kind of endogenous opioid shuts down pain in the DIC?
Enkephalin
What is the purpose of pain receptors?
To keep us from hurting ourselves
Name 3 locations that do not have pain receptors?
Brain itself, Alveoli of the lungs, & the liver
What part of the brain does contain pain receptors?
Dura mater & meninges
What part of the liver contains the pain receptors?
The fibrous coating
What kind of neurons are on muscles?
A- alpha
Does blocking prostaglandin inhibit pain stimulus?
No, it decreases bodies’ sensitivity to pain stimulus
What are the 3 Fast pain receptors responding to Glutamate?
AMPA, NMDA, Kainate
Activating an AMPA receptor will result in?
Na+ influx then action potential
If an NMDA receptor is activated, it will result in?
Na+ &/or Ca++ influx
Enkephalin receptors increase what?
Cell p
Opioid receptors are only found in the CNS?
False, there are some in the periphery
What location do opioids always exert their effect?
At the synapse
What is the pain benefit of SSRI’s & SNRI’s & TCA’s?
They block serotonin re-uptake, which results in more enkephalin release.
What kind of drug would most likely be given for someone with depression & a history of chronic pain?
TCA
What kind of receptors are NMDA & AMPA?
Ionotropic receptors
What are the primary & secondary Glutamate receptors?
Primary= AMPA, Secondary= NMDA
A resting cell receives Glutamate, what happens to the NMDA receptors?
Nothing, they are blocked by magnesium
What happens to NMDA receptors once a cell is depolarized?
The intracellular magnesium unblocks the channel
NMDA receptors in the brain help us with what?
Learning & memory
iNOS produces ____ from _____ causing relaxation of smooth muscle?
Nitric oxide & arginine
What does Nitric Oxide do to the 1st order neuron cell?
Increase Glutamate release & sensitivity of which glutamate will be released –> increased pain
What do prostaglandins do to the 1st order neuron?
Increase sensitivity & amount of neurotransmitter released
Enkephalin or opioid receptors increase cell wall permeability to what?
K+ –> cell inhibition
Activating Alpha-2 receptors decrease _____ release & shutting down the ____ synaptic cell?
Neurotransmitter & Pre
Anesthetic gasses directly work on cells by what mechanism?
Increase cell permeability to K+
What is the indirect mechanism of anesthetic gasses?
Activation of Periaqueductal gray & Periventricular nuclei
What is the benefit of using Ketamine in anesthesia?
Able to keep BP & ventilation pretty normal
Chronic ketamine exposure can lead to what?
Lead to decreasing NMDA receptor formation
What is the main inhibitory neurotransmitter in the spinal cord?
Glycine
The capability to distinguish two points of stimulation, even if very close together is an example of what?
Lateral inhibition
Cranial nerves 5 & 9 are associated with what kind of syndrome?
tic douloureux
Paroxysmal facial, mouth or throat pain caused by touch or cold is indicative of?
tic douloureux
In what column do pain sensation, crude touch, & temperature sensation signals travel?
Anterolateral columns
Where is the Somatosensory cortex located?
In the postcentral gyrus
Where is the primary motor cortex located?
In the precentral gyrus
Anterolateral signals cross in the?
Anterior white commisure
Information about highly localized touch sensation & body position is conveyed through what system?
DCML
Where are the 1st order afferent neuron cell bodies of the DCML found?
In the dorsal root ganglia
What carries axons from the nucleus gracilis to the thalamus?
medial lemniscus
What kind of fibers need to be stimulated to decrease peripheral sharp pain & this is an example of what?
Beta type A from peripheral tactile receptors.
Lateral inhibition
What body part is superior & medial of the post-central gyrus (Hemunculus)?
Lower limb
Loss of vibration & motor function on the right hand would be indicative of?
Loss or damage to the right side of the spinal cord @C-2
Loss of all activity off the right side of the spinal cord @ C-2 would result in what kind of loss in the left hand?
Crude touch, pain sensation, & temperature sensation.
(those travel on the contralateral side in the anterolateral system)
What disorder is characterized by loss of pain on one side & loss of sensation on the other?
Brown-Sequard syndrome
