CNS Focused Study (Exam II) Flashcards
What are two portions of the Dorsal Column Medial Lemniscus Pathway? What information do the two portions transmit?
Fasciculus Cuneatus - Upper Body Sensation
Fasciculus Grascilis - Lower Body Sensation
What sensory information does the DCML pathway transmit? How fast is the signal propogation?
- High Fidelity Sensory
(pinpoint touch, pressure, vibration, think hands)
- Very Fast
Where does crossover of the DCML pathway occur?
Crossover occurs at the Lemniscal Decussation of the Medulla Oblongata
Do any of the signals from the DCML interact with the gray matter of the spinal cord?
No
need to verify
What structure organizes sensory information from the DCML and directs it to the appropriate processing region of the cerebrum?
Ventrobasal Complex of the Thalamus
Where does sensory pain information crossover in the CNS?
How does this compare to regular sensory information?
Pain crosses over at spinal cord.
Sensory information crosses over at Medulla/Pons.
Describe the path of a general motor signal through the corticalspinal tracts starting with the cortex.
- Cortex
- Internal Capsule
- Medulla Pyramids
- Medulla Decussation
- Antero-Lateral Corticospinal Pathway
How much information is transmitted through the Lateral Corticospinal Pathway?
How does this compare to the Anterior Corticospinal Pathway?
- Lateral Corticospinal = 90% of motor output
- Anterior Corticospinal = 8-9% of motor output
What portion of motor information never crosses over at the pyramidal decussation or further down in the spinal cord?
1-2%
Where does motor output crossover for the lateral corticospinal tract occur?
Medulla Pyramidal Decussation
What are the two main paths of the Pyramidal Tracts? Which is the primary?
- Lateral Corticospinal Tract (Primary)
- Anterior Corticospinal Tract
Where does crossover occur for the Anterior Corticospinal Tract?
The level of activity initiation
(Ex. Signal going to calf muscle, crossover occurs at spinal nerve controlling calf)
What are the two Spinocerebellar Tracts?
Anterior Spinocerebellar Tract
Posterior Spinocerebellar Tract
What information is carried by the spinocerebellar tracts?
Feedback on the Coordination of movement.
What structure senses information for the Posterior SpinoCerebellar Tract?
Spindle Fibers in the Skeletal Muscle
What is the structure of spindle fibers and how does this relate to the information they transmit?
Where is this information sent primarily?
- Spring-like structure that “senses” contraction/stretch of muscle.
- Information is sent primarily to the Posterior Spinocerebellar tract.
Are muscle spindle fibers myelinated or unmyelinated? What does this mean in terms of pathophysiology?
- Spindle fibers are myelinated.
- Spindle fibers can be affected by demyelinating pathologies such as MS or Guillan Barre.
What sensors located in tendons send information to the spinocerebellar tract on muscle contraction?
Which spinocerebellar tract is this information primarily sent to?
- Golgi Tendon Stretch Sensors
- Anterior spinocerebellar tract.
Where do the Anterior (Ventral) spinocerebellar tracts end?
Superior Cerebellar Peduncle
Where do the Posterior (Dorsal) spinocerebellar tracts end?
Inferior Cerebellar Peduncle
What are the two divisions of the Spinothalamic (Anterolateral) Tracts?
Lateral Spinothalamic - Fast pain - A-δ
Anterior Spinothalamic - Slow pain - C
Where are A-δ fibers found in the spinothalamic tract?
What neurotransmitter(s) is used by this pathway?
How precise is the information delivered by this pathway?
- Lateral Pathway
- Glutamate
- Very precise (detailed pinpoint info)
Where are C-fibers found in the spinothalamic tract?
What neurotransmitter(s) is used by this pathway?
How precise is the information delivered by this pathway?
- Anterior Pathway
- Glutamate, Substance P, CGRP
- Imprecise (think stomach pain)
What two sensory receptor types run alongside C-fibers?
What is the consequence of this?
Thermoreceptors and Vibration receptors
*When slow pain is “activated” you can feeling heat, cold, tickles, and itching* (needs verification)
Which two neurotransmitters are slower to release, bind, and breakdown? Which neurotransmitter is faster in all aspects?
CGRP & Substance P = Slow
Glutamate = Fast
Which lamina are associated with slow pain?
Which tract is utilized with these lamina?
What is another name for this tract?
Lamina II, III, and V
Anterior Spinothalamic Tract
“Paleospinothalamic Tract”
Which lamina are associated with fast pain?
What tract is utilized with this lamina?
What is another name for this tract?
Lamina I
Lateral Spinothalamic Tract
Neospinothalamic Tract
Where does fast pain processing occur?
What processing occurs alongside it?
Ventrobasal Complex of Hypothalamus
Sensory Information from DCML
Where does slow pain cross over at? What tract carries this information?
Anterior White Commissure
Anterior Spinothalamic Tract
Why is there poor localization of slow pain?
Only 15% of the signal progresses to the parietal lobe for higher level of processing.
Where are both fast pain and slow pain processed?
Where does most of slow pain signalling terminate?
How does this compare to fast pain signaling?
- Hypothalamus
- Most slow pain signaling terminates in the pons.
- Fast Pain → Ventrobasal complex of hypothalamus → Parietal Lobe
What brain structure determines wakefulness and emotion processing?
Where is this structure located?
Reticular Formation
Interior of Brainstem (spans medulla, pons, and midbrain)
What would two byproducts of chronic pain processing be? Why?
Feeling shitty and Sleeping shitty.
Wakefullness and Emotions are processes in Reticular formation of brainstem alongside C-fiber pain.
Where does fast pain crossover?
Are these axons carrying this information myelinated all the way through?
Lamina X
Yes, even through Lamina X
What are the 4 extrapyramidal tracts?
What are all 4 of these extrapyramidal tracts characterized by?
- Vestibulospinal
- Olivospinal
- Reticulospinal
- Rubrospinal
All are CNS efferent outputs to spinal cord.
What information is pertinent to the Vestibulospinal Tract?
Eye fixation w/ muscle coordination during acceleration
What information is pertinent to the Olivospinal Tract?
Cerebellar output to coordinate movement
What information is pertinent to the Reticulospinal Tract?
What would occur with injury to this tract?
Maintenance of Muscle Tone
Crazy Movement (flaccidity or jerkiness)
What information is pertinent to the Rubrospinal Tract?
Modulation of Voluntary Movement
What does DIC stand for in the context of the CNS?
What does the DIC do?
What activates the DIC?
- Descending Inhibitor Complex
- Pain suppression system from CNS output
- Brain or hormones activate DIC
Where are two origins for a DIC signal?
- Periventricular Nuclei
- Periaqueductal Gray Matter
Where does the DIC synapse at?
Which portion of the DIC specifically?
What is released at this synapse?
- The DIC synapses at the synapse of the 1st nociceptor and the 2nd signaling neuron.
- 3rd Order Enkephalin Neurons.
- Enkephalin
How do enkephalins decrease pain?
- Enkephalins bind to receptors on the pre-synaptic neuron and the post-synaptic neuron
- ↑ pK+
- ↑ Action Potential Threshold
How would physical damage to a free nerve ending cause an action potential?
- ↑ K+
- ↑ H+
- Physical damage to cell (crushing, burning, etc.) would cause an increase of both of the above, thus causing a Na+ influx.