N6 Anterolateral System: Pain & Temp

Front 1

Describe the Central projections of sensory info to 3 general regions:

Back 1

1. Axon collaterals for: Reflex activity in spinal cord & brainstem
2. Tracts that project to the Cerebral Cortex for Perception & Relay in the Thalamus.
3. Axons that end in the Brain Stem Reticular Formation for arousal & modulation

Front 2

Describe the pathway for reflex circuit & where the neurons are located

Back 2

Primary: Sensory neuron in DRG
Secondary: Interneuron (relfex)
Tertiary: Lower motor neuron

Front 3

Describe the pathway for sensory relay circuit

Back 3

Primary: DRG
Secondary => decussation => Tertiary in the thalamus => to post central gyrus

Front 4

Describe the pathway for reflex & relay with the reticular formation involved

Back 4

Primary neuron in DRG
Secondary neuron sends off colaterals to RF & main axon to Sensory perception or response with RF input leading to diffuse pain

Front 5

What main sensory modalities are involved in the Antero-Lateral System (ALS)?
What fibers are included?

Back 5

Pain & Temperature
Spinothalamic & Spinoreticular

Front 6

What specific senses are involved in the ALS pathway?
What fibers sense which specific type of pain?
What pathway does FAST pain take?
What pathway does SLOW pain take?

Back 6

For LIGHT TOUCH, TEMPERATURE, itch, tickle as well as FAST (A-delta) and SLOW (C-fiber) pain.
Fast pain: localization of sharp pain Thalamus => Cortex
Slow pain: uses the RF & is diffuse

Front 7

Primary Sensory Neurons

Location?
Innervate what?
Terminate where?
Collateral's form which tract?
-Where do collaterals connect?

Back 7

-DRG
-Receive info from DERMATOME
-Dorsal horn
-Dorsolateral fasiculus
-Go to cord segments above & below the level of entry & are important for reflex

Front 8

Secondary Sensory Neurons

Location?
Where do they cross?
Course?

Back 8

-Cell bodies in the Dorsal horn.
-CROSS the midline via the ventral or anterior white commissure w/in 1-3 spinal cord segments.
-Axons form the ALS or spinothalamic tract on the OPPOSITE side of the spinal cord.
-Course along the LATERAL aspect of the brain stem
-Terminate in the Ventral Posterior Lateral nucleus (VPL) of the thalamus.

Front 9

Tertiary Sensory Neurons

-Location of neuruons & their cell bodies?
-Projection of axons?

Back 9

-3rd order are in the thalamus with the cell bodies residing in the VPL
-Axons project via the posterior limb of the internal capsule to the POSTCENTRAL GYRUS & posterior part of the paracentral lobule.

Front 10

Primary somatosensory cortex = Postcentral Gyrus

How is it organized?

Back 10

Somatotopically organized & represented by homunculus.

Front 11

What is the role of the RETICULAR FORMATION and what type of sensory fibers does it contain?

Back 11

PAIN & C-Fibers.

It is the DIFFUSE type of pain signal

Front 12

Describe the DCML pathway to the cortex.

Primary sensory neuron location? what types of sensation?
Where does it synapse?
Somatotopic organization?

Back 12

Primary sensory neurons: in the DRG receptors for FINE DISCRIMINATING TOUCH, VIBRATION, JOINT POSITION (proprioception)
-Does NOT synapse in dorsal horn, ascends up the dorsal column.
-Leg(medial) arm (lateral)

Front 13

DCML 2ndry neurons

Location of nuclei?
Name of nuclei input & output?
What is the name of the band formes by these neurons?

Back 13

Located in the medulla
INPUT: Gracile & cuneate fasciculi
OUTPUT: axons decussate below dorsal colun nuclei in the medulla
-Medial Lemniscus (ML)

Front 14

What spinal levels does the Cuneate fasciculus cover?

Back 14

C1-T6 upper trunk & arm

Front 15

What spinal levels does the Gracile fasciculus cover?

Back 15

T7-S5 lower trunk & leg

Front 16

3rd sensory neurons

Location?
Where do they input?
Where do they output?

Back 16

-Ventral Posterior Lateral Nucleus (VPL)
-INPUT: Medial lemniscus
-OUTPUT: Somatosensory radiations, project to postcentral gyrus & posterior paracentral lobule