Anterolateral System
What type of modality is transmitted via this tract?
Body or face?
Pain and temperature
Body
What type of modality is transmitted via this tract?
Body or face?
Fine touch/vibration/proprioception
Body
This is the most common type of neuron.
(Extra 100 if you tell me what the least common type is AND draw it on the board)
Most common: Multipolar
Least common: Bipolar
Where are primary cell bodies found in the spinothalamic tract?
Dorsal root ganglion
The PCML axons travel up the spinal cord in this structure, until it reaches the medulla.
Dorsal column:
Fasciculus gracilis (leg and lower trunk)
Fasciculus cuneatus (upper trunk and arm)
Which axons decussate in the sensory systems?
Second axon decussates
Your patient is unable to feel any kind of sensation on the left side of their body. What is damaged?
Right VPL
The first soma of the PCML goes + synapses here:
Bonus points (200) if you can tell me where it decussates after synapsing here.
Medulla- Synapses in the nucleus gracilis (lower trunk and leg) and nucleus cuneatus (upper trunk and arm).
Decussates in the internal arcuate fibers of the medulla.
What is the difference between a fasciculus and a nucleus in terms of the fasciculus gracilis vs gracilis nucleus?
Fasciculus - Contains axons of primary neurons
Nucleus - contains somas of secondary neurons
What are the three divisions of the anterolateral system? If they've gotten this far in the slides:
What are the functions of each?
Spinomesencephalic: sends pain fibers directly to midbrain for pain control
Spinoreticular: walked you up/arouses you upon pain
Spinothalamic: carries pain/temp info from body to brain
After decussating, second-degree axons of the PCML travel up the brainstem through this white matter structure.
Bonus (200) points if you can tell me where the secondary neuron will synapse.
Medial lemniscus.
Will synapse in the VPL nucleus of the thalamus
What happens in the anterior commissure?
ACT bifurcates and spinothalamic tract decussates.
Name the organization of the anterolateral system of the spinal cord from lateral to medial.
Extra 100 if you do the organization of the dorsal column from lateral to medial as well!
Anterolateral: Leg, trunk, arm, and neck
Dorsal column: Occiput (back of head), neck, arm, upper trunk, lower trunk, leg
If I damage the left side of my midbrain, what would the damage look like to the body sensation tracts? Pain/temp loss? Fine touch loss? Ipsilateral? Contralateral? Would you also lose motor?
Contralateral loss of both pain/temp and fine touch for the body since both paths have already decussated.
If damaging the peduncles, could impact the LCT and ACT contralaterally (R side)
You receive a pinch on the back of your right shoulder. Draw on a neuron carrying this information on this cross-section.
Draw/Trace in a neuron carrying information of a feather touching your left calf on the midbrain!