Neuroscience L21 Somatosensory 2- Discriminative Touch

Front 1

What are the functional modalities coveyed in the PCMLS (posterior column medial lemniscus system)

Back 1

this conveys:
Fine touch
Proprioception (concious)
Vibratory sense

Front 2

Where is the 1st neuron in the PCMLS pathway located? Cell body? Processes?

Back 2

The primary sensory neuron for the PCMLS is located in the PRG (cell body)
It receives info from the body, and synapses in the posterior horn (for reflexs)

Front 3

Where is the 1st neuron in the PCMLS Process ascending in? in what tract? going to?

Back 3

the 1st neuron's body is in the PRG, its entry is in the medial division of the posterior root entry zone.

The axon ascends in the posterior columns (gracilis or cuneatus) to the Medulla

Front 4

Where does the 1st neuron in the PCMLS synapse on the 2nd neuron?

Back 4

the 2nd neuron cell body is in the gracile or cuneate nuclei in the medulla.

Front 5

Where does the 2nd neuron in the PCMLS send its axons?

Back 5

The 2nd order neurons of the PCMLS, located in the cuneate/gracile nucleus (still ipsilateral to side of body of origin), NOW send arcuate fibers across in the medulla, to the contralateral Medial lemniscus

Front 6

Once the 2nd order neruons of the PCMLS enter the medial lemniscus, where do these axons go?

Back 6

they travel to the Ventral Posterolateral (VPL) nucleus of the thalamus

Front 7

From the VLP of the thalamus, where do PCMLS axons travel?

Back 7

these then follow the posterior limb of the internal capsule and ascend to the cerebral cortex

Front 8

What artery supplies the posterior limb of the internal capsule?

Back 8

the lenticulostriate artery

Front 9

Where do axons from the PCMLS enter the brain?

Back 9

these enter in layer IV of the primary somatosensory cortex (S1), broadmann areas 3,1,2 (postcentral gyrus)

Front 10

What is the somatotopic organization of the PCMLS like?

Back 10

the upper body parts are seen on the lateral surface, while the lower portions are see medially on the surface of the gyrus

Front 11

What do broadman areas 3a and 2 receive input of?

Back 11

These get proprioceptive input from the PCMLS

Front 12

What do broadman areas 3b and 1 receive input from?

Back 12

these get cutaneous mechanorecptor input from the PCMLS

Front 13

From the S1, where the does the PCMLS go?

Back 13

this then sends info to the the parietal lobe, (broadmann 5/7)
and the pariteal operculum (SII, upper bank of lateral fissure)

Front 14

What is the somatotopic organization of the PCMLS like in the spinal cord?

Back 14

Here the lower limbs are most posterior medial (gracilis)

and the trunk and upper limbs are added laterally (cuneatus)

Front 15

What is the somatotopic organization of the PCMLS like in the medulla?

Back 15

Here it is organized in a posterior-anterior fassion, where the person appears to be standing up. Legs posterior (bottom of screen), and arms superior (anterior/top of screen)

Front 16

What is the somatotopic organization of the PCMLS like?

Back 16

the upper body parts are seen on the lateral surface, while the lower portions are see medially on the surface of the gyrus

Front 17

What do broadman areas 3a and 2 receive input of?

Back 17

These get proprioceptive input from the PCMLS

Front 18

What do broadman areas 3b and 1 receive input from?

Back 18

these get cutaneous mechanorecptor input from the PCMLS

Front 19

From the S1, where the does the PCMLS go?

Back 19

this then sends info to the the parietal lobe, (broadmann 5/7)
and the pariteal operculum (SII, upper bank of lateral fissure)

Front 20

What is the somatotopic organization of the PCMLS like in the spinal cord?

Back 20

Here the lower limbs are most posterior medial (gracilis)

and the trunk and upper limbs are added laterally (cuneatus)

Front 21

What is the somatotopic organization of the PCMLS like in the medulla?

Back 21

Here it is organized in a posterior-anterior fassion, where the person appears to be standing up. Legs posterior (bottom of screen), and arms superior (anterior/top of screen)

Front 22

what is the somatotopic organization of the PCMLS like in the midbrain (so ML portion)

Back 22

Here the arms/upper body are most midline, and the lower limbs are lateral and anterior

Front 23

What pathways carries Visceral pain?

Back 23

the PCMLS pathway

Front 24

What causes astereognosis?

Back 24

this is caused by a lesion to S1 and S2- unable to recognize size and shape of objects by tactile manipulation