Posterior Column-Medial Lemniscus (PCML)

Question 1

Origin of 1, 2, 3 order neurons

Answer 1

1: DRG
2: Nucleus cuneatus and nucleus grascilis
3: Originate from the VPL of the thalamus

Question 2

Posterior column lesion sx and side

Answer 2

R column lesion = R sided loss of proprioception, discriminative touch, and vibratory sense below lesion.

L column lesion = L sided loss below lesion

Question 3

Spinal cord hemisection PCML sx

Answer 3

Ipsilateral PCML loss at and below lesion

Question 4

Spinal cord hemisection ALS sx

Answer 4

Contralateral loss of pain/thermal sensation beginning about 2 levels below the lesion

Question 5

Spinal cord hemisection CTS sx

Answer 5

R sided paralysis below lesion

Question 6

Sx of a lesion in the caudal pons related to sensation and motor sx

Answer 6

PCML loss to CL UE and LE. Hemiplegia of right UE and LE.

Question 7

Sx of a lesion in the caudal pons related to other nuclei around this region

Answer 7

TOngue weakness: deviate to ipsilateral side due to hypoglossal nucleus damage

Ipsilateral facial and lateral rectus paralysis

Ipsilateral ptosis, miosis, anhidrosis

Question 8

Sx of a lesion in the mid to rostral pons

Answer 8

PCML loss on CL side. ALS loss on CL side.

Loss of discriminative touch to IL face and paralysis of masticatory muscles because trigeminal nuclei are involved.

Question 9

If we injure the lateral part of medial lemniscus in the midbrain, sx?

Answer 9

PCML loss to CL LE. If we injure the more medial part of ML in midbrain, get PCML loss to CL UE too.

Question 10

VPL damage sx

Answer 10

Transient CL hemiplegia
Paresthesias
PCML and ALS loss to CL side. If VPM is damaged, lose PCML and ALS sensations to face and oral cavity too.

Question 11

PC in spinal cord blood supply. Injury?

Answer 11

Arterial vascerona of posterior spinal artery

IL and below loss of senation at and below lesion.

Question 12

ML in medulla blood supply. Injury?

Answer 12

Anterior spinal A

Loss of sensation to BL body below head

Question 13

ML in pons blood supply

Answer 13

Overlap of paramedial and long circumferential branches of basilar A

Question 14

ML in midbrain blood supply

Answer 14

Short circumferential branches of posterior cerebral, quadrigemnial, choroidal arteries

Question 15

VPL blood supply. Injury?

Answer 15

Thalamogeniculate branches of posterior cerebral A

Loss of all tactile sensations to CL body and head. Face and oral cavity if VPM involved.

Question 16

Posterior limb of IC blood supply

Answer 16

Lateral striate branches of MCA

Question 17

ACA damage

Answer 17

CL loss LE

Question 18

MCA damage

Answer 18

Tactile loss over CL upper body and face

Question 19

Describe the somatoptopic transition of LE from spinal cord to thalamus

Answer 19

SC: LE is most medial
Medulla: LE is inferior
Pons: LE is lateral
Rostral pons: Lateral, a bit more superior
Thalamus: Inferior and lateral

Question 20

Describe the somatoptopic transition of UE from spinal cord to thalamus

Answer 20

SC: UE is lateral, neck is most lateral
Medulla: UE is superior
Pons: UE is medial
Rostral pons: UE is medial and inferior
Thalamus: UE is most superior and medial

Question 21

Which NTs are invovled?

Answer 21

ACh, Glutamate, and Aspartate w/ large diameter heavily myelinated fibers of posterior horn and in posterior columns