Anatomy - PCML Flashcards Preview

Maddy - Neuro II - tracks > Anatomy - PCML > Flashcards

Flashcards in Anatomy - PCML Deck (30)
Loading flashcards...
1
Q

where do fibers from the DRG go into the spinal cord in PCML

A

posterior horn

2
Q

large-diameter fibers relay what kind of info

A

touch, flutter, vibrations, proprioception

3
Q

how do fibers of PCML enter the spinal cord

A

via medial division of posterior root

4
Q

once in the spinal cord where do fibers of the PCML go

A

synapse onto second order neurons at, above, or below level of entry

5
Q

the largest set of branches of PCML from the DRG do what once in the spinal cord

A

ascend cranially to form the fasciculus gracilis or fasciulus cuneatus (posterior/dorsal columns)

6
Q

describe the topographical organization of the posterior columns

A

from medial to lateral:

sacral/coccygeal levels –> lumbar and thoracic levels below T6 –> thoracic levels above T6 –> low cervical levels –> upper cervical levels

7
Q

what makes up the fasciculus gracile

A

sacral and coccygeal levels, lumbar and thoracic levels below T6

8
Q

what makes up the fasciculus cuneatus

A

thoracic levels above T6, lower cervical, and upper cervical levels

9
Q

spinal cord lesions of the PCML result in ____

A

ipsilateral loss of discriminative, positional, and vibratory tactile sensations at or below the level of injury

10
Q

if patient has a wide based stance and is placing feet to the floor with force, what might you susepct

A

damage to PCML (they are trying to create the missing proprioceptive input)

11
Q

describe the segregation of tactile inputs within the nuclei gracile and nuclei cuneatus and also the VPL

A

the core clusters receive inputs from rapidly and slowly adapting afferents

the outer shells receive input from muscle spindles, joints, and pacinian corpuscles

12
Q

describe the tract of the PCML once it hits the medulla

A

the axons cross in the medulla as internal arcuate fibers and then ascend as the medial leminiscus to the thalamus contralateral to where the fibers originated in the spinal cord

13
Q

how does the organization of the upper and lower extremities change in the pons for the PCML

A

as the medial leminiscus ascends it rotates laterally in the pons which causes the upper extremity fibers to lie medially and the lower extremity fibers to lie laterally

14
Q

where does the medial leminiscus terminate in the PCML

A

the ventral posterolateral nucleus (VPL)

15
Q

what is the arterial supply for the PCML in the spinal cord and then once its gets to the medulla

A

spinal cord: posterior spinal a.

medulla: anterior spinal a.

16
Q

brainstem lesions of the PCML result in ______

A

contralateral loss of discriminative touch, vibratory, and positional sensibilities

17
Q

where are the VPL and VPM located

A

in the caudal thalamus

18
Q

what is the blood supply to the VPL and VPM

A

thalamogeniculate arteries from the posterior cerebral a.

19
Q

what separates the VPL and VPM

A

fibers of the arcuate lamina

20
Q

what is the main type of neuron in the VPL and what do they do

A

third order neurons that leave the VPL, traverse the posterior limb of internal capsule, and terminate in primary and secondary somatosensory cortices

21
Q

what is the minor type of neuron in the VPL and what do they do

A

local circuit interneurons that moderate the frequency at which information is relayed to the cortex by other third order neurons
(inhibitory)

22
Q

what is the blood supply to the primary somatosensory cortex

A

anterior and middle cerebral arteries

23
Q

compare the effects of MCA and ACA lesions

A

MCA: tactile loss over contralateral upper body and face
ACA: contralateral lower limb

24
Q

what are Brodmann areas

A

subdivisions of the primary somatosensory cortex on the postcentral gyrus
- anterior to posterior: 3a, 3b, 1, 2

25
Q

describe the locations of Brodmann areas

A

3a: in the depths of the central sulcus
3b an 1: extend up back of sulcus onto shoulder of posctentral gyrus
2: lies on gyral surface

26
Q

what inputs does the secondary somatosensory cortex receive

A

from ipsilateral primary somatosensory cortex and VPI of thalamus

27
Q

where is the secondary somatosensory cortex

A

inside the lateral sulcus

28
Q

what are the parietal cortical regions

A

another cortical somatosensory region; receives tactile inputs; located posterior to the primary somatosensory cortex

29
Q

lesions in the parietal cortical regions cause what

A

agnosia (inability to interpret sensations and hence to recognize things)

  • contralateral body parts are lost from personal body map
  • not recognizing limbs
30
Q

what is the function of the afferent cerebellar pathway (spinocerebellar)

A

transmits proprioceptive and limited cutaneous info to the cerebellum
- info about limb position, joint angles, muscle tension