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Touch and proprioception of trunk and limbs > deck 1 > Flashcards

Flashcards in deck 1 Deck (25)
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1
Q

where does the 1st order sensory enter the spinal cord?

A

dorsal horn at the dorsal root entry zone (DREZ)

2
Q

Where does touch and conscious proprioception primary axons collect at?

A

as the dorsal column

Collateral branches are involved in intra- and intersegmenal reflexes

3
Q

Where does Aalpha and Abeta fibers enter?

A

medially near the dorsal column

more myelin ids more darker

4
Q

What does the lower limb axons below T6 form?

A

gracile fasciculus

5
Q

What does the upper limb axons above T6 form?

A

collect to form the cuneate fasciculus

6
Q

How are dorsal column somatopy fibers added?

A

fibers are added from medial to lateral

This avoids having upper fibers pass through the tract to take up position

7
Q

Where does each dorsal fascilucus ends/

A

caudal medulla at a corresponding nucleus

1st order axons of the fascicles synapse on 2nd order neurons in the nuclei

8
Q

Where does does 2nd order neurons decussate?

A

as internal arcuate fibers

9
Q

Where does the gracile fibers decussate?

A

cross to a ventral position

10
Q

Where does cuneate fibers decussate?

A

cross to a dorsal position

11
Q

What does the internal arcuate fibers organize as?

A

the vertical rectangular medial lemniscus Vertical medial lemniscus passes inferior olivary nuc. to upper medulla

12
Q

how does the medial lemniscus shift?

A

At the medullopontine junction, medial lemniscus begins to shift
Ventral part (foot) swings laterally (slips on inferior (oily) olivary nucleus)
By mid-pons, medial lemniscus is horizontal

13
Q

How does the medial lemniscus shift through pons and midbrain?

A

Through pons and midbrain, the lateral end continues to swing upward
Midbrain somatotopy has the little headless half-man upside down

14
Q

Where does 2nd order neurons of the ML synapse on 3rd order neurons?

A

2nd order neurons of the ML synapse on 3rd order neurons of the ventral posterolateral thalamus (VPL)

15
Q

Where does the 3rd order neurons of the VPL enter where?

A

enter posterior limb of internal capsule (PLIC)

These thalamocortical fibers ascend in PLIC and corona radiata to terminate in appropriate parts of the sensory homunculus of the postcentral gyrus

16
Q

How are the somatotopy for DC-ML pathway arrange?

A

leg posterior, arm anterior

17
Q

what does lesions of the ML, VPL thalamus and PLIC and medial and upper lateral post central gyrus (above the internal arcuate fibers)

A

produce contralateral loss of descriminative touch and conscious proprioception from the limbs and trunk

18
Q

What does lesions of the dorsal column or gracile and cuneate nuclei produce (below the internal arcuate fibers)

A

produce ipsilateral loss of descriminative touch and conscious proprioception from the limbs and trunk

19
Q

How is Loss of lower limb conscious proprioception can be tested?

A

Romberg test

20
Q

Where does MS attack usually happens at?

A

The dorsal column is a common locus of attack for multiple sclerosis, a demyelinating disease.

21
Q

Where does unconscious proprioception originate for lower limb?

A

2nd order tracts originate in the dorsal horn (2 proprioceptor-mechanoceptor combinations for each of 2 limbs)
from LOWER limb: dorsal (posterior) & ventral (anterior) spinocerebellar tracts – DSCT (PSCT) & VSCT (ASCT)

Cerebellum receives all (and only ) signals originating on ipsilateral side

22
Q

Where does unconscious proprioception originate for upper limb?

A

2nd order tracts originate in the dorsal horn (2 proprioceptor-mechanoceptor combinations for each of 2 limbs)
from UPPER limb: cuneo- & rostral spinocerebellar tracts - CCT & RSCT

Cerebellum receives all (and only ) signals originating on ipsilateral side

23
Q

Where does the Cuneocerebellar and dorsal spinocerebellar tracts switch over at?

A

T6

24
Q

Where does Ventral spinocerebellar and rostral spinocerebellar tracts switch?

A

C8

25
Q

Where does he dorsal/ventral/Rostral and Cuneo CT originates?

A

Dorsal SCT originates in dorsal nucleus (of Clark)
Ventral SCT originates from spinal border cells (mostly lamina VII)
Cuneo CT originates in accessory cuneate nucleus of caudal medulla
Rostral SCT originates in lamina VII