Anterolateral System (ALS) & Spinal Trigem. Nuclei Flashcards

1
Q

What does the Anterolateral System communicate?

A

Pain, temperature and non-discriminative touch

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2
Q

What are the main tracts of the ALS?

A

Spinothalamic and Spinoreticular

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3
Q

The spinothalamic pathway is a ____ pathway

A

Direct

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4
Q

The spinoreticular pathway is a ______ pathway

A

Indirect

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5
Q

Where do the afferent fibers of the ALS pathway enter the spinal cord?

A

Lateral division of the posterior root

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6
Q

Once the afferent fibers of the ALS enter the posterior root, then where do they go?

A

They either ascend or descend 1-2 levels in the posterolateral tract/fasciculus and then synapse

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7
Q

Another name for the posterolateral tract/fasciculus?

A

Lissauer’s tract

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8
Q

Where are the 2nd order neurons located for the ALS?

A

Posterior horn lamina

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9
Q

What lamina layers do the afferent fibers synapse to in the posterior horn?

A

1,2,3,4

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10
Q

What are laminas 3 and 4 called?

A

Nucleus proprius

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11
Q

Where do the 2nd order neurons go for the ALS pathway?

A

Across the midline using the anterior white commissure to the contralateral ALS

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12
Q

Where is the ALS?

A

Anterior and lateral within the spinal cord

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13
Q

As the 2nd order neurons ascend within the ALS, where do they synapse?

A

VPL of thalamus to 3rd order neurons

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14
Q

Where do the 3rd order neurons of the ALS go?

A

Somatosensory cortex

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15
Q

Is the ALS somatotopy the same as the PCML?

A

NO; they are exact opposites

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16
Q

Describe the ALS somatotopy

A

The medial side of the ALS = upper arm/neck fibers

The lateral side of the ALS = lower extremity fibers

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17
Q

What lamina levels do the spinoreticular fibers synapse on to 2nd order neurons at?

A

2 and 3

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18
Q

What is the extra step in the spinoreticular tract?

A

2nd order neurons synapse at the Reticular Formation (RF)

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19
Q

Once the spinoreticular 2nd order neurons have synapsed at the RF, where do the 3rd order neurons go?

A

To the thalamus and resume normal pathway

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20
Q

What is the benefit of the spinoreticular tract?

A

It adds higher order neural processing of the sensory information = more specific information about the stimulus

21
Q

Blood supply to the ALS?

A

Arterial Vasocorona and anterior spinal A.

22
Q

What will a lesion of the blood supply to the ALS cause?

A

Patchy loss of nociception, thermal and touch on the contralateral side of body starting 1-2 segments below where the lesion is

23
Q

Bilateral loss of sensory and motor function at/below site of injury

A

complete spinal cord injury

24
Q

Some function at or below site of injury

A

Incomplete spinal cord injury

25
Q

If a patient has sensation and proprioception, but has loss of motor and pain/temp sensation, what syndrome?

A

Anterior cord syndrome - anterior half (anterior horn and ALS pathways) have been injured but PCML still in tact

26
Q

If a patient has loss of pain and temperature pathways, what is the likely syndrome?

A

Central cord - damage to anterior white commissure

27
Q

Transient symptoms like numbness, tingling, burning that resolve in 1-2 days

A

spinal contusion

28
Q

Damage to 1/2 of the spinal cord

A

Brown-sequard syndrome (hemisection)

29
Q

What is damaged with brown-sequard syndrome?

A

PCML, ALS, CST pathways

30
Q

Describe the unique sensation result from a brown-sequard syndrome

A

Loss of touch/pressure/proprioception from the ipsilateral side (PCML)
Loss of pain and temperature from the contralateral side 1-2 segments below injury (ALS)
Loss of motor function from ipsilateral side (CST)

31
Q

What happens with syringomyelia?

A

Cyst cavitation in central regions of the spinal cord

32
Q

What is initially damaged with syringomyelia?

A

Anterior white commissure of ALS

33
Q

As the cyst in syringomyelia accumulates fluid and grows, what region will then be damaged?

A

Anterior horn of the spinal cord

34
Q

What is the result of syringomyelia?

A

Bilateral cape pain/temp lost = both arms and shoulders; eventually UE muscle weakness

35
Q

What is the blood supply to the medullary ALS?

A

PICA - posterior inferior cerebellar A.

36
Q

What is the blood supply to the pons ALS?

A

Basilar or anterior inferior cerebellar or superior cerebellar

37
Q

What is the result of both medullary ALS lesion and pons ALS lesion?

A

Contralateral loss of pain/temp.

38
Q

What does the spinal trigeminal nucleus communicate?

A

Pain, temperature and non-discriminative touch

39
Q

Where does the spinal trigeminal nucleus span?

A

Obex -> C2,C3

40
Q

What is the main division within the spinal trigeminal nucleus?

A

Pars caudalis

41
Q

The afferent signals from the trigeminal enter at the level of the midpons, how do the reach the spinal nucleus?

A

They must descend to synapse to their 2nd order neurons in this nucleus

42
Q

What do the afferent signals descend down to reach the spinal trigeminal nucleus?

A

Spinal trigeminal tract

43
Q

Once synapsed at their 2nd order neurons in the spinal trigeminal nucleus, what do the 2nd order neurons travel?

A

Ascend the anterior trigeminothalamic tract

44
Q

Where do the 2nd order neurons travel to once they are in the anterior trigeminothalamic tract?

A

VPM of thalamus

45
Q

What 2 planes is the spinal trigeminal nucleus somatotopy in?

A

Anterior -> posterior

Rostal -> caudal

46
Q

Describe the anterior to posterior mapping for the spinal trigeminal nucleus

A
Anteriorly = V1
Posteriorly = V3
47
Q

Describe the rostral to caudal mapping for the spinal trigeminal nucleus

A

Rostal (near obex) = mouth
Middle = midcheek
Caudal (near C2,C3) = lateral edges of face near ears

48
Q

Lesions that affect the rostal to caudal ends of the spinal nucleus is referred to as what type of sensory loss?

A

Onion-peel sensory loss

Sensory loss in layers from mouth back to the ears when going from rostral to caudal in the nucleus

49
Q

Lateral medullary and lateral pontine lesions affect the spinal trigeminal nucleus how?

A

IPSILATERAL loss of pain and temperature sensation