LEC-7/8 Spinal Path I & II

Question 1

A group of neurons with a similar embryonic origin and function is referred to as a ___________.

Answer 1

Nucleus

Ex. Caudate nucleus

Question 2

A ___________ is a group of nerve fibers in the CNS that have a similar origin and function.

Answer 2

Tract

Ex. Sensory - Spinothalamic tract; Motor - Corticospinal tract

Question 3

The path of sensory information that a signal follows from receptors to the cortex is a ___________.

Answer 3

Pathway

Question 4

The (medial lemniscus/spinothalamic) pathway is primarily associated with touch, vibration, and proprioception.

Answer 4

Medial lemniscus

Question 5

The (medial lemniscus/spinothalamic) pathway is primarily associated with pain and temperature.

Answer 5

Spinothalamic

Question 6

The fasciculus gracilis carries sensory information from the (upper/lower) body.

Answer 6

Lower body (below T6)

Question 7

The fasciculus cuneatus carries sensory information from the (upper/lower) body.

Answer 7

Upper body (above T6)

Question 8

The dorsal column-medial lemniscal pathway decussates at the (upper medulla/pons/lower medulla).

Answer 8

Lower medulla

Question 9

Second-order neurons of the dorsal column-medial lemniscal pathway decussate as _____________ fibers.

Answer 9

Internal arcuate fibers

Question 10

After internal arcuate fibers decussate at the lower medulla in the dorsal column-medial lemniscal pathway, they form the _________ on the other side of the medulla.

Answer 10

Medial lemniscus

Question 11

The medial lemniscus axons terminate in the (VPL/VPM) of the thalamus.

Answer 11

VPL

Question 12

Axons in the spinothalamic tract begin to decussate immediately after entering the spinal cord, passing through the ____________ in the central gray matter.

Answer 12

Anterior commisure

Question 13

(T/F) Axons in the spinothalamic tract decussate immediately in the same spinal segment the sensory information originated from.

Answer 13

False. Axons in the spinothalamic tract begin to decussate immediately after entering the spinal cord, but it takes 2-3 spinal cord segments to accomplish this. Therefore, a lesion in the spinothalamic tract will affect contralateral pain perception beginning a few segments below the level of the lesion.

Question 14

The corticospinal tract has neuronal origins in the ____________, ____________, and _____________.

Answer 14

I. Primary motor cortex (Brodmann’s 4)
II. Premotor and supplementary motor areas (Brodmann’s 6)
III. Primary somatosensory and parietal association cortices (Brodmann’s 3,1,2,5,7)

Question 15

Corticospinal fibers course through the (anterior limb/genu/posterior limb) of the internal capsule.

Answer 15

Posterior limb

Question 16

The internal capsule is white matter present in the forebrain that separates the __________ and __________ from the __________ and __________.

Answer 16

-Thalamus
-Head of caudate nucleus
from the
-Putamen
-Globus pallidus

Question 17

Corticospinal fibers course through the (substantia nigra/basis pedunculi) of the cerebral peduncles in the midbrain.

Answer 17

Basis pedunculi

Question 18

About __% of corticospinal (pyramidal) tract fibers decussate in the pyramidal decussation to become the lateral corticospinal tract.

Answer 18

80%

Question 19

The remaining 20% of fibers that do not decussate in the pyramidal decussation become the ________________.

Answer 19

Anterior (ventral) corticospinal tract

Question 20

Lateral corticospinal fibers typically terminate on lamina __ of the spinal cord.

Answer 20

IX

Question 21

Lesions in the corticospinal tract above the pyramidal decussation will elicit effects (contralaterally/ipsilaterally).

Answer 21

Contralaterally

Question 22

A lesion in the motor cortex will affect motor neurons (ipsilateral/contralateral) to the lesion.

Answer 22

Contralateral

Question 23

A lesion in the internal capsule will affect motor neurons (ipsilateral/contralateral) to the lesion.

Answer 23

Contralateral

Question 24

A lesion in the midbrain will affect motor neurons (ipsilateral/contralateral) to the lesion.

Answer 24

Contralateral

Question 25

A lesion in the pons will affect motor neurons (ipsilateral/contralateral) to the lesion.

Answer 25

Contralateral

Question 26

A lesion in the medulla will affect motor neurons (ipsilateral/contralateral) to the lesion.

Answer 26

Contralateral

Question 27

A lesion in the spinal cord will affect motor neurons (ipsilateral/contralateral) to the lesion.

Answer 27

Ipsilateral (Spinal cord is below the cervicomedullary junction and foramen magnum, which is where the pyramidal decussation occurs)

Question 28

A lesion in (upper/lower) motor neurons causes hyper-reflexia.

Answer 28

Upper motor neurons

Lower motor neurons cause hypo-reflexia

Question 29

A lesion in (upper/lower) motor neurons causes decreased muscle tone.

Answer 29

Lower motor neurons.

Upper motor neuron lesions cause increased muscle tone

Question 30

(T/F) Fasciculations and muscle atrophy are typically present in upper motor neuron lesions.

Answer 30

False. Fasciculations and muscle atrophy are characteristic of lower motor neuron lesions.