Tuesday, 4/19-Basic Sensory And Motor Pathways-Stephens

Question 1

In a conscious sensory pathway for FAST PAIN/TEMPERATURE, list the following components:

Primary neuron and what it is conveyed by: ___

Secondary neuron and what it is conveyed by: ___

Tertiary neuron and where it goes to: ___

Answer 1

Primary neuron: spinal ganglion and conveyed by Dorsolateral fasciculus

Secondary neuron: Substantia gelatinosa and conveyed by Spinal Lemniscus (SL) and Lateral spinothalamic tract (LSTT)

Tertiary neuron: Ventral Posterior Lateral Nucleus (VPLN) and goes to Primary Somesthetic Cortex

Question 2

In a conscious sensory pathway for PROPRIOCEPTION/2-PT TACTILE DISCRIMINATION, list the following components:

Primary neuron and what it is conveyed by: ___

Secondary neuron and what it is conveyed by: ___

Tertiary neuron and where it goes: ___

Answer 2

Primary neuron: Spinal ganglion and is conveyed by Long Ascending fibers in the POSTERIOR COLUMNS–> Fasciculus Gracilis and Cuneatus

Secondary neuron: Nucleus Gracilis (LE) and Nucleus Cuneatus (UE) and conveyed by Medial Lemniscus (ML)

Tertiary neuron: Ventral Posterior Lateral Nucleus (VPLN) and projects to Primary Somesthetic Cortex

Question 3

___ are the final effectors of the motor system. Their cell bodies are located in one of the craniospinal motor nuclei and their processes form the motor nerves that innervate skeletal muscles.

Answer 3

LMN’s

Question 4

What are the two types of LMN’s?

Answer 4

Alpha motor neurons

Gamma motor neurons

Question 5

This LMN innervates extrafusal or skeletal muscle fibers: ___

This LMN exclusively innervates the modified muscle cells (intrafusal fibers) that form part of the proprioceptive neuromuscular spindles: __

Answer 5

Alpha motor neurons

Gamma motor neurons

Question 6

___-Muscle is completely “limp” and there is no resistance to passive movement

___-Loss of efferent component of the reflex arc to a muscle results in the absence of the associated muscle reflex

Atonia is a destruction of ___ motor neurons or their axons and results in the absence of muscle tone

Answer 6

Flaccid paralysis

Areflexia

Gamma

Question 7

Denervated muscle atrophies due to loss of stimulation from the ___ neurons

Fasciculations or twitching of the denervated muscle is probably due to hypersensitivity of the ___

Answer 7

Motor

Motor end plate

Question 8

Acute anterior poliomyelitis selectively involves the motor neurons of the ___.

Answer 8

Anterior (ventral) horns and the CN motor nuclei

Initially, there is often severe inflammation, vasodilation, edema, and macrophage activity. Subsequently, these neurons die and there is significant astrocytic gliosis.

Question 9

In the Corticospinal pathway, where do the corticospinal fibers decussate and what do they form?

Answer 9

Decussate at the pyramidal decussation and form the Lateral Corticospinal Tract (LCST)

The remaining uncrossed fibers continue as the Anterior Corticospinal Tract (ACST)

Question 10

In the SC, the LCST descends in the ___ and most of the fibers distribute to the cervical (55%) and lumbosacral (25%) enlargements

Answer 10

Lateral funiculus

Question 11

The corticospinal tracts primarily terminate in ___ pools which, in turn, exert their collective influence upon intrinsic spinal reflex circuits

Answer 11

LMN

Question 12

Unilateral lesions of the LCST result in ___ paralysis or paresis of the distal limb musculature innervated by those spinal segments ___ the level of the lesion

Answer 12

Ipsilateral

Below

Question 13

UMN paralysis is commonly due to interruption of ___

Answer 13

-Motor cortex
-Corticospinal tract
And/or
-Corticobulbar tract

Question 14

___ is defined as abnormal, passive resistance to movement in 1 direction

___ is defined as abnormal, passive resistance to movement in all directions

Answer 14

Spasticity

Rigidity

Question 15

Classify the following as either an UMN or LMN lesion:

__-Paralysis of movements in hemiplegic, quadriplegic, or paraplegic distribution, not individual muscles

__-Paralysis of individual muscles or sets of muscles in root or peripheral nerve distributions

__-Atrophy or disuse only (late or slight)

Answer 15

UMN

LMN

UMN

Question 16

Classify the following as either an UMN or LMN lesion:

__-Atrophy of denervation (early and severe)

__-fasciculation and fibrillations

__-hyperactive DTR’s

__-hypoactive or absent DTR’s

Answer 16

LMN

LMN

UMN

LMN

Question 17

Classify the following as either an UMN or LMN lesion:

__-Clonus

__-clasp-knife spasticity

__-Hypotonia

__-Babinski reflex

Answer 17

UMN

UMN

LMN

UMN

Question 18

The fasciculi gracilis and cuneatus, areas for proprioception and 2-pt tactile discrimination are associated with this part of the SC:

Answer 18

Posterior region

Question 19

The lateral corticospinal tract and UMN are associated with this region of the SC:

Answer 19

Lateral region

Question 20

The Lateral spinothalamic tract and area for perceiving pain and temperature are associated with this part of the SC:

Answer 20

Anterolateral region

Question 21

The anterior horn cells and LMN are associated with this part of the SC:

Answer 21

Anterior region

Question 22

In a conscious sensory pathway, a primary neuron is a pseudounipolar neuron whose cell body is located in a ___

In a conscious sensory pathway, the secondary axon always decussates and ascends as a ___. It terminates upon a tertiary neuron in the ___ and sends collateral fibers to the RF and tectum

In a conscious sensory pathway, the tertiary axon projects to the ___ via the thalamic radiations of the internal capsule and corona radiata

Answer 22

Spinal ganglion

Lemniscus

Dorsal thalamus

Primary somesthetic cortex