General Sensory And Motor Systems - 4/19 Stephens

Question 1

In the conscious sensory pathway where is the secondary neuron located?

What does it always do?
Terminates where?

Where does it send collateral fibers?

Answer 1

Spinal cord (pain/temp) or medulla (proprio)

Decussates and ascends as a lemniscus
Terminates upon tertiary neuron or dorsal thalamus

RF or rectus

Question 2

In the conscious sensory pathway where is the soma of a tertiary neuron located?

Where does it project to?
Via what?

Answer 2

Specific nucleus of the dorsal thalamus

Primary somesthetic cortex via the thalamic radiations of in the internal capsule and corona Radiata

Question 3

What does the primary somesthetic cortex play a role in?

Answer 3

Perception and discrimination of sensory stimuli

Question 4

What is the association cortex involved in?

Answer 4

Integration, modification and interpretation of sensory information

Question 5

From the primary neuron where does the secondary neuron synapse in the pain/temp pathway?

How does it travel?

Answer 5

Substantia Gelatinosa

Dorsolateral Fasciculus of Lissauer

Question 6

From the secondary neuron, where does the tertiary neuron synapse in the pain/temp pathway?

Travels via what?

Decussates where?

Answer 6

Ventral Posterior Lateral Nucleus (VPLN)

Lateral Spinothalamic Tract then to the Spinal Lemniscus @ the brainstem

Anterior white commissure

Question 7

After synapsing in the VPLN, where does the pain/temp pathway finally reach?

How does it get there?

Answer 7

Primary somesthetic cortex

Posterior limb of the internal capsule

Question 8

From the primary neuron (in the spinal ganglion) where does the secondary neuron synapse in the proprioception/2pt pathway?

How does it travel?

Answer 8

Nucleus Gracilis (lower limb)
Nucleus Cuneatus (upper limb)

Fasciculus Gracilis (lower)
Fasciculus Cuneatus (upper)

Question 9

From the secondary neuron, where does the tertiary neuron synapse in the proprioception/2pt pathway?

Travels via what?

Decussates where?

Answer 9

Ventral Posterior Lateral Nucleus (VPLN)

Medial Lemniscus

Thalamus

Question 10

After synapsing in the VPLN, where does the proprioception/2pt pathway finally reach?

How does it get there?

Answer 10

Primary Somesthetic cortex

Posterior limb of internal capsule

Question 11

From the primary neuron (in the spinal ganglion) where does the secondary neuron synapse in the crude tactile pathway?

How does it travel?

Answer 11

Nucleus Proprius Intermediate Gray

Short Ascending fibers in posterior columns

Question 12

From the secondary neuron, where does the tertiary neuron synapse in the crude tactile pathway?

Travels via what?

Finally reaches what?

Answer 12

VPLN

VSTT

Primary somesthetic cortex

Question 13

What do lower motor neurons innervate?

Where are their cell bodies located?

What 2 types are there?

Answer 13

Striated muscle

Craniospinal motor nuclei

Alpha and gamma

Question 14

What do alpha motor neurons innervate?

Gamma?

Answer 14

Extrafusal or skeletal muscle fibers

Intrafusal fibers that form part of proprioceptive neuromuscular spindles

Question 15

Activating gamma motor neurons will increase what?

Answer 15

Muscle tension and TONE

Question 16

Nuclei that innervate branchiomeric muscles are what type?

Myotomic?

Answer 16

SVE

GSE

Question 17

Poliomyelitis involves what neurons? Located where?

Clinical symptoms?

Prognosis/result?

Answer 17

Motor neurons of ventral horns (LMN) and cranial nerve motor nuclei

Inflammation, vasodilation, edema

Nonparalytic or paralytic

Question 18

The corticospinal pathway arises from what cortex and gyrus?

What does it descend through?

Answer 18

Primary motor cortex and pre central gyrus

Descends through corona Radiata, posterior limb of internal capsule, cerebral peduncle so (mid 3/5), pons and upper medulla

Question 19

In the lower medulla, 85-90% of the corticospinal fibers decussate where?

Form what?

Remainder form what?

Answer 19

Pyramidal decussation

Form the lateral corticospinal tract (LCST)

Remainder continue as the anterior corticospinal tract (ACST)

Question 20

Most of the fibers from the LCST distribute to where?

Answer 20

Cervical (55%) and lumbosacral (25%) enlargements

Question 21

Unilateral lesions of the LCST result in what?

Answer 21

Ipsilateral paralysis of the distal limb musculature innervated by those spinal segments below the level of the lesion

Question 22

What is defined as abnormal passive resistance to movement in all directions?

Answer 22

Rigidity

Question 23

What is defined as abnormal, passive resistance to movement in one direction?

Answer 23

Spasticity

Usually due to hypersensitivity of LMN pools

Question 24

What clinical region is contained in the posterior columns of the spinal cord?

Answer 24

Proprioception

2-pt tactile discrimination

Question 25

What important clinical structures are contained in the lateral region of the spinal cord?

Answer 25

LCST

UMN

Question 26

What important clinical structures are contained in the anterior (ventral) region of the spinal cord?

Answer 26

LMN

Question 27

What important clinical structures are contained in the anterolateral region of the spinal cord?

Answer 27

LSTT

Pain and temperature pathway

Question 28

In the conscious sensory pathway where is the primary neuron located?

What kind of neuron is it?

Where does it terminate?

Answer 28

Cell body located in a spinal ganglion

Pseudounipolar

Secondary neuron