Lecture 27: Major Neuroanatomical Pathways I

Question 1

Central pathways definition

Answer 1

Axon tracts to and from brain that carry motor commands or sensory info

Question 2

Sensory tracts definition

Answer 2

Carry info on stimuli by ascending the spinal cord to brainstem and cortex

Question 3

motor tracts definition

Answer 3

Leave cortex and descend through spinal cord carrying motor commands

Question 4

What kind of info do spinal nerves carry (4)

Answer 4

Somatic motor
Somatic sensory
Visceral sensory
Visceral motor/autonomic

Question 5

2 primary motor tracts

Answer 5

Pyramidal
Extrapyramidal

Question 6

Pyramidal motor tracts: type of movement, originating location

Answer 6

Finely adjusted movements
Originate in cortex
Aka corticospinal tract

Question 7

Extrapyramidal system/motor tracts: type of movement, originating location

Answer 7

Coarser/larger movements
Originates in brainstem
Aka rubrospinal tract

Question 8

Motor tracts are made of what kind of neurons

Answer 8

Upper motor neurons

Question 9

Upper motor neurons definition

Answer 9

Delivery motor impulses from brain through spinal cord

Question 10

Where do upper motor neurons synapse

Answer 10

On lower motor neurons

Question 11

Lower motor neurons

Answer 11

Cell bodies in ventral horn of spinal gray matter
Innervate muscle tissue

Question 12

Do upper or motor neurons contribute to reflexes

Answer 12

Lower

Question 13

Collections of axons are called

Answer 13

Tracts

Question 14

Where do pyramidal tracts begin and decussate/cross (what brain regions)

Answer 14

Motor cortex
Medulla

Question 15

within the spinal cord: Tracts will innervate lower motor neurons on (same OR opposite?) side

Answer 15

Same

Question 16

Somatic motor pathways are _______ projecting pathways

Answer 16

Caudally

Question 17

Upper motor neuron damage: definition

Answer 17

No longer synapse on Lowe motor neuron cell bodies
No initial damage to lower motor neurons (can still function for a little while)

Question 18

Lower motor neuron damage: definition

Answer 18

Lower motors neurons don’t synapse on motor endplates of muscles
Upper motor neurons not damaged

Question 19

Upper motor neuron damage: clinical signs (3)

Answer 19

Spastic paralysis – muscles may be excessively and uncontrollable contracted
Hyperreflexia – exaggerated muscle reflexes
Clonus - rapid uncontrollable rhythmic muscle contractions

Question 20

Lower motor neuron damage: clinical signs (3)

Answer 20

Flaccid paralysis – muscles soft
Hyporeflexia – lacks reflex signs
Atrophy of muscle after weeks or month

Question 21

If Large groups of muscles may be affected, such as entire limbs or an entire side of the body —> is this Lower or upper motor neuron damage?

Answer 21

Upper

Question 22

If peripheral nerve lesions are localized, is this upper or lower motor neuron damage

Answer 22

Lower