Neuro Anatomy For Motor Speech Disorders (1)

Front 1

What are the three types of neurons?

Back 1

1-Sensory (afferent)
2-Motor (efferent)
3-Interneurons

Front 2

What are 3 major functions of sensory neurons?

Back 2

1-Conduct nerve impulses from a sensory receptor
2-Deliver sensory info to brain & spinal cord
3-Travel from periphery to more central structures

* ~ 5 million

Front 3

What are the major functions of motor neurons?

Back 3

1-Carry neural instructions from brain to muscles or glands
2-Travel from CNS to periphery

* A few hundred thousand

Front 4

What is the function of interneurons?

Back 4

Make up the neural tissues of brain & spinal cord

*most numerous: billions

Front 5

What are the 3 types of neurons making up the efferent nervous system?

Back 5

1-Upper Motor Neuron (UMN); do not directly stimulate target muscle
2-Lower Motor Neuron (LMN); bring nerve impulse to muscles
3-Interneuron - synapse between UMN & LMN

Front 6

Name the 4 functional subdivisions of the Motor System

Back 6

1-Direct activation pathway (UMN)
2-Indirect activation pathway (UMN)
3-Control circuits (UMN)
4-Final common pathway

Front 7

Name the subdivisions of the direct activation pathway

Back 7

Direction activation pathway:
1-Corticobulbar tracts (cortex to brain stem)
2-Corticospinal (cortex to spinal)

Front 8

Name the subdivisions of the Indirect activation pathway

Back 8

1-Corticorubral
2-Corticoreticular
3-Rubrospinal
4-Vestibulospinal

Front 9

What are the control circuits of the UMN pathway?

Back 9

1-Basal ganglia
2-Cerebellum

Front 10

Name the two types of nerves of the final common pathway (LMN)

Back 10

1-Cranial
2-Spinal

Front 11

What is a motor unit?

Back 11

A LMN and the muscle fibers innervated by it.

* Each axon in a nerve may innervate several muscle fibers
* Each muscle fiber may receive input from branches of several different alpha motor neurons

Front 12

What are the 2 ways by which muscle contraction can be gradiated?

Back 12

1-temporal summation: increase rate of firing
2-spatial summation: recruit a greater number of motor units

Front 13

What is the innervation ratio?

Back 13

The number of muscle fibers per axon

* greater number of muscle fibers per axon = stronger, but cruder movements
* fine discrete movements have smaller innervation ratios

Front 14

What are the two types of motor neurons?

Back 14

1-Alpha motor neurons
2-Gamma motor neurons

Front 15

What is the function of alpha motor neurons?

Back 15

1-Innervate skeletal muscle
2-innervate interneurons (Renshaw cells)

Front 16

What is the function of gamma motor neurons?

Back 16

1-Indirect activation pathway of CNS
2-Involuntary reflexes, limited to specific muscles
3-Maintenance of muscle tone
* influenced by cerebellum & basal ganglia

Front 17

What is the result of damage to a alpha motor neuron:
1-single alpha motor neuron
2-all alpha motor neurons supplying a muscle

Back 17

1-weakness or paresis
2-paralysis

Front 18

What is the result of damage to gamma motor neurons

Back 18

Muscle tone is too tight or too loose

Front 19

What is the result of loss of innervation of muscle fibers?

Back 19

1-Atrophy
2-Fasciculations (spontaneous motor unit discharges)
3-Fibrillation (slow repetitive action potentials, regular contraction - not able to be seen)

Front 20

What is the result of damage to any of the FCP's for muscles of speech?

*FCP: Final Common Pathway

Back 20

Flaccid dysartria

Front 21

What types of nerves make up the FCP for speech?

Back 21

1-Paired cranial nerves for phonation, resonance, articulation, prosody
2-Spinal nerves for respiration & prosody

Front 22

What are the supportive or glial cells?

Back 22

1-Schwann cells - myelin sheath around axons in PNS
2-Oligodendrogliocytes - myelin sheath aroun axons in CNS
3-Microglia - remove dead cells
4-Astrocytes - connective tissue of CNS
*10x more glial cells than neourons