Somatic Motor System Spinal Control Of Movement

Question 0

Signal cord

Answer 0

Starting point of CNS
Motor neurons
Autonomic efferents pass through spinal cord
Receives afferent info from periphery

Question 1

Somatic nervous system

Answer 1

Voluntary
Skeletal muscle and nervous system control of them
Sensation-pain, pressure, touch, temp, proprioception

Generates behavior

Question 2

Dermatome

Answer 2

Area of skin innervated by single posterior root

Question 3

Myotome

Answer 3

A group of muscles innervated by a single anterior root

Question 4

Dorsal horn of gray matter of spinal cord

Answer 4

Contains sensory nerve fibers-pain, temp
Inter neurons and projection neurons that ASCEND to CNS
Somatic and visceral information

Question 5

Lateral horn of gray matter of spinal cord

Answer 5

Contains cell bodies of autonomic neurons

Seen only in thoracic and lumbar (T1-L3)

Question 6

Ventral horn of gray matter of spinal cord

Answer 6

Contains large cell bodies of skeletal muscle motor neurons

Anterior

Question 7

Laminae

Answer 7

“Layers” of spinal cord

Question 8

Laminae 1 and 2

Answer 8

Marginal layer
Substantia gelatinosa
Process noxious stimuli- pain

Question 9

Laminae 3 and 4

Answer 9

Nucleus proprius

Proprioception and 2-point discrimination

Question 10

Laminae 5

Answer 10

Noxious stimuli from viscera (organs)

Question 11

Laminae 6

Answer 11

Proprioceptive input

Question 12

Laminae 7

Answer 12

Nucleus dorsalis
Receives proprioceptive input
Relays unconscious proprioceptive information to cerebellum

Question 13

Laminae 8

Answer 13

Comissural nucleus

Connect contralateral cord to the brain

Question 14

Laminae 9

Answer 14

Motor nuclei

Contains cell bodies of lower motor neurons

Question 15

Laminae 10

Answer 15

Grisea centralis

Axons that cross the cord to opposite side

Question 16

Spinal cord white matter

Answer 16

Contains columns of axons
Ascending tracts (afferent)- sensory info to brain
Descending tracts (efferent)- motor signals from brain to body

Question 17

Lower motor neurons

Answer 17

Directly commands muscle contraction
Originate in ventral horn of spinal cord
Part of PNS
Includes cranial nerves, spinal nerves, cauda equina, and ventral horn

Question 18

Distribution of LMNs in spinal cord

Answer 18

Axial muscle LMNs- medial

Distal muscle LMNs- lateral

Question 19

Alpha motor neurons

Answer 19

Trigger generation of force

Innervate extrafusal fibers

Question 20

Gamma motor fibers

Answer 20

Regulate sensitivity of muscle to stretch

Innervate intrafusal fibers

Question 21

Motor unit

Answer 21

Recruited in order from smallest to largest

The alpha motor neuron and all muscle fibers it innervates

Question 22

Motor neuron pool

Answer 22

Alpha motor neurons that innervate a single muscle

Question 23

Grading muscle contractions

Answer 23

Determine the correct amount of force needed to complete an activity
CNS varies firing rate and recruitment
Alpha motor neuron releases acetylcholine
Causes excitatory postsynaptic potential

Question 24

Fast motor units

Answer 24

Rapid fatigue Escape muscles Ex. Jumping UE

Question 25

Slow motor units

Answer 25

Slow fatigue | Antigravity muscles of LE

Question 26

Reflexes

Answer 26

Involuntary, stereotypical response to sensory input | Typically involves one or more inter neurons

Question 27

Myotatic (stretch) reflexes

Answer 27

Mono synaptic | Biceps, brachioradialis, triceps, quadriceps, Achilles

Question 28

Abnormal reflexes

Answer 28

Diminished reflexes- abnormalities in muscles, sensory neurons, LMNs, neuromuscular junction Increased relfexes- UMN lesions

Question 29

Reverse myotatic reflexes

Answer 29

Regulates muscle tension in normal range

Question 30

Spinal inter neurons

Answer 30

Reduces the amount of information

Question 31

Reciprocal inhibition

Answer 31

Contraction of agonist with simultaneous relaxation of antagonist Helps us protect the joint-con/eccentric

Question 32

Withdrawal reflexes

Answer 32

Interneurons are excitatory Slower response than myotatic Combines with crossed extensor reflex to keep balance Ex. Hopping off a tack

Question 33

Ascending tracts | UMNs

Answer 33

Somatosensory