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Somatic Motor System Flashcards

0
Q

What is a myotome?

A

Group of muscles innervated by a single anterior root

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1
Q

What is a dermatome?

A

Area of skin innervated by a single posterior root

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2
Q

Myotome for elbow flexion?

A

Musculocutaneous nerve. Segment C5.

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3
Q

Myotome for wrist extension?

A

Radial nerve. Segment C6

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4
Q

Myotome for elbow extension?

A

Radial nerve. Segment C7

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5
Q

Myotome for finger flexion?

A

Median, Ulnar nerves. Segment C8

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6
Q

Myotome for finger abduction?

A

Median, Ulnar nerve. Segment T1

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7
Q

Myotome for hip flexion?

A

Femoral nerve (iliopsoas). Segment L2

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8
Q

Myotome for knee extension?

A

Femoral nerve (quadriceps). Segment L3

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9
Q

Myotome for dorsiflexion?

A

Peroneal nerve. Segment L4

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10
Q

Myotome for great toe extension?

A

Peroneal nerve. Segment L5

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11
Q

Myotome for plantarflexion?

A

Tibial nerve. Segment S1

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12
Q

What part of the spinal cord are there lateral horns? What is the significance?

A

Lateral horns are located in the thoracic spine due to the presence of the autonomic nervous system.

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13
Q

Cervical enlargement segments? Lumbosacral enlargement segments?

A

Cervical enlargement found C3-T1.

Lumbosacral enlargement found L1-S2.

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14
Q

Spinal cord gray matter includes what kind of neurons? Dorsal horn? Lateral horn? Ventral horn?

A

Dorsal horn - contains sensory nerve fibers
Lateral horn - contains autonomic nerve fibers
Ventral horn - contains motor nerve fibers

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15
Q

Dorsal horn info?

A

Interneurons and projection neurons that ascend to CNS. Relay pain, temperature, visceral and sensory information.

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16
Q

Lateral horn info?

A

Contains cell bodies of preganglionic sympathetic neurons.

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17
Q

Ventral horn info?

A

Large cell bodies (LMNs) of skeletal muscle motor neurons

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18
Q

Laminae I and II are for?

A

Processing noxious stimuli

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19
Q

Laminae III and IV are for?

A

Proprioception and 2 point discrimination (Being able to identify two different points of contact on a given body part)

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20
Q

Lamina V is for?

A

Noxious stimuli from viscera

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21
Q

Lamina VI is for?

A

Proprioceptive input

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22
Q

Lamina VII is for?

A

Receiving proprioceptive input and relays unconscious proprioceptive information to cerebellum

23
Q

Lamina VIII is for?

A

Connecting the contralateral cord to the brain

24
Lamina IX is for?
Motor nuclei. Contain cell bodies of LMNs
25
Lamina X is for?
Axons crossing to the other side of the spinal cord
26
UMN vs LMN?
UMN originates in the cortex and synapses with LMN in the spinal cord.
27
LMN function?
Directly command muscle contraction. Originate in the ventral horns. Are apart of the Peripheral Nervous System (PNS)
28
Distribution of LMNs in spinal cord?
Axial muscle LMNs medial ventral horn. | Distal muscle LMNs lateral ventral horn.
29
Alpha and gamma motor neurons do what?
Alpha: trigger generation of force Gamma: regulate sensitivity of muscle to stretch
30
Alpha motor neurons receive input from 3 sources?
1) dorsal root ganglion 2) upper motor neurons 3) spinal cord interneurons
31
What is a motor neuron pool?
Group of alpha motor neurons that innervate a single muscle
32
Graded muscle control is what?
Helps determine the correct amount of force necessary to complete an activity. - the CNS varies the firing rate of muscular contractions - alpha motor neuron release acetylcholine at neuromuscular junction and causes excitatory post synaptic potential - rapid succession of action potentials can create desired strength of contraction
33
Fast motor units are?
Rapid fatigue white. Escaping muscles; jumping; UE
34
Slow motor units are?
Slow fatigue red. Antigravity muscles of LE
35
Excitation contraction coupling?
- alpha motor neurons release ACh - ACh produces large EPSP in muscle fiber - EPSP evokes muscle action potential - action potential triggers calcium release - fiber contracts - calcium reuptake - fiber relaxes
36
Gamma motor neurons are?
Innervate intrafusal fibers contained in a muscle spindle
37
Reflexes?
Involuntary, stereotypical response to sensory input and typically involve one or more interneurons
38
Myotatic (stretch) reflexes are?
Monosynaptic. - biceps (C5-C6) - brachioradialis (C6) - triceps (C7) - quadriceps (L3-4) - Achilles (S1-2)
39
Diminished reflexes are?
Typically a result of abnormalities in muscles, sensory neurons, LMNs, and/or neuromuscular junction
40
Increased reflexes are?
Typically result of UMN lesions
41
Spinal interneuron functions?
All actions of Golgi tendon and alpha motor neurons are mediated by interneurons. Reciprocal inhibition is simultaneous contraction of the agonist and relaxation of the antagonist.
42
Withdrawal reflexes are?
Interneurons are excitatory and produce slower responses than myotatic reflexes. Combined with crossed extensor reflex to keep balance
43
Descending tracts lateral and medial?
Lateral: Corticospinal and rubrospinal Medial: reticulospinal, vestibulospinal and tectospinal
44
Lateral corticospinal tract does what?
Fine control of distal extremities and coarse regulation of proximal flexors (contralateral) Allows fractionation of movement. Longest/largest tract in cord. Ex: tie knots, play keys on a piano, pick up small objects
45
Anterior corticospinal tract does what?
Synapse in the cervical and thoracic regions only. Conveys info to LMNs that control neck, shoulder, and trunk muscles. Originates in the motor cortex of frontal lobe and somatosensory area of parietal lobe
46
Rubrospinal tract does what?
Movement of contralateral limbs (function uncertain in humans) Axons decussate in the pons and join with axons of corticospinal tract in lateral column of spinal cord.
47
Corticospinal and rubrospinal tract impairments cause?
Poor fractionated movements of the arms and hands (use all fingers at once) Voluntary movements slower (less accurate) Baseball pitcher analogy - can stand on mound but cannot throw accurately
48
Reticulospinal tract does what?
Pontine tract: Facilitates extensor motor neurons, enhances antigravity reflexes, helps maintain standing posture. Medullary tract: Facilitates flexor motor neurons, liberates antigravity muscles from reflex control
49
Vestibulospinal tract does what?
Responds to stimuli from the vestibular apparatus. Medial tract: controls neck and upper back muscles for positioning. Lateral tract: facilitates extensors and inhibits flexors for balance Impairment would lead to ataxia and balance problems
50
Tectospinal tract does what?
Receives direct input from the retina and projections from the visual cortex. Directs head movements toward novel visual and auditory stimuli
51
Central cord syndrome. What tracts are involved? What kind of symptoms?
Tracts involved: corticospinal and spinothalamic Symptoms: Falls, UE and LE weakness, sensory loss of pain, temperature, light tough, and position below the level of the lesion
52
Anterior cord syndrome. What tracts are involved? What symptoms?
Tracts: ascending spinothalamic Symptoms: pain and temperature sensation altered and motor control will be impaired
53
Brown-Sequard syndrome. Symptoms?
Ipsilateral voluntary motor control, conscious proprioception, discriminative touch, contralateral pain and temperature below the level of the lesion (Effects one either the right or left side of the spinal cord)
54
Posterior cord syndrome symptoms?
Loss of proprioception, variable loss of motor function, pain, and temperature

Neuroscience (4 decks)

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